TWI392711B - Aqueous coating composition - Google Patents

Description

Waterborne coating composition Field of invention

The present invention relates to an aqueous coating composition of a coating film which is capable of forming chemical resistance, corrosion resistance of a flat portion of a metal sheet, corrosion resistance and adhesion of a processed portion of a metal sheet and an end surface portion, and has a composition comprising the aqueous coating material A metal plate coated with a coating film formed by the object.

Background of the invention

In the past, pre-coated metal sheets such as precoated steel sheets coated with coil coatings and the like have been widely used as building materials for roofs, walls, shutters, garages, etc., various home appliances, and switchboards. Use of residential related products such as frozen display cabinets, steel furniture and kitchen appliances.

In the case of these residential-related products made of pre-coated metal sheets, the pre-coated metal sheets are usually cut and joined by press molding. Therefore, in many of these house-related products, there are many metal exposed portions of the cut surface or crack generating portions due to press working. Since the metal exposed portion or the crack generating portion is more likely to have lower corrosion resistance than other portions, it is generally practiced to use a chromium-based rust preventive pigment in the undercoat coating film which is used for precoating a metal plate to improve corrosion resistance.

However, a chromium-based rust-preventive pigment or a hexavalent chromium excellent in rust-preventing property may generate hexavalent chromium. The hexavalent chromium poses a problem from the viewpoint of the health of the human body and environmental protection.

So far, non-chromium anti-rust pigments have zinc phosphate and tripolyphosphate. A large number of products such as aluminum acid and zinc molybdate are on the market, and various products have been proposed as primers for combining non-chromium pigments. In addition, in order to reduce volatile organic compounds (VOCs) from the environmental issues, the development of water-based coatings has been demanded.

For example, Patent Document 1 discloses an anti-rust pigment in which a combination of an epoxy resin and a phenol resin is mixed, a combination of calcium citrate and phosphorus vanadate, or calcium carbonate and calcium citrate with aluminum phosphate and vanadic acid. A combination of phosphorus and anti-rust pigments.

Further, Patent Document 2 discloses that diammonium phosphate and manganese oxide are mixed in the polyester. The vanadium oxide sinter is used as a coating for anti-rust pigments and a coating of calcium phosphate and vanadium oxide.

However, when the rust preventive pigments described in Patent Documents 1 and 2 are applied to an aqueous paint, corrosion resistance is inferior to that of a paint using a chromium-based pigment, and particularly, the corrosion resistance of the processed portion and the end surface portion of the metal plate is insufficient. In addition, there are cases in which chemical resistance or water resistance such as alkali resistance or acid resistance is poor.

Further, Patent Document 3 describes a coating composition containing an oil-absorbing amount of 30 to 200 ml/100 g and a pore volume of 0.05 to 1.2 in a vehicle component formed of an organic resin containing a hydroxyl group or an epoxy group and a curing agent. A coating of ml/g of cerium oxide microparticles, and the glass transition temperature of the hardened coating film formed by the coating is in the range of 40 to 125 °C. However, the coating film obtained by applying the cerium oxide fine particles described in Patent Document 3 to an aqueous coating material is inferior in corrosion resistance and chemical resistance to a coating material using a chromium-based pigment, and particularly has insufficient corrosion resistance at the end face of the metal plate. .

Further, Patent Document 4 discloses a chromium-free coated steel excellent in corrosion resistance A plate characterized by being mixed with a primer coating film selected from the group consisting of magnesium phosphate, zinc phosphate, magnesium hydrogen phosphate, aluminum dihydrogen phosphate, calcium citrate, or two or more non-chromium rust-preventing pigments. And a partial hydrolysis-condensation product of tetra-alkoxysilane as a topcoat coating film of a hydrophilic agent, which is laminated on the surface of the plating layer.

Further, Patent Document 5 discloses an internal gelled hard polymer particle (a) having an average particle diameter of 0.4 to 0.6 μm, water-dispersible cerium oxide (b), glycidoxyalkyl-trialkyloxy group. Aqueous anti-rust coating agent for glycidoxyalkyl trialkoxysilanes (c), organic vanadium compound (d), water-dispersible urethane resin (e), zirconium compound (f) and diammonium hydrogen phosphate (g) The galvanized steel sheet coated with the composition was treated.

However, the coating film obtained by coating the coating material containing the rust preventive pigment described in Patent Document 4 or Patent Document 5 is inferior in corrosion resistance and chemical resistance as compared with the coating film obtained by coating a coating material containing a chromium-based pigment. In particular, the corrosion resistance of the end face of the metal plate is insufficient.

Patent Document 1: Japanese Patent Publication No. 11-61001

Patent Document 2: JP-A-2000-199078

Patent Document 3: JP-A-2000-129163

Patent Document 4: JP-A-2007-260953

Patent Document 5: JP-A-2008-81785

Summary of invention

An object of the present invention is to provide a non-chromium-based aqueous coating composition which can form a coating film which is excellent in chemical resistance, corrosion resistance of a flat portion of a metal plate, and corrosion resistance and adhesion of a processed portion of a metal plate and an end surface portion. A coated metal sheet having a coating film excellent in coating film properties is provided.

Therefore, the present inventors have repeatedly studied intensively to solve the above-mentioned problems, and as a result, it has been found that a specific vanadium compound (c1) is mixed in a predetermined amount by adding a cationic resin (A) and a polyisocyanate hardener (B). The rust preventive pigment mixture (C) obtained by the hydrazine compound (c2) and the phosphate calcium salt (c3) is formed into an aqueous coating composition, and can form not only chemical resistance but also corrosion resistance of the flat portion of the coated metal sheet. The present invention has been completed by coating a film having excellent corrosion resistance in a processed portion such as a metal plate or the like.

That is, the present invention relates to the following aqueous coating compositions.

An aqueous coating composition comprising a cationic resin (A), a polyisocyanate curing agent (B), and a rust preventive pigment mixture (C) described below.

The rust preventive pigment mixture (C) is composed of at least one of vanadium pentoxide, calcium vanadate and ammonium metavanadate (c1), bismuth compound (c2) and calcium phosphate (c3). And the amount of the vanadium compound (c1) is 1 to 30 parts by mass, and the amount of the cerium compound (c2) is 1 to 30 mass, based on 100 parts by mass of the total solid content of the resin (A) and the curing agent (B). The amount of the phosphate-based calcium salt (c3) is 1 to 30 parts by mass, and the amount of the rust-preventing pigment mixture (C) is 3 to 90 parts by mass.

2. The aqueous coating composition according to the above item 1, wherein the cationic resin (A) is an amino group-containing epoxy resin.

3. The aqueous coating composition according to the above item 1, wherein the cerium compound (c2) is at least one selected from the group consisting of a metal citrate salt, cerium oxide microparticles, and metal ion-exchanged cerium oxide microparticles.

4. The aqueous coating composition according to the above item 1, wherein the phosphate-based calcium salt (c3) is at least one of calcium phosphate, calcium monohydrogen phosphate, calcium dihydrogen phosphate, and calcium tripolyphosphate.

5. The aqueous coating composition according to the above item 1, which contains 0.1 to 10 parts by mass of a Resole type phenol resin in a total amount of the solid content of the cationic resin (A) and the polyisocyanate (B).

A method of forming a coating film, comprising forming a cured coating film obtained by using the aqueous coating composition according to the above item 1 on a metal plate, and forming at least one of the surface of the cured coating film. Coating film for lacquer coatings.

A coated metal plate comprising the coating film obtained by the method for forming a coating film according to the above item 6.

8. A coated article obtained by processing the coated metal sheet according to item 7 above.

The aqueous coating composition containing a specific anti-rust pigment mixture of the present invention is advantageous in terms of environmental hygiene because it does not contain a chromium-based anti-rust pigment and is an aqueous coating.

The coating film obtained by coating the aqueous coating composition of the present invention is excellent in chemical resistance, and is excellent in corrosion resistance not only in the flat portion of the metal sheet but also in the water-based coating containing a conventional non-chromium-based rust-preventing pigment. Difficult to achieve The corrosion resistance or adhesion of the processed portion and the end surface portion of the coated metal sheet can also exhibit excellent effects.

