JPH11241048A - Aqueous coating composition and article coated with this composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aqueous coating which forms a film having a good corrosion resistance on an aluminum-plated steel plate without using an anticor rosive agent containing harmful heavy metals. SOLUTION: An aqueous coating composition contains, against 100 pts.wt. total amount of a film-forming resin component comprising (A) from 50 to 100 pts.wt. at least one aqueous resin chosen from an aqueous alkyd resin and an aqueous epoxy ester resin, (B) from 0 to 50 pts.wt. aqueous acrylic resin and (C) from 0 to 30 pts.wt. aqueous melamine resin, (D) from 0 to 50 pts.wt. at least non-chromic anticorrosive pigment chosen from a zinc compound and a molybdenum compound and (E) from 5 to 50 pts.wt. calcium ion-exchanged noncrystalline silica fine particle. A coated article uses an aluminum-plated steel plate, on which a film is formed from this composition, as a base material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous coating composition which does not contain harmful heavy metals and has excellent anticorrosion properties, and a coated article based on an aluminum-plated steel sheet coated with the coating composition.

[0002]

2. Description of the Related Art
Lead / tin alloy plated steel sheet (turn sheet) is used as a material for gasoline tanks, but from the viewpoint of global environmental conservation such as not using harmful lead, the material was changed from turn sheet to aluminum plated steel sheet. Considerations are being made.

[0003] Paints currently used for turn sheets, both solvent-based paints and water-soluble paints, are applied to an aluminum-plated steel sheet with the same composition, and as a result, the anti-corrosion property is higher than when applied to a turn sheet. There was a problem of being extremely inferior. As a measure to solve this problem, it is conceivable to use a large amount of harmful heavy metals such as chromium-based rust preventives and lead-based rust preventives. It does not fit the purpose.
Further, the solvent type paint is not preferable from the viewpoint of regulation of CO ₂ gas emission for preventing global warming.

Accordingly, the present inventors have conducted intensive studies to obtain a water-based paint capable of forming a coating film having excellent anticorrosion properties on an aluminum-plated steel sheet without using a rust inhibitor containing harmful heavy metals. As a result, the present inventors have found that a desired paint can be obtained by combining a specific aqueous resin with calcium ion-exchanged silica fine particles and, if necessary, a specific non-chromium rust preventive pigment, and have completed the present invention. Was.

[0005]

That is, the present invention provides:
(A) 50 to 100 parts by weight of at least one aqueous resin selected from an aqueous alkyd resin and an aqueous epoxy ester resin; (B) 0 to 50 parts by weight of an aqueous acrylic resin; and (C) 0 to 30 parts by weight of an aqueous melamine resin. (D) 0 to 50 parts by weight of at least one non-chromium rust preventive pigment selected from a zinc compound and a molybdate compound, based on 100 parts by weight of the total amount of the film-forming resin component
Calcium ion exchanged amorphous silica fine particles 5-5
The present invention provides an aqueous coating composition characterized by containing 0 parts by weight.

[0006] The present invention also provides an aluminum-plated steel sheet comprising a water-based coating composition formed on an aluminum-plated steel sheet substrate which may be subjected to a chemical conversion treatment and / or an organic coating treatment. To provide a coated article.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Each component of the coating composition of the present invention will be described in detail below.

Aqueous resin (A) The aqueous resin as the component (A) of the composition of the present invention is at least one resin selected from aqueous alkyd resins and aqueous epoxy ester resins. In the present invention, "aqueous"
Means water-soluble or water-dispersible.

The aqueous alkyd resin comprises a polybasic acid component,
The resin is not particularly limited as long as it is a resin obtained by esterifying a polyhydric alcohol component and an oil fatty acid, and is water-based and has a film-forming ability.

The polybasic acid component is selected from, for example, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, succinic acid, fumaric acid, adipic acid, sebacic acid, maleic anhydride and the like. One or more dibasic acids and lower alkyl esterified products of these acids are mainly used, and if necessary, tribasic or higher polybasic acids such as trimellitic anhydride, methylcyclohexentricarboxylic acid, and pyromellitic anhydride. Are used together. As the acid component, a monobasic acid such as benzoic acid, crotonic acid, pt-butylbenzoic acid, and the like can be used in combination for the purpose of adjusting the molecular weight.

