JP5584108B2 - Coating composition with excellent corrosion resistance - Google Patents

Description

The present invention relates to a non-chromium coating composition having excellent corrosion resistance and a coated metal plate using the same, and more specifically, a coating composition effective for improving the corrosion resistance of a plated steel sheet mainly composed of aluminum and the same. It relates to the coated metal plate used.

Conventionally, coating-formed galvanized steel sheets such as pre-coated steel sheets painted by coil coating, etc. are used for building materials such as roofs, walls, shutters, garages, various household appliances, switchboards, frozen showcases, steel furniture, Widely used as housing-related products such as kitchen appliances.
In order to manufacture these housing-related products from a film-formed galvanized steel sheet, the film-formed galvanized steel sheet such as a pre-coated steel sheet is usually cut, press-molded and joined. Therefore, these house-related products often have a metal exposed portion that is a cut surface and a crack generating portion due to press working. The exposed metal parts and cracking parts are likely to have lower corrosion resistance than other parts. Therefore, in order to improve corrosion resistance, chrome-based rust preventive pigments should be included in the undercoat film of the galvanized steel sheet. However, chromium-based anti-corrosion pigments contain or produce hexavalent chromium with excellent anti-rust properties, and this hexavalent chromium is good for human health and environmental protection. It is a problem from the point of view.
Until now, various materials have been proposed as a metal material having good corrosion resistance in which a coating composition in which a non-chromium pigment is combined and a coating film coated with the coating composition is formed.
For example, Patent Document 1 discloses a paint composition in which a predetermined amount of a specific vanadium compound, a specific metal silicate, and a specific hydrogen phosphate metal salt are blended as a rust preventive pigment in a hydroxyl group-containing film-forming resin system. Is described.
Patent Document 2 discloses a rust preventive coating composition in which a specific amount of a specific vanadium compound, a specific silicon-containing material, and a phosphate calcium salt are blended as a rust preventive pigment in a hydroxyl group-containing film-forming resin system. A coating-forming metal material in which a rust-proof coating film is formed on both front and back surfaces of a metal material is described.
However, the metal material on which the coating film by the coating composition described in Patent Documents 1 and 2 is formed has generally good corrosion resistance, but the metal material is a plated steel sheet mainly composed of aluminum. In this case, the corrosion resistance is insufficient as compared with a metal material on which a coating film is formed by a coating composition using a chromium pigment, and there is a problem that the corrosion resistance is particularly insufficient in the processed part and the end face part.

JP 2008-291160 A JP 2000-266444 A

  The object of the present invention is not only the corrosion resistance of general parts in coated metal plates, but also excellent corrosion resistance of processed parts and end face parts in the process of coating deterioration due to photolysis and hydrolysis in an outdoor environment. It is to provide a non-chromium paint composition capable of forming a coated film, particularly a non-chromium paint composition effective for improving the corrosion resistance of a plated steel sheet mainly composed of aluminum, and a coated metal plate using the same.

As a result of diligent research to solve the above-mentioned problems, the present inventors have found that a specific vanadium compound, a specific phosphate metal salt, and a metal silicate as a rust preventive pigment in a hydroxyl group-containing film-forming resin system A coating composition containing a predetermined amount of salt, not only for the corrosion resistance of flat surfaces, but also for coatings with excellent corrosion resistance at the processed and end surfaces of painted metal plates, etc., especially in plated steel sheets mainly composed of aluminum. As a result, the present invention was completed.
That is, the present invention
(A) A coating composition containing a hydroxyl group-containing coating film-forming resin, (B) a crosslinking agent, and (C) a rust preventive pigment mixture, wherein the rust preventive pigment mixture (C) is:
(1) at least one vanadium compound of vanadium pentoxide, calcium vanadate and ammonium metavanadate,
(2) a phosphoric acid metal salt which is at least one salt of phosphoric acid, phosphorous acid, and tripolyphosphoric acid, containing at least one of cobalt and nickel;
(3) It consists of a metal silicate salt that is at least one of a cobalt salt, a nickel salt and a calcium salt,
Based on the total solid content of the resin (A) and the crosslinking agent (B)
The amount of the vanadium compound (1) is 3 to 50% by mass,
The amount of the phosphate metal salt (2) is 1 to 50% by mass, and
The amount of the metal silicate (3) is 1 to 50% by mass
And the amount of this antirust pigment mixture (C) is 10-150 mass%, and provides the coating composition characterized by the above-mentioned.
Moreover, this invention provides the coating metal plate by which the cured coating film based on the said coating composition is formed on the metal plate in which the chemical conversion treatment may be performed on the surface.
Furthermore, this invention provides the coating metal plate by which the cured coating film based on the said coating composition is formed on the plated steel plate which has aluminum as a main component.

  The coating composition of the present invention does not contain a chromium-based rust preventive pigment and is a coating composition that is advantageous in terms of environmental hygiene. By the coating composition of the present invention, not only is the corrosion resistance of the flat part improved, It is possible to form a coating film with excellent corrosion resistance on the processed parts and end faces of coated metal plates, etc., which was difficult to achieve with non-chromium anticorrosive coatings, especially with coated steel sheets mainly composed of aluminum. The effect is demonstrated.

  The coated metal plate on which the cured coating film based on the coating composition of the present invention is formed has excellent corrosion resistance at the flat portion, processed portion and end face portion, and uses a conventional chromate rust preventive pigment such as strontium chromate. It has a corrosion resistance equal to or higher than that of a coated metal plate on which a cured coating film based on a paint is formed.

  The coated metal plate formed with the cured coating film based on the coating composition of the present invention is excellent in the corrosion resistance of the flat portion, the processed portion and the end face portion. When a galvanized steel sheet or an aluminum-zinc alloy plated steel sheet is used as a metal plate to be coated, particularly when used for a plated steel sheet containing aluminum as a main component, a plane is obtained by applying the coating composition of the present invention. Excellent corrosion resistance can be obtained not only at the part but also at the end face part and the processed part.

The coating composition of the present invention (hereinafter sometimes referred to as “the present coating”) is a coating composition containing the following hydroxyl group-containing film-forming resin (A), crosslinking agent (B), and antirust pigment mixture (C). It is a thing.
Hydroxyl-containing film-forming resin (A)
The hydroxyl group-containing coating film-forming resin in the coating composition of the present invention can be used without particular limitation as long as it is a hydroxyl group-containing resin having a coating film-forming ability that can be usually used in the paint field. , Polyester resin, epoxy resin, acrylic resin, fluororesin, vinyl chloride resin and the like can be used. As the film-forming resin, among them, at least one organic resin selected from a hydroxyl group-containing polyester resin and an epoxy resin can be preferably used.
Examples of the hydroxyl group-containing polyester resin include oil-free polyester resins, oil-modified alkyd resins, and modified products of these resins such as urethane-modified polyester resins, urethane-modified alkyd resins, epoxy-modified polyester resins, and acrylic-modified polyester resins. Is done. The hydroxyl group-containing polyester resin has a number average molecular weight of 1500 to 35000, preferably 2000 to 25000, a glass transition temperature (Tg point) of 10 to 100 ° C., preferably 20 to 80 ° C., and a hydroxyl value of 2 to 100 mgKOH / g, preferably Those having 5 to 80 mg KOH / g are preferred.
In the present specification, the “number average molecular weight” of the resin is a value calculated based on the molecular weight of standard polystyrene from a chromatogram measured by gel permeation chromatograph (“HLC8120GPC” manufactured by Tosoh Corporation). The column used was “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL”, “TSKgel G-2000HXL” (both manufactured by Tosoh Corporation, trade name), and moved. Phase: Tetrahydrofuran, Measurement temperature: 40 ° C., Flow rate: 1 cc / min, Detector: Under the conditions of RI. Moreover, in this specification, the glass transition temperature (Tg) of resin is based on a differential thermal analysis (DSC).

