JP5835775B2 - Rust preventive coating composition for galvanized or zinc alloy plated steel sheet - Google Patents

Description

  The present invention relates to a rust-preventive paint composition for a zinc-plated or zinc alloy-plated steel sheet excellent in corrosion resistance without containing a chromium-based rust-preventive pigment, a coating method using the rust-proof paint composition, and a coated steel sheet. More specifically, this coating composition is an effective coating composition for improving not only the corrosion resistance of the flat surface portion in the coated galvanized or zinc alloy plated steel plate but also the corrosion resistance of the processed portion and the end surface portion.

  Conventionally, pre-coated steel sheets such as galvanized or zinc alloy-plated steel sheets painted by coil coating, etc. are used for building materials such as roofs, walls, shutters, garages, home appliances, switchboards, refrigerated showcases, and steel furniture. And widely used as housing-related products such as kitchen appliances.

  In order to manufacture these housing-related products from a pre-coated steel sheet, the pre-coated steel sheet is usually cut, press-molded and joined. Therefore, these housing-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 part and cracking part are more likely to have a lower corrosion resistance than other parts, so it is common to include a chromium-based rust-preventive pigment in the precoat steel base coat to improve corrosion resistance. Has been done.

  However, chromium-based anticorrosive pigments contain or produce hexavalent chromium having excellent antirust properties, and this hexavalent chromium is a problem from the viewpoint of human health and environmental protection. .

So far, many non-chromium anticorrosion pigments such as zinc phosphate, aluminum tripolyphosphate, and zinc molybdate have been put on the market, and various primers have been proposed as a combination of non-chromium pigments. ing.
For example, Patent Document 1 discloses a combination of epoxy resin and phenol resin vehicle components, a combination of calcium silicate and phosphorus vanadate, and a combination of calcium carbonate, calcium silicate, aluminum phosphate, and phosphorus vanadate as antirust pigments. A paint containing a rust preventive pigment is described. Patent Document 2 describes a paint in which polyester is combined with a combination of a second magnesium phosphate and a fired product of manganese oxide / vanadium oxide or a fired product of calcium phosphate and vanadium oxide as a rust preventive pigment. Yes. However, the coating film formed from the paint described in Patent Documents 1 and 2 is inferior in corrosion resistance as compared with a paint using a chromium pigment, and in particular, the corrosion resistance in the processed part and the end face part is insufficient. . In addition, chemical resistance such as alkali resistance and acid resistance is often inferior. Further, when a large amount of rust preventive pigment is used, the water resistance is often inferior, and it has not yet been possible to replace chromium-based rust preventive pigments in the production of precoated steel sheets.

  Patent Document 3 discloses silica fine particles having an oil absorption of 30 to 200 ml / 100 g and a pore volume of 0.05 to 1.2 ml / g in a vehicle component composed of an organic resin containing a hydroxyl group or an epoxy group and a curing agent. And a coating composition in which a glass transition temperature of a cured coating film formed from the coating material is in the range of 40 to 125 ° C. However, although the coating film formed from the paint described in Patent Document 3 shows considerable corrosion resistance, it is still inferior in corrosion resistance and chemical resistance compared to a paint using a chromium-based pigment. Insufficient corrosion resistance.

Japanese Patent Laid-Open No. 11-61001 JP 2000-199078 A JP 2000-129163 A

  The object of the present invention is to prevent corrosion not only in the general part of the galvanized or zinc alloy plated steel sheet but also in the coated part having excellent corrosion resistance in the processed part and the end face part, even if it does not contain chromium-based anticorrosive pigments. It is providing a coating composition and a coating metal plate using the same.

Therefore, as a result of intensive studies to solve the above-described conventional problems, the present inventors have determined that a coating composition containing a specific amine-modified epoxy resin, (B) a curing agent, and (C) a rust preventive pigment. The inventors have found that it is possible to form a coating film having excellent corrosion resistance not only on the flat surface portion but also on the processed portion and the end surface portion of the coated metal plate and the like, thereby completing the present invention.
That is, the present invention provides (A) an amine-modified epoxy resin having a number average molecular weight of 1000 to 10,000, an amine value of 10 to 50 mgKOH / g, and a hydroxyl value of 180 to 280 mgKOH / g, (B) a curing agent, and (C) a non-chromium-based resin. What coating composition der containing anticorrosive pigment, bisphenols the amine-modified epoxy resin (a), by reacting an alkyl group-containing primary amines 4 to 18 carbon atoms in the bisphenol type polyepoxide chain extension Type epoxy resin and an amine containing a primary hydroxyl group are subjected to addition reaction, and based on 100 parts by mass of the total solid content of the amine-modified epoxy resin (A) and the curing agent (B), The solid content is such that the amine-modified epoxy resin (A) is 85 to 97 parts by mass, and the curing agent (B) is 3 to 15 parts by mass. Galvanized or zinc alloy-plated steel sheet for organic solvent-type anticorrosive coating composition is about.
Moreover, this invention relates to the coating method characterized by apply | coating the said rust preventive coating composition on the zinc plating or zinc alloy plating steel plate in which the chemical conversion treatment may be given to the surface.
Furthermore, this invention relates to the coating metal plate by which the hardened coating film based on the said antirust coating composition is formed on the zinc plating or zinc alloy plating steel plate in which the chemical conversion treatment may be given to the surface.

  Even if the coating composition of the present invention does not contain a chromium-based anticorrosive pigment, the galvanized or zinc alloy-plated steel sheet on which the coating film of this coating composition is formed not only has excellent corrosion resistance on the flat surface, but also It exhibits the effect of excellent corrosion resistance of processed parts and end faces, which was difficult to achieve with non-chromium anticorrosive paints, and is cured based on paints using conventional chromate anticorrosive pigments such as strontium chromate. It has a corrosion resistance equivalent to or better than that of a coated steel sheet on which a coating film is formed.

  The coating composition of the present invention exhibits excellent corrosion resistance when a galvanized steel sheet or a galvanized steel sheet is used as an object to be coated. In particular, the object to be coated has Al: 2 to 19 mass. %, Mg: 1 to 10% by mass, Si: 0 to 2% by mass, and the total of Al and Mg is 20% by mass or less, and the balance is substantially Zn-Al-Mg-based. Even in the case of a zinc alloy plated steel sheet having a plating layer, it is possible to exhibit particularly excellent corrosion resistance such as a flat portion, a processed portion, and an end face portion.