In addition, on a hot-dip galvanized steel sheet (GI steel sheet) which is not subjected to chemical conversion treatment, a coated steel sheet coated with a hardened coating film obtained by coating the aqueous coating composition of the present invention and dried by heating is applied thereto. In the hot-dip galvanized steel sheet (GI steel sheet) subjected to the chemical conversion treatment, the coated steel sheet coated with the hardened coating film containing the chromate-based anti-rust pigment may have corrosion resistance equal to or higher than that. Therefore, the chemical conversion treatment program (see Fig. 1) can be omitted, which is advantageous for the proceduralization and resource saving of the coating line.

Simple illustration

[Fig. 1] An example of a continuous coil coating line is illustrated.

[Fig. 2] An example of a coating film structure of a coating film containing the aqueous coating composition of the present invention.

Form for implementing the invention

The aqueous coating composition of the present invention relates to an aqueous coating composition characterized by containing a specific amount of a cationic resin (A) and a polyisocyanate curing agent (B) and a specific rust preventive pigment mixture (C). Hereinafter, it will be described in detail.

Metal plate

Examples of the metal plate to be coated include a galvanized steel sheet such as an electric galvanized steel sheet, an electric galvanized-nickel steel sheet, a hot-dip galvanized steel sheet, a hot-dip galvanized-aluminum steel sheet, a hot-rolled steel sheet, a cold-rolled steel sheet, or a stainless steel. Steel plate, copper plated steel plate, aluminum plate, hot-dip tin-zinc (Sn-10% Zn) steel plate, hot-dip aluminized steel plate, Al-Mg alloy, and the like.

2. Cationic resin (A)

The cationic resin (A) is a resin having a cationizable group such as an amine group, an ammonium group, a decyl base or a decyl base in the molecule. The type of the resin is usually a user, and examples thereof include an epoxy resin, an acrylic resin, a polybutadiene resin, an alkyd resin, and a polyester resin. In particular, an amine group-containing epoxy resin obtained by subjecting an amine group-containing compound to an addition reaction in an epoxy resin is excellent in chemical resistance and excellent in corrosion resistance in a flat portion of a metal plate, and is improved from a processing portion and The corrosion resistance of the end face is also suitable.

The above-mentioned epoxy group-containing epoxy resin may, for example, be an adduct of (1) an epoxy resin with a primary mono- and polyamine, a secondary mono- and polyamine or a primary or secondary mixed polyamine (for example, see U.S. Patent No. 3,984,299; (2) an epoxy resin and an adduct of a secondary mono- and polyamine containing a ketimine-substituted primary amine group (for example, see U.S. Patent No. 4,017,438); 3) A reaction product obtained by etherification of an epoxy resin and a hydroxy compound containing a ketimine-substituted primary amino group (see, for example, JP-A-59-43013).

The epoxy resin used in the production of the above-described epoxy group-containing epoxy resin is one having at least one epoxy group in one molecule and preferably two or more. The molecular weight of the epoxy resin is generally at least 300, preferably 400 to 4,000, more preferably "number average molecular weight" in the range of 800 to 2,500, and at least 160 g/eq, at 180 to 2,500 g/eq. Preferably, it is preferably an epoxy equivalent in the range of 400 to 1,500 g/eq, especially through polyphenol compounds. The reaction of epihalohydrin is preferred.

In the present specification, the "number average molecular weight" is in accordance with the method described in JIS K 0124-83, and the following four separation columns are used, and a solution (GPC tetrahydrofuran) is used at 40 ° C and a flow rate of 1.0 ml / min. Calculated from a chromatogram obtained using an RI refractometer and a standard curve of standard polystyrene.

Separation column: "TSK GEL4000HXL", "TSK G3000HXL", "TSK G2500HXL", "TSK G2000HXL" (each is manufactured by Tosoh Corporation).

Examples of the polyphenol compound used for forming the epoxy resin include 2,2-bis(4-hydroxyphenyl)propane [bisphenol A] and bis(4-hydroxyphenyl)methane [bisphenol F]. Bis(4-hydroxycyclohexyl)methane [hydrogenated bisphenol F], 2,2-bis(4-hydroxycyclohexyl)propane [hydrogenated bisphenol A], 4,4'-dihydroxybenzophenone, 1, 1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)isobutane, 2,2-bis(4-hydroxy-3-tert-butyl-phenyl)propane, Bis(2-hydroxynaphthyl)methane, 1,1,2,2-tetrakis(4-hydroxyphenyl)methane, 4,4'-dihydroxydiphenylanthracene, Novolac- Type phenolic, cresol novolac, and the like.

Further, an epoxy resin obtained by a reaction of a polyphenol compound with epichlorohydrin is used, and among them, a resin of the following formula derived from bisphenol A is particularly suitable.

In the above formula, n is preferably represented by 0 to 8.

Commercial products of related epoxy resins include, for example, jER828EL, jER1002, jER1004, jER1007 (Japan Epoxy Resins Co. Ltd., trade name), Araldite AER6099 (manufactured by Asahi Ciba Co., Ltd., trade name), and EPOMIK R-309. (manufactured by Mitsui Chemicals Inc., trade name).

The epoxy resin may be a modified epoxy resin which is reacted with a modified component such as a polyol, a polyether polyol, a polyester polyol, a polyamidoamine, a polybasic acid or a polyisocyanate compound. Further, it may be a modified epoxy resin obtained by graft-polymerizing a lactone such as ε-caprolactone or an acrylic monomer.

Further, a method of reacting the above-mentioned modified component with an epoxy resin to produce a modified epoxy resin is not particularly limited. The reaction between the modified component and the epoxy resin can be transmitted, for example, in a solvent capable of dissolving the respective components, if necessary, in the presence of a reaction catalyst, usually at 100 to 150 ° C for 1 to 5 hours. , proceed properly.

The reaction catalyst may, for example, be a catalyst of a quaternary salt such as tetra-ethylammonium bromide, tetrabutylammonium bromide or triphenylbenzylphosphonium chloride. An amine such as triethylamine.

The primary mono- and polyamines, the secondary mono- and polyamines, or the primary and secondary mixed polyamines used in the production of the amine group-containing epoxy resin of the above (1), for example, monomethylamine, Mono- or di-alkylamines such as methylamine, monoethylamine, diethylamine, monoisopropylamine, diisopropylamine, monobutylamine, dibutylamine, etc.; monoethanolamine, diethanolamine, mono(2-hydroxypropyl) An alkanolamine such as an amine or monomethylamine ethanol; ethylenediamine, propylenediamine, butanediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine An amine compound such as an alkylene polyamine.

A secondary mono- and polyamine having a ketimine-substituted primary amine group used in the production of the amine group-containing epoxy resin of the above (2), for example, in the production of the epoxy resin of the above (1) Among the first-stage mixed polyamines used in the amine adduct, for example, a ketimine of an amine compound which is formed by reacting a ketone compound in diethylenetriamine or the like.

The hydroxy compound having a ketimine-substituted primary amine group used in the production of the amine group-containing epoxy resin of the above (3), for example, in the production of the epoxy resin amine adduct of the above (1) Among the primary mono- and polyamines, secondary mono- and polyamines or mixed primary and secondary polyamines, compounds containing a primary amine group and a hydroxyl group, for example, monoethanolamine, mono(2-hydroxypropyl) A hydroxyketone imide of an amine compound which is formed by a ketone compound in an amine or the like.

In particular, among the amine-containing epoxy resins, from the viewpoint of improving the corrosion resistance of the processed portion in the precoated steel sheet, a preferred resin is, for example, an amine compound or the like added to a carbon number of 4 to 36. The aliphatic polybasic acid and epoxy resin are reacted to form a modified epoxy resin, and the aliphatic polybasic acid is modified with an amine-based epoxy resin; others, such as an amine compound or the like, is added to the polyisocyanate compound and An amine-containing epoxy resin modified by a diisocyanate compound formed by a modified epoxy resin obtained by reacting an epoxy resin.