The oil-free polyester resin is an esterified product of a polybasic acid component and a polyhydric alcohol component. Examples of the polybasic acid component include one or more selected from phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, succinic acid, fumaric acid, adipic acid, sebacic acid, maleic anhydride, and the like. Dibasic acids and lower alkyl esterified products of these acids are mainly used, and if necessary, monobasic acids such as benzoic acid, crotonic acid, pt-butylbenzoic acid, trimellitic anhydride, methylcyclohexentricarboxylic acid , Tribasic or higher polybasic acids such as pyromellitic anhydride are used in combination.
Examples of the polyhydric alcohol component include bivalent compounds such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 3-methylpentanediol, 1,4-hexanediol, and 1,6-hexanediol. Alcohol is mainly used, and a trihydric or higher polyhydric alcohol such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol can be used in combination as necessary. These polyhydric alcohols can be used alone or in admixture of two or more. The esterification or transesterification reaction of both components can be carried out by a method known per se.
In addition to the acid component and alcohol component of the oil-free polyester resin, the alkyd resin is obtained by reacting an oil fatty acid by a method known per se. Examples of the oil fatty acid include coconut oil fatty acid, soybean oil fatty acid, Examples thereof include linseed oil fatty acid, safflower oil fatty acid, tall oil fatty acid, dehydrated castor oil fatty acid, and kiri oil fatty acid. The oil length of the alkyd resin is preferably 30% or less, particularly about 5 to 20%.

As the urethane-modified polyester resin, the oil-free polyester resin or the low-molecular weight oil-free polyester resin obtained by reacting an acid component and an alcohol component used in the production of the oil-free polyester resin, a polyisocyanate compound and Examples thereof include those reacted by a method known per se. The urethane-modified alkyd resin is obtained by reacting the alkyd resin or a low molecular weight alkyd resin obtained by reacting each component used in the production of the alkyd resin with a polyisocyanate compound by a method known per se. Things are included. Polyisocyanate compounds that can be used in the production of urethane-modified polyester resins and urethane-modified alkyd resins include hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4 ′. -Methylenebis (cyclohexyl isocyanate), 2,4,6-triisocyanatotoluene and the like. In general, as the urethane-modified resin, those having a modification degree such that the amount of the polyisocyanate compound forming the urethane-modified resin is 30% by mass or less with respect to the urethane-modified resin can be preferably used.
As an epoxy-modified polyester resin, a polyester resin produced from each component used in the production of the polyester resin is used, a reaction product of a carboxyl group of the resin and an epoxy group-containing resin, a hydroxyl group in the polyester resin and an epoxy resin. The reaction product by reaction, such as addition of a polyester resin and an epoxy resin, condensation, grafting, etc., such as the product which couple | bonded the hydroxyl group in it through the polyisocyanate compound, can be mentioned. In general, the degree of modification in the epoxy-modified polyester resin is preferably such that the amount of the epoxy resin is 0.1 to 30% by mass with respect to the epoxy-modified polyester resin.

As the acrylic-modified polyester resin, a polyester resin produced from each component used in the production of the polyester resin is used, and a group having reactivity with these groups on the carboxyl group or hydroxyl group of the resin, for example, carboxyl group, hydroxyl group or epoxy. Reaction products obtained by graft polymerization of a (meth) acrylic acid or (meth) acrylic acid ester to a polyester resin using a peroxide polymerization initiator are listed. be able to. In general, the degree of modification in the acrylic-modified polyester resin is preferably such that the amount of the acrylic resin is 0.1 to 50% by mass with respect to the acrylic-modified polyester resin.
Of the polyester resins described above, among them, oil-free polyester resins and epoxy-modified polyester resins are preferable from the viewpoint of balance such as processability and corrosion resistance.
Examples of the epoxy resin suitable as the hydroxyl group-containing coating film-forming resin include bisphenol-type epoxy resins, novolac-type epoxy resins; and modified epoxy resins in which various modifiers are reacted with epoxy groups or hydroxyl groups in these epoxy resins. Can do. In the production of the modified epoxy resin, the modification time with the modifier is not particularly limited, and it may be modified in the middle of the epoxy resin production or in the final stage of the epoxy resin production.
The bisphenol-type epoxy resin is, for example, a resin obtained by condensing epichlorohydrin and bisphenol to a high molecular weight in the presence of a catalyst such as an alkali catalyst, if necessary, epichlorohydrin and bisphenol, and if necessary, an alkali catalyst or the like. Any of resins obtained by condensing into a low molecular weight epoxy resin in the presence of a catalyst and polyaddition reaction of the low molecular weight epoxy resin and bisphenol may be used.
Examples of the bisphenol include bis (4-hydroxyphenyl) methane [bisphenol F], 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane [bisphenol A], 2, 2-bis (4-hydroxyphenyl) butane [bisphenol B], bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-tert-butyl-phenyl) -2,2-propane, p- (4-hydroxyphenyl) phenol, oxybis (4-hydroxyphenyl), sulfonylbis (4-hydroxyphenyl), 4,4′-dihydroxybenzophenone, bis (2-hydroxynaphthyl) methane and the like can be mentioned among others. Bisphenol A and bisphenol F are preferably used . The bisphenols can be used alone or as a mixture of two or more.
As commercial products of bisphenol type epoxy resins, for example, Epicoat 828, 812, 815, 820, 834, 1001, 1004, 1007, 1009, 1010 manufactured by Japan Epoxy Resin; Asahi Ciba Examples include Araldite AER6099 manufactured by the company, and Epomic R-309 manufactured by Mitsui Chemicals.

  Examples of the novolac type epoxy resin which is an epoxy resin suitable as a hydroxyl group-containing coating film-forming resin include, for example, phenol novolac type epoxy resins, cresol novolac type epoxy resins, and phenol glyoxal type epoxy having a large number of epoxy groups in the molecule. Various novolak-type epoxy resins such as resins can be mentioned.

  Examples of the modified epoxy resin include an epoxy ester resin obtained by reacting, for example, a dry oil fatty acid with the bisphenol type epoxy resin or the novolac type epoxy resin; and a polymerizable unsaturated monomer component containing acrylic acid or methacrylic acid. Epoxy acrylate resin; Urethane-modified epoxy resin reacted with isocyanate compound; Amino group or quaternary by reacting amine compound with epoxy group in bisphenol type epoxy resin, novolac type epoxy resin or various modified epoxy resins An amine-modified epoxy resin obtained by introducing an ammonium salt can be used.

