WO2012039217A1

WO2012039217A1 - Aqueous primer composition, method for forming multi layer coating and coated article

Info

Publication number: WO2012039217A1
Application number: PCT/JP2011/068717
Authority: WO
Inventors: 松田　英樹; 眞弘林; 裕也三好; 伸司対馬
Original assignee: 関西ペイント株式会社
Priority date: 2010-09-24
Filing date: 2011-08-12
Publication date: 2012-03-29

Abstract

The objective of the present invention is to provide an aqueous primer composition capable of forming a coating which has excellent workability and corrosion resistance in the worked portion. This aqueous primer composition has a constitution as described below. The aqueous primer composition comprises a carbonyl group-containing modified epoxy resin (A), a crosslinking agent (B), and a rust preventive pigment (C), and is characterized in that the carbonyl group-containing modified epoxy resin (A) is produced by reacting an amine compound (a₁) having a carbonyl group and at least one active hydrogen bonded to a nitrogen atom per molecule and an epoxy resin (a₂) having two or more epoxy groups per molecule.

Description

Aqueous primer composition, multilayer coating film forming method, and coated article

The present invention provides an aqueous primer composition capable of forming a coating film excellent in workability and corrosion resistance of a processed part, a method for forming a multilayer coating film using the aqueous primer composition, and the aqueous primer composition. It is related with the coated article formed by this.

Pre-coated steel sheets are widely used for building roofs, walls, building materials such as shutters, home appliances, and steel furniture. Since the precoated steel sheet is processed into various forms corresponding to such a wide use, the coating film on the steel sheet is required to have excellent workability. Although the processability has been improved by improving the physical properties of the top coat film, problems such as cracking of the coating film and generation of rust still remain in the processed part. Therefore, not only the top coating film but also the primer coating film is strongly desired to improve not only the corrosion resistance which is the original function but also the workability.
In the conventional primer, a composition mainly composed of an epoxy resin is used as a base resin, but a linear polyester resin is used at a ratio of 50% by mass or more of the resin component with the aim of improving the workability of the primer coating. A primer composition was disclosed in Patent Document 1. However, the primer coating film obtained from this primer composition has poor adhesion to the steel sheet, and thus may have insufficient corrosion resistance.

Patent Document 2 discloses a self-curing amide epoxy resin into which an amide bond having a strong hydrogen bonding property is introduced. The amide epoxy resin can be obtained by reacting a compound obtained by the Michael addition reaction of an amine compound and an acrylamide compound with an epoxy resin, and a part of the epoxy group contained in the epoxy resin remains unreacted. The remaining epoxy group is used as a crosslinking reactive group for the crosslinking reaction of the coating film. The resin disclosed in Patent Document 2 is applicable to thermosetting paints such as a primer, and the obtained coating film is excellent in corrosion resistance, but because the processability is insufficient, it causes cracks in the processed part. There was a thing.

On the other hand, in recent years, adverse effects on the environment due to volatilization of organic substances into the atmosphere have become a problem, and there is a need to reduce the use of organic solvents. In Patent Document 3, a resin obtained by copolymerizing an unsaturated aromatic epoxy resin obtained by adding an unsaturated carboxylic acid to an aromatic epoxy resin and an unsaturated carboxylic acid is neutralized with a basic compound. Thus, a water-dispersible resin composition produced by water dispersion is disclosed. The coating film obtained from this composition may cause cracks in the processed part, and the corrosion resistance of the processed part may be insufficient.

For pre-coated steel sheets, a primer coating is applied to the plated steel sheet and baked to reach the maximum material temperature of 180 ° C or higher, and then a top coating is applied to reach the maximum material temperature of 180 ° C or higher. However, from the viewpoint of energy saving, it is desired to lower the baking temperature.
However, when a conventional primer coating is applied and the top coating is applied and baked on a primer coating that has been baked at a low temperature such that the maximum material temperature is less than 180 ° C, for example, A mixed layer occurs at the interface with the paint, and not only the finished appearance of the finally obtained multilayer coating film is lowered, but the appearance of the top coating film may be deteriorated when used outdoors.

For example, Patent Document 4 discloses a resin composition containing a carbonyl group-containing acrylic resin emulsion and a dihydrazide compound suitable for a one-component water-based paint capable of forming a cured coating film by drying at room temperature. However, when this resin composition is used as a water-based primer coating for a pre-coated steel sheet, even if it is baked so that the material reaching maximum temperature is 180 ° C. or higher, the water resistance and corrosion resistance may be inferior.

Patent Document 5 discloses an aqueous coating composition containing an aqueous polymer having a carboxyl group as a low-temperature curable aqueous coating composition suitable for precoated steel sheet applications and an aqueous polymer having an oxazoline group as a crosslinking agent. ing. Although this composition was excellent in storability, the obtained coating film was sometimes inferior in water resistance and corrosion resistance.

JP-A-6-220355 JP 7-48435 A JP-A-6-136241 JP-A-8-157775 JP-A-9-328656

Therefore, an object of the present invention is to provide an aqueous primer composition capable of forming a primer coating film having excellent processability and processed portion corrosion resistance.

As a result of intensive studies to achieve the above object, the present inventors have obtained an aqueous primer composition containing a carbonyl group-containing modified epoxy resin (A), a crosslinking agent (B) and a rust preventive pigment (C). The carbonyl group-containing modified epoxy resin (A) has an amine compound (a ₁ ) having at least one active hydrogen bonded to a nitrogen atom and having a carbonyl group, and 2 epoxy groups in one molecule. the aqueous primer composition characterized in that it is manufactured by reacting an epoxy resin (a ₂₎ having more than five, can solve the above problems, and have completed the present invention.

That is, this invention consists of the following aspects.
[Aspect 1]
An aqueous primer composition comprising a carbonyl group-containing modified epoxy resin (A), a crosslinking agent (B) and a rust preventive pigment (C),
The carbonyl group-containing modified epoxy resin (A) has at least one active hydrogen bonded to a nitrogen atom and an amine compound (a ₁ ) having a carbonyl group, and two epoxy groups in one molecule. Produced by reacting with the epoxy resin (a ₂ ) having the above,
The aqueous primer composition.

[Aspect 2]
The amine compound (a ₁ ) is produced by a Michael addition reaction between diacetone acrylamide and an amine compound (a ₁₁ ) having two or more active hydrogens bonded to a nitrogen atom in one molecule. Aqueous primer composition.
[Aspect 3]
The aqueous primer composition according to embodiment 1 or 2, wherein the carbonyl group-containing modified epoxy resin (A) has at least one hydrophilic group selected from the group consisting of an anionic group, a cationic group, and a nonionic group.

[Aspect 4]
Any one of Embodiments 1 to 3, wherein the crosslinking agent (B) is at least one crosslinking agent selected from the group consisting of an isocyanate compound, a blocked isocyanate compound, an amino resin, a phenol resin, a hydrazide compound, and a semicarbazide compound. An aqueous primer composition as described in 1.
[Aspect 5]
The aqueous primer composition according to any one of aspects 1 to 4, wherein the crosslinking agent (B) comprises a hydrazide compound and / or a semicarbazide compound.

[Aspect 6]
The aqueous primer composition according to any one of aspects 1 to 5, wherein the antirust pigment (C) contains a vanadium compound (c ₁ ), a silicon-containing compound (c ₂ ), and a phosphoric acid compound (c ₃ ). object.
[Aspect 7]
A step (1) of forming a cured primer coating by applying the aqueous primer composition according to any one of Embodiments 1 to 6 onto a metal material, and then drying, and the cured primer coating Coating the top coat on the film and then drying to reach the maximum material temperature of 180 ° C. to 300 ° C. to form a top coat film (2);
A method for forming a multilayer coating film comprising:

[Aspect 8]
The crosslinking agent (B) contains a hydrazide compound and / or a semicarbazide compound, and dried in step (1) so as to reach the maximum material temperature not lower than 10 ° C. and lower than 180 ° C. The method of embodiment 7, wherein the method is formed.
[Aspect 9]
A coated article formed by coating the aqueous primer composition according to any one of Embodiments 1 to 6 on a metal material, or by the method according to Embodiment 7 or 8.

According to the aqueous primer composition of the present invention, a primer coating film excellent in processability and processed part corrosion resistance can be obtained.

Hereinafter, the aqueous primer composition of the present invention will be described in more detail.
The aqueous primer composition of the present invention contains a carbonyl group-containing modified epoxy resin (A), a crosslinking agent (B) and a rust preventive pigment (C).

[Carbonyl group-containing modified epoxy resin (A)]
The carbonyl group-containing modified epoxy resin (A) has at least one active hydrogen bonded to a nitrogen atom in one molecule and has at least 2 amine compounds (a ₁ ) having a carbonyl group and an epoxy group in one molecule. It is prepared by reacting the epoxy resin (a ₂₎ having pieces.
The amine compound (a ₁ ) can be obtained by a Michael addition reaction between diacetone acrylamide and an amine compound (a ₁₁ ) having two or more active hydrogens bonded to a nitrogen atom in one molecule.