The above aliphatic polybasic acid having 4 to 36 carbon atoms is preferably a saturated or unsaturated aliphatic polybasic acid having 6 to 36, and examples thereof include hexa-hydroisophthalic acid and hexahydro-p-benzoic acid. Formic acid (hexahydro-terephthalic acid), hexahydrophthalic acid, methylhexahydrophthalic acid, methylhexahydroterephthalic acid, 1-four Hydrogen phthalic acid, 2-tetrahydrophthalic acid, 3-tetrahydrophthalic acid, 4-tetrahydrophthalic acid, 1-tetrahydroisophthalic acid, 2-tetrahydroisophthalic acid , 3-tetrahydroisophthalic acid, 4-tetrahydroisophthalic acid, 1-tetrahydroterephthalic acid, 2-tetrahydroterephthalic acid, methyltetrahydrophthalic acid, endamethylene An alicyclic dicarboxylic acid anhydride such as endomethylene tetrahydrophthalic acid, methyl endomethylenetetrahydrophthalic acid or hexachloromethylenetetrahydrophthalic acid; amber Acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, tetradecanedioic acid, suberic acid, pimelic acid, maleic acid, reversed Fumaric acid, Itaconic acid, brassylic acid, citraconic acid, chloromaleic acid An aliphatic dicarboxylic acid such as a dimer acid or the like; an aliphatic polybasic acid having a trivalent or higher value such as a hexahydrotrimellitic acid; or a lower alkyl ester of a methyl ester or an ethyl ester of such an acid; .

The above polyisocyanate compound may, for example, be tolylene diisocyanate, xylylene diisocyanate, phenylene diisocyanate, diphenylmethane-2,2'-diisocyanate or diphenyl. Methane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, crude MDI [polymethylene polyphenyl isocyanate], bis(isocyanatomethyl) ring Aromatic, aliphatic or aliphatic such as bis (isocyanatomethyl)-cyclohexane, tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, isophorone diisocyanate Ring polyisocyanate compounds; these polyisocyanates a cyclized polymer or biuret of a compound; or a combination thereof.

In particular, hexamethylene diisocyanate is suitable from the viewpoint of improving the corrosion resistance of the processed portion and the end surface portion.

Furthermore, when the amine-containing epoxy resin is produced, the addition reaction of the epoxy resin (modified epoxy resin) and the amine-containing compound can be usually carried out in a suitable solvent, preferably at 80 to 170 ° C (more The temperature is preferably from 90 to 150 ° C for 1 to 6 hours (preferably 1 to 5 hours). The solvent may, for example, be a hydrocarbon solvent such as toluene, xylene, cyclohexane or n-hexane; an ester solvent such as methyl acetate, ethyl acetate or propyl acetate; acetone, methyl ethyl ketone or methyl isobutyl ketone; a ketone solvent such as methyl amyl ketone; a guanamine solvent such as dimethylformamide or dimethylacetamide; methanol, ethanol, n-propanol or isopropanol; An alcohol solvent; or a mixture thereof or the like.

The proportion of the respective reaction components in the above-mentioned addition reaction may be appropriately changed without strict restrictions, but the epoxy resin (modified epoxy resin) and the amine-containing compound are used as a reference for the solid content quality, and the epoxy resin is preferably used. 70 to 97% by mass, preferably 70 to 95% by mass, more preferably 80 to 95% by mass; and the amine-containing compound is preferably used in an amount of 3 to 30% by mass, preferably 5 to 30% by mass, more preferably It is in the range of 5 to 20% by mass.

Further, the amount of the amine group-containing compound used is from the viewpoint of improving water dispersibility and coating film corrosion resistance, and the amine resin of the final product of the present invention has an amine price of 10 to 80 mgKOH/g to fall at 20 to 70 mgKOH. The range of /g is better.

3. Polyisocyanate hardener (B)

The aqueous coating composition of the present invention is mixed in a cationic resin (A) A thermosetting coating made of a polyisocyanate curing agent (B).

As the polyisocyanate compound used in the polyisocyanate hardener (B), a known compound such as toluene diisocyanate, benzodimethylisocyanate, phenylene diisocyanate, diphenylmethane-2,2'-di can be used. Isocyanate, diphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, crude MDI [polymethylene polyphenyl isocyanate], bis(isocyanatomethyl)cyclohexane An aromatic, aliphatic or alicyclic polyisocyanate compound such as an alkane, tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate or isophorone diisocyanate; a ring of such polyisocyanate compounds a polymer or biuret; or a combination thereof.

In particular, aromatics such as toluene diisocyanate, benzodimethyl diisocyanate, phenylene diisocyanate, diphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, and crude MDI The isocyanate compound is particularly suitable from the viewpoint of corrosion resistance of the flat portion of the metal plate.

In particular, when hexamethylene diisocyanate is used as the type of isocyanate, since the curability is improved and the flexibility of the coating film is imparted, it is preferable to improve the corrosion resistance of the processed portion and the end surface portion of the precoated steel sheet.

Further, in the present invention, as the polyisocyanate curing agent (B), a blocked polyisocyanate compound obtained by subjecting the polyisocyanate compound and the isocyanate blocking agent to an addition reaction amount close to a stoichiometric amount can be suitably used.

The aforementioned isocyanate blocking agent is added to the isocyanate group of the polyisocyanate compound to be blocked. The blocked polyisocyanate compound formed by the addition is stable at normal temperature, but is heated to the sintering temperature of the coating film. At a degree (usually 100 to 200 ° C), it is desirable that the isocyanate blocking agent be dissociated to form free isocyanate groups.

The isocyanate blocking agent may, for example, be an oxime compound such as methyl-ethylketoxime, methylamylketoxime or cyclohexanone oxime; or a phenolic compound such as phenol, p-tert-butylphenol or cresol. An aliphatic alcohol such as n-butanol or 2-ethylhexanol; an aromatic alkanol such as benzyl alcohol or methyl benzyl alcohol; an ether alcohol such as ethylene glycol monobutyl ether or diethylene glycol monoethyl ether; a compound; an indoleamine compound such as ε-caprolactam or γ-butyrolactam or the like.

The mixing ratio of the cationic resin (A) and the polyisocyanate curing agent (B) is preferably 60 to 95% by mass based on the total mass of the solid content of the component (A) and the component (B). It is preferably 70 to 90% by mass, and the component (B) is preferably 5 to 40% by mass, preferably 10 to 30% by mass, which is suitable from the viewpoint of coating stability and hardenability.

In the production of the aqueous coating composition of the present invention, in addition to the cationic resin (A) and the polyisocyanate curing agent (B), various additives and organic solvents such as a surfactant, a surface conditioner, and a Resole type phenol resin are sufficiently mixed. After the blending resin is prepared, the blending resin may be an organic carboxylic acid such as acetic acid, phosphoric acid, formic acid, propionic acid or lactic acid; or an inorganic acid such as hydrochloric acid or sulfuric acid may be dissolved in water or dehydrated to obtain an emulsion.

The Resole-type phenol resin further includes a phenol resin formed by a condensation reaction between a phenol such as phenol or bisphenol A and an aldehyde such as formaldehyde in the presence of a reaction catalyst, or a phenol resin formed by introducing a methylol group, or a carbon number. The alcohol of 6 or less is formed by alkyl etherification of a part of the introduced methylol group.

The number average molecular weight of the Resole type phenolic resin (Note 1) is preferably from 200 to 1,000, preferably from 300 to 900, and the average number of hydroxymethyl groups per benzene nucleus is from 0.3 to 2.5. It is preferably in the range of 0.3 to 2.0. By using the above-described Resole type phenol resin, it is possible to form a coating film having excellent coating properties such as sealing properties.

(Note 1) The number average molecular weight is as described in the above "Crystal Resin (A)".

The commercially available product of the above-mentioned Resole type phenol resin may, for example, be Sumilite Resin PR-55317 (manufactured by Sumitomo Bakelite, trade name) or Shonol BKS-316.

The amount of the above-mentioned Resole-type phenol resin is preferably from 1 to 20% by mass based on the total mass of the solid content of the component (A) and the component (B), from the viewpoint of film adhesion and film stability. 2 to 7 mass% is preferred.

4. Anti-rust pigment mixture (C)

The aqueous coating composition of the present invention can obtain a coating metal plate excellent in chemical resistance, corrosion resistance at a flat portion, corrosion resistance and adhesion of a processed portion and an end portion due to a certain amount of a specific rust preventive pigment mixture (C). . The rust preventive pigment mixture (C) is composed of a vanadium compound (c1), a hydrazine compound (c2), and a phosphate-based calcium salt (c3). Further, the rust preventive pigment mixture (C) may contain a compound other than the vanadium compound (c1), the ruthenium compound (c2), and the phosphate calcium salt (c3).

The details will be described below.