Cross-linking agent (B)
The crosslinking agent (B) reacts with the hydroxyl group-containing coating film-forming resin (A) to form a cured coating film, and reacts with the hydroxyl group-containing coating film-forming resin (A) by heating or the like. As long as it can be cured, it can be used without particular limitation. Among them, amino resins, phenol resins and polyisocyanate compounds which may be blocked are suitable. These crosslinking agents can be used alone or in combination of two or more.

  Examples of the amino resin include methylolated amino resins obtained by reacting an amino component such as melamine, urea, benzoguanamine, acetogranamamine, steroguanamine, spiroguanamine, and dicyandiamide with an aldehyde. Examples of the aldehyde used in the reaction include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde. Moreover, what etherified the said methylolated amino resin with suitable alcohol can also be used as an amino resin. Examples of alcohols used for etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-ethylbutanol, 2-ethylhexanol and the like.

  The phenol resin that can be used as the cross-linking agent is one that undergoes a cross-linking reaction with the hydroxyl group-containing coating film-forming resin (A), and a phenol component and formaldehyde are heated in the presence of a catalyst to undergo a condensation reaction to form a methylol group. A resol type phenol resin obtained by alkyl etherifying a part or all of the methylol group of a methylolated phenol resin obtained by introducing an alcohol with alcohol.

  In the production of a resol-type phenol resin, a bifunctional phenol compound, a trifunctional phenol compound, a tetrafunctional or higher functional phenol compound, or the like can be used as the phenol component as a starting material.

  Examples of the phenol compound include, for example, bifunctional phenol compounds such as o-cresol, p-cresol, p-tert-butylphenol, p-ethylphenol, 2,3-xylenol, and 2,5-xylenol. Examples of the trifunctional phenol compound include carboxylic acid, m-cresol, m-ethylphenol, 3,5-xylenol, and m-methoxyphenol. Examples of the tetrafunctional phenol compound include bisphenol A and bisphenol F. Can be mentioned. Among these, from the viewpoint of improving scratch resistance, it is preferable to use a trifunctional or higher functional phenol compound, in particular, carboxylic acid and / or m-cresol. These phenol compounds can be used alone or in combination of two or more.

Examples of formaldehydes used in the production of the phenol resin include formaldehyde, paraformaldehyde, trioxane and the like, and they can be used alone or in combination of two or more.
As the alcohol used for alkyl etherifying a part of the methylol group of the methylolated phenol resin, a monohydric alcohol having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, can be suitably used. Suitable monohydric alcohols include methanol, ethanol, n-propanol, n-butanol, isobutanol and the like.

  The phenol resin has an average of 0.5 or more, preferably 0.6 to 3.0 alkoxymethyl groups per benzene nucleus from the viewpoint of reactivity with the hydroxyl group-containing film-forming resin (A). What you have is suitable.

Examples of the non-blocked polyisocyanate compound that can be used as the crosslinking agent as the crosslinking agent include aliphatic diisocyanates such as hexamethylene diisocyanate or trimethylhexamethylene diisocyanate; hydrogenated xylylene diisocyanate Or cycloaliphatic diisocyanates such as isophorone diisocyanate; organic diisocyanates per se such as tolylene diisocyanate, xylylene diisocyanate or 4,4′-diphenylmethane diisocyanate, aromatic diisocyanates such as crude MDI, or each of these organic diisocyanates Adducts with polyhydric alcohols, low molecular weight polyester resins or water, or as described above Examples thereof include cyclized polymers of organic diisocyanates, and isocyanate / biuret bodies.
The blocked polyisocyanate compound is obtained by blocking free isocyanate groups of the polyisocyanate compound with a blocking agent. Examples of the blocking agent include phenols such as phenol, cresol and xylenol; ε-caprolactam; lactones such as δ-valerolactam and γ-butyrolactam; methanol, ethanol, n-, i- or t-butyl alcohol, ethylene Alcohols such as glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and benzyl alcohol; oximes such as formamidoxime, acetaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexane oxime System: Active methylene such as dimethyl malonate, diethyl malonate, ethyl acetoacetate, acetylacetone It can be suitably used blocking agent, such as. By mixing the polyisocyanate compound and the blocking agent, free isocyanate groups of the polyisocyanate compound can be easily blocked.

  The mixing ratio of the hydroxyl group-containing coating film-forming resin (A) and the crosslinking agent (B) is based on the total solid content of 100 parts by mass of the components (A) and (B), and the hydroxyl group-containing coating film-forming resin. (A) is 55 to 95 parts by mass, more preferably 60 to 95 parts by mass, and the crosslinking agent (B) is in the range of 5 to 45 parts by mass, and further 5 to 40 parts by mass. It is suitable in terms of boiling water, processability, curability and the like.

A curing catalyst can be blended as necessary to improve the curability of the paint. When the crosslinking agent (B) contains an amino resin, particularly a low molecular weight, methyl etherified or mixed etherified melamine resin of methyl ether and butyl ether, sulfonic acid compound or amine neutralization of sulfonic acid compound as a curing catalyst A thing is used suitably. 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 the stability of the coating, the reaction promoting effect, and the physical properties of the obtained coating film. .
When the crosslinking agent (B) is a phenol resin, the sulfonic acid compound or an amine neutralized product of the sulfonic acid compound is suitably used as the curing catalyst.

  When the crosslinking agent (B) is a blocked polyisocyanate compound, a curing catalyst that promotes dissociation of the blocking agent is suitable. Examples of suitable curing catalysts include tin octylate and dibutyltin di (2-ethyl). Hexanoates), dioctyltin di (2-ethylhexanoate), dioctyltin diacetate, dibutyltin dilaurate, dibutyltin oxide, dioctyltin oxide, and organometallic catalysts such as lead 2-ethylhexanoate. it can.

  When the crosslinking agent (B) is a combination of two or more kinds of crosslinking agents, an effective curing catalyst can be used in combination with each crosslinking agent.

Antirust pigment mixture (C)
In the coating composition of the present invention, the rust preventive pigment mixture (C) is composed of the following vanadium compound (1), phosphate metal salt (2) and silicate metal salt (3).

Vanadium compound (1)
The vanadium compound (1) is at least one vanadium compound selected from vanadium pentoxide, calcium vanadate, and ammonium metavanadate. Vanadium pentoxide, calcium vanadate and ammonium metavanadate are excellent in elution of pentavalent vanadium ions into water, and the pentavalent vanadium ions released from the vanadium compound (1) react with the material metal, It works effectively to improve corrosion resistance by reacting with ions from other antirust pigment mixtures.
Phosphate metal salts (2)
The phosphoric acid metal salt (2) is at least one metal salt selected from a metal phosphate, a metal hydrogen phosphate, a metal phosphite, and a metal metal tripolyphosphate. The phosphate metal salt (2) is a phosphate metal salt in which the metal salt contains at least one of cobalt and nickel, or the metal salt is at least one of cobalt and nickel. It is a phosphate metal salt surface-treated with an oxide of a seed metal.