Examples of the polyhydric alcohol component include ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 3-methylpentanediol, 1,4-hexanediol, and 1,6-hexanediol. A dihydric alcohol such as glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol can be used as needed. These polyhydric alcohols can be used alone or in combination of two or more. Further, a part of the acid component and the alcohol component may be dimethylolpropionic acid, oxypivalic acid, paraoxybenzoic acid, etc .; lower alkyl esters of these acids;
-It can be replaced with an oxyacid component such as lactones such as caprolactone.

Examples of the oil fatty acids include coconut oil fatty acids, soybean oil fatty acids, linseed oil fatty acids, safflower oil fatty acids, tall oil fatty acids, dehydrated castor oil fatty acids, and tung oil fatty acids. Oil length of alkyd resin is 3
0% or less, especially about 5 to 20% is preferable.

The esterification reaction (including the transesterification reaction) of these components can be carried out by a method known per se.

The present invention also includes an epoxy-modified alkyd resin obtained by partially esterifying an epoxy compound with an epoxy compound as a part of the alcohol component, and a vinyl-modified alkyd resin obtained by graft-polymerizing a vinyl monomer such as styrene onto the alkyd resin. Included in alkyd resins.

In order to make the alkyd resin aqueous, for example, a method in which the alkyd resin has a high acid value and is neutralized with a basic compound such as an amine compound to make the alkyd resin aqueous, a polyoxyethylene group is contained in the alkyd resin. Introduce hydrophilic groups such as
A method of self-emulsifying in water by the action of the hydrophilic group, a method of forcibly stirring an alkyd resin in water in the presence of an emulsifier, and a method of dispersing the resin in water can be used.

Although the molecular weight of the aqueous alkyd resin is not particularly limited, it is usually a number average molecular weight of 2,0.
Preferably, it is in the range of from 00 to 10,000.

Commercially available aqueous alkyd resins include, for example, Residrol VWA5377 and VWA5499.
AX246W and AX906W (both are VI
ANOVA (Vianova), Watersol BC
-3010, S-118, and S-346 (all, manufactured by Dainippon Ink and Chemicals, Inc.).

The aqueous epoxy ester resin which can be used as the component (A) is a resin in which an epoxy resin and an acid component are ester-bonded and are stably dissolved or dispersed in water.

As the aqueous epoxy ester resin, for example, a carboxyl group-excess partial reactant obtained by reacting a carboxyl group-containing polymer such as an acrylic resin with an epoxy resin is dispersed in an aqueous medium in the presence of ammonia or an amine. (For example, Japanese Patent Application Laid-Open No. 54-75)
460, JP-A-55-3481, and JP-A-5-3481.
JP-A-5-3482), an adduct having a polymerizable unsaturated double bond in a molecule obtained by partially reacting an epoxy resin with a carboxyl group-containing polymerizable unsaturated compound such as (meth) acrylic acid, A polymer obtained by polymerizing a monomer mixture containing (meth) acrylic acid, neutralizing a carboxyl group of the polymer of the monomer mixture with a basic compound, and dispersing the polymer in an aqueous medium (for example, JP-A-57-105418). JP-A-58-198513), a resin obtained by reacting an epoxy resin with a dibasic acid such as succinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, dodecane diacid, and hexahydrophthalic acid. And the like, which are obtained by neutralizing the carboxyl group with a basic compound and dispersing the same in an aqueous medium.

Examples of the epoxy resin include a bisphenol type epoxy resin and a novolak type epoxy resin. 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, if necessary, in the presence of a catalyst such as an alkali catalyst, condensation This may be a low-molecular-weight epoxy resin, and any resin obtained by subjecting the low-molecular-weight epoxy resin to a bisphenol to undergo a polyaddition reaction may be used.

As the bisphenol, 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, and among them, bisphenol A and bisphenol F are preferably used. The above bisphenols can be used alone or as a mixture of two or more.

Commercially available bisphenol type epoxy resins include, for example, Epicoat 828 (epoxy equivalent: about 190, number average molecular weight: about 350) and Epicoat 812 (epoxy equivalent: about 150, manufactured by Yuka Shell Epoxy Co., Ltd.).
Epicoat 815 (epoxy equivalent: about 180, number average molecular weight: about 350), Epicoat 8
20 (epoxy equivalent about 190, number average molecular weight about 35
0), Epicoat 834 (epoxy equivalent: about 250, number average molecular weight: about 470), Epicoat 1001 (epoxy equivalent: about 490, number average molecular weight: about 900), Epicoat 10
04 (epoxy equivalent about 950, number average molecular weight about 140
0), Epicoat 1007 (epoxy equivalent about 1,70
0, number average molecular weight about 2,900), Epicoat 1009
(Epoxy equivalent about 3,500, number average molecular weight about 3,75
0), Epicoat 1010 (epoxy equivalent of about 4,50
0, number average molecular weight of about 5,500); Araldite AER6099 (epoxy equivalent of about 3,500;
A number average molecular weight of about 3,800); and Epomic R-309 (epoxy equivalent of about 3,50) manufactured by Mitsui Chemicals, Inc.
0, a number average molecular weight of about 3,800).