The amine compound (a ₁₁ ) may be a compound containing an oxygen atom, a sulfur atom, a nitrogen atom, etc., for example, methylamine, ethylamine, propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, t-butylamine, hexylamine, 2-methoxyethylamine, 2-ethoxyethylamine, 3-methoxypropylamine, 3-methylthiopropylamine, ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepenta Min, iminobispropylamine, methyliminobispropylamine, lauryliminobispropylamine, N, N′-bisaminopropyl-1,3-propylenediamine, N, N ′ -Bisaminopropyl-1,3-butylenediamine, 1,2-diaminopropane, bis- (3-aminopropyl) ether, bis- (3-aminopropoxy) ethane, 1,3-bis- (3-aminopropoxy) ) -2,2-dimethyl-propane, N- lauryl propylene diamine, N, N'-di -t- butyl ethylenediamine, N- methyl ethylenediamine, N- ethyl ethylenediamine, N, N- dimethylethylenediamine, _{C 1} ~ of allylamine aliphatic amine compounds having a carbon number of C _16; cyclopentylamine, cyclohexylamine, cycloheptylamine, cyclooctyl amine, aminomethyl cyclohexane, 4-methyl cyclohexylamine, 1-cyclohexylethyl amine, 3,3,5-trimethyl cyclohexylamine Isophoronediamine, alicyclic amine compound having a carbon number of _{C 1} ~ _{C 16,} such as bis aminomethyl cyclohexane; benzylamine, phenethylamine, 4-methylbenzylamine, N- aminopropyl aniline, 2-amino-1,2 Diphenylethanol, 9-aminofluorene, benzhydrylamine, xylylenediamine, phenylenediamine, diaminodiphenylmethane, N-benzylethylenediamine, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, 2,3-diaminopyridine, 2 , 5-diaminopyridine, 2,3,6-triaminopyridine, N-aminopropylaniline, 2-amino-3-methylpyridine, 2-amino-4-methylpyridine, 2-amino-6-methylpyridine, 2 -Amino-3-ethylpi Gin, 2-amino-3-propylpyridine, 2-amino-4,6-dimethylpyridine, 2,6-diamino-4-methylpyridine, 3-amino-6-isopropylpyridine, 2,6-diaminopyridine, etc. aromatic amine compounds having a carbon number of _C ₁ ~ C _16; piperazine, N- aminopropyl piperazine, 2-methylpiperazine, 2,6-dimethylpiperazine, 2,5-dimethylpiperazine, 3-methylamino-piperidine, 2- Aminomethylpiperazine, 3-aminopyrrolidine, homopiperazine, N-aminopropylpiperazine, 1,4- (bisaminopropyl) piperazine, N-aminoethylpiperidine, N-aminopropylpiperidine, 2-aminomethylpiperidine, 4-amino Methylpiperidine, furfurylamine, tetrahydrofur Complex with Riruamin, 3- (methylamino) pyrrolidine, 5-methyl furfuryl amine, 2- (Furufuriruchio) ethylamine, 2- picolylamine, 3-picolylamine, of _{C 1} ~ _{C 16} and 4-picolylamine carbon atoms Cyclic compounds; 2-hydroxyethylamine, methyl (2-hydroxyethyl) amine, 1-amino-2-propanol, 3-amino-1-propanol, 2-amino-1-propanol, 1-amino-2-propanol, 1 hydroxyl group such as diethanolamine, 3-amino-1,2-propanediol, 2- (2-aminoethoxy) ethanol, N- (2-hydroxyethyl) ethylenediamine, 2-amino-1,3-propanediol, etc. Mention may be made of amine compounds having at least one.

Among the amine compounds (a ₁₁ ), an amine compound having one primary amino group in one molecule, an amine compound having one primary amino group and one secondary amino group in each molecule, 2 The amine compound having two primary amino groups in one molecule and the amine compound having two primary amino groups in one molecule can increase the carbonyl group concentration of the carbonyl group-containing modified epoxy resin (A) in the present invention. From the viewpoint, or from the viewpoint of easy adjustment of the molecular weight of the resin.

Amine compounds as (a _11), if you select one perforated to n- butylamine in one molecule a primary amino group, the reaction to produce compound according Michael addition reaction to diacetone acrylamide (a _1), under It is shown by Formula (1).

When N-ethylethylenediamine, which is an amine compound having one primary amino group and one secondary amino group in the molecule, is selected as the amine compound (a ₁₁ ), Michael addition reaction to diacetone acrylamide The reaction to produce the amine compound (a ₁ ) by is represented by the following formula (2).

In the present invention, the Michael addition reaction is usually performed at a temperature of about 0 to about 200 ° C. from the viewpoint of obtaining an amine compound (a ₁ ) that is a desired reaction product in a short time and from the viewpoint of suppressing side reactions. It is carried out within the range, preferably within the range of about 50 to about 120 ° C. In the above Michael addition reaction, from the viewpoint of not leaving unreacted diacetone acrylamide and suppressing the formation of a compound having no active hydrogen that reacts with an epoxy group, the mole of diacetone acrylamide and the amine compound (a ₁₁ ). The ratio is preferably in the range of about 1 / 0.8 to about 1 / 5.0, and more preferably in the range of about 1 / 0.9 to about 1 / 2.2.

The Michael addition reaction can be performed in the presence of a solvent such as water or an organic solvent, but the solvent may not be present. Although the kind in particular is not limited as said organic solvent, For example, well-known organic solvents, such as ester type, ether type, alcohol type, are mentioned. When a solvent is used in the Michael addition reaction, the concentration of the amine compound (a ₁₁ ) and diacetone acrylamide is preferably about 20% by mass or more, and more preferably about 50% by mass or more. If it is more dilute than this, it is not preferable because the reaction hardly proceeds. The reaction time varies depending on the type of amino compound to be used, but is usually completed in about 30 minutes to about 5 hours.

From the standpoint of corrosion resistance, the above Michael addition reaction is preferably carried out without a catalyst, but a catalyst can be used if necessary. The catalyst is not particularly limited. For example, metal alkoxides such as sodium methoxide, sodium ethoxide, and magnesium ethoxide; metal phenoxides such as sodium phenoxide; metal carbochelates such as sodium benzoate and potassium benzoate; triethylamine, Triethylenediamine, N, N-diethylaniline, N, N-dimethylaniline, N, N-dimethylbenzylamine, N-methylmorpholine, N-ethylmorpholine, N, N′-dimethylpiperazine, pyridine, picoline, 1,8 -Tertiary amines such as diaza-bicyclo (5,4,0) undecene-7; tetraethylammonium bromide, tetrabutylammonium bromide, benzyltriethylammonium chloride, trioctylmethylammonium chloride, cetyltrimethyl bromide Quaternary ammonium salts such as ruammonium iodide, tetrabutylammonium iodide, dodecyltrimethylammonium iodide, benzyldimethyltetradecylammonium acetate; quaternary phosphonium salts such as tetraphenylphosphonium chloride, triphenylmethylphosphonium chloride, tetramethylphosphonium bromide 2-methylimidazole, 2-ethylimidazole, 2-methyl-4-methylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 2-phenyl-4-methyl-5-hydroxymethyl Examples include basic compounds such as imidazole compounds such as imidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and 1-azine-2-methylimidazole. The catalyst used for the Michael addition reaction is not limited to one type, and a plurality of types of catalysts may be used. When a catalyst is used for the Michael addition reaction, the amount is preferably about 10 mol% or less based on the amount of the amine compound.

The amine compound (a ₁ ) produced by the Michael addition reaction includes an unreacted amine compound (a ₁₁ ), a compound in which the carbonyl group in the Michael addition reaction product is ketiminated by the amine compound (a ₁₁ ), and the like. In some cases.

When the mixture containing the amine compound (a ₁ ) produced by the Michael addition reaction contains a large amount of unreacted amino compound (a ₁₁ ), the amine compound (a ₁ ) and epoxy resin (described later) In the reaction with a ₂ ), the carbonyl group-containing modified epoxy resin (A) may be extremely polymerized or gelled, so that the unreacted amino compound (a ₁₁ ) is removed from the mixture. It is preferable.

The unreacted amine compound (a ₁₁ ) can be removed from the mixture containing the amine compound (a ₁ ) by distillation, azeotropy with water and / or an organic solvent under normal pressure or reduced pressure conditions. As the organic solvent, the solvent used in the Michael addition reaction can be used. After the Michael addition reaction, a known solvent such as alcohol or ether is further added to azeotrope. Can do.

When the mixture containing the amine compound (a ₁ ) contains a ketiminated compound, the carbonyl group-containing modified epoxy resin (A) produced by the reaction of the mixture with the epoxy resin is used. Viscosity may increase. Furthermore, when the amine compound (a ₁ ) contains a ketiminated compound, in the aqueous primer composition of the present invention, the ketiminated portion may be hydrolyzed to produce a volatile organic compound. . Therefore, it is preferable to regenerate the carbonyl group by adding excess water to the mixture obtained by the Michael addition reaction to hydrolyze the ketiminated portion of the ketiminated compound. The amine compound produced by this hydrolysis can be removed in the same manner as the unreacted amine compound (a ₁₁ ).

The unreacted amine compound (a ₁₁ ) and the amine compound produced by hydrolyzing the ketiminated compound can be removed together during the Michael addition reaction, or the Michael addition reaction It may be removed later.

Diacetone acrylamide is a hydrogen atom bonded to a carbon atom forming a carbon-carbon double bond (CH ₂ ═CH) at 6.19 to 6.23 ppm in ¹ H-NMR measurement using a deuterated chloroform solvent. The originating peak is observed. In the measurement of ¹ H-NMR using the deuterated chloroform solvent of the reaction product, no peak is observed at 6.19 to 6.23 ppm. Therefore, in the present invention, the reaction rate of the Michael addition reaction is determined by the NMR measurement. You can watch.

In the reaction of the amine compound (a ₁ ) and the epoxy resin (a ₂ ), the amine compound (a ₁ ) can be an amine compound having one active hydrogen bonded to a nitrogen atom in one molecule, or It can be an amine compound having two active hydrogens bonded to a nitrogen atom in one molecule, or a mixture thereof.

In the present invention, the epoxy resin (a ₂ ) having two or more epoxy groups in one molecule is not particularly limited as long as it has two or more epoxy groups in the molecule. The epoxy resin (a ₂ ) is obtained by reacting, for example, polyphenols such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol A / F type epoxy resin, and novolac type phenol resin with epihalohydrin such as epichlorohydrin. Epoxy resin such as aliphatic epoxy resin, cycloaliphatic epoxy resin, etc .; epoxy resin containing a group-introduced resin, or a resin in which this glycidyl group is further introduced, and a polyphenol is further reacted to increase the molecular weight; Examples thereof include an epoxy group-containing acrylic copolymer produced by copolymerizing a polymerizable unsaturated monomer and another polymerizable unsaturated monomer; a polybutadiene resin having an epoxy group; a polyurethane resin having an epoxy group. The epoxy resin (a ₂ ) has an epoxy equivalent weight in the range of about 140 to about 5,000, preferably in the range of about 150 to about 2,000, and the number average molecular weight in the range of about 200 to about 50,000. Among them, it is preferable to use those having a range of about 160 to about 10,000 from the viewpoint of stability and viscosity of the modified epoxy resin aqueous dispersion.
In this specification, the epoxy resin (a ₂ ) having two or more epoxy groups in one molecule may be simply referred to as an epoxy resin (a ₂ ).