  Examples of the phosphate metal salt (2) include cobalt orthophosphate, cobalt phosphite, cobalt pyrophosphate, cobalt ammonium phosphate, cobalt phosphate / calcium eutectoid, nickel orthophosphate, nickel metaphosphate, phosphorus phosphite Examples include nickel oxide, cobalt hydrogen phosphate, nickel hydrogen phosphate, and aluminum trihydrogen phosphate treated with cobalt oxide, calcium phosphate treated with nickel oxide, and the like.

Cobalt, nickel metal ions, and phosphate ions released from the phosphate metal salt (2) effectively work to improve corrosion resistance.
Silicate metal salt (3)
The silicate metal salt (3) is a salt composed of silicon dioxide and a metal oxide, and may be any of orthosilicate, polysilicate, and the like. The metal salt of the silicate metal salt (3) is at least one of a cobalt salt, a nickel salt, and a calcium salt.
Examples of the metal silicate (3) include calcium silicate, aluminum silicate / calcium eutectoid, calcium orthosilicate, calcium metasilicate, calcium silicate / sodium eutectoid, magnesium silicate / calcium eutectoid , Cobalt orthosilicate, cobalt metasilicate, nickel orthosilicate, nickel metasilicate, and the like.
As the metal silicate (3), among them, calcium silicate, calcium orthosilicate, and calcium metasilicate can be preferably used.
In the coating composition of the present invention, with respect to the total solid content of the resin (A) and the crosslinking agent (B), the rust preventive pigment mixture (C) contains the vanadium compound (1), a phosphoric acid metal salt ( From the viewpoint of corrosion resistance, 2) and the metal silicate salt (3) are within the following range, and the amount of the rust preventive pigment mixture (C) is 10 to 150% by mass, preferably 15 to 90% by mass. Is preferred.

Vanadium compound (1): 3 to 50% by mass, preferably 5 to 40% by mass,
Phosphate metal salt (2): 1 to 50% by mass, preferably 2 to 30% by mass,
Silicate metal salt (3): 1 to 50% by mass, preferably 2 to 30% by mass.

  In the coating composition of the present invention, the corrosion resistance can be synergistically improved by combining a predetermined amount of these (1), (2) and (3) as the anticorrosive pigment mixture (C). is there.

  Moreover, the vanadium compound (1) which comprises the antirust pigment mixture (C) mix | blended with respect to 100 mass parts of total solids of the said resin (A) and a crosslinking agent (B), phosphoric acid type metal salt (2) And a mixture of each part by weight of each pigment of the silicate metal salt (3) was added to 10000 parts by weight of a 5% by weight sodium chloride aqueous solution at 25 ° C., stirred for 6 hours, and allowed to stand at 25 ° C. for 48 hours. The solubility of the vanadium compound (1), the phosphate metal salt (2) and the silicate metal salt (3) due to moisture is such that the pH of the filtrate obtained by filtering the supernatant is 3 to 9, preferably 5 to 8. And it is suitable from the viewpoint of the reactivity between the solution of the anticorrosive pigment and the metal plate, and being in this range is more preferred from the viewpoint of corrosion resistance.

That is, the filtrate for measuring pH is phosphoric acid in any amount within the range of 3 to 50 parts by mass of the vanadium compound (1) with respect to 10000 parts by mass of a 5 mass% sodium chloride aqueous solution at 25 ° C. The amount of the metal salt (2) in the range of 1 to 50 parts by mass and the amount of the silicate metal salt (3) in the range of 1 to 50 parts by mass added and dissolved The filtrate.
In addition to the hydroxyl group-containing film-forming resin (A), the crosslinking agent (B), the rust preventive pigment mixture (C), and a curing catalyst blended as necessary, the paint composition of the present invention includes a rust preventive pigment. Rust preventive pigments other than the rust preventive pigments used in the mixture (C), colored pigments that can be used in the paint field, extender pigments, UV absorbers, UV stabilizers, organic solvents; anti-settling agents, antifoaming agents, coating surface adjustment An additive such as an agent can be blended as necessary.
Examples of the rust preventive pigment other than the rust preventive pigment used in the rust preventive pigment mixture (C) include a phosphate metal salt other than the phosphate metal salt (2) and a silica other than the silicate metal salt (3). Examples thereof include acid metal salts, silica fine particles, zinc molybdate, a fired product of manganese oxide and vanadium oxide, and a fired product of calcium phosphate and vanadium oxide. These rust preventive pigments can be used alone or in combination of two or more.
The phosphate metal salt other than the phosphate metal salt (2) is a phosphate metal salt which is a metal salt other than the cobalt salt and the nickel salt.
Specifically, for example, calcium phosphate, calcium phosphate / ammonium eutectoid, calcium monohydrogen phosphate, calcium dihydrogen phosphate, calcium phosphate phosphate, zinc phosphate, aluminum phosphate, magnesium phosphate, secondary phosphorus Magnesium phosphate, zinc hydrogen phosphate, aluminum phosphate, magnesium phosphate, aluminum hydrogen phosphate, magnesium hydrogen phosphate, magnesium phosphate / ammonium eutectoid; metal element such as aluminum tripolyphosphate, aluminum trihydrogen phosphate And metal tripolyphosphates such as aluminum, zinc or calcium.
The silicate metal salt other than the silicate metal salt (3) is a silicate metal salt which is a metal salt other than a cobalt salt, a nickel salt and a calcium salt.
Specifically, for example, zinc silicate, aluminum silicate, aluminum orthosilicate, hydrated aluminum silicate, aluminum silicate / sodium eutectoid, aluminum silicate / beryllium eutectoid, sodium silicate, zirconium silicate , Magnesium orthosilicate, Magnesium metasilicate, Manganese silicate, Barium silicate, Olivine, Pomegranate, Tortobitite, Oysterite, Benitoite, Neptunite, Ryokuchuite, Kamakai stone, Baraki stone, Tosenite, Zonotra Stones, talc, gyoganite, aluminosilicates, borosilicates, beryllosilicates, cholite, fluorite and the like can be mentioned.

  The silica fine particles can be used without particular limitation as long as they are silica fine particles, and examples thereof include silica fine powder having an untreated surface, silica fine powder having a surface treated with an organic material, and organic solvent-dispersible colloidal silica. .