  The coating composition of the present invention contains the following amine-modified epoxy resin (A), a curing agent (B), and a rust preventive pigment (C).

Amine-modified epoxy resin (A)
The amine-modified epoxy resin which is the component (A) in the coating composition of the present invention is one in which an amino group is introduced into the epoxy resin, and has a number average molecular weight of 1000 to 10,000, preferably 2000 to 6000, an amine value of 10 to 50 mgKOH / g, preferably 15 to 40 mg KOH / g, and a hydroxyl value of 180 to 280 mg KOH / g, preferably 200 to 260 mg KOH / g. Among the hydroxyl values, those based on primary hydroxyl groups are preferably about 15 to 50 mgKOH / g.
In the amine-modified epoxy resin (A), the number-average molecular weight, the amine value, and the hydroxyl value are within the above ranges, so that the amine-modified epoxy resin (A) is reactive with the curing agent (B). The coating film obtained is excellent and can be a coating film having excellent toughness, adhesion to the metal to be coated and the top coating film, and corrosion resistance (corrosion resistance at the plane portion, the cut end surface portion and the processed portion).
As the amine-modified epoxy resin (A), an amine-added epoxy resin obtained by subjecting a polyepoxide compound to an addition reaction of an amino group-containing compound is preferable.

  Examples of the amine-added epoxy resin include (1) an adduct of a polyepoxide compound and a primary mono- and polyamine, a secondary mono- and polyamine, or a primary and secondary mixed polyamine (for example, US Pat. No. 3,984,299). (2) Adducts of polyepoxide compounds with secondary mono- and polyamines having a ketiminated primary amino group (see, for example, US Pat. No. 4,017,438); (3) Examples include a reaction product obtained by etherification of a polyepoxide compound and a ketiminated hydroxy compound having a primary amino group (see, for example, JP-A-59-43013).

  The polyepoxide compound used in the production of the above amine-added epoxy resin is a compound having one or more, preferably two or more epoxy groups in one molecule, generally at least 200, preferably 400 to 4,000, Suitable are those having a number average molecular weight preferably in the range of 800 to 2,500, and an epoxy equivalent weight of at least 160, preferably 180 to 2,500, more preferably 400 to 1,500, especially Those obtained by the reaction of a polyphenol compound and epichlorohydrin are preferred.

In the present specification, the “number average molecular weight” of the resin is a gel permeation chromatograph (
It is a value calculated on the basis of the molecular weight of standard polystyrene from a chromatogram measured with Tosoh Corporation's “HLC8120GPC”. The column is “TSKgel G-40.
00HXL "," TSKgel G-3000HXL "," TSKgel G-2500
HXL ”,“ TSKgel G-2000HXL ”(both manufactured by Tosoh Corporation, trade name), mobile phase: tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 cc / min,
Detector: Performed under RI conditions. Moreover, in this specification, the glass transition temperature (Tg) of resin is based on a differential thermal analysis (DSC).

  Examples of the suitable polyepoxide compound include bisphenol type epoxy resins and novolac type epoxy resins; modified epoxy resins in which various modifiers are reacted with epoxy groups or hydroxyl groups in these epoxy resins. 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, jER828EL, 812, 815, 820, 834, 1001, 1004, 1007, 1009, 1010 manufactured by Mitsubishi Chemical Corporation; Asahi Examples include Araldite AER 6099 manufactured by Ciba, and Epomic R-309 manufactured by Mitsui Chemicals.

  The modified epoxy resin is obtained by reacting various modifiers with an epoxy group or a hydroxyl group in the bisphenol type epoxy resin or novolac type epoxy resin.

  As a particularly suitable polyepoxide compound for use in the amine-modified epoxy resin (A) of the coating composition of the present invention, the chain extension is carried out by reacting the bisphenol type epoxy resin with an alkyl group-containing primary amine having 4 to 18 carbon atoms. The thing which was done is mentioned. Both reactions can be carried out under normal reaction conditions in the reaction between an epoxy group and an amino group. In both reactions, the bisphenol-type epoxy resin and the carbon atom so that the equivalent ratio of primary amino group / epoxy group is within the range of 0.15-0.35, preferably 0.2-0.3. It is preferable to blend with an alkyl group-containing primary amine of formula 4-18.

  Examples of the primary amine containing 4 to 18 carbon atoms include butylamine, amylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, Examples include linear or branched alkyl group-containing primary amines such as pentadecylamine and cetylamine; and alicyclic alkyl group-containing primary amines such as cyclobutylamine, cyclopentylamine, and cyclohexylamine. Of these, alkyl group-containing primary amines having 6 to 12 carbon atoms are preferred.

In order to obtain an amine-added epoxy resin suitable as the amine-modified epoxy resin (A), the amino group-containing compound used for the addition reaction with the polyepoxide compound includes a primary amine, a secondary amine, and a tertiary amine. And polyamines. These amino group-containing compounds are reacted with an epoxy group by a known method to introduce a cationic group such as a secondary amino group, a tertiary amino group, or a quaternary ammonium base into the resin.
Examples of the primary amine include methylamine, ethylamine, n-propylamine, isopropylamine, monoethanolamine, n-propanolamine, and isopropanolamine. Examples of secondary amines include diethylamine, diethanolamine, di-n-propanolamine, diisopropanolamine, N-methylethanolamine, and N-ethylethanolamine. Examples of the tertiary amine include triethylamine, triethanolamine, N, N-dimethylethanolamine, N-methyldiethanolamine, N, N-diethylethanolamine, and N-ethyldiethanolamine. Examples of the polyamine include ethylenediamine, diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, methylaminopropylamine, dimethylaminoethylamine, dimethylaminopropylamine and the like.

  Examples of the amino group-containing compound include monoethanolamine, n-propanolamine, isopropanolamine, diethanolamine, din-propanolamine, diisopropanolamine, N-methylethanolamine, N-ethylethanolamine, triethanolamine, Preferred are amines containing primary hydroxyl groups such as N, N-dimethylethanolamine, N-methyldiethanolamine, N, N-diethylethanolamine, N-ethyldiethanolamine, especially diethanolamine, di-n-propanolamine, Secondary amines containing primary hydroxyl groups such as diisopropanolamine, N-methylethanolamine, N-ethylethanolamine are preferred.