Examples of the novolak type epoxy resin usable as the epoxy resin include various novolak types such as phenol novolak type epoxy resin, cresol novolak type epoxy resin, and phenol glyoxal type epoxy resin having a large number of epoxy groups in a molecule. Type epoxy resin.

Aqueous Acrylic Resin (B) In the composition of the present invention, the aqueous acrylic resin (B) is a water-soluble or water-dispersible acrylic resin, and a carboxyl group-containing acrylic resin polymerized in an organic solvent. Examples thereof include a water-soluble or water-dispersible acrylic resin neutralized and made aqueous with a basic compound such as an amine compound, and an acrylic resin aqueous dispersion obtained by emulsion polymerization. The aqueous acrylic resin (B) is a resin that is blended into the composition of the present invention as needed.

The aqueous acrylic resin (B) is a copolymer resin containing a carboxyl group-containing polymerizable unsaturated monomer and another polymerizable unsaturated monomer as monomer components.

Examples of the carboxyl group-containing polymerizable unsaturated monomer include one or a mixture of two or more of acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid.

The other polymerizable unsaturated monomer may be any monomer that can be copolymerized with the above-mentioned carboxyl group-containing polymerizable unsaturated monomer, and can be appropriately selected and used according to the required performance. For example, aromatic vinyl monomers such as styrene, vinyltoluene, 2-methylstyrene, t-butylstyrene, and chlorostyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, and n-acrylate , I- or t-butyl, hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate,
Decyl acrylate, lauryl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-, i- or t-butyl methacrylate, hexyl methacrylate, 2-methacrylate Ethylhexyl, octyl methacrylate, decyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate or the like, alkyl or cycloalkyl esters of acrylic acid or methacrylic acid having 1 to 18 carbon atoms; 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate,
C2 of acrylic acid or methacrylic acid such as 3-hydroxypropyl acrylate, hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, and hydroxybutyl methacrylate
-C8 hydroxyalkyl ester; N-methylolacrylamide, N-butoxymethylacrylamide, N
One or a mixture of two or more of N-substituted acrylamide-based or N-substituted methacrylamide-based monomers such as -methoxymethylacrylamide, N-methylolmethacrylamide, and N-butoxymethylmethacrylamide.

A copolymer of the above monomer components can be obtained by a polymerization method known per se, such as solution polymerization or emulsion polymerization. The copolymer obtained by solution polymerization can be made aqueous by neutralizing with a basic compound.

Although the molecular weight of the water-based acrylic resin (B) is not particularly limited, it is usually a number average molecular weight of 5,0.
It is preferably in the range of 100 to 100,000.

Aqueous Melamine Resin (C) The aqueous melamine resin (C) functions as a curing agent that reacts with the aqueous resin (A) and the above-mentioned aqueous acrylic resin (B), which is blended as required. Of a methylolated amino resin obtained by the reaction of a phenol with an aldehyde and an etherified amino resin obtained by etherifying a methylolated amino resin with an appropriate alcohol, those having water solubility or water dispersibility. As the aldehyde used in the above reaction, formaldehyde,
Examples include paraformaldehyde, acetaldehyde, and benzaldehyde. Examples of the alcohol used for etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, i-propyl alcohol, n-butyl alcohol, i-butyl alcohol, and the like. Methyl alcohol is preferably used. You.

Specific examples of the aqueous melamine resin (C) include, for example, Cymel 300, 303, 325, and 3
27, 350, 370 [all, manufactured by Mitsui Cytec Co., Ltd.], Nicaraq MS15, MS17, MX430, MX650 [all, manufactured by Sanwa Chemical Co., Ltd.], Sumimar M-55 [ Sumitomo Chemical Co., Ltd.
Melamine resins such as Resin 740, 741 [all and Monsanto Co.]; Cymel 202, 235, 238, 254, 27
2, 1130 [all, Mitsui Cytec Co., Ltd.
Melamine resins mixed with methyl ether and butyl ether, such as Nikalac MX485 and MX487 (all of which are manufactured by Sanwa Chemical Co., Ltd.) and Resimin 755 (manufactured by Monsanto Co., Ltd.). These melamine resins can be used alone or as a mixture of two or more.