The ratio of the amine compound (a ₁ ) to the epoxy resin (a ₂ ) is such that the carbonyl group concentration in the carbonyl group-containing modified epoxy resin (A) is about 0.1 to about 3.5 mol / wt based on the solid content. From the viewpoint of the corrosion resistance of the primer coating film obtained from the aqueous primer composition of the present invention, it is preferable to determine to be in the range of kg, and the above ratio is in the range of about 0.4 to about 3 mol / kg. It is more preferable.
In the present specification, the “solid content” means a solid content from which volatile components such as water and organic solvent in the paint are removed, and is measured by drying about 2 g of a sample at 105 ° C. for 3 hours. be able to.

The carbonyl group-containing modified epoxy resin (A) preferably has a weight average molecular weight within the range of about 2,000 to about 50,000, and has a weight average molecular weight within the range of about 5,000 to about 20,000. More preferably. When the weight average molecular weight is larger than about 50,000, the viscosity is high, the production becomes difficult, and the finish of the primer coating film to be formed may be problematic. Moreover, when the said weight average molecular weight is smaller than about 5,000, sufficient water resistance may not be obtained.

In the present specification, the number average molecular weight and weight average molecular weight of resins other than those having a cationic group introduced are the same as the retention time (retention capacity) measured using a gel permeation chromatograph (GPC). It is a value obtained by converting to the molecular weight of polystyrene based on the retention time (retention capacity) of standard polystyrene with a known molecular weight measured in (1). Specifically, “HLC8120GPC” (trade name, manufactured by Tosoh Corporation) is used as a gel permeation chromatograph, and “TSKgel G-4000HXL”, “TSKgel G-3000HXL”, “TSKgel G-2500HXL” are used as columns. ”And“ TSKgel G-2000HXL ”(trade names, both manufactured by Tosoh Corporation), a differential refractometer is used as a detector, mobile phase: tetrahydrofuran, measurement temperature: 40 ° C., flow rate: It can be measured under the condition of 1 mL / min.

Specifically, the number average molecular weight and the weight average molecular weight of the resin into which the cationic group is introduced are “HLC-8120GPC” (trade name, manufactured by Tosoh Corporation) as a gel permeation chromatograph apparatus, and “ Using a total of three TSKgel Super-H3000 and two TSKgel Super-H2500 (trade names, all manufactured by Tosoh Corporation), a differential refractometer was used as a detector. , Mobile phase: tetrahydrofuran (containing 0.5% by mass of triethanolamine), measurement temperature; 25 ° C., flow rate: 0.6 mL / min.

In the present invention, the reaction between the amine compound (a ₁ ) and the epoxy resin (a ₂ ) can be performed in the presence of an organic solvent. Although it does not specifically limit as said organic solvent, Well-known organic solvents, such as ester type | system | group, alcohol type | system | group, ether type | system | group, ketone type, are mentioned. The concentration of the solution containing the amine compound (a ₁ ) and the epoxy resin (a ₂ ) is preferably in the range of 50 to 90% by mass when the reaction rate and the obtained resin are dispersed with water. It is preferable from the viewpoint that the remaining solvent can be reduced, and more preferably in the range of about 55 to about 80% by mass. In addition, the reaction temperature of the above reaction is preferably in the range of about 40 to about 160 ° C., and more preferably in the range of about 60 to about 140 ° C. from the viewpoint of reaction rate, viscosity, and the like.

The molecular weight of the carbonyl group-containing modified epoxy resin (A) can be adjusted by the ratio of the amine compound (a ₁ ) and the epoxy resin (a ₂ ). Also, amine compounds such as isophoronediamine, 2-ethylhexylamine and cyclohexylamine having two or more active hydrogens capable of reacting with an epoxy group, compounds having a phenolic hydroxyl group and dibasic acids such as terephthalic acid and adipic acid Etc. can be added to the reaction system of the amine compound (a ₁ ) and the epoxy resin (a ₂ ) and reacted to adjust the molecular weight of the carbonyl group-containing modified epoxy resin (A).

The carbonyl group-containing modified epoxy resin (A) preferably has an amine value in the range of about 10 to about 200 mg-KOH / g from the viewpoint of achieving both water dispersibility and water resistance during neutralization, More preferably, it has an amine value within the range of about 20 to about 180 mg-KOH / g.
In addition, in this specification, an amine value means the total amine value by the titration method prescribed | regulated to JISK7237: 1995.

In the present invention, the carbonyl group-containing modified epoxy resin (A) preferably has an epoxy equivalent of more than about 1,000. When the said epoxy equivalent is about 1,000 or less, the storage stability of the aqueous primer composition of this invention may fall.
In addition, in this specification, an epoxy equivalent means the value measured according to JISK7236: 2001.

The carbonyl group-containing modified epoxy resin (A) can be contained in the aqueous primer composition of the present invention as an aqueous dispersion dispersed in water or a medium containing water (hereinafter sometimes referred to as an aqueous medium). In the present specification, the aqueous dispersion includes not only the carbonyl group-containing modified epoxy resin (A) dispersed in an aqueous medium but also the carbonyl group-containing modified epoxy resin (A) dissolved in an aqueous medium. Is also included. Examples of the medium containing water include water and a mixture of water and an organic solvent such as a water-soluble organic solvent. Dispersion of the carbonyl group-containing modified epoxy resin (A) is not particularly limited, and a shearing force is applied to the carbonyl group-containing modified epoxy resin (A) in a conventionally known method, for example, in the presence of an emulsifier in an aqueous medium. A method of microparticulation, a method of microparticulation by applying shear force to the carbonyl group-containing modified epoxy resin (A) into which a hydrophilic group such as an anionic group, a cationic group, or a nonionic group is introduced in an aqueous medium, or Examples thereof include a method of applying a shear force to the carbonyl group-containing modified epoxy resin (A) having the hydrophilic group introduced therein to form fine particles in an aqueous medium in the presence of an emulsifier.

The emulsifier is not particularly limited, and examples thereof include an anionic emulsifier, a cationic emulsifier, a nonionic emulsifier, an amphoteric emulsifier, and a reactive emulsifier.
Specific examples of the emulsifier include, for example, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate and sodium dodecylsulfate, fatty acid salts, rosinates, alkylsulfates, alkylsulfosuccinates, α-olefin sulfonates, and alkylnaphthalenes. Anionic emulsifiers such as sulfonates and polyoxyethylene alkyl (aryl) sulfates; quaternary ammonium salts such as lauryl trialkyl ammonium salts, stearyl trialkyl ammonium salts and trialkyl benzyl ammonium salts, primary to primary Cationic surfactants such as tertiary amine salts, lauryl pyridinium salts, benzalkonium salts, benzethonium salts, or lauryl amine acetates; polyoxyethylene alkyl ethers, polyoxyethylene alkyls Nonionic surfactants such as phenol ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan alkyl ester; amphoteric surfactants such as carboxybetaine type, sulfobetaine type, aminocarboxylic acid type, imidazoline derivative type; Eleminol JS-2 (Manufactured by Sanyo Chemical Industries), Eleminol RS-30 (manufactured by Sanyo Chemical Industries), latemul S-180A (manufactured by Kao), Aqualon HS-05 (manufactured by Daiichi Kogyo Seiyaku), Aqualon RN-10 (manufactured by Daiichi Kogyo Seiyaku) And reactive emulsifiers such as ADEKA rear soap SE-10N (manufactured by Asahi Denka).

The emulsifier is about 0 to about 20 parts by mass with respect to 100 parts by mass of the solid content of the carbonyl group-containing modified epoxy resin (A) from the viewpoint of the stability of the aqueous dispersion and the water resistance of the formed primer coating film. And more preferably within the range of about 0 to about 15 parts by weight.
In the present invention, one or more hydrophilic groups selected from an anionic group, a cationic group, and a nonionic group may be introduced into the carbonyl group-containing modified epoxy resin (A) and then dispersed in an aqueous medium. .

Examples of introducing an anionic group into the carbonyl group-containing modified epoxy resin (A) include the following methods for imparting a carboxyl group. Carboxylic anhydride is added to a solution of a carbonyl group-containing modified epoxy resin (A) produced using a cyclic ether such as dioxane, a dialkyl ether having an oxyethylene chain such as glyme or diglyme, or an aprotic organic solvent such as acetone. The carbonyl group-containing modified epoxy resin (A) having a carboxyl group is obtained by adding and reacting by raising the temperature to about 90 ° C. Further, if a basic compound is added to neutralize the carboxyl group and then phase inversion in an aqueous medium, an aqueous dispersion of the carbonyl group-containing modified epoxy resin (A) can be obtained.

The carboxylic anhydride may be an anhydride of a compound having two or more carboxyl groups in one molecule. For example, succinic anhydride, itaconic anhydride, maleic anhydride, citraconic anhydride, phthalic anhydride, anhydrous And trimellitic acid. Examples of the basic compound include amines, alkaline earth metal hydroxides and / or alkali metal hydroxides.

As an example of introducing a cationic group into the carbonyl group-containing modified epoxy resin (A), a basic amino group is introduced into the epoxy group of the carbonyl group-containing modified epoxy resin (A), neutralized with an acid, and then an aqueous medium. Among them, a dispersion method can be mentioned. Specifically, the carbonyl group-containing modified epoxy resin (A) can be reacted with an amino group-containing compound to give an amino group, and then neutralized with an acidic compound such as a carboxylic acid.