4-1. Vanadium compound (c1)

The vanadium compound (c1) is at least one vanadium compound of vanadium pentoxide, calcium vanadate, and ammonium metavanadate. Vanadium pentoxide, calcium vanadate and ammonium metavanadate, using 5 The vanadium-doped particles are excellent in water elution property, and the pentavalent vanadium particles released from the vanadium compound (c1) react with the material metal or react with ions from the other anti-rust pigment mixture, thereby exerting an effect of improving corrosion resistance. Among them, vanadium pentoxide has an obvious effect of improving corrosion resistance.

4-2. 矽 compound (c2)

The ruthenium compound (c2) contains at least one compound selected from the group consisting of a metal ruthenate salt, a cerium oxide microparticle, and a metal ion-exchanged cerium oxide microparticle.

The metal citrate is a salt formed of cerium oxide and a metal oxide, and may be any of orthosilicate or polysilicate. The bismuth citrate may, for example, be zinc citrate, aluminum citrate, aluminum orthosilicate, aluminum hydrated citrate, calcium aluminum citrate, sodium aluminum citrate, aluminum bismuth citrate, sodium citrate, calcium ortho citrate, partial Calcium citrate, sodium calcium citrate, zirconium silicate, magnesium orthosilicate, magnesium metasilicate, calcium magnesium citrate, manganese citrate, barium strontium, olivine, garnet, thorveitite, different Polar ore, benitopite, neptunite, beryl, diopside, ash, rhodochro, tremolite, hard ochnotite, talc, fisheye, aluminum bismuth Acid salts, borosilicates, strontium salts, feldspars, zeolites, and the like. Among them, as the metal citrate, calcium orthosilicate, calcium metasilicate, magnesium metasilicate, and aluminum citrate are preferred, and calcium orthosilicate and calcium metasilicate are particularly suitable.

The cerium oxide microparticles can be used without any particular limitation as long as it is cerium oxide microparticles, and examples thereof include cerium oxide micropowder which has no surface treatment, cerium oxide micropowder which has been treated with an organic substance on the surface, and calcium ion-exchanged cerium oxide. Microparticles, organic solvent-dispersible colloidal cerium oxide, and the like.

The cerium oxide microparticles having no surface treatment or organic treatment may, for example, preferably have an average particle diameter of 0.5 to 15 μm, preferably 1 to 10 μm. 矽 矽 micro powder.

The oil absorption of the cerium oxide micropowder is 30 to 350 ml/100 g, and can be suitably used in the range of 30 to 150 ml/100 g. Commercially available products, for example, Sylysia 710, Sylysia 740, Sylysia 550, Aerosil R 972 (all of which are manufactured by Fuji Silysia Chemical Ltd.), MIZUKASIL P-73 (manufactured by Mizusawa Chemical Industry Co., Ltd.), Gasil 200 DF (manufactured by Crosfield Chemical Inc.) or the like.

The organic solvent-dispersible colloidal cerium oxide is also known as an organic cerium oxide sol (Organosilica Sol), and is stably dispersed in an organic solvent such as an alcohol, a glycol or an ether, and has a particle size of about 5 to 120 nm. For example, an Oscar (OSCAL) series (manufactured by Catalyst Chemical Co., Ltd.) or an organosol (manufactured by Nissan Chemical Co., Ltd.) can be used.

The metal ion-exchanged cerium oxide microparticles are introduced into the fine porous cerium oxide carrier cerium oxide microparticles by ion exchange. Specifically, calcium or magnesium cerium oxide microparticles are introduced. Commercially available products of calcium ion-exchanged cerium oxide include, for example, SHIELDEX (Shield, registered trademark) C303, SHIELDEX AC-3, and SHIELDEX C-5 (each of which is manufactured by W.R. Grace & Co.).

The alkaline earth metal ions released by metal ion exchange of cerium oxide are related to electrochemical action or formation of various salts, and can effectively improve corrosion resistance. Further, the cerium oxide fixed in the coating film effectively suppresses peeling of the coating film in a corrosive atmosphere.

4-3. Phosphate-based calcium salt (c3)

Phosphate-based calcium salt (c3) is a phosphate containing calcium as a metal element, For example, calcium phosphate, ammonium calcium phosphate, calcium hydrogen phosphate, calcium dihydrogen phosphate, calcium chlorofluorophosphate, calcium tripolyphosphate, and the like. The phosphate ion and calcium ion released from the calcium phosphate salt (c3) effectively improve the corrosion resistance.

In the aqueous coating composition of the present invention, the vanadium compound (c1) and ruthenium of the rust preventive pigment mixture (C) are 100 parts by mass based on the total solid content of the cationic resin (A) and the polyisocyanate curing agent (B). The compound (c2) and the phosphate calcium salt (c3) are within the following ranges.

Vanadium compound (c1): 1 to 30 parts by mass, preferably 1 to 20 parts by mass, hydrazine compound (c2): 1 to 30 parts by mass, preferably 1 to 20 parts by mass, and calcium phosphate salt (c3): 1 to 30 parts by mass, preferably 1 to 20 parts by mass.

Further, the mixing ratio (mass basis) of the vanadium compound (c1), the cerium compound (c2), and the calcium phosphate salt (c3) is preferably 3 to 20/3 to 20/5 to 20, more preferably 5 to 15. /5~15/10~20. When it is in the above range, it is possible to obtain not only chemical resistance but also corrosion resistance of the flat portion of the metal plate, and a coating film having excellent corrosion resistance and adhesion of the processed portion and the end surface portion of the metal plate.

When the amount of the vanadium compound (c1), the cerium compound (c2), and the phosphoric acid calcium salt (c3) is within the above range, not only chemical resistance but also corrosion resistance of the flat portion of the metal plate can be obtained, and a metal plate can be obtained. A coating film having excellent corrosion resistance and adhesion of the processed portion and the end surface portion is suitable.

Further, in the aqueous coating composition of the present invention, the amount of the rust preventive pigment mixture (C) is 3 to 90 by mass based on 100 parts by mass of the total solid content of the cationic resin (A) and the polyisocyanate curing agent (B). It is preferably 9 to 60 parts by mass. When the amount of the rust preventive pigment mixture (C) is within the foregoing range, The chemical resistance and the corrosion resistance of the flat portion of the metal plate can be obtained, and a coating film having excellent corrosion resistance and adhesion of the processed portion and the end surface portion of the metal plate can be obtained, which is suitable.

The aqueous coating composition of the present invention can form a rust preventive pigment mixture (C) by combining these vanadium compound (c1), bismuth compound (c2) and phosphoric acid calcium salt (c3) in a predetermined amount, and multiply Corrosion resistance. The rust preventive pigment mixture (C) is preferably a mixture containing vanadium pentoxide, calcium metasilicate, and calcium phosphate, and vanadium pentoxide, calcium metasilicate, and calcium phosphate are preferred from the viewpoint of corrosion resistance. The combination is particularly suitable.

Further, the vanadium compound (c1) and the ruthenium compound which constitute the rust preventive pigment mixture (C) are mixed with 100 parts by mass of the total solid content of the cationic resin (A) and the polyisocyanate curing agent (B). C2) and a mixture of the calcium phosphate salt (c3) (the amount of (c1) to (c3) is in the above range), and added to 50,000 parts by mass of a 5 mass% sodium chloride aqueous solution at 25 ° C, and stirred for 6 hours. The filtrate obtained by filtering the supernatant after standing at 25 ° C for 48 hours has a pH of preferably 3 to 8, preferably 4 to 6. When the pH of the filtrate is in the above range, from the viewpoints of the solubility of the vanadium compound (c1), the ruthenium compound (c2), and the phosphate calcium salt (c3) in water and the reactivity of the solution of the rust preventive pigment with the metal plate, Or the viewpoint of corrosion resistance is appropriate.

In other words, the filtrate obtained by the above pH measurement is an amount of the vanadium compound (c1) in an amount of from 1 to 30 parts by mass, based on 5% by mass of a 5% by mass aqueous sodium chloride solution at 25 ° C, and the antimony compound (c2) is added. Any amount in the range of 1 to 30 parts by mass, and any amount in the range of 1 to 30 parts by mass of the phosphate-based calcium salt (c3), the filtrate of the dissolved solution obtained by dissolution.

When the aqueous coating composition of the present invention is produced, the above-mentioned rust preventive pigment mixture (C) and, if necessary, pigment dispersion resin, coloring pigment, extender pigment, organotin compound, ultraviolet absorber, ultraviolet stabilizer, organic An additive for a coating material, a neutralizing agent (for example, an acid, such as acetic acid, phosphoric acid, lactic acid, or the like, which is known from the past, such as a solvent, a decane coupling agent, an anti-settling agent, an antifoaming agent, and a coating surface adjusting agent. a mixture such as a mixture thereof, a vanadium compound (c1), a ruthenium compound (c2), or a phosphate-based calcium salt (c3), and a dispersion mixer in a ball mill, a sand mill, a pebble mill, or the like A dispersion treatment is carried out to mix into the obtained pigment dispersion slurry.