Examples of the silica fine particles whose surface is not treated or treated with an organic substance include silica fine powder having an average particle size of 0.5 to 15 μm, preferably 1 to 10 μm, and organic solvent-dispersible colloidal silica. As the fine silica powder, those having an oil absorption of 30 to 350 ml / 100 g, preferably 30 to 150 ml / 100 g can be suitably used, and as commercially available products, silicia 710, silicia 740, silicia 550, Examples include Aerosil R972 (all of which are manufactured by Fuji Silysia Chemical Co., Ltd.), Mizukacil P-73 (manufactured by Mizusawa Chemical Co., Ltd.), Gasil 200DF (manufactured by Crossfield).
The organic solvent-dispersible colloidal silica is also called an organosilica sol, in which silica fine particles having a particle size of about 5 to 120 nm are stably dispersed in an organic solvent such as alcohols, glycols, and ethers. Examples of commercially available products include the OSCAL series (manufactured by JGC Catalysts & Chemicals Co., Ltd.), organosol (manufactured by Nissan Chemical Co., Ltd.), and the like.
Furthermore, examples of the silica fine particles include metal ion exchanged silica using various metal ions such as calcium, magnesium, cobalt, and nickel.

  Examples of the coloring pigment include organic coloring pigments such as cyanine blue, cyanine green, organic red pigments such as azo and quinacridone; and inorganic coloring pigments such as titanium white, titanium yellow, bengara, carbon black, and various fired pigments. Among them, titanium white can be preferably used.

Examples of the extender pigment include talc, clay, silica, mica, alumina, calcium carbonate, and barium sulfate.
Examples of the ultraviolet absorber include 2- (2-hydroxy-3,5-di-t-amylphenyl) -2H-benzotriazole and isooctyl-3- (3- (2H-benzotriazol-2-yl). -5-t-butyl-4-hydroxyphenylpropionate, 2- [2-hydroxy-3,5-di (1,1-dimethylbenzidine) phenyl] -2H-benzotriazole, 2- [2-hydroxy-3 -Dimethylbenzyl-5- (1,1,3,3-tetramethylbutyl) phenyl] -2H-benzotriazole, methyl-3- [3-t-butyl-5- (2H-benzotriazol-2-yl) Benzotriazole derivatives such as condensates with -4-hydroxyphenyl] propionate / polyethylene glycol 300; 2- [4- (2-hydro Cis-3-dodecyloxypropyl) oxy] -2-hydroxyphenyl-4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine and the like; ethanediamide-N- (2- Succinic acid such as ethoxyphenyl) -N ′-(2-ethylphenyl)-(oxalic amide), ethanediamide-N- (2-ethoxyphenyl) -N ′-(4-isododecylphenyl)-(oxalic amide) Examples include anilide derivatives.
Examples of the UV stabilizer include hindered amine compounds, hindered phenol compounds; CHIMASORB 944, TINUVIN 144, TINUVIN 292, TINUVIN 770, IRGANOX 1010, IRGANOX 1098 (all of these products are products of Ciba Specialty Chemicals) Product)).
By blending an ultraviolet absorber or an ultraviolet stabilizer in the paint, it is possible to suppress the deterioration of the coating surface due to light. When this paint is used as a primer, deterioration of the primer surface due to light passing through the upper layer coating and reaching the surface of the primer coating can be suppressed. Delamination with the film can be prevented, and excellent corrosion resistance can be maintained.

  The said organic solvent which can be mix | blended with this invention coating composition is mix | blended as needed for the coating property improvement of this invention composition, etc., and a hydroxyl-containing film-forming resin (A) and a crosslinking agent ( B) which can dissolve or disperse can be used. Specifically, for example, hydrocarbon solvents such as toluene, xylene and high boiling petroleum hydrocarbons, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and isophorone Ester solvents such as ethyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, alcohol solvents such as methanol, ethanol, isopropanol, butanol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, It can be mentioned ether alcohol solvents such as ethylene glycol monobutyl ether, which may be used alone or in combination of two or more.

In the coating composition of the present invention, the glass transition temperature of the cured coating film obtained from the composition of the present invention is 40 to 115 ° C, preferably 50 to 105 ° C, such as the corrosion resistance, acid resistance and workability of the coating film. To preferred. The glass transition temperature of the coating film was tan δ by temperature dispersion measurement at a frequency of 110 Hz using a DINAMIC VISCOELASTOMETER MODEL VIBRON (dynamic viscoelastometer model vibron) DDV-IIEA type (manufactured by Toyo Baldwin, automatic dynamic viscoelasticity measuring machine). It is the maximum temperature obtained from the change in.
The coating composition formed by coating the coating composition of the present invention on a metal plate exhibits excellent corrosion resistance. The reason for this is that the present inventor has found that metal ions generated by dissolution of a raw material metal by chloride ions in a corrosive environment and pentavalent vanadium ions (VO ₃ ⁻ and VO ₄ ³⁻ vanadate ions). Direct precipitation of salt without oxidation-reduction reaction Trivalent vanadium ions and material metal ions generated by oxidation-reduction reaction of pentavalent vanadium ion and material metal effectively form a precipitate, and the material metal I think that ion elution may be suppressed.
On the other hand, phosphate ions are eluted, and the corrosion progressing site and its periphery have the effect of quickly adjusting to a pH range suitable for the oxidation-reduction reaction between the pentavalent vanadium ions and the material metal to proceed. Believes that phosphate ions also contribute to film formation.
In particular, in the case of corrosion of metals such as aluminum, which have a strong self-passivation action, dissolution proceeds at once when the passivation is destroyed by chloride ions, so it is necessary to effectively suppress the anode reaction for corrosion protection. There is. Cobalt ions and nickel ions released into the corrosive atmosphere act synergistically with silicate ions in such cases, and the anodic dissolution resistance of the coating components formed by various reactions with the metal surface of the material is marked. I think that it has been improved.
Further, as the anticorrosive pigment (C), by using the above (1), (2) and (3) in combination, the acid resistance and alkali resistance of each of the above (1), (2) and (3) and The weak water resistance can be effectively canceled out. It is considered that the synergistic effect of the action based on these rust preventive pigments worked greatly and achieved excellent corrosion resistance.

Furthermore, in the process of deterioration of the top coating film, the corrosion promoting factor in the environment penetrates from the surface of the coating film and eventually reaches the bottom of the coating film, forming a cathode electrode at that site, and the origin of the swelling of the coating film However, the cobalt ions and nickel ions in the present invention are integrated with the metal hydroxide formed on the cathode electrode under the coating, and the structure of the product is densified to suppress further corrosion progression. I think that there is an action to effectively improve the resistance to electrochemical corrosion reaction.
Painted metal plate The coating composition of the present invention can obtain a painted metal plate by coating and curing on a metal plate. As the metal plate to be coated, cold rolled steel plate, hot dip galvanized steel plate, electrogalvanized steel plate, iron-zinc alloy plated steel plate (galvanyl steel plate), aluminum-zinc alloy plated steel plate (containing about 55% aluminum in the alloy) Metal plates such as “galvanium steel plate”, “galfan” containing about 5% aluminum in the alloy), aluminum plated steel plate, nickel-zinc alloy plated steel plate, stainless steel plate, aluminum plate, copper plate, copper plated steel plate, tin plated steel plate, etc. I can give you.