Among the amino group-containing compounds, examples of the primary amino group-containing compound include monoethanolamine, propanolamine, hydroxyethylaminopropylamine, diethylenetriamine, 2-ethylhexylamine, cyclohexylamine, and triethylenetetramine. it can. Examples of secondary amino group-containing compounds include diethylamine, diisopropylamine, diethanolamine, di (2-hydroxypropyl) amine, monomethylaminoethanol, monoethylaminoethanol, and the like. The amino group-containing compound can be used alone or as a mixture of two or more.

Moreover, after neutralizing the amino group derived from the amine compound (a ₁ ) used in the production of the carbonyl group-containing modified epoxy resin (A) or the amine compound used to adjust the molecular weight of the resin with an acidic compound. The carbonyl group-containing modified epoxy resin (A) may be dispersed in an aqueous medium to obtain an aqueous dispersion.

In the method in which the amino group contained in the carbonyl group-containing modified epoxy resin (A) is neutralized with an acidic compound and dispersed in water, examples of the acidic compound include formic acid, acetic acid, lactic acid, phosphoric acid, and organic phosphoric acid. Is mentioned. These acidic compounds may be mixed with the carbonyl group-containing modified epoxy resin (A) to neutralize the amino groups, and then dispersed while adding an aqueous medium. You may neutralize and disperse | distribute, mixing with a modified epoxy resin (A).

As a method for introducing a nonionic group into the carbonyl group-containing modified epoxy resin (A), specifically, in the production of the carbonyl group-containing modified epoxy resin (A), an amine compound (a ₁ ) and an epoxy resin (a ₂ ) and a method of reacting a polyoxyalkyleneamine compound and the like. As said polyoxyalkylene amine compound, the compound represented by following formula (3) which has an amino group which can react with an epoxy group can be mentioned, for example.

(Wherein R ¹ represents a hydroxyl group or an alkoxy group having C ₁ to C ₄ carbon atoms, R ² represents a hydrogen atom or a methyl group, and m is from about 2 to about 220, preferably about 5 Is an integer of about 180, n is an integer of 2 or 3, preferably 2, and the m oxyalkylene units (C _n H _2n O) may be the same or different from each other. Also good)

From the viewpoint of achieving both water dispersibility and water resistance, the polyoxyalkylene compound is preferably added to the carbonyl group-containing modified epoxy resin (A) based on the solid content, preferably about 1 to about 25% by mass, and more preferably. Is contained in the range of about 3 to about 15% by mass.

As another method for introducing a nonionic group into the carbonyl group-containing modified epoxy resin (A), specifically, in the production of the carbonyl group-containing modified epoxy resin (A), an amine compound (a ₁ ) and an epoxy resin Examples thereof include a method of reacting (a ₂ ) with a polyoxyalkylene unsaturated compound having an unsaturated group capable of Michael addition reaction. As said polyoxyalkylene unsaturated compound, the compound represented, for example by following formula (4) can be mentioned.

(Wherein R ³ represents a hydrogen atom or an alkyl group having C ₁ to C ₄ carbon atoms, m is an integer of about 2 to about 220, preferably about 5 to about 180, and n is An integer of 2 or 3, preferably 2, and the m oxyalkylene units (C _n H _2n O) may be the same or different from one another).

Specific examples of the polyoxyalkylene unsaturated compound include polyethylene glycol acrylate, polypropylene glycol acrylate, methoxy polyethylene glycol acrylate, ethoxy polyethylene glycol acrylate, and the like.

In the present invention, the carbonyl group-containing modified epoxy resin (A) having at least one hydrophilic group selected from the group consisting of an anionic group, a cationic group, and a nonionic group includes an amine compound (a ₁ ) and an epoxy resin. After reacting with (a ₂ ) to obtain a carbonyl group-containing modified epoxy resin (A), it is generated by introducing one or more hydrophilic groups selected from an anionic group, a cationic group and a nonionic group The reaction of the amine compound (a ₁ ) and the epoxy resin (a ₂ ) and the reaction for introducing the hydrophilicity may be performed simultaneously.

In addition, the aqueous dispersion of the carbonyl group-containing modified epoxy resin (A) preferably has a solid content in the range of about 10 to about 50% by mass from the viewpoint of stability and viscosity, and about 20 to about 45. It is more preferable to have a solid content in the range of mass%.
In the present invention, the carbonyl group-containing modified epoxy resin (A) having a nonionic group can be obtained by dispersing it in an aqueous medium as it is, and an aqueous dispersion thereof can be obtained. The aqueous dispersion can be obtained by neutralizing the amino group contained in the resin (A) with an acidic compound and then dispersing in an aqueous medium.

[Crosslinking agent (B)]
In the aqueous primer composition of the present invention, the crosslinking agent (B) is a component included for imparting a crosslinked structure to the primer coating film obtained after baking to improve water resistance or improve physical properties. As a crosslinking agent (B), for example, amino resin, polyaldehyde compound, phenol resin, epoxy compound, isocyanate compound, blocked isocyanate compound, metal compound (metal salt, metal complex, metal oxide, metal hydroxide, etc.), Examples include silicate compounds, hydrazide compounds, semicarbazide compounds, and the like.

In the aqueous primer composition of the present invention, the amount of the crosslinking agent (B) is generally 1 in terms of the functional group 1 in the carbonyl group-containing modified epoxy resin (A) in consideration of the general performance of the cured primer coating film to be formed. The amount of the functional group in the crosslinking agent (B) is preferably such that the amount of the functional group in the crosslinking agent (B) is in the range of about 0.05 to about 10 mol, and in the range of about 0.05 to about 3 mol. More preferably, the amount is such that it is in the range of about 0.1 to about 2 moles.
The functional group varies depending on the type of the crosslinking agent (B), the reactive group of the carbonyl group-containing modified epoxy resin (A), and the like. For example, when the crosslinking agent (B) is an epoxy compound, the functional group contains a carbonyl group Examples of the functional group in the modified epoxy resin (A) include a carboxyl group and / or a hydroxyl group, and examples of the functional group in the crosslinking agent (B) include an epoxy group.

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

The polyaldehyde compound is preferably a compound having at least two aldehyde groups in one molecule, and specific examples thereof include glyoxal and glutaraldehyde.

For example, the phenol resin is obtained by, for example, heating a phenol component and an aldehyde in the presence of a reaction catalyst to cause a condensation reaction to introduce a methylol group, and a part or all of the methylol group of a methylolated phenol resin obtained with an alcohol is alcohol. Examples include resol-type phenolic resins produced by alkyl etherification. In the production of a resol-type phenol resin, a bifunctional phenol compound, a trifunctional phenol compound, a tetrafunctional or higher functional phenol compound, or the like can be used as the phenol component that is a starting material.

Examples of the bifunctional phenol compound include o-cresol, p-cresol, p-tert-butylphenol, p-ethylphenol, 2,3-xylenol, and 2,5-xylenol. Examples of the phenol compound include carboxylic acid, m-cresol, m-ethylphenol, 3,5-xylenol, and m-methoxyphenol. Examples of the tetrafunctional phenol compound include bisphenol A and bisphenol F. be able to. In order to improve the scratch resistance, it is preferable to use a trifunctional or higher functional phenol compound, particularly carboxylic acid and / or m-cresol. These phenol compounds may be used alone or as a mixture of two or more.

Examples of the aldehydes used for producing the phenol resin include formaldehyde, paraformaldehyde, trioxane and the like, and can be used alone or as a mixture of two or more.

The alcohol used for alkyl etherifying part or all of the methylol group of the methylolated phenol resin is preferably C ₁ -C ₈ carbon atoms, more preferably C ₁ -C ₄ carbon atoms. The monohydric alcohol which has. Suitable monohydric alcohols include, for example, methanol, ethanol, n-propanol, n-butanol, isobutanol and the like.

As the phenol resin, from the viewpoint of reactivity with the carbonyl group-containing modified epoxy resin (A), the average number of alkoxymethyl groups per benzene nucleus is about 0.5 or more, preferably about 0.6 to Those having about 3.0 are suitable.

The epoxy compound is preferably a compound having at least two epoxy groups in one molecule, and typical examples thereof include ethylene glycol diglycidyl ether, hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and glycerin diglycidyl. Polyhydric alcohols such as ether, glycerin triglycidyl ether, diglycerin triglycidyl ether, sorbitol polyglycidyl ether, hydrogenated bisphenol A diglycidyl ether, bisphenol A diglycidyl ether, phenol novolac polyglycidyl ether or cresol novolac polyglycidyl ether Polyglycidyl ether of polyhydric phenol; glycidyl ester and glycidyl etherified product of p-oxybenzoic acid Polyglycidyl esters of polyvalent carboxylic acids such as diglycidyl phthalate, diglycidyl hexahydrophthalate or (meth) acrylic acid glycidyl ester copolymers; polyepoxy compounds containing nitrogen-containing heterocycles such as hydantoin rings; Epoxy resin that is an adduct of a compound having two or more epoxy groups in one molecule and a polyhydric alcohol, polyhydric phenol, or polybasic acid; modified epoxy resin such as fatty acid-modified epoxy resin or amine-modified epoxy resin; Examples thereof include vinyl polymers having an epoxy group in the chain.

In the aqueous primer composition of the present invention, when the crosslinking agent (B) is an epoxy compound, the amount thereof is based on 1 mol of the total of carboxyl groups and hydroxyl groups contained in the carbonyl group-containing modified epoxy resin (A). The amount of the epoxy group in the epoxy compound is preferably adjusted to be in the range of about 0.05 to about 3 mol, preferably about 0.1 to about 2 mol.

The isocyanate compound is preferably a compound having two or more isocyanate groups in one molecule, and those conventionally used in the production of polyurethane, such as aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic fats. Group polyisocyanates, aromatic polyisocyanates, and derivatives of these polyisocyanates.