  As the amine-modified epoxy resin (A), a polyepoxide compound which is a modified epoxy resin obtained by reacting a bisphenol-type epoxy resin with an alkyl group-containing primary amine having 4 to 18 carbon atoms and extending the chain, and a primary An amine-modified epoxy resin in which an amino group and a primary hydroxyl group are introduced into the resin by an addition reaction with a hydroxyl group-containing amine can be mentioned as a particularly suitable one.

Curing agent (B)
The curing agent which is the component (B) in the coating composition of the present invention reacts with the amine-modified epoxy resin (A) to form a cured coating film, and is heated with the amine-modified epoxy resin (A). Any material that can be cured by reaction can be used without particular limitation. Of these, amino resins, phenol resins and polyisocyanate compounds which may be blocked are preferred. These curing 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 curing agent is a part of the methylol group of the methylolated phenol resin obtained by introducing a methylol group by heating and condensation reaction of a phenol component and formaldehyde in the presence of a reaction catalyst, or A resol type phenolic resin obtained by alkylating all of them with an alcohol is exemplified.

  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 them, in order to improve 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 may be used alone or in combination of two or more.

  Examples of formaldehydes used in the production of phenol resins include formaldehyde, paraformaldehyde, trioxane, and the like, which 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 phenolic 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 amine-modified epoxy resin (A). Is suitable.

  Examples of the non-blocked polyisocyanate compound that can be used as the curing agent (B) include aliphatic diisocyanates such as hexamethylene diisocyanate or trimethylhexamethylene diisocyanate; Cycloaliphatic diisocyanates such as diisocyanates or isophorone diisocyanates; organic diisocyanates themselves such as tolylene diisocyanate, xylylene diisocyanate or 4,4'-diphenylmethane diisocyanate, aromatic diisocyanates such as crude MDI, or each of these organic diisocyanates And an adduct of polyhydric alcohol, low molecular weight polyester resin or water, or the above Such cyclic polymer of the organic diisocyanate comrades, further include isocyanate-biuret, or the like.

  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 amine-modified epoxy resin (A) and the curing agent (B) is based on 100 parts by weight of the total solid content of the components (A) and (B), and the amine-modified epoxy resin (A) is 85 to 85 parts. 97 parts by mass, further 88 to 95 parts by mass, the curing agent (B) being in the range of 3 to 15 parts by weight, further 5 to 12 parts by weight, corrosion resistance, boiling water resistance, workability, This is preferable from the viewpoint of curability.

  In order to increase the curability of the coating composition of the present invention, a curing catalyst can be blended as necessary. When the curing 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 curing agent (B) is a phenol resin, the sulfonic acid compound or an amine neutralized product of the sulfonic acid compound is preferably used as the curing catalyst.

  When the curing agent (B) is a blocked polyisocyanate compound, a curing catalyst that promotes dissociation of the blocking agent of the blocked polyisocyanate compound, which is a curing agent, is suitable. As a suitable curing catalyst, for example, octyl Tin oxide, dibutyltin di (2-ethylhexanoate), dioctyltin di (2-ethylhexanoate), dioctyltin diacetate, dibutyltin dilaurate, dibutyltin oxide, dioctyltin oxide, lead 2-ethylhexanoate And organometallic catalysts such as

When the crosslinking agent (B) is a combination of two or more crosslinking agents, an effective curing catalyst can be used in combination with each curing agent.
Antirust pigment (C)
As the anti-corrosion pigment (C), any chromium-based pigment or non-chromium pigment can be used as long as it has anti-rust properties. However, it is non-chromium from the viewpoint of human health and environmental protection. It is preferable to be a pigment.

  Examples of the chromium-based rust preventive pigment include strontium chromate, zinc chromate, zinc potassium chromate, barium chromate, chromium chromate, and chromium phosphate. Non-chromium rust preventive pigments include zinc phosphate, aluminum tripolyphosphate, calcium molybdate silicate, vanadium pentoxide, calcium vanadate, ammonium metavanadate, phosphorus vanadate, aluminum phosphate, calcium phosphate, dibasic magnesium phosphate, Various products such as calcined products of manganese oxide and vanadium oxide, calcined products of calcium phosphate and vanadium oxide, silica fine particles having an oil absorption of 30 to 200 ml / 100 g and a pore volume of 0.05 to 1.2 ml / g. Can be mentioned. These rust preventive pigments can be used alone or in combination of two or more.

  In the coating composition of the present invention, as the anticorrosive pigment (C), in particular, a combination of the following (1) vanadium compound, (2) silicon-containing compound and (3) phosphate metal salt can be suitably used.

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.

Silicon-containing compound (2)
The silicon-containing compound (2) is at least one of metal silicate and silica fine particles. The metal silicate is a salt made of silicon dioxide and a metal oxide, and may be any of orthosilicate, polysilicate, and the like. Examples of the silicate include zinc silicate, aluminum silicate, aluminum orthosilicate, hydrated aluminum silicate, aluminum calcium silicate, sodium aluminum silicate, beryllium aluminum silicate, sodium silicate, calcium orthosilicate, calcium metasilicate, calcium calcium silicate, and silicic acid. Zirconium, magnesium orthosilicate, magnesium metasilicate, calcium magnesium silicate, manganese silicate, cobalt orthosilicate, cobalt metasilicate, nickel orthosilicate, nickel metasilicate, barium silicate, olivine, garnet, tortobiite, cyllite, beitoite , Neptunite, Ryokuchu stone, Toki stone, Kaikai stone, Baraki stone, Tohoku stone, Zonotra stone, Talc, Gyogan stone, Aluminosilicate, Borosilicate, Bezo Russia silicate, butterfly stone, and the like can be given fluoride stone. Among them, calcium orthosilicate, calcium metasilicate, orthosilicate magnesium, magnesium metasilicate, magnesium calcium silicate, cobalt orthosilicate, cobalt metasilicate, nickel orthosilicate, and nickel metasilicate are preferred as the metal silicate.