In the composition of the present invention, the mixing ratio of the aqueous resin (A), the aqueous acrylic resin (B) and the aqueous melamine resin (C) is the sum of (A), (B) and (C). The aqueous resin (A) is 50 to 1 in 100 parts by weight of the solid content.
00 parts by weight, preferably 60 to 90 parts by weight, the aqueous acrylic resin (B) is 0 to 50 parts by weight, preferably 0 to 40 parts by weight, and the aqueous melamine resin (C) is 0 to 30 parts by weight, preferably 0 to 0 parts by weight. It is in the range of 20 parts by weight.

Non-chromium rust preventive pigment (D) The non- chromium rust preventive pigment (D) in the composition of the present invention is at least one kind of rust preventive pigment selected from a zinc compound and a molybdate compound. And contributes to the improvement of the anticorrosion property together with the component (E) described below.

Specific examples of the chromium-free rust preventive pigment (D) include zinc oxide, zinc phosphate, phosphorous zinc silicate, aluminum zinc phosphate, calcium zinc phosphate, zinc zinc cyanamide, zinc-treated aluminum polyphosphate, and molybdenum. Calcium zincate, zinc molybdate,
Zinc phosphomolybdate, aluminum phosphomolybdate, and the like can be given. Among them, zinc oxide, zinc phosphate and zinc calcium molybdate are preferred.

The amount of the chromium-free rust-preventive pigment (D) is from 0 to 50 parts by weight based on 100 parts by weight of the total of the film-forming resin components (A), (B) and (C). ,
Preferably 1 to 40 parts by weight, more preferably 2 to 30 parts by weight
It is within the range of parts by weight.

Calcium ion exchanged amorphous silica
Fine Particles (E) In the composition of the present invention, the component (E), calcium ion-exchanged amorphous silica fine particles (hereinafter sometimes abbreviated as “ion-exchanged silica”), is a fine porous silica carrier. These are silica fine particles into which calcium ions have been introduced by ion exchange. The ion-exchanged silica compounded in the coating film is ion-exchanged with H ⁺ ions transmitted through the coating film, and calcium ion Ca, which is a rust preventive seed ion,
It is believed that ²⁺ is released to protect the metal surface.
Commercially available ion-exchanged silica is SHIELDEX
(Shielddex, registered trademark) C303, AC-3,
C-5 (both are WR Grace & C
o. And the like).

In the composition of the present invention, the amount of the ion-exchanged silica (E) is based on 100 parts by weight of the total amount of the film-forming resin components (A), (B) and (C). It is in the range of 5 to 50 parts by weight, preferably 10 to 30 parts by weight.

The coating composition of the present invention comprises a film-forming resin component comprising the above-mentioned aqueous resin (A), an aqueous acrylic resin (B) and an aqueous melamine resin (C), if necessary, (D), which can be substantially composed of ion-exchanged silica (E) and water, and further, if necessary, an organic solvent, a curing catalyst; pigments such as color pigments and extenders; neutralizing agents; Or a known additive such as an antifoaming agent, a coating surface adjusting agent, and an anti-settling agent.

The above-mentioned organic solvent is blended as required for improving the coating property of the composition of the present invention and the like.
A hydrophilic organic solvent capable of dissolving or dispersing the resins (A), (B) and (C) in water is preferably used. Specifically, for example, ethylene glycol monoethyl ether,
Examples thereof include ether solvents such as ethylene glycol monobutyl ether and diethylene glycol monobutyl ether, alcohol solvents such as methanol, ethanol, isopropanol and butanol, and acetone. These may be used alone or as a mixture of two or more. be able to.

The curing catalyst is an aqueous melamine resin (C)
Is blended as necessary to promote the reaction between the aqueous resin (A) or the aqueous acrylic resin (B) and the aqueous melamine resin (C), and the sulfonic acid compound or the sulfonic acid An amine neutralized product of the compound is preferably used. Representative examples of the sulfonic acid compound include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, and dinonylnaphthalenedisulfonic acid. The amine in the amine-neutralized sulfonic acid compound may be any of a primary amine, a secondary amine and a tertiary amine. Among these, an amine neutralized product of p-toluenesulfonic acid and / or an amine neutralized product of dodecylbenzenesulfonic acid are preferred from the viewpoints of the stability of the paint, the reaction promoting effect, and the physical properties of the obtained coating film. .