Examples of the alicyclic polyisocyanate include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (common name) : Isophorone diisocyanate), 4,4'-methylenebis (cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3- or 1,4-bis (isocyanatomethyl) cyclohexane (Common name: hydrogenated xylylene diisocyanate) or mixtures thereof, alicyclic diisocyanates such as norbornane diisocyanate, for example 1,3,5-triisocyanatocyclohexane 1,3,5-trimethylisocyanatocyclohexane, 2- (3-isocyanatopropyl) -2,5-di (isocyanatomethyl) -bicyclo (2.2.1) heptane, 2- (3-isocyanatopropyl ) -2,6-di (isocyanatomethyl) -bicyclo (2.2.1) heptane, 3- (3-isocyanatopropyl) -2,5-di (isocyanatomethyl) -bicyclo (2.2. 1) Heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 6- (2-isocyanatoethyl)- 2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-iso Anatopropyl) -bicyclo (2.2.1) -heptane, 6- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane And alicyclic triisocyanates such as

Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3. -Aliphatic diisocyanates such as butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, for example lysine ester triisocyanate, 1,4,8 -Triisocyanatooctane, 1,6,11-triisocyanatoundecane, 1,8-diisocyanato-4-isocyanatomethyloctane, 1,3,6-triisocyanatohexane, , And aliphatic triisocyanate such as 5,7-trimethyl-1,8-diisocyanato-5-isocyanatomethyl octane.

Examples of the araliphatic polyisocyanate include 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω, ω′-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4- Aromatic aliphatic diisocyanates such as bis (1-isocyanato-1-methylethyl) benzene (common name: tetramethylxylylene diisocyanate) or mixtures thereof, for example, aromatic fats such as 1,3,5-triisocyanatomethylbenzene Group triisocyanate and the like.

Examples of the aromatic polyisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4′- or 4,4′-diphenylmethane diisocyanate or the like. 2,4- or 2,6-tolylene diisocyanate or mixtures thereof, aromatic diisocyanates such as 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, for example, triphenylmethane-4,4 Aromatic triisocyanates such as ', 4' ''-triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, such as 4,4'-diphenylmethane-2,2 ', 5, '- and aromatic tetraisocyanates such as tetra isocyanates.

Examples of the polyisocyanate derivative include dimer, trimer, biuret, allophanate, carbodiimide, uretdione, uretoimine, isocyanurate, oxadiazine trione, polymethylene polyphenyl polyisocyanate (crude MDI, polymeric). MDI) and a crude product of tolylene diisocyanate (crude TDI).

If desired, the isocyanate compound may be a part of the isocyanate group modified with a compound containing about 1 to about 5 active hydrogens per molecule, such as a hydroxyl group or an amino group.
The said isocyanate compound may be added individually or as a 2 or more types of mixture.
As a blocked isocyanate compound as a crosslinking agent (B), the compound which blocked the isocyanate group of the said isocyanate compound with the blocking agent is mentioned, for example.

The reaction between the isocyanate compound and the blocking agent can be performed under known conditions. Moreover, it is preferable that the ratio of both components is a ratio that the functional group in a blocking agent becomes a little excess with respect to all the isocyanate groups in an isocyanate compound so that an isocyanate group may not remain. In order to perform blocking (react the blocking agent), a solvent can be added as desired. The solvent that can be used for the blocking reaction is preferably a solvent that is not reactive with an isocyanate group, such as ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate, N-methylpyrrolidone (NMP), and the like. Can be mentioned.

The blocking agent is a compound that blocks an isocyanate group. When the blocked isocyanate group is heated to, for example, about 100 ° C. or higher, preferably about 130 ° C. or higher, the blocking agent dissociates and the isocyanate group is regenerated. It can be easily reacted with a hydroxyl group or the like.

Examples of the blocking agent include phenols such as phenol and cresol; lactams such as ε-caprolactam and δ-valerolactam; aliphatics such as methanol, ethanol, propyl alcohol, butyl alcohol and lauryl alcohol; ethylene glycol monomethyl Ethers such as ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether; benzyl alcohol; glycolic acid esters such as methyl glycolate and ethyl glycolate; lactic acid, methyl lactate, ethyl lactate, butyl lactate, etc. Lactic acid esters; alcohols such as methylol urea and diacetone alcohol; acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone Oxime series such as oxime and cyclohexaneoxime; active methylene series such as diethyl malonate, ethyl acetoacetate, methyl acetoacetate, and acetylacetone; butyl mercaptan, t-butyl mercaptan, hexyl mercaptan, t-dodecyl mercaptan, thiophenol, ethylthiophenol Mercaptans such as acetanilide, acetanisidide, acid amides such as methacrylamide, acetic acid amide and benzamide; imides such as phthalimide and maleic imide; amines such as diphenylamine, phenylnaphthylamine, carbazole, aniline, naphthylamine and butylamine; Imidazoles such as imidazole and 2-ethylimidazole; Ureas such as urea, thiourea, ethyleneurea and diphenylurea; N-phenylcarbamate Carbamate esters such as Nyl; Imines such as ethyleneimine and propyleneimine; Sulphites such as sodium bisulfite and potassium bisulfite; 3,5-dimethylpyrazole, 3-methylpyrazole, 4-nitro-3,5 -Pyrazole compounds such as dimethylpyrazole and 4-bromo-3,5-dimethylpyrazole can be mentioned. The blocking agent can be used alone or as a mixture of two or more.

The blocked isocyanate compound may be added to the aqueous primer composition of the present invention alone or as a mixture of two or more. In the aqueous primer composition of the present invention, when the crosslinking agent (B) is a blocked isocyanate compound, the amount thereof is blocked with respect to 1 mol of hydroxyl group contained in the carbonyl group-containing modified epoxy resin (A). It is preferable that the amount of the isocyanate group is usually adjusted to be in the range of about 0.05 to about 3 mol, and preferably about 0.1 to about 2 mol.

The hydrazide compound and semicarbazide compound are each a compound containing one or more hydrazide groups and semicarbazide groups, and compounds each containing two or more hydrazide groups and semicarbazide groups are preferred. Examples of these include succinic acid dihydrazide, malonic acid dihydrazide, glutaric acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, etc., saturated chain dicarboxylic acid dihydrazide having C ₂ to C ₁₈ carbon atoms; maleic acid dihydrazide Monoolefinic unsaturated dicarboxylic acid dihydrazide such as fumaric acid dihydrazide, itaconic acid dihydrazide; aromatic carboxylic acid hydrazide such as phthalic acid, terephthalic acid or isophthalic acid dihydrazide, and pyromellitic acid dihydrazide, trihydrazide or tetrahydrazide; nitrilotri Sacetohydrazide, citric acid trihydrazide, 1,2,4-benzenetricarboxylic acid trihydrazide, ethylenediaminetetraacetic acid tetrahydrazide, 1,4,5,8-naphtho Polyhydrazide formed by reacting acid tetrahydrazide, a low polymer having two or more carboxylic acid lower alkyl ester groups in one molecule with hydrazine or hydrazine hydrate (hydrazine hydride) (see Japanese Patent Publication No. 52-22878) ), Polyhydrazide compounds such as carbonic dihydrazide; polyisocyanates containing diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate and the like and polyisocyanate compounds derived therefrom by reaction with hydrazine and monoalkyl-substituted hydrazine Polyhydrazide compound, polyisocyanate compound and polyethylene glycol monoalkyl obtained by reacting the above compound with the above dihydrazide compound or polyhydrazide compound Polysemicarbazide compounds and modified polyisocyanate compounds obtained by reacting hydrazine, monoalkyl-substituted hydrazine and the like with isocyanate groups in modified polyisocyanate compounds obtained by reaction with polyethers having active hydrogen such as ethers, polyols, etc. The polyhydrazide compound etc. which are obtained by making the said dihydrazide, polyhydrazide, etc. react with an isocyanate group are mentioned, These can be used individually or in mixture of 2 or more types.
Further, a compound having one or more hydrazide groups and one or more semicarbazide groups in one molecule can also be included in the crosslinking agent (B), and is treated as a hydrazide compound for convenience in this specification. .

In the aqueous primer composition of the present invention, when the crosslinking agent (B) is the hydrazide compound and / or semicarbazide compound, the hydrazide compound and / or semicarbazide compound is the carbonyl group-containing modified epoxy resin (A). In an amount such that the total of hydrazide groups and / or semicarbazide groups contained in the hydrazide compound and / or semicarbazide compound is generally in the range of about 0.01 to about 2 moles per mole of carbonyl group. Preferably, it is present in an amount that is within the range of about 0.1 to about 1.5 moles. This is from the viewpoint of low-temperature curability.

The aqueous primer composition of the present invention in which the crosslinking agent (B) contains the hydrazide compound and / or semicarbazide compound reacts efficiently with the carbonyl group of the carbonyl group-containing modified epoxy resin (A) at a relatively low temperature. A cured primer coating film having a dense cross-linked structure can be formed. For example, when the aqueous primer composition of the present invention is applied and dried to form a primer coating, the maximum material temperature (sometimes abbreviated as “PMT”) is about 10 ° C. or more and less than about 180 ° C. It can be dried to a range.
In addition to the hydrazide compound and / or semicarbazide compound, the cross-linking agent (B) is the above-mentioned amino resin, polyaldehyde compound, phenol resin, epoxy compound, isocyanate compound, blocked isocyanate compound, metal compound (metal salt, metal Complexes, metal oxides, metal hydroxides, etc.) and silicate compounds, when forming a primer coating film, the maximum material reaching temperature is in the range of about 10 ° C. to less than about 180 ° C. The drying temperature can be lowered.