In addition, when a rust preventive agent other than the vanadium compound (c1), the ruthenium compound (c2), or the phosphate-based calcium salt (c3) is added, it can be added in such a manner that the effect of the addition of the rust preventive pigment mixture (C) is not inhibited. .

The pigment dispersion resin can be used, and for example, a base resin containing a hydroxyl group and a cationic group, a tertiary amine type epoxy resin, a quaternary ammonium salt type epoxy resin, a tertiary sulfonium type epoxy resin, or the like can be used. Resin. The amount of the pigment dispersion resin to be used is preferably in the range of 1 to 150 parts by mass, particularly preferably 10 to 100 parts by mass, per 100 parts by mass of the pigment component.

The coloring pigment may, for example, be an organic coloring pigment such as an organic red pigment such as phthalocyanine blue, phthalocyanine green, azo or quinacridone; titanium white, titanium yellow, iron oxide, carbon black, or the like. Inorganic coloring pigments of various sintered pigments and the like, among which titanium white is particularly suitably used.

The above-mentioned extender pigment may, for example, be talc, clay, cerium oxide, mica, alumina, calcium carbonate or barium sulfate.

The amount of the above colored pigment and extender pigment is not particularly limited, but For example, it is about 1 to 100 parts by mass based on 100 parts by mass of the total solid content of the cationic resin (A) and the polyisocyanate curing agent (B).

As the above organotin compound, dibutyl tin dibenzoate, dioctyltin oxide, dibutyltin oxide or the like can be suitably used.

The organic solvent is an organic solvent capable of dissolving or dispersing the cationic resin (A) and the polycyanate curing agent (B) in order to improve the coating property of the aqueous coating composition of the present invention and the like. . Specific examples thereof include hydrocarbon solvents such as toluene, xylene, and high-boiling petroleum hydrocarbons; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone; ethyl acetate and butyl acetate; An ester solvent such as ester, ethylene glycol monoethyl ether acetate or diethylene glycol monoethyl ether acetate, an alcohol solvent such as methanol, ethanol, isopropanol or butanol, ethylene glycol monoethyl ether or ethylene glycol An ether alcohol-based solvent such as butyl ether or diethylene glycol monobutyl ether may be used alone or in combination of two or more.

The aforementioned decane coupling agent may, for example, be β-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, γ-glycidoxypropyltrimethoxysilane, γ-glycidyl ether. Propyl methyl diethoxy decane, γ-glycidyl ether propyl triethoxy decane, N-β (aminoethyl) γ-aminopropyl methyl dimethoxy decane, N-β (amine B Γ-aminopropyltrimethoxydecane, γ-aminopropyltrimethoxydecane, β-aminopropyltriethoxydecane, N-phenyl-γ-aminopropyltrimethoxydecane, N- (Vinylbenzylamine)-β-aminoethyl-γ-aminopropyltrimethoxydecane, etc., may be used alone or in combination of two or more.

It is possible to utilize a pigment which will contain the rust preventive pigment mixture (C) as described above. The dispersion slurry is added to the aforementioned emulsion, and the aqueous coating composition is adjusted in a water-adjusted manner.

5. Coating film forming method

The aqueous coating composition of the present invention can be obtained by coating a metal plate and hardening it. The metal plate to be coated may, for example, be a metal plate as described above. In addition, the surface of these metal plates may be subjected to chemical conversion treatment (pretreatment).

Fig. 1 is a schematic view showing a coating line when the aqueous coating composition of the present invention is used as a primer. Here, since the coating film obtained by coating the aqueous coating composition of the present invention on the hot-dip galvanized steel sheet can obtain a coating film excellent in corrosion resistance even without performing a chemical conversion treatment (pretreatment), coating is performed. The process of chemical conversion treatment (pre-treatment) can also be omitted from the line, and it can contribute to provincial engineering and resource saving.

Further, the chemical conversion treatment (pretreatment) which can be carried out as needed may, for example, be a phosphate treatment such as zinc phosphate treatment or iron phosphate treatment, a composite oxide film treatment, a chromium phosphate treatment, or a chromate treatment.

The coating method of the aqueous coating composition of the present invention can be carried out by a known method such as a roll coating method, a curtain flow coating method, a spray coating method, a brush coating method, or a dipping method on the above metal sheet. To paint.

The thickness of the cured film of the coating film obtained from the aqueous coating composition is not particularly limited, but is usually in the range of 0.5 to 10 μm, preferably 2 to 7 μm.

The curing of the coating film may be appropriately set depending on the type of the resin to be used, and when the coating film coated by the coil coating method or the like is continuously sintered, The maximum temperature at which the material arrives is 100 to 250 ° C, and it is preferably 180 to 230 ° C for 15 to 60 seconds. In the case of batch sintering, it can also be sintered at 80 to 200 ° C for 10 to 30 minutes.

The aqueous coating composition of the present invention is coated on a metal plate, and the formed coating film exhibits excellent corrosion resistance not only in the flat portion of the metal plate but also in the processed portion and the end surface portion of the metal plate.

The reason for this is considered to be the following three points.

1. In a corrosive environment, metal ions generated by dissolution of material metal due to chloride ions, etc., and 5-valent vanadium ions (VO ₃ ^- or VO ₄ ^3- vanadate ions) do not undergo redox reaction directly A precipitated salt is formed, and a trivalent vanadium ion and a material metal ion which are formed by a redox reaction of a pentavalent vanadium ion and a material metal, and a cerium acid ion form a precipitated salt or a compound, thereby effectively coating a material. Exposed face. Further, it is considered that the phosphate ion which is simultaneously eluted causes the corrosion progressing portion and its periphery to be adjusted to a pH range which is particularly suitable for the redox reaction of the pentavalent vanadium ion and the material metal.

2. A part of the rust preventive agent in the aqueous coating composition is dissolved and exists in a metal ion state. When the aqueous coating composition is applied to a metal material and dried by heating to form a coating film, the dissolved component is effectively reacted at the interface of the material metal, and under the coating film, a film such as a chemical conversion treatment film is formed. Oxide film. Further, even if the coating film on the film is damaged, it is possible to form a coating film having a function of protecting the damage (self-healing property) by eluting the metal ions of the rust-preventing pigment mixture (C) from the coating film. The above-mentioned "film and coating film" can be formed by one coating and heat drying. This is presumably helpful for obtaining a coated article excellent in corrosion resistance.

3. By using the vanadium compound (c1), the ruthenium compound (c2) and the phosphate calcium salt (c3) constituting the rust preventive pigment mixture, the above (c1), (c2) and (c3) can be effectively controlled. A weak part of acid resistance or alkali resistance and water resistance. In addition, since calcium ions have a function of suppressing dissolution of the material metal in a strong alkali atmosphere in which the metal of the material exceeding pH 10 is easily dissolved, excellent chemical resistance and water resistance can be simultaneously achieved. The multiplication effect of the action based on these anti-rust pigment mixtures exerts a great function, and it is inferred that this also contributes greatly to the excellent corrosion resistance of the water-based paint.

Further, the glass transition temperature of the cured coating film obtained from the aqueous coating composition of the present invention is 40 to 115 ° C, preferably 50 to 105 ° C from the viewpoints of corrosion resistance, acid resistance and processability of the coating film. .

However, the glass transition temperature of the coating film was measured using DINAMIC VISCO-ELASTO METER MODEL VIBRON (Vibration Type Dynamic Viscoelastic Spectrometer) DDV-IIEA (manufactured by Toyo Baldwin Co., Automatic Dynamic Viscoelasticity Tester), according to the frequency at 110 Hz. The maximum temperature obtained by the change in tan δ obtained by the temperature dispersion measurement.

On the coating film obtained by sintering and drying the aqueous coating composition, a top coat film may be provided as needed (see Fig. 2). The film thickness of the top coat film is 5 to 10 μm, preferably 10 to 50 μm.