  The silica fine particles can be used without particular limitation as long as they are silica fine particles. For example, silica fine powder with an untreated surface, silica fine powder with a surface treated with an organic substance, ion exchange with a cation such as calcium ion or magnesium ion. Examples thereof include ion-exchanged silica fine particles 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 Industry Co., Ltd.), Gasil 200DF (manufactured by Crossfield).
Calcium ion exchanged silica fine particles are silica fine particles in which calcium ions are introduced into a fine porous silica carrier by ion exchange. Examples of commercially available calcium ion-exchange silica include SHIELDEX (Shielddex, registered trademark) C303, AC-3, and C-5 (all of which are manufactured by WR Grace & Co.). it can. Magnesium ion exchanged silica fine particles are silica fine particles in which magnesium ions are introduced into a fine porous silica carrier by ion exchange. The ion exchange silica preferably has an average particle size of 0.5 to 15 μm, particularly 1 to 10 μm, and the oil absorption is preferably 30 to 300 cc / 100 g, particularly 30 to 150 cc / 100 g.
Cations such as calcium ions and magnesium ions released from ion-exchange silica are involved in electrochemical action and various salt forming actions, and effectively work to improve corrosion resistance. Moreover, the silica fixed in the coating film effectively acts to suppress peeling of the coating film in a corrosive atmosphere.
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 Catalyst Kasei Co., Ltd.) and organosols (manufactured by Nissan Chemical Co., Ltd.).
Among these silica fine particles, calcium ion exchanged silica fine particles and magnesium ion exchanged silica fine particles are preferable.

Each metal silicate and each silica fine particle can be used as a silicon-containing compound (2) by 1 type or in combination of 2 or more types.
Phosphate metal salt (3)
The phosphoric acid metal salt (3) is at least one of a phosphoric acid metal salt, a hydrogen phosphate metal salt, and a tripolyphosphate metal salt. The metal of the phosphate metal salt is not particularly limited, and examples of suitable metals include Ca, Co, Ni, Mg, Zn, and Al.

  Examples of the phosphate metal salt include calcium orthophosphate, calcium metaphosphate, calcium ammonium phosphate, calcium monohydrogen phosphate, calcium dihydrogen phosphate, calcium phosphate phosphate, cobalt orthophosphate, cobalt metaphosphate, and phosphorous acid. Cobalt, cobalt hydrogen phosphate, cobalt pyrophosphate, cobalt ammonium phosphate, cobalt phosphate / calcium eutectoid, surface treatment with cobalt trioxide of cobalt trihydrogen phosphate, nickel orthophosphate, nickel metaphosphate, nickel phosphite , Nickel hydrogen phosphate, Surface treatment with calcium phosphate nickel oxide, Magnesium phosphate, Magnesium hydrogen phosphate, Magnesium ammonium phosphate, Magnesium phosphate / cobalt eutectoid, Tripolyphosphorus Surface treatment with magnesium oxide of magnesium, aluminum trihydrogenphosphate, magnesium oxide, Surface treatment with magnesium oxide of zinc trihydrogenphosphate, aluminum phosphate, aluminum hydrogen phosphate, aluminum trihydrogen phosphate, zinc phosphate, hydrogen phosphate Zinc and the like can be mentioned. Of these, calcium salts, magnesium salts, cobalt salts, and nickel salts are particularly preferred from the standpoint of corrosion resistance. Metal ions such as phosphate ions, Ca, Mg, Co, and Ni released from the phosphate metal salt (3) effectively act to improve corrosion resistance.

  In the coating composition of the present invention, the amount of the rust preventive pigment (C) is preferably 10 to 150 parts by mass based on 100 parts by mass of the total solid content of the amine-modified epoxy resin (A) and the curing agent (B). Is preferably from 15 to 90 parts by mass from the viewpoint of corrosion resistance. Among them, as the anticorrosive pigment (C), the vanadium compound (1), the silicon-containing compound (2) and the phosphate metal salt (3) are as follows: Within the range, it is non-chromium and is preferable from the viewpoint of improving corrosion resistance.

Vanadium compound (1): 1-50 parts by mass, preferably 5-30 parts by mass,
Silicon-containing compound (2): 1 to 50 parts by mass, preferably 5 to 30 parts by mass,
Phosphate metal salt (3): 1 to 50 parts by mass, preferably 5 to 30 parts 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 a rust preventive pigment.

  In addition to the amine-modified epoxy resin (A), the curing agent (B), the rust preventive pigment (C), and the curing catalyst blended as necessary, the coating composition of the present invention can be used as a coloring pigment. , Extender pigments, UV absorbers, UV stabilizers, organic solvents; other resins other than amine-modified epoxy resins (A) and curing agents (B); additives such as antisettling agents, antifoaming agents, coating surface conditioners, etc. Can be blended as necessary.

  Examples of the colored pigment include organic colored pigments such as cyanine blue, cyanine green, organic red pigments such as azo and quinacridone; and inorganic colored 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, mica, alumina, calcium carbonate, barium sulfate and the like.

  Examples of the ultraviolet absorber include 2- (2-hydroxy-3,5-di-t-amylphenyl) -2H-benzotriazole, 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-triazole, 2- [2-hydroxy-3-dimethylbenzyl-5 (1,1,3,3-butyl-5- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] propionate / polyethyleneglycol Benzotriazole derivatives such as condensates with diol 300; 2- [4- (2-hydroxy-3-dodecyloxypropyl) oxy] -2-hydroxyphenyl-4,6-bis (2,4-dimethylphenyl) ) -1,3,5-triazine and other triazine derivatives; ethanediamide-N- (2-ethoxyphenyl) -N ′-(2-ethylphenyl)-(oxalic amide), ethanediamide-N- (2-ethoxy) Mention may be made of oxalic acid anilide derivatives such as phenyl) -N ′-(4-isododecylphenyl)-(oxalic amide).

  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 UV absorbers and UV stabilizers in the paint, it is possible to suppress the deterioration of the coating surface due to light. Even when this paint is used as a primer, it passes through the upper coating film and becomes a primer. Since the deterioration of the primer surface due to the light reaching the coating surface can be suppressed, delamination between the primer coating and the upper coating due to the deterioration of the primer coating surface can be prevented, and excellent corrosion resistance can be maintained.