[Anti-rust pigment (C)]
As the rust preventive pigment (C), those used as rust preventive pigments in this technical field can be adopted without particular limitation, and for example, chromate, vanadium compound, silicon-containing compound, phosphoric acid Compounds, phosphite pigments, calcium compounds, aluminum oxides, zinc oxides, zirconic acid, zirconate compounds, molybdate compounds, and combinations thereof.
In the aqueous primer composition of the present invention, the amount of the rust preventive pigment (C) is generally determined based on the solid content based on the solid content of the carbonyl group-containing modified epoxy resin (C) in consideration of the general performance of the cured primer coating film to be formed. The amount is about 5 to about 200 parts by weight, and preferably about 9 to about 150 parts by weight with respect to 100 parts by weight of the total of A) and the crosslinking agent (B).

The rust preventive pigment (C) is preferably a non-chromium rust preventive pigment other than chromate from the viewpoint of human health and environmental protection. As the non-chromium rust preventive pigment, a mixture of a vanadium compound (c ₁ ), a silicon-containing compound (c ₂ ), and a phosphoric acid compound (c ₃ ) is particularly preferable from the viewpoint of corrosion resistance.

The vanadium compound (c ₁ ) is not particularly limited as long as it is a compound containing vanadium, and examples thereof include vanadium pentoxide, calcium vanadate, ammonium metavanadate, and combinations thereof. In particular, in vanadium pentoxide and calcium vanadate, pentavalent vanadium ions are excellent in elution into water, and pentavalent vanadium ions released from the vanadium compound (c ₁ ) react with the material metal. Corrosion resistance can be improved by reacting with ions from the antirust pigment mixture.

The silicon-containing compound (c ₂ ) is not particularly limited as long as it is a compound containing silicon, and examples thereof include metal silicate salts, silica fine particles, and combinations thereof. The silicate metal salt is a salt composed of silicon dioxide and a metal oxide, and examples thereof include orthosilicate and polysilicate. Examples of the silicate include, for example, zinc silicate, aluminum silicate, aluminum orthosilicate, hydrated aluminum silicate, calcium aluminum silicate, sodium aluminum silicate, beryllium aluminum silicate, sodium silicate, calcium orthosilicate, calcium metasilicate, sodium calcium silicate, Zirconium silicate, magnesium orthosilicate, magnesium metasilicate, magnesium calcium silicate, manganese silicate, barium silicate, olivine, garnet, tortovite, cyllite, Benitoite, Neptunite, Ryokuchu, garnet, quartzite, barkite, Examples include torsite, zonotorite, talc, gyoganite, aluminosilicate, borosilicate, beryllosilicate, cholite, and fluorite. As the metal silicate, calcium orthosilicate and calcium metasilicate are suitable.

The silica fine particles can be used without particular limitation as long as they are silica fine particles. For example, silica fine particles having an untreated surface, silica fine particles having a surface treated with an organic substance, metal ion-exchanged silica fine particles, organic solvent-dispersible colloidal silica Etc. Examples of silica fine particles whose surface is not treated or treated with an organic substance include silica fine powder having an average particle diameter of about 0.5 to about 15 μm, preferably about 1 to about 10 μm, and organic solvent-dispersible colloidal silica. As the silica fine powder, those having an oil absorption in the range of about 30 to about 350 mL / 100 g, preferably about 30 to about 150 mL / 100 g can be suitably used. As commercially available products, Silysia 710 and Silysia 740 are available. , Silicia 550, Aerosil R972 (all of which are manufactured by Fuji Silysia Chemical Co., Ltd.), Mizukasil P-73 (manufactured by Mizusawa Chemical Co., Ltd.), Gasil 200DF (manufactured by Crossfield), and the like. The organic solvent-dispersible colloidal silica is also called an organosilica sol, in which silica fine particles having an average particle size of about 5 to about 120 nm are stably dispersed in an organic solvent such as alcohols, glycols, ethers, etc. In addition, examples of commercially available products include the OSCAL series (manufactured by Catalyst Chemicals Co., Ltd.), organosol (manufactured by Nissan Chemical Co., Ltd.), and the like.

The metal ion exchange silica fine particles are silica fine particles in which metal ions are introduced into a fine porous silica carrier by ion exchange. Specifically, silica fine particles into which calcium, magnesium or the like is introduced, for example, calcium ion exchanged silica fine particles can be mentioned. Examples of commercially available calcium ion-exchanged silica fine particles include SHIELDEX (Shielddex, registered trademark) C303, SHIELDEXAC-3, SHIELDEXC-5 (all of which are manufactured by WR Grace & Co.).

The phosphate compound (c ₃ ) is not particularly limited as long as it is a compound containing phosphorus. For example, calcium phosphate, calcium ammonium phosphate, calcium monohydrogen phosphate, calcium dihydrogen phosphate, calcium phosphate phosphate, phosphorus Phosphate-based metals such as zinc phosphate, aluminum phosphate, magnesium phosphate, zinc hydrogen phosphate, aluminum phosphate, magnesium phosphate, aluminum hydrogen phosphate, magnesium hydrogen phosphate, magnesium ammonium phosphate, aluminum trihydrogen phosphate Examples thereof include salts, phosphoric acid, and organic phosphoric acid compounds. In addition to phosphate ions released from the phosphate compound (c ₃ ), metal ions such as Ca, Zn, Al, and Mg can improve the corrosion resistance.

In the aqueous primer composition of the present invention, when the rust preventive pigment (C) contains the vanadium compound (c ₁ ), the silicon-containing compound (c ₂ ), and the phosphate compound (c ₃ ), the vanadium compound ( c ₁ ), silicon-containing compound (c ₂ ) and phosphoric acid-based compound (c ₃ ), based on the solid content, a total of 100 parts by mass of the carbonyl group-containing modified epoxy resin (A) and the crosslinking agent (B) And preferably within the following range.
Vanadium compound (c ₁ ): about 3 to about 50 parts by mass, preferably about 5 to about 30 parts by mass,
Silicon-containing compound (c ₂ ): about 3 to about 50 parts by mass, preferably about 5 to about 30 parts by mass,
Phosphoric acid compound (c ₃ ): about 3 to about 50 parts by mass, preferably about 5 to about 30 parts by mass.

In the aqueous primer composition of the present invention, when the rust preventive pigment (C) contains a vanadium compound (c ₁ ), a silicon-containing compound (c ₂ ), and a phosphate compound (c ₃ ), vanadium. The total amount of the compound (c ₁ ), the silicon-containing compound (c ₂ ) and the phosphoric acid compound (c ₃ ) is a total of 100 of the carbonyl group-containing modified epoxy resin (A) and the crosslinking agent (B) based on the solid content. From the viewpoint of corrosion resistance, the amount is preferably about 10 to about 150 parts by weight, preferably about 15 to about 90 parts by weight with respect to parts by weight.

In the aqueous primer composition of the present invention, when the rust preventive pigment (C) contains a vanadium compound (c ₁ ), a silicon-containing compound (c ₂ ), and a phosphoric acid compound (c ₃ ), the solid content Based on the above, the amount of vanadium compound (c ₁ ), silicon-containing compound (c ₂ ) and phosphoric acid to be added to a total of 100 parts by mass of the carbonyl group-containing modified epoxy resin (A) and the crosslinking agent (B) The system compound (c ₃ ) is added to 10,000 parts by mass of a 5% by mass sodium chloride aqueous solution at 25 ° C., stirred for 6 hours, allowed to stand at 25 ° C. for 48 hours, and the pH of the filtrate obtained by filtering the supernatant is adjusted. Preferably in the range of about 3 to about 10, and more preferably in the range of about 4 to about 8. The pH range is preferable from the viewpoint of the corrosion resistance of a coated article obtained by coating the aqueous primer composition.

That is, the filtrate to be subjected to pH measurement is any one in which the vanadium compound (c ₁ ) is in the range of about 3 to about 50 parts by mass with respect to 10,000 parts by mass of a 5% by mass sodium chloride aqueous solution at 25 ° C. Any amount within the range of about 3 to about 50 parts by mass of the silicon-containing compound (c ₂ ), and any of about 3 to about 50 parts by mass of the phosphate compound (c ₃ ) Is the filtrate of the solution in which they are added and dissolved.

The aqueous primer composition of the present invention is usually used in the art in addition to the carbonyl group-containing modified epoxy resin (A), the crosslinking agent (B), the rust preventive pigment (C), and an optional curing catalyst. Additives such as coloring pigments, extender pigments, UV absorbers, UV stabilizers, organic solvents, anti-settling agents, antifoaming agents, coating surface modifiers, and the like can be included as desired.

Examples of the coloring pigment include organic coloring pigments such as organic red pigments such as cyanine blue, cyanine green, azo, and quinacridone; and inorganic coloring pigments such as titanium white, titanium yellow, bengara, carbon black, and various fired pigments. And titanium white is preferred.
Examples of the extender pigment include talc, clay, silica, mica, alumina, calcium carbonate, and barium sulfate.

Examples of the ultraviolet absorber include 2- (2-hydroxy-3,5-di-tert-amylphenyl) -2H-benzotriazole, isooctyl-3- (3- (2H-benzotriazole-2-ol). Yl) -5-tert-butyl-4-hydroxyphenylpropionate, 2- [2-hydroxy-3,5-di (1,1-dimethylbenzidine) phenyl] -2H-benzotriazole, 2- [2 -Hydroxy-3-dimethylbenzyl-5- (1,1,3,3-tetramethylbutyl) phenyl] -2H-benzotriazole, methyl-3- [3-t-butyl-5- (2H-benzotriazole- 2-yl) -4-hydroxyphenyl] propionate / benzotriazole derivatives such as condensates with polyethylene glycol 300; 2- [4- ( -Hydroxy-3-dodecyloxypropyl) oxy] -2-hydroxyphenyl-4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine and the like; ethanediamide-N- (2 -Ethoxyphenyl) -N '-(2-ethylphenyl)-(oxalic amide), ethanediamide-N- (2-ethoxyphenyl) -N'-(4-isododecylphenyl)-(oxalic amide), etc. And oxalic acid anilide derivatives.

Examples of the ultraviolet stabilizer include, for example, hindered amine compounds, hindered phenol compounds; CHIMASORB 944, TINUVIN 144, TINUVIN 292, TINUVIN 770, IRGANOX 1010, IRGANOX 1098. Product)).