The above-mentioned top coat paint may, for example, be a known polyester resin type, an alkyd resin type, a silicone modified polyester resin, an anthrone modified acrylic resin type, or a fluororesin as a precoated steel sheet. A top coat of paint. The type of the top coat is not limited to the above types. In addition, in In the case where workability is particularly emphasized, a polyester-based top coat paint for high processing can be used to obtain a coated metal sheet having particularly excellent workability.

In addition, when a galvanized steel sheet or an aluminized-zinc alloy steel sheet is used as the metal sheet of the object to be coated, the corrosion resistance of the flat portion of the metal sheet is greatly improved, but as of the current technology, the cut end portion and the molding process are processed. The processing department has insufficient corrosion resistance. However, by coating the water-based paint composition of the present invention, it is possible to obtain a coating film which is chemically resistant and which exhibits excellent corrosion resistance regardless of the flat portion, the end surface portion, and the processed portion of the metal plate.

Example

Hereinafter, the present invention will be described in more detail by way of Production Examples, Examples and Comparative Examples, but the present invention is not limited thereto. In each example, "parts" means mass parts, and "%" means mass%.

Production of cationic resin (A) Production Example 1 Production Example of Cationic Epoxy Resin No. 1 (Epoxy Resin)

Using a flask equipped with a stirrer, a thermometer, a nitrogen inlet tube and a reflux cooler, jER1004 (bisphenol A type epoxy resin, epoxy value 0.108 mol/100 g, number average molecular weight 1,650, Japan Epoxy Resins Co., Ltd. 100 parts of 100 parts of 3-methoxybutyl acetate were mixed and heated at 100 °C.

After confirming that it was uniformly dissolved, 2.75 parts of monoethanolamine was added, and the reaction was carried out for 2 hours. After confirming that the epoxy value reached 0.018 mol/100 g, 1.89 parts of diethanolamine was added, and the reaction was further continued for 2 hours. If the epoxy value falls below 0.005 mol/100g, it is diluted with a mixed solvent previously mixed with methyl ethyl ketone oxime / xylene / butanol = 1 / 1 / 1 to obtain a cationic ring with a solid content of 65%. Oxygen resin No. 1. Further, the obtained cationic epoxy resin No. 1 had an amine value of 35.1 mgKOH/g.

Production Example 2 Production Example of Cationic Epoxy Resin No. 2 (Diisocyanate Compound Modification System)

Using a flask equipped with a stirrer, a thermometer, a nitrogen inlet tube and a reflux cooler, jER1004 (bisphenol A type epoxy resin, epoxy value 0.108 mol/100 g, number average molecular weight 1,650, Japan Epoxy Resins Co., Ltd. And, 25 parts of 3-methoxyacetic acid butyl ester were mixed and heated at 100 °C.

After confirming that it was uniformly dissolved, 6.75 parts of n-methylethanolamine was added, and the reaction was carried out for 2 hours. After confirming that the epoxy value reached 0.018 mol/100 g, 11.1 parts of a mixed solvent previously mixed into methyl ethyl ketone oxime / xylene = 1 / 1 was added, and the reaction temperature was cooled to 40 °C.

After confirming uniform dissolution, 7.56 parts of hexamethylene diisocyanate was added, and the reaction was carried out for 1 hour. Thereafter, the reaction temperature was again raised to 100 ° C, 1.89 parts of diethanolamine was added, and the reaction was further continued for 1 hour. If the epoxy value falls below 0.005 mol/100g, it is diluted with a mixed solvent previously mixed with methyl ethyl ketone oxime/xylene/butanol = 1/1/1 to obtain a cationically modified diisocyanate compound having a solid content of 65%. Epoxy resin No. 2. Further, the obtained cationic epoxy resin No. 2 had an amine value of 53.0 mgKOH/g.

Production Example 3 Production Example of Cationic Epoxy Resin No. 3 (Dibasic Acid Modification System)

Using a flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, and a reflux condenser, jER1004 (bisphenol A type epoxy resin, epoxy value 0.108 mol/100 g, number average molecular weight 1,650, Japan Epoxy Resins Co., 100 parts, manufactured by Ltd., mixed with 25 parts of 3-methoxyacetic acid butyl ester at 100 ° C.

After confirming that it was uniformly dissolved, 10 parts of Tsunodime 205 (dimer acid, manufactured by TSUNO CO., LTD.) was added, and the reaction was carried out for 2 hours. After confirming that the acid value reached 0.5 mgKOH/g or less, 2.36 parts of monoethanolamine was added, and the reaction was further maintained for 2 hours. After confirming that the epoxy value reached 0.018 mol/100 g, 1.89 parts of diethanolamine was added, and the reaction was further carried out for 1 hour. If the epoxy value is reduced to 0.005 mol/100 g or less, it is diluted with a mixed solvent previously mixed with methyl ethyl ketone oxime/xylene/butanol = 1/1/1 to obtain a cationic property of a dimer acid modified with a solid content of 65%. Epoxy resin No. 3. Further, the obtained cationic epoxy resin No. 3 had an amine value of 28.9 mgKOH/g.

Manufacture of emulsions for waterborne coatings Production Example 4 Production Example of Latex No. 1

123.1 parts of cationic epoxy resin No. 1 (solid content: 80 parts) obtained in Production Example 1 and Desmodur BL-3175 (manufactured by Sumitomo Bayer Urethane Co., Ltd., hexamethylene dichloride blocked with methyl ethyl ketone oxime) Isocyanate type polyisocyanate compound solution, solid content about 75%) 26.7 parts (solid content 20 parts), ethylene glycol monobutyl ether 20 parts are mixed, then mixed 10% acetic acid 30.3 parts and stirred and mixed, deionized water 133.2 parts were dropped with vigorous stirring for about 30 minutes to obtain an emulsion No. 1 having a resin solid content of 30%.

Production Example 5 to 10 Manufacturing Example of Latex No. 2 to No. 7

In the same manner as in Production Example 4 except for the contents of the mixing in Table 1, emulsion Nos. 2 to No. 7 were obtained.

(Note 2) Desmodur BL-3175: a solution of a hexamethylene diisocyanate type polyisocyanate compound sealed with methyl ethyl ketone oxime, manufactured by Sumitomo Bayer Urethane Co., Ltd., having a solid content of about 75%.

(Note 3) Duranate MF-K60X: Resin solution of active methylene-blocked hexamethylene diisocyanate manufactured by Asahi Kasei Chemicals Corp., solid content 60%

Production Example 11 Production Example of Pigment Dispersing Resin

390 parts of bisphenol A, 240 parts of Plaxel 212 (polycaprolactone diol, Daicel Chemical Industries Ltd., trade name, weight average molecular weight about 1,250) and 0.2 parts of dimethylbenzylamine were added. To 1010 parts of jER828EL (Note 4), the reaction was carried out at 130 ° C until the epoxy equivalent became about 1,090 g / eq.

Next, 134 parts of dimethylethanolamine and 150 parts of a 90% aqueous lactic acid solution were added, and the mixture was reacted at 120 ° C for 4 hours. Next, methyl isobutyl ketone was added to adjust the solid content to obtain a pigment dispersion resin of an ammonium salt type resin having a solid content of 60%. The ammonium salt concentration of the above dispersion resin was 0.78 mmol/g.

(Note 4) jER828EL: trade name, epoxy resin, manufactured by Japan Epoxy Resins Co., Ltd.

Production Example 12 Production Example of Pigment Dispersion Pulp No. 1

8.3 parts of a pigment dispersion resin having a solid content of 60% obtained in Production Example 11 (solid content: 5 parts), vanadium pentoxide 2 parts, 1 part calcium metasilicate, 2 parts of calcium phosphate, 20 parts of titanium white, 20 parts of cerium oxide (barium sulphate) and 37.6 parts of deionized water were dispersed in a ball mill for 20 hours, and pigment dispersion was carried out until the particles (particle diameter of the pigment coarse particles) became 20 μm or less, and a pigment dispersion slurry No. 1 having a solid content of 55% was obtained. .

To 10,000 parts of a 5 mass% sodium chloride aqueous solution at 25 ° C, a mixture of 2 parts of vanadium pentoxide constituting the rust preventive pigment mixture (C), 1 part of calcium metasilicate, and 2 parts of calcium phosphate was added and stirred for 6 hours. The pH of the filtrate obtained by allowing the supernatant to stand at 25 ° C for 48 hours was filtered. The pH of the filtrate was 5.5.