  The organic solvent that can be blended in the coating composition of the present invention is blended as necessary for improving the paintability of the composition of the present invention, and contains an amine-modified epoxy resin (A) and a curing agent (B). Soluble or dispersible materials can be used. Specifically, for example, hydrocarbon solvents such as toluene, xylene, high boiling petroleum hydrocarbons, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, ethyl acetate Ester solvents such as 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, di And ether alcohol-based solvents such as Chi glycol monobutyl ether can be cited, which may be used alone or in combination of two or more.

  Other resins other than the amine-modified epoxy resin (A) and the curing agent (B) are blended as necessary for the purpose of modifying the obtained coating film, and can be used normally in the paint field. A resin having a forming ability can be used. This other resin is preferably a hydroxyl group-containing resin, and, as a typical example, one or two or more types of mixed resins such as a polyester resin, an epoxy resin, an acrylic resin, a fluororesin, and a vinyl chloride resin that contain a hydroxyl group. Can be mentioned. When mix | blending this other resin, the compounding quantity is 30 mass parts or less based on 100 mass parts of total solid content of an amine modified epoxy resin (A) and a hardening | curing agent (B).

  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 is 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 film 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 resin component in the coating composition of the present invention has a stress relaxation capability. This is considered to be due to the ability to form a coating film that is excellent and has an excellent balance between elastic modulus and elongation.

Coating method The coating method of the present invention is characterized in that the anticorrosive coating composition of the present invention is applied onto a zinc-plated or zinc alloy-plated steel sheet whose surface may be subjected to chemical conversion treatment. .

The coating composition of the present invention can be applied on the galvanized or zinc alloy plated steel sheet 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 composition is not specifically limited, Usually, 2-10 micrometers, Preferably it is the range of 3-6 micrometers. What is necessary is just to set hardening of a coating film suitably according to the kind of resin to be used, a hardening | curing agent, the thickness of a to-be-coated object, a coating means, etc.
In the case of continuously baking what is coated by a coil coating method or the like, it is usually baked for 15 to 60 seconds under a condition that the maximum material reaching temperature is 160 to 250 ° C, preferably 180 to 230 ° C. When baking by a batch type, it can usually carry out by baking at 80-200 degreeC for 10 to 30 minutes. In the case of a combination that does not require heating for the curing reaction in the coating film formation process, such as when a non-blocked polyisocyanate is used as the curing agent (B), it is dried at room temperature according to a conventional method. Can be cured.

Painted metal plate The coated metal plate of the present invention has a cured coating film formed on the galvanized or zinc alloy plated steel sheet, the surface of which may be subjected to chemical conversion treatment, based on the rust preventive coating composition of the present invention. It will be.
Examples of the galvanized or zinc alloy plated steel sheet to be coated with a cured coating film include hot dip galvanized steel sheet, electrogalvanized steel sheet, iron-zinc alloy plated steel sheet (galvanyl steel sheet), aluminum-zinc alloy plated steel sheet ( "Galbarium steel plate" containing about 55% aluminum in the alloy, "Galfan" containing about 5% aluminum in the alloy), zinc-aluminum-magnesium alloy plated steel plate (Al: 2 to 19% by mass, Mg: 1 to 1) 10% by mass, Si: 0 to 2% by mass, and the total of Al and Mg is 20% by mass or less, and the balance is an alloy-plated steel sheet having a plating layer having a substantially Zn composition), nickel-zinc An alloy plated steel sheet can be used.
These galvanized or zinc alloy-plated steel sheet surfaces may be subjected to chemical conversion treatment. Examples of chemical conversion treatment include phosphate treatment such as zinc phosphate treatment and iron phosphate treatment, composite oxide film treatment, A zirconium oxide process etc. can be mentioned.

The coated metal plate of the present invention is provided with a coating film of the above-described coating composition of the present invention on an object to be coated. The coating film by the coating composition of the present invention can be formed by the coating method of the present invention.
The coated metal plate itself having a coating film formed from the coating composition of the present invention can be used for use, and 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 coatings that are known for pre-coated steel sheets. Can do. 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 galvanized steel plate or an aluminum-zinc alloy plated steel plate is used as the metal plate to be coated, the corrosion resistance of the flat surface portion has been considerably improved, while the cut end surface portion and the molded processed portion have corrosion resistance. However, when the coating composition of the present invention is applied, excellent corrosion resistance can be obtained even at the end face portion and the processed portion.
In particular, when the zinc-aluminum-magnesium alloy-plated steel sheet is an object to be coated, there has been a problem that the coating film adhesion is poor. However, even in the case of this object to be coated, The formed coating film based on the coating composition of the present invention exhibits excellent coating film adhesion, and can exhibit excellent corrosion resistance in a flat portion, a processed portion, an end surface portion, and the like.

  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 Example 1 Production of amine-modified epoxy resin AE1 solution In a reaction vessel equipped with a stirrer and a heating / temperature control device, 20 parts of methoxybutyl acetate solvent, jER828 (manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin, several Average molecular weight of about 370, epoxy equivalent of about 190) 29.1 parts, bisphenol A 9.5 parts and octylamine 1.5 parts were charged and heated to 160 ° C. in a nitrogen atmosphere with stirring for 2 hours. Reaction was performed. To this reaction product, 3.1 parts of dimethylolpropionic acid was added and reacted at 160 ° C. for 1 hour with stirring. After confirming that the resin acid value was 1 or less, 1.7 parts of methylethanolamine was added, and further reacted at 160 ° C. for 1 hour, and then diluted with a methoxybutyl acetate solvent to obtain a solid content of 45%. An amine-modified epoxy resin AE1 solution was obtained. The solid content of the obtained resin had an amine value of 43, a hydroxyl value of 278, and a number average molecular weight of about 2000.