Since the aqueous primer composition of the present invention contains an ultraviolet absorber, an ultraviolet stabilizer, etc., it is possible to suppress deterioration of the primer surface due to light that has passed through the top coat film and reached the primer coat surface, It is possible to prevent delamination between the primer coating film and the top coating film due to the deterioration of the primer coating surface, and maintain excellent corrosion resistance.

The organic solvent that can be contained in the aqueous primer composition of the present invention is a component that is optionally added to improve the paintability of the aqueous primer composition of the present invention, and includes a carbonyl group-containing modified epoxy resin (A). And those that can dissolve or disperse the crosslinking agent (B), specifically, hydrocarbon solvents such as toluene, xylene, high-boiling petroleum hydrocarbons; methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, etc. Ketone solvents; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate; methanol, ethanol, isopropanol, butanol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether , Can be mentioned alcohol solvents such as diethylene glycol monobutyl ether, it can be added alone or in combination thereof.

The aqueous primer composition of the present invention can be coated on a metal material to form a primer coating film. The formed primer coating film exhibits excellent processability and processed portion corrosion resistance. The reason for this is that, in the carbonyl group-containing modified epoxy resin (A), the structure of the amine compound (a ₁ ) having a carbonyl group is incorporated next to the rigid epoxy resin skeleton to provide flexibility. In addition, the workability of the primer coating film formed is improved, and the amide bond and carbonyl group having high polarity contained in the amine compound (a ₁ ) in the carbonyl group-containing modified epoxy resin (A) are further formed. It is thought that improving the cohesive strength of the resin in the coating film also contributes to the improvement of workability. Moreover, in addition to the corrosion resistance inherent to the epoxy resin of the carbonyl group-containing modified epoxy resin (A), a primer that forms a highly polar amide bond and carbonyl group contained in the carbonyl group-containing modified epoxy resin (A) It is believed that the coating film contributes to adhesion to the metal substrate and improves corrosion resistance.

[Multilayer coating film forming method]
The method for forming a multilayer coating film of the present invention includes a step (1) of coating the above-mentioned aqueous primer composition on a metal material and then forming a cured primer coating film, and then overcoating the cured primer coating film. The method includes a step (2) of applying a paint and then drying it so that the highest material temperature reaches about 180 ° C. to about 300 ° C. to form a top coat film.

Step (1) is a step of obtaining a coated article by coating the water-based primer composition on a metal material, for example, a metal plate, and curing it. Examples of the metal plate to be painted include cold-rolled steel plate, hot-dip galvanized steel plate, electrogalvanized steel plate, iron-zinc alloy plated steel plate (galvanyl steel plate), aluminum-zinc alloy plated steel plate (about 55% by mass of aluminum in the alloy). “Galvanium steel plate”, “galfan” containing about 5% by mass of aluminum in the alloy), nickel-zinc alloy plated steel plate, stainless steel plate, aluminum plate, copper plate, copper plated steel plate, tin plated steel plate, etc. Chemical conversion treatment may be performed on the surfaces of these metal plates. Examples of the chemical conversion treatment include phosphate treatment such as zinc phosphate treatment and iron phosphate treatment, composite oxide film treatment, chromium phosphate treatment, and chromate treatment.

The aqueous primer composition can be coated on the metal material by a known method such as a roll coating method, a curtain flow coating method, a spray method, a brush coating method, or a dipping method. The cured film thickness of the primer coating film formed from the aqueous primer composition of the present invention is not particularly limited, but is usually in the range of about 2 to about 10 μm, and preferably about 3 to about 6 μm. The curing temperature and time of the coated primer coating can be set as appropriate according to the type of resin, particularly the crosslinking agent (B), and the aqueous primer composition of the present invention is applied by a coil coating method or the like. And when baked continuously, for example, it can be baked for about 15 to about 60 seconds under conditions where the maximum material temperature reaches about 160 to about 250 ° C., preferably about 180 to about 230 ° C. When the coated primer coating is baked in a batch system, it can be baked at a material arrival temperature of about 80 to about 200 ° C. for about 10 to about 30 minutes.

Moreover, when the crosslinking agent (B) is a hydrazide compound and / or a semicarbazide compound, the aqueous primer composition is excellent in low-temperature curability, and therefore, the coated aqueous primer composition has a maximum material reaching temperature of about 10 The cured primer coating film can be formed by drying for about 15 seconds to about 24 hours so that the temperature reaches not lower than about 180 ° C. but preferably about 20 ° C. to about 160 ° C. The drying can be carried out by simply leaving the coated aqueous primer composition at room temperature. When the maximum material reaching temperature is less than about 10 ° C., the primer coating film formed may be insufficiently cured. In addition, when the maximum material reaching temperature is about 180 ° C. or higher, there is no problem in performance of the cured primer coating film, but the energy saving effect may be reduced.

Further, when the crosslinking agent (B) is an isocyanate compound that is not blocked, when heating is not required for the crosslinking reaction in the primer coating formation process, it is dried at room temperature according to a conventional method. Can be cured.
When the metal material is a metal plate, an aqueous primer composition is coated on the back surface in the same manner as described above, and dried to form a cured primer coating on both surfaces of the metal plate.

Step (2) is a step of forming a top coat by applying a top coat onto the cured primer coating and then drying it so that the maximum material temperature reaches about 180 ° C. to about 300 ° C. . In step (2), the drying time is preferably in the range of about 5 seconds to about 30 minutes. The film thickness of the top coat film is not particularly limited, but a dry film thickness of 3 to 30 μm is preferable. When the above-mentioned maximum material temperature is less than 180 ° C., drying of the top coat film may be insufficient. Moreover, when the maximum material temperature reaches 300 ° C., the energy saving effect may be reduced. When the metal material is a metal plate, the top coat film may be formed on the back surface of the surface on which the top coat film is formed in the same manner as described above. Examples of the top coat include solid color paints, metallic paints, light interference color paints, clear paints, and the like, and a single layer or two or more layers of top coats can be formed on the primer coat. Examples of the top coating include various water-based or organic solvent-type coatings known per se.

The coated article in which the primer coating film by the water-based primer composition of the present invention is formed on a metal material can be used as it is, and a known top coating is applied on the primer coating film, and a top coating is applied. A film may be formed.

Hereinafter, the present invention will be described more specifically with reference to production examples and examples. The present invention is not limited to the following examples. Hereinafter, “parts” and “%” are based on mass.

[Production of amine compound (a ₁ )]
[Production Example 1]
Air in a 1 L flask equipped with a stirrer, thermometer, condenser and nitrogen gas inlet was replaced with nitrogen, and 338.4 g of diacetone acrylamide, 180.2 g of deionized water, and N- 352.6 g of ethylethylenediamine was added and stirred, and the temperature in the flask was raised to 80 ° C. and kept at 80 ° C. for 3 hours. Next, the pressure in the flask was maintained at 60 to 80 ° C. for 2 hours while reducing the pressure to about 100 mmHg, and about 240 g of a mixture of water and unreacted N-ethylethylenediamine was removed azeotropically. Thereafter, 200 g of water was added to the flask and held at 80 ° C. for 1 hour, and then held at 60 to 80 ° C. for 1.5 hours while reducing the pressure to about 100 mmHg, and about 200 g of a mixture of water and N-ethylethylenediamine was added together. The operation of removing by boiling was repeated twice. Thereafter, while reducing the pressure in the flask to about 10 mmHg, the mixture was kept at 60 to 80 ° C. for 1.5 hours to remove the remaining water and N-ethylethylenediamine, whereby a secondary amino acid was contained in one molecule. The amine compound (a ₁ -1) which is a Michael addition reaction product having two groups and a carbonyl group was obtained. In the ¹ H-NMR measurement of the amine compound (a ₁ -1) using a deuterated chloroform solvent, a peak of 6.19 to 6.23 ppm attributable to diacetone acrylamide is not observed, and thus unreacted diacetone acrylamide is present. It was confirmed that it did not remain.

In a 100 mL Erlenmeyer flask, 0.1 g of the obtained amine compound (a ₁ -1) was weighed, 30 mL of acetic acid was added and dissolved, and then an indicator (a solution in which 0.3 g of alphazulin G was dissolved in 100 mL of glacial acetic acid). And 0.2 ml of a mixture of 1.5 g of thymol blue dissolved in methanol, and titrated with 0.1 N perchloric acid (acetic acid solution) until the solution changed from green to red. As a result, the amine value of the amine compound (a ₁ -1) was 426 mg-KOH / g.

[Production Example 2]
The air in the 2 L flask equipped with a stirrer, thermometer, condenser and nitrogen gas inlet was replaced with nitrogen, and 507.7 g of diacetone acrylamide, 270.3 g of water, and 438.8 g of butylamine were added. The mixture was stirred, and the temperature in the flask was raised to 80 ° C. and kept at 80 ° C. for 2 hours. Next, while reducing the pressure in the flask to about 100 mmHg, the temperature was maintained at 60 to 80 ° C. for 1.5 hours, and about 430 g of a mixture of water and unreacted butylamine was removed azeotropically. Thereafter, a moisture quantification receiver is attached to the flask, 270 g of water is added to the flask, the temperature in the flask is raised to 105 ° C., maintained at 103 to 105 ° C. for 1 hour under normal pressure, and a mixture of water and butylamine. The operation of removing about 200 g by azeotropy was repeated twice. Next, while reducing the pressure in the flask to about 10 mmHg, the mixture is held at 60 to 80 ° C. for 1.5 hours to remove the remaining water and butylamine, so that one secondary amino group is contained in one molecule. When, and a carbonyl group, to give the amine compound is a Michael addition reaction product (a 1 _-2). In the ¹ H-NMR measurement of the amine compound (a _1-2 ) using a deuterated chloroform solvent, a peak of 6.19 to 6.23 ppm due to diacetone acrylamide is not observed. It was confirmed that it did not remain. The amine value of the obtained amine compound (a _1-2 ) was 230 mg-KOH / g.