Among these metal plates, the coating composition of the present invention is particularly excellent in the effect of improving the corrosion resistance of a plated steel plate mainly composed of aluminum. Specifically, the effect of improving the corrosion resistance of a plated steel sheet having an aluminum content of 50% or more in a plating component such as a “galvalume steel sheet” containing about 55% aluminum in the alloy or an aluminum plated steel sheet is particularly excellent.
These metal plate surfaces may be subjected to chemical conversion treatment. Examples of the chemical conversion treatment include phosphate treatment such as zinc phosphate treatment and iron phosphate treatment, composite oxide film treatment, chromium phosphate treatment, and chromate treatment.

  The coating composition of the present invention can be applied onto the metal plate by a known method such as a roll coating method, a curtain flow coating method, a spray method, a brush coating method, or a dipping method. Although the cured film thickness of the coating film obtained from this invention coating composition is not specifically limited, Usually, 2-10 micrometers, Preferably it is used in the range of 3-6 micrometers. Curing of the coating film may be appropriately set according to the type of resin used, etc., and when the material coated by the coil coating method is continuously baked, the material reached maximum temperature is usually 160 to 250 ° C. It is preferably baked for 15 to 60 seconds under the condition of 180 to 230 ° C. In the case of baking in a batch system, it can be carried out by baking at 80 to 200 ° C. for 10 to 30 minutes. In addition, when a non-blocked polyisocyanate is used as the crosslinking agent (B), or when a bisphenol type epoxy resin is used as the resin (A) and an amine compound is used as the crosslinking agent (B), a coating film is formed. In the case of a combination that does not particularly require heating for the crosslinking reaction in the process, it can be cured by drying at room temperature according to a conventional method.

  The coated metal plate of the present invention has a coating film formed of the above-described coating composition of the present invention on a metal plate which may be subjected to chemical conversion treatment, and the coated metal plate formed with the coating film of the present coating composition The coating itself can be used, but a top coating film can also be provided on this coating film. The film thickness of the top coat film is usually 8 to 30 μm, preferably 10 to 25 μm.

  Examples of the top coating for forming the top coating film include, for example, top coatings such as polyester resin-based, alkyd resin-based, silicon-modified polyester resin-based, silicon-modified acrylic resin-based, and fluororesin-based, which are known for precoated steel sheets. be able to. When workability is particularly important, a coated steel sheet having particularly excellent workability can be obtained by using a polyester-based top coat for advanced processing. The coated metal plate of this invention can show the coating-film performance excellent in corrosion resistance.

  When a plated steel sheet having a high aluminum content in the plating component such as a “galvanium steel sheet” containing about 55% aluminum in the alloy or an aluminum-zinc alloy plated steel sheet is used as the metal plate to be coated, While the corrosion resistance has been considerably improved, until now, the corrosion resistance was insufficient in the cut end face part and the processed part processed by molding, but by coating the coating composition of the present invention, the end face part and the processed part were processed. Excellent corrosion resistance can also be obtained in the part.

  Moreover, the coating film by this invention coating composition may be provided in both surfaces of to-be-coated article, and the said top coating film is further formed on the coating film by this invention coating composition as needed. May be. By forming the coating composition of the present invention on both sides, that is, on the back side, it is possible to obtain a coated metal plate that does not contain a chromium-based rust preventive pigment, is advantageous in terms of environmental hygiene and has excellent corrosion resistance. .

Hereinafter, the present invention will be described more specifically with reference to production examples, examples and comparative examples. However, the present invention is not limited to these. In each example, “parts” and “%” are based on mass unless otherwise specified. Moreover, the film thickness of a coating film is based on a cured coating film.
Manufacture of resole phenolic resin
Production Example 1
In a reaction vessel, 100 parts of bisphenol A, 178 parts of 37% formaldehyde aqueous solution and 1 part of sodium hydroxide were blended, reacted at 60 ° C. for 3 hours, and dehydrated at 50 ° C. for 1 hour under reduced pressure. Then, 100 parts of n-butanol and 3 parts of phosphoric acid were added and reacted at 110 to 120 ° C. for 2 hours. After completion of the reaction, the resulting solution was filtered to remove sodium phosphate, which was obtained, thereby obtaining a solution of a resol type phenol resin (B1) having a solid content of about 50%. The obtained resin had a number average molecular weight of 880, an average number of methylol groups per benzene nucleus of 0.4, and an average number of alkoxymethyl groups of 1.0.

Production Example 1 of Coating Composition
Epicote # 1009 (Japan Epoxy Resin, bisphenol A type epoxy resin, hydroxyl group-containing resin) 85 parts mixed solvent 1 [cyclohexanone / ethylene glycol monobutyl ether / Sorvesso 150 (Esso Petroleum, high boiling aromatic hydrocarbon solvent) ) = 3/1/1 (mass ratio)] 220 parts of epoxy resin solution dissolved in 135 parts, 5 parts vanadium pentoxide, 3 parts cobalt orthophosphate, 2 parts calcium orthosilicate, 20 parts titanium white, 20 parts barita And an appropriate amount of mixed solvent 2 [Solvesso 150 (manufactured by Esso Petroleum Corporation, high-boiling aromatic hydrocarbon solvent) / cyclohexanone = 1/1 (mass ratio)] is mixed to obtain a tube (particle diameter of coarse pigment particles). Pigment dispersion was performed until the thickness became 20 μm or less. Next, Desmodur BL-3175 (manufactured by Sumika Bayer Urethane Co., Ltd., HDI isocyanurate type polyisocyanate compound solution blocked with methyl ethyl ketoxime, about 75% solid content) in this dispersion was 20 parts (15 parts in solid content), Takenate TK-1 (manufactured by Takeda Pharmaceutical Co., Ltd., organotin blocking agent dissociation catalyst, solid content of about 10%) is added and mixed uniformly. Further, the above mixed solvent 2 is added and the viscosity is about 80 seconds (Ford Cup # 4/25 ° C.) to obtain a coating composition 1.
Examples 2 to 30, Comparative Examples 1 to 8 and Reference Examples 1 and 2
In Example 1, except that the hydroxyl group-containing resin, the crosslinking agent, the rust preventive pigment, and other pigments used were as shown in Table 1 below, the same procedure as in Example 1 was performed to obtain coating compositions 2 to 40. . Reference Examples 1 and 2 are rust preventive coating compositions containing conventional chromate rust preventive pigments. The amounts of the hydroxyl group-containing resin, the crosslinking agent, the pigment component, etc. in Table 1 are all expressed by solid mass.