When a curing catalyst is blended, it is usually blended in an amount of 0.1 to 2.0 parts by weight of the sulfonic acid compound based on 100 parts by weight of the total amount of the film-forming resin component.

As the extender, at least one selected from the group consisting of barita, calcium carbonate, and a mixed crystal of calcium carbonate and magnesium carbonate is preferably used from the viewpoint of coating film hardness, coating film properties, coating film adhesion and the like. Can be used.
The blending amount of the extender is not particularly limited,
It is usually used in an amount of 200 parts by weight or less, preferably 30 to 150 parts by weight, based on 100 parts by weight of the total amount of the film-forming resin component.

Next, a method for coating the composition of the present invention will be described.

The composition of the present invention can be applied to, for example, metal, mortar, cement, plastics, glass, etc., but can be suitably applied to metal, especially steel plate.
The steel sheet used as the coated object includes cold-rolled steel sheet, hot-dip galvanized steel sheet, electro-galvanized steel sheet, zinc alloy-plated steel sheet, aluminum-plated steel sheet, stainless steel sheet, copper-plated steel sheet, tin-plated steel sheet, lead-tin alloy plating Examples thereof include steel sheets (turn sheets) and steel sheets obtained by subjecting these steel sheets to a chemical conversion treatment such as a phosphate treatment or a chromate treatment and / or an organic coating treatment. As the steel sheet subjected to the chemical conversion treatment and / or the organic film treatment, the above-mentioned steel sheet was subjected to the chemical treatment such as the one subjected to the chemical treatment, the one subjected to the organic film treatment, and the organic film treatment after the chemical treatment such as the chromate treatment. Things can be mentioned. As organic film treatment,
Film formation by an acrylic emulsion, film formation by a phenoxy resin, film formation by an epoxy resin, and the like can be given. The thickness of the organic film in the organic film treatment is not particularly limited, but is usually 0.3 to 3
About μm is appropriate.

Among the substrates to be coated, chemical conversion treatment and / or
Alternatively, an aluminum-plated steel sheet which may be subjected to an organic film treatment can be particularly preferably used. These steel sheets may be in the form of a sheet before being processed or may be formed.

The composition of the present invention is suitably used as an undercoat or a one-coat finish, and can be coated on the steel plate by a known method such as a roll coating method, a spray method, a brush coating method, and a dipping method. it can. The thickness of the coating film obtained from the composition of the present invention is not particularly limited, but when used as an undercoat paint, it is usually 2 to 40.
μm, preferably in the range of 5 to 30 μm, and when used as a one-coat finish paint, usually 8 to 50 μm.
m, preferably in the range of 10 to 40 μm.

When the coating film of the composition of the present invention is dried by continuous baking of the coating film by the coil coating method or the like, the maximum temperature at which the material reaches the material is usually 160 to 2 times.
50 ° C., preferably 180 to 230 ° C.
This is a condition for about 60 seconds, and when baking is performed in a batch system, it can be usually performed by baking at 80 to 160 ° C. for about 10 to 30 minutes.

[0048]

The present invention will be described more specifically with reference to the following examples. Hereinafter, “parts” and “%” are based on weight unless otherwise specified.

Preparation of Pigment Paste Production Example 1 Oil length 4 modified with tall oil fatty acid and linseed oil fatty acid
2%, an alkyd resin having an acid value of 40 mgKOH / g is neutralized with triethylamine in an equivalent amount, and the non-volatile content is 68
% Of an alkyd resin aqueous solution adjusted to 20% (20 parts in terms of nonvolatile content), 13.2 parts of ethylene glycol monobutyl ether, 56 parts of deionized water, and carbon black 1
1 part, 100 parts of calcium carbonate, and 2.5 parts of zinc oxide were added, and after uniform mixing, the particle size of the pigment was 20 μm with a tub gauge.
m, and then dispersed with a paint shaker to obtain 212.1 parts of pigment paste A (133.5 parts in terms of solid content).
Obtained.