Production Example 2 Production of amine-modified epoxy resin AE1 solution In a reaction vessel equipped with a stirrer and a heating / temperature control device, 20 parts of methoxybutyl acetate solvent, jER1004 (Mitsubishi Chemical Corporation, bisphenol A type epoxy resin, several 41.2 parts of an average molecular weight of about 1700 and an epoxy equivalent of about 920) and 1.4 parts of octylamine were charged, and the mixture was heated to 160 ° C. with stirring in a nitrogen atmosphere and reacted for 2 hours. To this reaction product, 2.4 parts of diethanolamine was added and further reacted at 160 ° C. for 1 hour, and then diluted with a methoxybutyl acetate solvent to obtain an amine-modified epoxy resin AE2 solution having a solid content of 45%. . The solid content of the obtained resin had an amine value of 42, a hydroxyl value of 246, and a number average molecular weight of about 4000.
Production Examples 3, 4, 8, and 10
In Production Example 2, an amine-modified epoxy resin having a solid content of 45% was obtained in the same manner as in Production Example 2 except that the raw materials other than the solvent were changed to the formulation shown in Table 1 below. The amine-modified epoxy resins obtained in Production Examples 8 and 10 are for comparative examples.
Production Examples 5 to 7, 9 and 11
In Production Example 1, an amine-modified epoxy resin having a solid content of 45% was obtained in the same manner as in Production Example 1 except that the raw materials other than the solvent were changed to the formulation shown in Table 1 below. The amine-modified epoxy resins obtained in Production Examples 7, 9, and 11 are for comparative examples.

  Table 1 shows the blending amounts and special values of the resins in Production Examples 1 to 11. The value of the hydroxyl value by the primary hydroxyl group in the special value column of Table 1 is a value based on the calculated value (mgKOH / g resin). Moreover, all the compounding quantity in Table 1 is a display by solid content mass (active ingredient mass).

(Note) in Table 1 has the following meaning.
(Note 1) jER1007: manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin, number average molecular weight of about 2900, epoxy equivalent of about 2000.

Production Example 12 Production of Resol Type Phenol Resin R1 Solution In a reaction vessel, 100 parts of p-cresol, 178 parts of 37% aqueous formaldehyde solution and 1 part of sodium hydroxide were blended and reacted at 60 ° C. for 3 hours. Dehydrated at 50 ° C. for 1 hour. 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 the completion of the reaction, the resulting solution was filtered to remove sodium phosphate, which was obtained, thereby obtaining a resol type phenol resin R1 solution 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 13 Production of Back Surface Paint jER1009F (Mitsubishi Chemical Co., Ltd., bisphenol A type epoxy resin, epoxy equivalent of about 2000) mixed solvent 1 [cyclohexanone / ethylene glycol monobutyl ether / swazol 1500 (Maruzen Petrochemical Co., Ltd.) ), High boiling point aromatic hydrocarbon solvent) = 3/1/1 (mass ratio)] in 200 parts of an epoxy resin solution dissolved in 120 parts, titanium white 40 parts, barita 40 parts and mixed solvent 1 And the pigment was dispersed until the tub (particle diameter of the coarse pigment particles) became 20 microns or less. Next, 26.7 parts (20% by solid content) of 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) was added to this dispersion. Part), 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 1 is added and the viscosity is about 80 seconds ( Ford cup # 4/25 ° C.) to obtain a paint for the back surface.

Example 1 Production of Rust-Preventing Paint Composition
To 200 parts of the amine-modified epoxy resin AE1 solution having a solid content of 45% obtained in Production Example 1 (90 parts in solid content), 20 parts of vanadium pentoxide, 20 parts of calcium phosphate, 20 parts of calcium metasilicate, 20 parts of titanium white, and barita 20 parts and an appropriate amount of the mixed solvent 1 were mixed, and the pigment was dispersed until the tube (particle diameter of the coarse pigment particles) became 20 microns or less. Next, to this dispersion, 13.3 parts (10 parts by solid amount) of Death Module BL-3175, Takenate TK-1 (manufactured by Takeda Pharmaceutical Co., Ltd., organotin blocking agent dissociation catalyst, solid content of about 10%) 2 Then, the above mixed solvent 1 was added to adjust the viscosity to about 80 seconds (Ford Cup # 4/25 ° C.) to obtain a rust preventive coating composition.

Examples 2, 3 and 5-26, Reference Example 4 and Comparative Examples 1-13
In Example 1, except that the amine-modified epoxy resin, curing agent, other resin, rust preventive pigment, and other pigment used are as shown in Table 2 below, the same procedure as in Example 1 was carried out. Got. The pigment dispersion was performed using the amine-modified epoxy resin in Table 2 and other resins as the resin. However, in Examples 12 and 13 and Comparative Examples 2 and 9, NACURE 5225 (manufactured by King Industries Ltd., amine neutralized solution of dodecylbenzenesulfonic acid) 1 instead of 2 parts of Takenate TK-1 Each part was blended.

Comparative Example 12
jER1009F (manufactured by Japan Epoxy Resin Co., Ltd., bisphenol A type epoxy resin, epoxy equivalent of about 2000, amine value of 0 mg KOH / g) mixed solvent 1 [cyclohexanone / ethylene glycol monobutyl ether / swazol 1500 = 3/1/1 (mass ratio )] Was dissolved in 149 parts to obtain 229 parts of a 35% epoxy resin solution. A suitable amount of 50 parts of strontium chromate, 10 parts of titanium white, 10 parts of varita and mixed solvent 1 was mixed with 160 parts of the obtained 35% epoxy resin solution (56 parts by solid content). Pigment dispersion was performed until the particle diameter of the coarse particles was 20 microns or less. Subsequently, the remaining 69 parts of the 35% epoxy resin solution (24 parts by solid content), 26.7 parts of Death Module BL-3175 (20 parts by solid content), Takenate TK-1 ( 2 parts of 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 rust preventive coating composition.

Comparative Example 13
In Comparative Example 1, except that the pigment composition to be blended was changed as shown in Table 2, it was carried out in the same manner as in Comparative Example 1 to obtain a rust preventive coating composition having a viscosity of about 80 seconds (Ford Cup # 4/25 ° C.). It was.

  The amounts of each component in Table 2 are all expressed by solid mass.

In Table 2 above, (Note) in the table has the following meanings.
(Note 2) Cymel 303: Nippon Cytec Industries, Ltd., trade name, methyl etherified melamine resin.
(Note 3) jER154: manufactured by Mitsubishi Chemical Corporation, phenol novolac type epoxy resin, epoxy equivalent of about 178.
(Note 4) Ca ion exchange silica: R. Grace & Co. SHIELDEX (Shielddex, registered trademark) C303 manufactured by the company.
(Note 5) Mg ion-exchanged silica: 10 parts by mass of silicia 710 (manufactured by Fuji Silysia Chemical Co., Ltd., trade name, average particle size of about 2.8 μm, oil absorption in 10000 parts by mass of magnesium chloride aqueous solution having a concentration of 5% by mass. (Silica fine particles of a quantity of 105 cc / 100 g) was added and stirred and mixed for 5 hours, followed by filtration to take out the solid content, and the solid content was washed thoroughly with water and dried to obtain magnesium ion-exchanged silica.