In Table 1, the total amount of each rust preventive pigment relative to the resin component (total solid mass of hydroxyl group-containing resin and crosslinking agent is 100 parts by mass) is added to 10000 parts by mass of a 5% by mass sodium chloride aqueous solution at 25 ° C. The pH of the filtrate obtained by filtering the supernatant liquid stirred for 6 hours and allowed to stand at 25 ° C. for 48 hours is also shown. For example, the pH of the rust preventive pigment solution of Example 1 is 10000 parts by mass of a 5% strength by weight sodium chloride aqueous solution at 25 ° C., 5 parts by mass of vanadium pentoxide, 3 parts by mass of cobalt orthophosphate, and 2 parts by mass of calcium silicate. It is pH of the filtrate which filtered the supernatant liquid which added the part and was dissolved on the said conditions.
In Table 1 above, (Note) in the table has the following meanings.
(Note 1) Epokey 837: manufactured by Mitsui Chemicals, Inc., trade name, urethane-modified epoxy resin, hydroxyl group-containing resin, primary hydroxyl value of about 35, acid value of about 0.
(Note 2) Byron 296: manufactured by Toyobo Co., Ltd., trade name, epoxy-modified polyester resin, hydroxyl group-containing resin, hydroxyl value 7, acid value 6.
(Note 3) Sumidur N3300: manufactured by Sumika Bayer Urethane Co., Ltd., isocyanurate type polyisocyanate compound, solid content 100%.
(Note 4) Cymel 303: Nihon Cytec Industries, Ltd., trade name, methyl etherified melamine resin.
(Note 5) Phosphate metal salt A: Cobalt oxide treated product of aluminum dihydrogen tripolyphosphate.
(Note 6) Shieldex C303: R. Grace & Co. Product name, calcicum ion exchange silica.
(Note 7) sandvor 3058: product of Clariant, trade name, hindered amine UV stabilizer.
(Note 8) Nacure 5225: A neutralized amine solution of dodecylbenzenesulfonic acid, manufactured by King Industries, USA.

Preparation of test coating plate Using the coating compositions 1 to 40 and the top coating obtained in Examples 1 to 30, Comparative Examples 1 to 8 and Reference Examples 1 and 2, coating each material with the following coating specifications Thus, a paint plate for each test was obtained.

Coating specification 1 (Material: Galvalume steel plate)
Chemically treated galvalume steel sheet (thickness 0.35 mm, aluminum-zinc alloy plated steel sheet, about 55% aluminum in alloy, alloy plating basis weight 150 g / m ² , indicated as “GL steel sheet” in Table 1 The coating compositions 1 to 40 were coated with a bar coater so as to have a film thickness of 5 μm, and baked for 30 seconds so that the maximum material reaching temperature was 220 ° C. to form a back coating film. The same coating composition 1 to 40 is applied to the steel plate surface opposite to the back surface coating film of the coated plate on which this back surface coating film is formed with a bar coater so as to have a film thickness of 5 μm. Each primer coating was formed by baking at 40 ° C. for 40 seconds.
After cooling, a film thickness of 15 μm was applied to these primer coatings using a bar coater with KP Color 1580B40 (manufactured by Kansai Paint Co., Ltd., trade name, polyester-based top coating, blue, glass transition temperature of cured coating about 70 ° C.). Each test coating plate was obtained by baking for 40 seconds so that the maximum material arrival temperature was 220 ° C.

Coating specification 2 (Material: Hot-dip aluminized steel sheet)
Each of the coating compositions 1 to 40 is formed to a thickness of 5 μm on a hot-dip aluminized steel sheet (sheet thickness: 0.35 mm, basis weight: 200 g / m ² ; indicated as “AL steel sheet” in Table 1) subjected to chemical conversion treatment. Then, it was coated with a bar coater and baked for 30 seconds so that the maximum material arrival temperature was 220 ° C. to form a back coating film. The same coating composition 1 to 40 is applied to the steel plate surface opposite to the back surface coating film of the coated plate on which this back surface coating film is formed with a bar coater so as to have a film thickness of 5 μm. Each primer coating was formed by baking at 40 ° C. for 40 seconds.
After cooling, each test was carried out by coating KP color 1580B40 on these primer coatings with a bar coater to a film thickness of 15 μm and baking for 40 seconds so that the maximum material temperature reached 220 ° C. A painted plate was obtained.

Coating film performance test About coating plates for tests obtained by applying the coating compositions obtained in Examples 1 to 30, Comparative Examples 1 to 8 and Reference Examples 1 and 2, and top coatings The film performance test was conducted according to the following test method. The test results are also shown in Table 1.

Test method Boiling water resistance: After each test coating plate cut to a size of 5 cm × 10 cm is immersed in boiling water at about 100 ° C. for 5 hours, it is pulled up to evaluate the appearance of the coating film on the surface side, and a cross-cut tape An adhesion test was performed and evaluated. The cross-cut tape adhesion test is based on JIS K-5400 8.5.2 (1990) cross-cut tape method, the gap interval of the cuts is 1 mm, 100 cross-cuts are made, and cellophane adhesive tape is adhered to the surface. And the number of grids remaining on the coated surface after abrupt peeling was examined.

A: There is no abnormality such as blistering or whitening in the coating film, and there are 100 remaining grids,
○: There are no abnormalities such as blistering and whitening in the coating film, and a residual grid number of 91 to 99,
Δ: Slightly abnormalities such as blistering or whitening were observed in the coating film and the number of residual grids was 91 or more, or there were no abnormalities such as blistering or whitening in the coating film, but the remaining grids were 71 to 90 Pieces,
X: Generation | occurrence | production of the swelling of a coating film is recognized fairly or remarkably, or the number of remaining grids is 70 or less.

  Alkali resistance: The back surface and the cut surface of each test paint plate cut to a size of 5 cm × 10 cm were sealed with a rust-proof paint, and a cross cut reaching the substrate was put in the center of the front side of the paint plate. This coated plate was immersed in a 5% aqueous sodium hydroxide solution at 40 ° C. for 48 hours, then taken out, washed, and evaluated for the appearance of the coating on the surface side of the coated plate dried at room temperature. Was peeled off, and the peel width (one side) from the cut portion in the coating film after peeling off was evaluated.

A: There is no occurrence of blisters, and the peel width from the cut part is 1.5 mm or less,
○: No occurrence of swelling, peeling width from cut part exceeds 1.5 mm, 3 mm or less,
Δ: Slight occurrence of swelling is observed, but tape peeling width from the cut portion is 3 mm or less, or occurrence of swelling is not recognized, but the tape peeling width from the cut portion exceeds 3 mm,
X: Generation | occurrence | production of a swelling is recognized and the tape peeling width from a cut part exceeds 3 mm.

  Acid resistance: The back surface and cut surface of each test paint plate cut to a size of 5 cm × 10 cm were sealed with a rust-proof paint, and a cross cut reaching the substrate was put in the center of the front side of the paint plate. This coated plate was immersed in a 5% sulfuric acid aqueous solution at 40 ° C. for 48 hours, then taken out, washed with water, and the appearance of the coating on the surface side of the coated plate dried at room temperature was evaluated, and a cellophane adhesive tape was adhered to the crosscut part. The peel width (one side) from the cut portion in the coating film after being peeled off rapidly was evaluated.

A: There is no occurrence of swelling, and the tape peeling width from the cut part is 1.5 mm or less.
○: There is no occurrence of swelling, and the tape peeling width from the cut part exceeds 1.5 mm and is 3 mm or less.
Δ: Slight occurrence of swelling is observed, but tape peeling width from the cut portion is 3 mm or less, or occurrence of swelling is not recognized, but the tape peeling width from the cut portion exceeds 3 mm,
X: Generation | occurrence | production of a swelling is recognized and the tape peeling width from a cut part exceeds 3 mm.