Production Example 2 In Production Example 1, the amount of deionized water was changed from 56 parts to 85.3 parts, and instead of 100 parts of calcium carbonate, 50 parts of calcium carbonate and Shieldex C-303 (W.C.
R. Grace & Co. 50 parts and CD54
0 (manufactured by Dainippon Ink and Chemicals, Inc., epoxy ester emulsion with a nonvolatile content of 40%) 60 parts (solid content of 2
Pigment paste B was obtained in the same manner as in Production Example 1 except that 41.4 parts of the pigment paste B was used (157.5 parts in terms of solid content).

Preparation Example 3 Pigment paste C was prepared in the same manner as in Preparation Example 2 except that 2.5 parts of zinc oxide was not used.
(155.0 parts in terms of solid content).

Production Example 4 In Production Example 1, instead of 100 parts of calcium carbonate and 2.5 parts of zinc oxide, 80 parts of calcium carbonate and zinc calcium molybdate (trade name “LF Bosei MC400WR” manufactured by Kikuchi Color Co., Ltd.) were used. ) Pigment paste D was prepared in the same manner as in Production Example 1 except that 20 parts were used.
9.6 parts were obtained.

Preparation Example 5 In Preparation Example 1, instead of 100 parts of calcium carbonate and 2.5 parts of zinc oxide, 80 parts of calcium carbonate and zinc phosphate (trade name “ZP-S” manufactured by Kikuchi Color Co., Ltd.) were used.
B ") Performed in the same manner as in Production Example 1 except that 20 parts were used,
209.6 parts of pigment paste E were obtained.

Production Example 6 of paint base Production method 212.1 parts of pigment paste A obtained in Production Example 1, 46.9 parts of deionized water, CD540 having a nonvolatile content of 40% (as described above)
162.5 parts, 31.3 parts of AD69 (manufactured by Kanebo K.K., acrylic emulsion having a nonvolatile content of 48%), dryer (containing a nonvolatile content of 35% and a metal cobalt content of 3%)
1.5 parts of paint base 47% solids
I got

Production Examples 7 to 10 Production Example 6 was carried out in the same manner as in Production Example 6 except that the composition was as shown in Table 1 below to obtain paint bases b, c, d and e having a solid content of 47%. Was.

[0056]

[Table 1]

Production Examples of Water-based Coating Compositions Examples 1 to 6 and Comparative Example 1 Using the coating bases a, b and c obtained in the above-mentioned Production Examples 6 to 8, they were uniformly mixed in the composition shown in Table 2 below. Thus, each aqueous coating composition was obtained. Table 2 shows the resin component 10 in each paint.
The contents (parts, PHR) of Shieldex C303 and zinc oxide with respect to 0 parts are shown.

[0058]

[Table 2]

Examples 7 to 9 and Comparative Examples 2 to 3 The paint bases c, d and e obtained in the above Preparation Examples 8 to 10 were used and uniformly mixed according to the formulation shown in Table 3 below to obtain each aqueous solution. A coating composition was obtained. Table 3 shows the resin component 1 in each paint.
Content of Shieldex C303, zinc calcium molybdate and zinc phosphate with respect to 00 parts (parts, PHR)
Is shown.

[0060]

[Table 3]

Example 10 Watersol BC-3010 (manufactured by Dainippon Ink and Chemicals, Inc., aqueous alkyd resin, nonvolatile content 59%) 1
52.5 parts (90 parts in solid content), carbon black 5
Parts, zinc oxide 10 parts, Shielddex C303 25 parts
Parts, 50 parts of calcium carbonate, 15 parts of ethylene glycol monobutyl ether, 9.5 parts of ethyl 3-ethoxypropionate, Cymel 303 (Mitsui Cytec Co., Ltd.)
And 10 parts of methyl etherified melamine resin, 1.5 parts of triethylamine and deionized water were mixed and dispersed to obtain an aqueous coating composition. In the obtained aqueous coating composition,
The compounding ratio of Shieldex C303 is 25 PHR, and the compounding ratio of zinc oxide is 10 PHR.

Comparative Example 4 An aqueous coating composition for comparison was prepared in the same manner as in Example 10 except that 75 parts of calcium carbonate was used instead of 25 parts of Shieldex C303 and 50 parts of calcium carbonate. I got The mixing ratio of Shielddex C303 in the obtained aqueous coating composition was 0 PHR.
And the mixing ratio of zinc oxide is 10 PHR.