[Creation of test paint plate]
Using each rust preventive coating composition obtained in the above Examples , Reference Examples and Comparative Examples, the back coating obtained in Production Example 13 and the following top coating, each material was coated and baked with the following coating specifications, A test plate was obtained.

Paint specification 1:
Chemically treated galvalume steel sheet (thickness 0.35 mm, aluminum-zinc alloy plated steel sheet, containing about 55% aluminum in alloy, alloy plating basis weight 150 g / m ² , indicated as “GL steel sheet” in Table 2 The back coating obtained in Production Example 13 was applied with a bar coater to a dry film thickness of 8 μm, and baked for 30 seconds so that the maximum material temperature reached 180 ° C. Formed. On the steel plate surface opposite to the back surface coating film of the coated plate on which this back surface coating film was formed, each rust preventive coating composition obtained in each of the above examples was coated with a bar coater so as to have a dry film thickness of 5 μm. Each primer coating was formed by baking for 40 seconds so that the maximum temperature reached 220 ° C. After cooling, KP color 1580B40 (trade name, polyester-based top coating, blue, glass transition temperature of cured coating about 70 ° C.) is applied to these primer coatings with a bar coater. The coating was applied to a thickness of about 15 μm, and baked for 40 seconds so that the maximum material temperature reached 220 ° C., to obtain a test plate for each test.

Paint specification 2:
Chemically treated aluminum-magnesium-zinc alloy-plated steel sheet (manufactured by Nippon Steel Corp., plate thickness 0.35 mm, in alloy, 11% aluminum, 3% magnesium, trace amount of silicon, remaining amount of Containing zinc; alloy plating basis weight 160 g / m ² , indicated as “SD steel plate” in Table 2.), using a bar coater so that the back coating obtained in Production Example 13 has a dry film thickness of 8 μm. The film was painted and baked for 30 seconds so that the maximum material temperature reached 180 ° C. to form a back coating film. On the steel plate surface opposite to the back surface coating film of the coated plate on which this back surface coating film was formed, each rust preventive coating composition obtained in each of the above examples was coated with a bar coater so as to have a dry film thickness of 5 μm. Each primer coating was formed by baking for 40 seconds so that the maximum temperature reached 220 ° C. After cooling, KP color 1580B40 (trade name, polyester-based top coating, blue, glass transition temperature of cured coating about 70 ° C.) is applied to these primer coatings with a bar coater. The coating was applied to a thickness of about 15 μm, and baked for 40 seconds so that the maximum material temperature reached 220 ° C., to obtain a test plate for each test.

Paint specification 3:
On the hot-dip galvanized steel sheet subjected to chemical conversion treatment (plate thickness 0.35 mm, galvanized basis weight 250 g / m ² , indicated as “GI steel sheet” in Table 2), the coating for the back surface obtained in Production Example 13 Was coated with a bar coater so as to have a dry film thickness of 8 μm, and baked for 30 seconds so that the maximum material reaching temperature was 180 ° C. to form a back coating film. On the steel plate surface opposite to the back surface coating film of the coated plate on which this back surface coating film was formed, each rust preventive coating composition obtained in each of the above examples was coated with a bar coater so as to have a dry film thickness of 5 μm. Each primer coating plate was obtained by baking for 40 seconds so that the maximum temperature reached 220 ° C. After cooling, KP color 1580B40 (trade name, polyester-based top coating, blue, glass transition temperature of cured coating film of about 70 ° C.) is dried on these primer coating plates with a bar coater. The coating was applied to a thickness of about 15 μm, and baked for 40 seconds so that the maximum material temperature reached 220 ° C., to obtain a test plate for each test.

[Coating performance test]
About each coating plate for a test obtained by the said coating specification, the coating-film performance test was done according to the following test method. The test results are shown in Table 3 below.

Test method Folding workability: At a room temperature of 20 ° C., each test coating plate cut to a size of 6 cm × 12 cm is subjected to 4T bending processing (the surface side of the coating plate is applied so that the length of the bent portion is 6 cm). Folding was performed outside, and four plates having the same thickness as the painted plate were sandwiched inside, and the painted plate was bent 180 degrees in a vise). The crack resistance of the coating film in the bent portion and the adhesion of the coating film in the bent portion were evaluated according to the following criteria. The adhesiveness of the coating film in the bent portion was evaluated by the degree of peeling of the coated film in the bent portion when a cellophane adhesive tape was applied to the bent portion and the tape was peeled off instantaneously.
(Draft resistance of the coating film in the bent part)
◎: No cracking of the coating film is observed in the processed part ○: Slight cracking of the coating film is recognized in the processing part Δ: There is considerable cracking of the coating film in the processing part ×: Cracking of the coating film is observed in the processing part Remarkably recognized.
(Adhesion of the coating film in the bent part)
◎: No peeling of the coating film is observed in the processed area ○: A slight peeling of the coating film is observed in the processing area Δ: A considerable peeling of the coating film is observed in the processed area X: The coating film is peeled off on the entire processing area To do.

Impact resistance: according to JIS K-5400 8.3.2 (1990), using a DuPont impact tester, at a room temperature of 20 ° C., falling weight against the coating surface on the surface side of each test coating plate Performs under conditions of weight 500g, falling weight height 50cm, tip diameter 1/2 inch, close contact with cellophane adhesive tape on the surface of the coating, and the degree of cracking and peeling of the coating after abrupt peeling. Evaluated.
○: No cracking or peeling is observed in the coating film Δ: Slight cracking or peeling is observed in the coating film ×: Many cracking or peeling is recognized in the coating film.

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 adhesion test 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 residual grid number was 91 to 99, or the coating film had no abnormality such as blistering or whitening, but the residual grid number was 71 to 99. 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 30 ° 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 swelling, and the tape peeling width from the cut part is 1.5 mm or less.
○: There is no occurrence of blisters, and the tape peeling width from the 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.