  Scratch resistance: Using a coin scratch tester (manufactured by Kayaku Giken Kogyo Co., Ltd.) at a room temperature of 20 ° C., keep the edge of the 10-yen copper coin at a 45 ° angle on the surface of each test coating plate, 3 kg The degree of scratching when the coated surface was scratched by pulling a 10-yen copper coin at a speed of 10 mm / second for about 30 mm while being pressed with a load of was evaluated according to the following criteria.

A: No metal substrate is seen on the scratched part.
○: A slight metal base is seen on the scratched part.
△: A considerable amount of metal base is seen in the scratched part,
X: A coating film is hardly left on the scratched part, and the metal base is clearly seen.

  Composite Corrosion Resistance Test (CCT): Test specimens used for the composite corrosion resistance test are prepared as follows. Each test coating plate cut to a width of 7 cm x 15 cm in advance was subjected to an accelerated weathering test for 500 hours with a xenon accelerated weathering tester, and then cut with a shearing cutter at 5 mm from each end of the long side. Then, the burrs were cut so that the burrs faced to the front surface side on the right side and faced to the back side on the left side toward the surface-side coating surface. Insert a cross cut with a narrow angle of 30 degrees and a line width of 0.5 mm that reaches the substrate at the center of the front side of the test piece using the back of the cutter knife, and seal the upper edge of the paint plate with anticorrosive paint. 3T bend processing part (processing to bend with the front side of the paint plate on the outside, sandwich three sheets of the same thickness as the paint plate inside, and fold the paint plate 180 degrees in a vise) A test piece was prepared. Each obtained test piece was subjected to a combined cycle corrosion test according to JIS K-5621 (1990). The conditions of the combined cycle corrosion test are as follows: (5% saline sprayed at 30 ° C. for 0.5 hour)-(Test for 1.5 hours in a humidity tester with RH of 95% or higher at 30 ° C.)-(Dry at 50 ° C. for 2 hours) )-(Drying at 30 ° C. for 2 hours) is one cycle, and 200 cycles (total of 1200 hours) were tested. The state of the 3T bending process part, the edge part, the cross cut part, and the plane part of the test piece after this test was evaluated.

Processed part: The following criteria evaluated by the total length of the rust part in a 3T bending process part, and the presence or absence of generation | occurrence | production of red rust.
A: White rust is not recognized, or white rust is recognized, but less than 5 mm,
○: White rust is recognized but not less than 5 mm and less than 20 mm,
Δ: White rust is 20 mm or more and less than 40 mm,
X: Generation | occurrence | production of white rust 40 mm or more or red rust is recognized.

Edge portion: The test piece was evaluated according to the following criteria based on the average value of edge creep widths on the left and right long sides of the test piece and the presence or absence of red rust.
A: There is no red rust, and the average edge creep width is less than 3 mm.
○: No occurrence of red rust, average value of edge creep width of 3 mm or more and less than 7 mm,
Δ: No occurrence of red rust, edge creep width average value of 7 mm or more and less than 20 mm,
X: The average value of the edge creep width is 20 mm or more, or the occurrence of red rust is observed.

Cross cut portion: Corrosion state of the cross cut portion of the test piece, white rust occurrence length ratio in the bare metal exposed portion of 0.5 mm cut width, average value of the left and right swelling width (sum of both sides) of the cut portion, and Evaluation was made according to the following criteria depending on whether red rust occurred.
A: White rust generation length ratio in exposed metal portion is less than 30% and swelling width is less than 2 mm,
○: White rust generation length ratio in the bare metal exposed part is 30% or more and less than 2 mm in width, or white rust generation length ratio in the bare metal exposed part is less than 30% and in the bulge width is 2 mm or more and less than 5 mm,
Δ: White rust generation length ratio in exposed metal portion is 50% or more and swelling width is 5 mm or more and less than 10 mm,
X: White rust generation length ratio in the bare metal exposed portion is 50% or more, and a swelling width of 10 mm or more, or generation of red rust is observed.

Flat part: Non-continuous and sporadic swelling of the flat part, which occurred at a part away from the tip of the corrosion part from the continuous edge, was evaluated according to the following criteria.
A: No occurrence of blistering is observed,
○: The diameter of the swelling is less than about 2 mm, and the number is less than 10,
Δ: The diameter of the bulge is approximately 2 mm or more and less than 10 pieces, or the diameter of the bulge is less than 2 mm and the number is 10 or more.
X: The swelling diameter is about 2 mm or more and the number is 10 or more.

Claims (7)

(A) A coating composition containing a hydroxyl group-containing coating film-forming resin, (B) a crosslinking agent, and (C) a rust preventive pigment mixture, wherein the rust preventive pigment mixture (C) is:
(1) at least one vanadium compound of vanadium pentoxide, calcium vanadate and ammonium metavanadate,
(2) a phosphoric acid metal salt which is at least one salt of phosphoric acid, phosphorous acid, and tripolyphosphoric acid, containing at least one of cobalt and nickel;
(3) It consists of a metal silicate salt that is at least one of a cobalt salt, a nickel salt and a calcium salt,
Based on the total solid content of the resin (A) and the crosslinking agent (B)
The amount of the vanadium compound (1) is 3 to 50% by mass,
The amount of the phosphate metal salt (2) is 1 to 50% by mass, and
The amount of the metal silicate (3) is 1 to 50% by mass
A is, and-proof Ri amount 10 to 150% by mass of the rust pigment mixture (C), and wherein Rukoto aluminum content in the plating ingredient is used in the coating of the plated steel sheet is at least 50% Paint composition. The coating composition according to claim 1, wherein the hydroxyl group-containing film-forming resin (A) is at least one of a hydroxyl group-containing epoxy resin and a hydroxyl group-containing polyester resin. The coating composition according to claim 1 or 2, wherein the crosslinking agent (B) is at least one crosslinking agent among an amino resin, a phenol resin, and a polyisocyanate compound which may be blocked. Furthermore, the coating composition as described in any one of Claims 1-3 which contains at least 1 sort (s) of pigment component of a rust preventive pigment other than a rust preventive pigment mixture (C), a titanium dioxide pigment, and an extender pigment. . Furthermore, the coating composition as described in any one of Claims 1-4 containing at least 1 sort (s) of a ultraviolet absorber and a ultraviolet stabilizer. Vanadium compound (1), phosphoric acid metal salt (2) and silica constituting rust preventive pigment mixture (C) blended with respect to 100 parts by mass of the total solid content of resin (A) and crosslinking agent (B) A mixture of each part by weight of each pigment of the acid metal salt (3) was added to 10000 parts by weight of a 5% strength by weight sodium chloride aqueous solution at 25 ° C., stirred for 6 hours, and allowed to stand at 25 ° C. for 48 hours. The coating composition according to any one of claims 1 to 5, wherein the pH of the filtrate obtained by filtering is from 3 to 9. Chemical conversion treatment to the decorated with aluminum content in the plating components may have on plated steel plate is 50% or more on the surface, the cured coating based on the coating composition according to any one of claims 1 to 6 Painted metal plate with a film formed.