Manufacturing Example 13~21

The pigment dispersions No. 2 to No. 10 were obtained in the same manner as in Production Example 12 except for the contents of the mixing in Table 2. Further, the results of measuring the pH of the filtrate of the sodium chloride aqueous solution of the mixture of the compounds (c1) to (c3) are shown in Table 2 in the same manner as in Production Example 12.

"sylysia 710" and "shieldex C303" in Table 2 are as follows. Sylysia 710: cerium oxide micropowder, average particle size 2.8 μm, oil absorption 190 ml/100 g, BET specific surface area 700 m ² /g, shieldex C303 manufactured by Fuji Silysia Chemical Ltd.: calcium ion exchange ruthenium dioxide, WR Grace & Co Social system

Comparative Manufacturing Example 1~10

The pigment dispersion slurry No. 11 to No. 20 were obtained in the same manner as in Production Example 12 except for the contents of the mixing in Table 3. Further, the results of measuring the pH of the filtrate of the sodium chloride aqueous solution of the mixture of the compounds (c1) to (c3) are shown in Table 3 in the same manner as in Production Example 12.

Production Example 22 Production of Resole Type Phenolic Resin Crosslinking Solution

Into a reaction vessel, 100 parts of bisphenol A, 178 parts of a 37% aqueous formaldehyde solution, and 1 part of sodium hydroxide were mixed, and the mixture was reacted at 60 ° C for 3 hours, and then dehydrated at 50 ° C for 1 hour under reduced pressure. Next, 100 parts of n-butanol and 3 parts of phosphoric acid were added, and the mixture was reacted at 110 to 120 ° C for 2 hours. After completion of the reaction, the resulting solution was filtered and the resulting sodium phosphate was filtered off to obtain a Resole type phenol resin crosslinker 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.

Example 1 Manufacture of Aqueous Coating Composition No. 1

333.3 parts (solid content: 100 parts) of the latex No. 1, 90.9 parts (solid content: 50 parts) prepared in Production Example 4 were prepared in the pigment dispersion slurry obtained in Production Example 12 and 75.8 parts of deionized water to obtain a solid. 30% aqueous coating composition No.1.

Example 2 to 18 Production of water-based paint composition No. 2 to No. 18

The aqueous coating compositions No. 2 to No. 18 were obtained in the same manner as in Example 1 except for the mixing shown in the following Tables 4 and 5.

Comparative example 1~10

The aqueous coating compositions No. 19 to No. 28 were obtained in the same manner as in Example 1 except that the mixing shown in Table 6 below was carried out.

[Production of test coated board]

Using the water-based paint compositions No. 1 to No. 28 and the top coat paints obtained in the above Examples 1 to 18 and Comparative Examples 1 to 10, the following coating requirements, coating requirements 2, and coating requirements were used. 3. Each material was coated and sintered to obtain test plates for each test.

Painting requirements 1

On a galvanized steel sheet (Galvalume Steel) having a chromium-free chemical conversion treatment (pretreatment) (plate thickness: 0.35 mm, coating amount: 150 g/m ² , indicated as "GL steel sheet" in the table), Each of the aqueous coating compositions prepared in the examples and the comparative examples was coated with a bar coater to a dry film thickness of 3 μm, and dried at 140 ° C (the highest temperature at which the material reached) by a chain oven for 20 seconds. bell.

Next, on the opposite side of the painted surface (front side), the same aqueous coating composition as the front surface was applied to form a dry film thickness of 3 μm, and dried at a temperature of 210 ° C (the highest temperature at which the material reached) in a chain furnace for 40 seconds. , each primer coating plate is prepared.

After cooling, on these primer coating plates (front side), KP Color 1580B40 (manufactured by Kansai Paint Co., Ltd., trade name, polyester-based topcoat paint, blue, hardened coating film) was applied by a bar coater. The glass transition temperature is about 70 ° C). The thickness of the dried film is about 15 μm, and the maximum temperature reached at 220 ° C for 40 seconds to obtain the test plates GL-1 to GL-28 (tested on the front side). ).

Painting requirements 2

The molten galvanized steel sheet (thickness 0.35 mm, galvanized coating amount: 250 g/m ² , abbreviated as "GI steel plate" in the table) which was not subjected to chemical conversion treatment, each of the waters obtained by the examples and the comparative examples The coating composition was applied by a bar coater to a dry film thickness of 3 μm, and dried by heating in a chain type open hearth at 140 ° C (the highest temperature at which the material reached) for 15 seconds.

Next, on the opposite side of the coating surface (front side), the same aqueous coating composition as the front surface was coated with a bar coater to a dry film thickness of 3 μm, and a chain at 140 ° C (the highest temperature at which the material reached) was used. Each type of primer coating plate was prepared by heating and drying in an open hearth furnace for 15 seconds.

After cooling, on these primer coating plates (front side), using a bar coater will KP color 1510 (manufactured by Kansai Paint Co., Ltd., trade name, high molecular polyester top coat paint, brown color, glass transition temperature of hardened coating film of about 40 ° C) is applied to a dry film thickness of about 15 μm, with a chain The open hearth furnace was sintered at 220 ° C (the highest temperature at which the material reached) for 40 seconds, and each test plate GI-1 to GI-28 (tested on the front side) was prepared.

Painting requirements 3

Each of the aqueous coating compositions prepared in the examples and the comparative examples was coated with a bar coater on a cold-rolled steel sheet (0.8 mm thick sheet, referred to as "SPC steel sheet" in the table) subjected to zinc phosphate chemical conversion treatment. The film was dried to a thickness of 8 μm, and dried at 180 ° C (the highest temperature at which the material reached) in a chain type open hearth oven for 30 seconds.

Next, on the opposite side of the coating surface (front side), the same aqueous coating composition as the front surface was coated with a bar coater to a dry film thickness of 20 μm, and the chain was applied at 180 ° C (the highest temperature at which the material reached). The flat furnace was heated and dried for 30 minutes to obtain test plates SP-1 to SP-28 (tested on the front side) for each test.

Film performance test

Each of the test coated sheets GL-1 to GL-28, GI-1 to GI-28, and SP coated with each of the aqueous coating compositions prepared in the above Examples 1 to 18 and Comparative Examples 1 to 10 was used. -1~SP-28, the film performance test was carried out according to the following test method. The test results are shown in Tables 7 to 9.

experiment method

(Note 5) Coating adhesion: According to the sizing method of JIS K-5600-5-6 (1999), the gap interval of the cuts is set to 1 mm, 100 meshes are produced, and a transparent tape is adhered to the surface, and the investigation is sharp. The number of grids remaining on the coated surface after peeling.

◎: There is no abnormality such as swelling or whitening of the coating film, and the number of remaining grids is 100. ○: There is no abnormality such as swelling or whitening of the coating film, and the number of remaining grids is 91 to 99. △: The coating film is slightly confirmed. An abnormality such as swelling or whitening occurs, and the number of remaining grids is 91 to 99, or there is no abnormality such as swelling or whitening of the coating film, but the number of remaining grids is 71 to 90, ×: the coating film is considerably or obviously Confirm that the expansion has occurred, or The number of surviving grids is less than 70

(Note 6) Boiling water resistance: Each test coated sheet cut into a size of 5 cm × 10 cm was taken out in boiling water of about 100 ° C for 2 hours, and taken out, and the appearance of the coating film on the surface (front side) side was evaluated. Perform an evaluation of the cross-hatch test. The cross-hatch adhesion test follows the JIS K-5600-5-6 (1999) cross-hatch method, and the gap interval of the cut marks is set to 1 mm, 100 meshes are formed, and a transparent tape is adhered to the surface thereof, and the test is applied after the sharp peeling. The number of grids remaining on the surface.

◎: There is no abnormality such as swelling or whitening of the coating film, and the number of remaining grids is 100. ○: There is no abnormality such as swelling or whitening of the coating film, and the number of remaining grids is 91 to 99. △: The coating film is slightly confirmed. Abnormalities such as swelling or whitening, the number of remaining grids is 91 to 99, or there is no swelling or whitening of the coating film, but the number of remaining grids is 71 to 90, ×: considerable or obvious confirmation Expansion to the coating film, or the number of remaining meshes is 70 or less

(Note 7) Alkali resistance: The back surface and the cut surface of each test coated board which were cut into 5 cm × 10 cm were sealed with a rust preventive paint, and the substrate was cut deep into the center of the surface side of the coated sheet. Scratches. After immersing the coated plate in a 5% sodium hydroxide aqueous solution at 20 ° C for 24 hours, the appearance of the coating film on the surface side of the coated plate which was washed and dried at room temperature was taken out, and the cross-section was transparent. The tape was pasted and evaluated for the width (one side) of the peeling from the cut portion of the coating film after the sharp peeling.