Scratch resistance: At a room temperature of 20 ° C., the edge of the 10-yen copper coin is pressed at an angle of about 45 degrees against the coating surface on the surface side of each test plate, and the 10-yen copper coin is 10 mm while being pressed with a load of 1 kg. The film was evaluated according to the following criteria from the degree of scratching when the coating surface was scratched by pulling about 30 mm at a rate of / sec and the difficulty of peeling off the coating film from the substrate.
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.

Combined cycle corrosion test (CCT test): according to JASO M609-91 (automobile material corrosion test 1991). 6 cm x 12 cm so that the burrs at the edge of the long side of each test paint plate face toward the front side on the right side and face toward the front side and toward the back side on the left side.
Insert a crosscut with a narrow angle of 30 degrees and a line width of 0.5 mm into the center of the surface side of each test paint plate cut to the size of the plate using the back of the cutter knife to prevent the upper edge of the paint plate. Sealed with rust paint, 4T bent part at the upper end (folded with the surface side of the paint plate facing outward, sandwiching four plates of the same thickness as the paint plate inside, and the paint plate in a vise For coated plates provided with a process of bending 180 degrees (5% saline spray at 35 ° C for 2 hours)-(drying at 60 ° C for 4 hours relative humidity 95%)-(wet at 50 ° C for 2 hours relative humidity 95%) ) Was taken as one cycle, and a test was conducted for 100 cycles (total 800 hours). The state of the 4T bending process part, crosscut part, and edge part of the coated board after this test was evaluated.

(4T process part) The total length of the rust part in a 4T process part was evaluated.
A: No occurrence of rust,
○: White rust is observed, but 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.

(Cross cut part) Corrosion state of the cross cut part, by the average value of the white rust occurrence length ratio in the bare metal exposed part of 0.5mm cut width, and the left and right swelling width (sum of both sides) of the cut part, Evaluation was made according to the following criteria.
A: White rust generation length ratio in exposed metal portion is less than 50% and swelling width is less than 3 mm,
○: The white rust generation length ratio in the bare metal exposed portion is 50% or more and less than 3 mm, or the white rust occurrence length ratio in the bare metal exposed portion is less than 50% and the swelling width is 3 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: The white rust generation length ratio in the bare metal exposed part is 50% or more and the swelling width is 10 mm or more.

(Edge part) The average value of the edge creep widths of the left and right long sides of the coated plate was determined and evaluated according to the following criteria.
A: Less than 5 mm
○: 5 mm or more and less than 10 mm,
Δ: 10 mm or more and less than 20 mm,
X: 20 mm or more.

Weather-resistant salt spray test: Based on A method of accelerated weathering (xenon lamp method) test for long-term durability of coating film specified in JIS K 5600 7.7 on a test coating plate cut to a size of 5 cm × 10 cm, Irradiation was continued for 500 hours with a xenon weatherometer under repeated cycle conditions (wet 18 minutes-dry 102 minutes). Next, the back surface and the cut surface were sealed with a rust preventive paint, and a cross cut reaching the substrate was put in the center of the surface of the painted plate. About this coating board, after performing the salt spray test (JIS Z-2371) for 500 hours, the external appearance of the plane part was evaluated by the following reference | standard.
A: The swelling / rust progression width from the cut part is 3 mm or less on average across the cut, and no other abnormalities are observed.
○: The bulge / rust progression width from the cut part exceeds 3 mm and is 5 mm or less, and no abnormality is observed in the flat part or the like, or slight blistering is observed in the flat part, but from the cut part The swelling / rust progression width is 3 mm or less.
Δ: The swelling / rust progression width from the cut part exceeds 3 mm and is 5 mm or less, and slight swelling is observed in the flat part.
X: The swelling / rust progression width from the cut portion exceeds 5 mm, or significant swelling is observed in the flat portion.

Claims (8)

(A) Contains an amine-modified epoxy resin having a number average molecular weight of 1,000 to 10,000, an amine value of 10 to 50 mgKOH / g, and a hydroxyl value of 180 to 280 mgKOH / g, (B) a curing agent, and (C) a non-chromium rust preventive pigment. A coating composition, wherein the amine-modified epoxy resin (A) is a bisphenol-type epoxy resin obtained by reacting a bisphenol-type polyepoxide with a primary amine containing an alkyl group having 4 to 18 carbon atoms to extend a chain; An amine-modified epoxy having a solid content based on 100 parts by mass of the total solid content of the amine-modified epoxy resin (A) and the curing agent (B). Zinc plating or resin (A) is 85 to 97 parts by mass and the curing agent (B) is 3 to 15 parts by mass Lead alloy-plated steel sheet for an organic solvent-based anticorrosive coating composition. The rust preventive coating composition according to claim 1, wherein the curing agent (B) is at least one crosslinking agent selected from an amino resin and a polyisocyanate compound which may be blocked. The non-chromium rust preventive pigment (C) is (1) at least one vanadium compound of vanadium pentoxide, calcium vanadate and ammonium metavanadate, and (2) at least one of metal silicate and silica fine particles. The rust-preventive coating composition according to claim 1 or 2, comprising a silicon-containing compound of (3) and (3) a phosphate metal salt. The rust prevention according to claim 3, wherein at least one of the silicon-containing compound (2) and the phosphate metal salt (3) generates Ca ions, Mg ions, Co ions or Ni ions in water. Paint composition. Based on 100 parts by mass of the total solid content of the amine-modified epoxy resin (A) and the curing agent (B), the amount of vanadium compound (1) in the non-chromium rust preventive pigment (C) is 1 to 50 parts by mass, silicon The rust preventive coating composition according to claim 3 or 4, wherein the amount of the containing compound (2) is 1 to 50 parts by mass and the amount of the phosphoric acid metal salt (3) is 1 to 50 parts by mass. Furthermore, the antirust coating composition as described in any one of Claims 1-5 which contains a novolak-type epoxy resin as a resin component. The galvanized or zinc alloy plated steel sheet has Al: 2 to 19% by mass, Mg: 1 to 10% by mass, Si: 0 to 2% by mass, and the total of Al and Mg is 20% by mass or less, and the balance 7 is a zinc alloy plated steel sheet having a Zn—Al—Mg based plating layer substantially having a composition of Zn. 7. The rust preventive coating composition according to claim 1. A coating method comprising coating the anticorrosive coating composition according to any one of claims 1 to 7 on a zinc-plated or zinc alloy-plated steel sheet whose surface may be subjected to chemical conversion treatment. .