Preparation of Test Coated Plates The aqueous coating compositions obtained in Examples 1 to 10 and Comparative Examples 1 to 4 were coated on a 1.0 mm-thick aluminum-plated steel plate (trade name: Ulster, manufactured by Nissin Steel Co., Ltd.). )) And thickness 1.
On a 0 mm turn sheet (manufactured by Nippon Steel Corporation), coat with a bar coater so that the dry film thickness is about 23 μm.
Test drying was performed by forced drying. The forced drying conditions were as follows: each of the aqueous coating compositions obtained in Examples 1 to 9 and Comparative Examples 1 to 3 was baked at 80 ° C. for 20 minutes.
And about each of the aqueous coating compositions obtained in Comparative Example 4, 14
Baking was performed at 0 ° C. for 30 minutes.

Various performance tests were performed on the obtained test coated plates based on the following test methods. The test results are shown in Table 4 below.

Test Method Adhesion: JIS K-5400 8.5.2 (199
0) In accordance with the crosscut-tape method, 11 parallel vertical and horizontal straight lines were drawn at 1 mm intervals so as to reach the base material with a cutter knife on the coating surface of the test coated plate at 1 mm intervals.
100 × 1 mm squares were created. A cellophane adhesive tape was adhered to the surface, and the degree of peeling of the squares when the tape was abruptly peeled was observed and evaluated according to the following criteria. ：: No peeling of the coating film was observed at all. Δ: The coating film was slightly peeled, but 90 or more squares remained. ×: The coating film was considerably peeled, and the number of remaining squares was less than 90.

Moisture resistance: The test coated plate was cut into a size of 75 × 150 mm, and the back and sides were sealed with a rust preventive paint, and then subjected to a moisture resistance tester (internal temperature 49 ± 1 ° C., relative humidity 95%).
% Or more) for 120 hours, and the degree of blistering on the coated surface of the test coated plate was visually determined. When no swelling was observed on the coated surface, it was indicated as ○ (good).

Corrosion protection: A test coated plate was cut into a size of 75 × 150 mm, a cross cut was made on the coated surface with a knife so as to reach the base material, and the back surface and sides were sealed with a rust-preventive paint. A salt spray test was carried out for 500 hours according to 2371, and evaluated by the rust width (mm) on one side from a knife wound.

[0068]

[Table 4]

[0069]

The coating composition of the present invention is aqueous,
Since it does not need to contain harmful heavy metals, it is advantageous from the viewpoint of pollution prevention.

The aqueous coating composition of the present invention can form a coating film having excellent anticorrosion properties without containing harmful heavy metals.
The coated steel sheet obtained by coating the water-based coating composition of the present invention on an aluminum-plated steel sheet exhibits corrosion resistance equivalent to or higher than that of a conventional turn sheet coated sheet. Therefore, the turnsheet coated plate containing harmful lead can be replaced with an aluminum-plated steel plate coated plate by using the aqueous coating composition of the present invention, which is advantageous from the viewpoint of global environmental protection.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09D 133: 00 161: 28) (C09D 163/00 133: 00 161: 28)

Claims (5)

[Claims] (A) 50 to 100 parts by weight of at least one aqueous resin selected from an aqueous alkyd resin and an aqueous epoxy ester resin; (B) 0 to 50 parts by weight of an aqueous acrylic resin; and (C) an aqueous melamine resin. (D) 0 to 50 parts by weight of at least one non-chromium rust preventive pigment selected from a zinc compound and a molybdic acid compound, based on 100 parts by weight of the total amount of the film-forming resin component of from 30 to 30 parts by weight; An aqueous coating composition comprising 5 to 50 parts by weight of calcium ion-exchanged amorphous silica fine particles. 2. The compounding amount of the non-chromium rust preventive pigment (D) is as follows:
With respect to 100 parts by weight of the total amount of the film-forming resin component, 2
The aqueous coating composition according to claim 1, wherein the amount is from 30 to 30 parts by weight. 3. The aqueous coating composition according to claim 1, wherein the chromium-free rust preventive pigment (D) is one or a mixture of two or more of zinc oxide, zinc phosphate and zinc calcium molybdate. 4. The aqueous coating composition according to claim 1, further comprising at least one extender pigment selected from barita, calcium carbonate, and a mixed crystal of calcium carbonate and magnesium carbonate. Stuff. 5. The method according to claim 1, wherein the aluminum-plated steel sheet substrate, which may be subjected to a chemical conversion treatment and / or an organic coating treatment.
A coated article based on an aluminum-plated steel sheet having a coating film formed from the water-based coating composition as described above.