◎: No expansion occurred, and the width of the tape peeled off from the cut portion was 1.5 mm. In the following, ○: no expansion occurred, and the width of the tape peeled off from the cut portion exceeded 1.5 mm, and was 3 mm or less. Δ: Some expansion occurred, but the width of the tape peeled off from the cut portion was 3 mm or less, or expansion was not confirmed. Occurs, but the width of the tape peeled off from the cut portion exceeds 3 mm.

×: The occurrence of swelling was confirmed, and the width of the tape peeled off from the cut portion exceeded 3 mm.

(Note 8) Acid resistance: The back surface and the cut surface of each test coated sheet which were cut into a size of 5 cm × 10 cm were sealed with a rust preventive paint, and the substrate was cut deep into the center of the surface side of the coated sheet. mark. After immersing the coated plate in a 5% sulfuric acid aqueous solution at 20 ° C for 24 hours, the appearance of the coating film on the surface side of the coated plate which was washed and dried at room temperature was taken out, and the cross-section was pasted with a transparent tape. The width (one side) of the peeling from the cut portion of the coating film after the sharp peeling was evaluated.

◎: No expansion occurred, and the width of the tape peeled off from the cut portion was 1.5 mm or less. ○: No expansion occurred, and the width of the tape peeled off from the cut portion exceeded 1.5 mm, and was 3 mm or less. Δ: Some expansion occurred, but only some expansion occurred. The width of the tape peeled off from the cut portion was 3 mm or less, or expansion was not confirmed, but the width of the tape peeled off from the cut portion exceeded 3 mm.

×: It was confirmed that expansion occurred, and the width of the tape peeled off from the cut portion exceeded 3 mm.

(Note 9) Composite cyclic corrosion test: Approved according to JIS K-5621 (1990). will The coated plate was cut into a size of 6 cm × 12 cm so that the edge portion of the long side of each test coated sheet was directed toward the right side edge portion of the surface side of the coating film side, and there was a burr on the front side, and the left side of the coating film side toward the surface side The edge portion has a burr on the back side. In the central portion of the surface side of each of the test coated sheets that have been cut, the back of the substrate is cut into a narrow angle of 30 degrees and a line width of 0.5 mm by the back of the cutting blade, and the coating is sealed with an anti-rust paint. The upper end edge portion is provided with a 4T bending portion at the upper end portion. Here, the 4T bending process means that the surface side of the coated sheet is bent as the outer side, and four sheets of the same thickness as the coated sheet are sandwiched inside, and the coated sheet is bent by a vise 180. Degree of processing. For the test coated board subjected to the above processing, (spray 5% saline solution at 30 ° C for 0.5 hours) - (tested at 30 ° C, RH 95% or more in a moisture resistance tester for 1.5 hours) - (dry at 50 ° C) 2 hours) - (dried at 30 ° C for 2 hours) was a cycle, and 300 cycles (total 1800 hours) were tested. The state of the edge portion, the cross-hatched portion, and the 4T-processed portion of the coated sheet after the test was evaluated.

(4T processing unit) The total length of the rusted portion in the 4T processing portion is evaluated.

◎: No rust was observed, ○: White rust was confirmed, but it was less than 20 mm, △: white rust was 20 mm or more and less than 40 mm, ×: white rust was 40 mm or more, or red rust was confirmed.

(Edge portion) The average value of the edge creep widths of the left and right long sides of the coating plate was determined and evaluated based on the following criteria.

◎: less than 5 mm, ○: 5 mm or more and less than 10 mm, △: 10 mm or more and less than 20 mm, ×: 20 mm or more.

(cross-dash line portion) The scribe line portion was evaluated by the following standard using the ratio of the length of the white rust appearing in the exposed portion of the metal having a cut width of 0.5 mm and the average width of the left and right expansion of the cut portion (the sum of the both sides). Corrosion state.

◎: The length ratio of white rust in the exposed portion of the metal is less than 50% and the expansion width is less than 3 mm. ○: The ratio of the length of white rust in the exposed portion of the metal is 50% or more and the expansion width is less than 3 mm, or white appears in the exposed portion of the metal. The ratio of the length of the rust is less than 50% and the expansion width is less than 3 mm and less than 5 mm. △: the length ratio of white rust in the exposed portion of the metal is 50% or more and the expansion width is 5 mm or more and less than 10 mm, ×: appears in the exposed portion of the metal The white rust has a length ratio of 50% or more and an expansion width of 10 mm or more.

(Note 10) Salt spray test: The back surface and the cut surface of each test coated sheet having a size of 5 cm × 10 cm were sealed with a rust preventive paint, and a cross-substrate cross was placed at the center of the surface of the coated sheet. Scratches. The coated plate was subjected to a salt spray test (JIS Z-2371) with 5% saline solution at 35 ° C for 500 hours, and the appearance of red rust on the coated surface after the test was evaluated, and the scotch tape was adhered to the cross-hatched portion, and the evaluation was sharp. After peeling, the width of the tape peeled off from the cut portion of the coating film (one side).

◎: No or only some reddish rust occurred, the width of the tape peeled off from the cut portion was less than 5 mm, ○: the occurrence of red rust was confirmed to a considerable extent, and the width of the tape peeled off from the cut portion was less than 5 mm, or no or Only a little red rust Raw, but the width of the tape peeled off from the cut portion is less than 5mm and less than 10mm. △: The occurrence of red rust is confirmed in the whole part of the cut mark, but the width of the tape peeled off from the cut portion is 5mm or more and less than 10mm, or although not In the whole of the incision part, the occurrence of red rust was confirmed to a considerable extent, and the width of the tape peeled off from the cut portion was 10 mm or more. ×: The occurrence of red rust was confirmed in all the cut portions, and the tape was self-scratched. The partial peeling width is 10 mm or more.

Industrial use possibility

The present invention provides a coated metal sheet and a coated article which are excellent in chemical resistance, corrosion resistance in a flat portion, and corrosion resistance and adhesion of a processed portion and an end portion.

Part of the 1‧‧ ‧ steel plate

2‧‧‧ plating

3‧‧‧Chemical conversion treatment (pre-treatment) as required

4‧‧‧Undercoating film (aqueous coating composition of the invention)

5‧‧‧Face paint film

[Fig. 1] An example of a continuous coil coating line is illustrated.

[Fig. 2] An example of a coating film structure of a coating film containing the aqueous coating composition of the present invention.

Claims (7)

An aqueous coating composition for coating a precoated metal sheet comprising an amine group-containing epoxy resin (A), a polyisocyanate hardener (B), and a rust preventive pigment mixture (C) described below; an anti-rust pigment The mixture (C) is composed of at least one of vanadium pentoxide, calcium vanadate and ammonium metavanadate (c1), bismuth compound (c2) and calcium phosphate (c3), and The total solid content of the resin (A) and the curing agent (B) is 100 parts by mass, the amount of the vanadium compound (c1) is 1 to 30 parts by mass, and the amount of the cerium compound (c2) is 1 to 30 parts by mass. The amount of the calcium phosphate salt (c3) is 1 to 30 parts by mass, and the amount of the antirust pigment mixture (C) is 3 to 90 parts by mass. The aqueous coating composition according to claim 1, wherein the cerium compound (c2) is at least one selected from the group consisting of a metal ruthenate salt, cerium oxide microparticles, and metal ion-exchanged cerium oxide microparticles. The aqueous coating composition according to claim 1, wherein the phosphate-based calcium salt (c3) is at least one of calcium phosphate, calcium monohydrogen phosphate, calcium dihydrogen phosphate, and calcium tripolyphosphate. The aqueous coating composition according to claim 1, which contains 0.1 to 10 parts by mass of a Resole type phenol resin with respect to the solid content of the amine group-containing epoxy resin (A) and the polyisocyanate curing agent (B). . A method for forming a coating film, characterized in that the cured coating film is formed on a metal plate by the aqueous coating composition according to the first aspect of the invention, and at least one of the top coatings is formed on the cured coating film. Coating film. A coated metal sheet having a coating film obtained by the coating film forming method described in claim 5 of the patent application. A coated article obtained by processing a coated metal sheet as described in claim 6 of the patent application.