[Production Example 3]
The air in a 2 L flask equipped with a stirrer, thermometer, condenser and nitrogen gas inlet was replaced with nitrogen, 507.7 g of diacetone acrylamide, 270.3 g of water, and 366.5 g of 2-aminoethanol. Was added and stirred, and the temperature in the flask was raised to 80 ° C. and kept at 80 ° C. for 2 hours. Next, using a thin-film distillation apparatus (Tokyo Rika Kikai Co., Ltd., model: MF-10A, evaporation area 0.04 m ² ), thin-film distillation was performed on a wall surface at 100 ° C. under a reduced pressure of 5 mmHg, and water and unreacted The mixture with 2-aminoethanol was removed. Thereafter, the air in a 2 L flask equipped with a stirrer, a thermometer, a cooling pipe and a nitrogen gas inlet was replaced with nitrogen, and about 720 g of reaction product was obtained by removing unreacted 2-aminoethanol by thin-film distillation. In addition, 500 g of water was added, the temperature was raised to 105 ° C., and maintained at 103 to 105 ° C. under normal pressure for 1 hour to hydrolyze ketimine. Furthermore, thin film distillation is performed on a wall surface at 100 ° C. under a reduced pressure of 5 mmHg to remove a mixture of water and 2-aminoethanol produced by hydrolysis of ketimine, thereby allowing one secondary amino group in one molecule. If, to obtain a one hydroxyl group, and a carbonyl group, an amine compound is a Michael addition reaction product (a 1 _-3). In the ¹ H-NMR measurement of the amine compound (a ₁ -3) using deuterated chloroform solvent, a peak of 6.19 to 6.23 ppm due to diacetone acrylamide is not observed. It was confirmed that it did not remain. The amine value of the obtained amine compound (a ₁ -3) was 255 mg-KOH / g.

[Production of Carbonyl Group-Containing Modified Epoxy Resin (A) and Its Water Dispersion]
[Production Example 4]
The air in a 2 L flask equipped with a stirrer, thermometer, cooling pipe and nitrogen gas inlet was replaced with nitrogen, and “jER828” (trade name, manufactured by Japan Epoxy Resins Co., Ltd., bisphenol A type epoxy resin) 152.0 g and 281.1 g of propylene glycol monomethyl ether were added to the flask and stirred, and then the temperature was raised to 100 ° C. to dissolve jER828. Thereafter, a mixture of 28.1 g of 2-ethylhexylamine and 57.5 g of “Surfonamine L-100” (trade name, manufactured by Huntsman Corporation, polyoxyalkyleneamine compound) was added to the flask, and the flask was heated at 100 ° C. after 2 hours, to the flask, the amine compound _(a 1 -1) 19.3g, amine compound _(a 1 -2) 24.2g were added and the temperature was raised to 120 ° C., and at 120 ° C. 7 By holding for 5 hours, a solution of the carbonyl group-containing modified epoxy resin (A-1) was obtained. Thereafter, a mixture of 15.8 g of acetic acid, 8.1 g of 85% phosphoric acid, and 100.0 g of water is added to the solution of the carbonyl group-containing modified epoxy resin (A-1), and 1,200 g of water is added. And 980 g of the solvent and water mixture are removed azeotropically under reduced pressure, and diluted with water so that the solid content is about 30%, whereby the carbonyl group-containing modified epoxy resin (A-1) An aqueous dispersion (AD1) was obtained. Regarding the carbonyl group-containing modified epoxy resin (A-1), the carbonyl group concentration is 0.62 mol / Kg (based on the solid content), the amine value is 105 mg-KOH / g (based on the solid content), and weight. The average molecular weight was about 11,000.

[Production Example 5]
The air in a 2 L flask equipped with a stirrer, thermometer, condenser and nitrogen gas inlet was replaced with nitrogen, and 152.0 g of “jER828” and 282.9 g of propylene glycol monomethyl ether were added to the flask. Then, the temperature was raised to 100 ° C. to dissolve jER828. Thereafter, a mixture of 32.0 g of 2-ethylhexylamine and 56.0 g of “Surfonamine L-100” was added to the flask, and the flask was kept at 100 ° C. for 2 hours, and then the amine compound (a ₁ -1) 4.1 g and an amine compound _(a 1 -2) 38.8g were added and the temperature was raised to 120 ° C., and by maintaining at 120 ° C. 7.5 h, a carbonyl group-containing modified epoxy resin A solution of (A-2) was obtained. Thereafter, a mixture of 14.9 g of acetic acid, 7.6 g of 85% phosphoric acid, and 100.0 g of water was added to the solution of the carbonyl group-containing modified epoxy resin (A-2), and 1,200 g of water was added. And 980 g of a solvent and water mixture are removed azeotropically under reduced pressure, and diluted with water so that the solid content is about 30%, whereby the carbonyl group-containing modified epoxy resin (A-2) An aqueous dispersion (AD2) was obtained. Regarding the carbonyl group-containing modified epoxy resin (A-2), the carbonyl group concentration is 0.62 mol / Kg (based on solid content), the amine value is 98 mg-KOH / g (based on solid content), and weight. The average molecular weight was about 7,200.

[Production Example 6]
The air in a 2 L flask equipped with a stirrer, thermometer, condenser and nitrogen gas inlet was replaced with nitrogen, and 145.9 g of “jER828” and 267.4 g of propylene glycol monomethyl ether were added to the flask. Then, the temperature was raised to 100 ° C. to dissolve jER828. Thereafter, a mixture of 25.2 g of 2-ethylhexylamine and 54.4 g of “Surfonamine L-100” was added to the flask, and the flask was kept at 100 ° C. for 2 hours, and then the amine compound (a ₁ -1) 26.4 g and the amine compound _(a 1 -2) 15.5g were added and the temperature was raised to 120 ° C., and by maintaining at 120 ° C. 7.5 h, a carbonyl group-containing modified epoxy resin A solution of (A-3) was obtained. Thereafter, a mixture of 15.6 g of acetic acid, 8.0 g of 85% phosphoric acid and 100.0 g of water was added to the solution of the carbonyl group-containing modified epoxy resin (A-3), and 1,150 g of water was added. And, under reduced pressure, about 950 g of a mixture of solvent and water is removed azeotropically and diluted with water so that the solid content is about 30%, whereby the carbonyl group-containing modified epoxy resin (A-3) An aqueous dispersion (AD3) was obtained. For the carbonyl group-containing modified epoxy resin (A-3), the carbonyl group concentration is 0.62 mol / Kg (based on solids), the amine number is 109 mg-KOH / g (based on solids), and weight The average molecular weight was about 22,000.

[Production Example 7]
The air in a 2 L flask equipped with a stirrer, thermometer, condenser and nitrogen gas inlet was replaced with nitrogen, and 152.0 g of “jER828” and 271.9 g of propylene glycol monomethyl ether were added to the flask. Then, the temperature was raised to 100 ° C. to dissolve jER828. Thereafter, a mixture of 35.5 g of 2-ethylhexylamine and 55.0 g of “Surfonamine L-100” was added to the flask, and the flask was kept at 100 ° C. for 2 hours, and then the amine compound (a ₁ -1) 5.1 g and an amine compound _(a 1 -2) 24.2g were added and the temperature was raised to 120 ° C., and by maintaining at 120 ° C. 7.5 h, a carbonyl group-containing modified epoxy resin A solution of (A-4) was obtained. Thereafter, a mixture of 14.1 g of acetic acid, 7.2 g of 85% phosphoric acid, and 100.0 g of water was added to the solution of the carbonyl group-containing modified epoxy resin (A-4), and 1,150 g of water was added. Under reduced pressure, about 950 g of a mixture of solvent and water is removed azeotropically, and diluted with water so that the solid content is about 30%, whereby water of the carbonyl group-containing modified epoxy resin (A-4) is removed. A dispersion (AD4) was obtained. Regarding the carbonyl group-containing modified epoxy resin (A-4), the carbonyl group concentration is 0.45 mol / Kg (based on the solid content), the amine value is 97 mg-KOH / g (based on the solid content), and weight. The average molecular weight was about 10,000.

[Production Example 8]
The air in a 2 L flask equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet was replaced with nitrogen, and 145.9 g of “jER828” and 276.7 g of propylene glycol monomethyl ether were added to the flask. Then, the temperature was raised to 100 ° C. to dissolve jER828. Thereafter, a mixture of 20.2 g of 2-ethylhexylamine and 55.2 g of “Surfonamine L-100” was added to the flask, and the flask was kept at 100 ° C. for 2 hours, and then the amine compound (a ₁ -1) 32.1 g and the amine compound _(a 1 -2) 23.3g were added and the temperature was raised to 120 ° C., and by maintaining at 120 ° C. 7.5 h, a carbonyl group-containing modified epoxy resin A solution of (A-5) was obtained. Thereafter, a mixture of 16.7 g of acetic acid, 8.6 g of 85% phosphoric acid and 100.0 g of water was added to the solution of the carbonyl group-containing modified epoxy resin (A-5), 1200 g of water was added, and the pressure was reduced. While removing about 1,000 g of a mixture of solvent and water by azeotropic distillation and diluting with water to a solid content of about 30%, water dispersion of the carbonyl group-containing modified epoxy resin (A-5) A body (AD5) was obtained. For the carbonyl group-containing modified epoxy resin (A-5), the carbonyl group concentration is 0.80 mol / Kg (based on solids), the amine number is 113 mg-KOH / g (based on solids), and weight The average molecular weight was about 12,000.

[Production Example 9]
Air in a 2 L flask equipped with a stirrer, thermometer, cooling pipe and nitrogen gas inlet was replaced with nitrogen, and “jER1001” (trade name, manufactured by Japan Epoxy Resins Co., Ltd., bisphenol A type epoxy resin) 176.4 g and 271.0 g of propylene glycol monomethyl ether were added to the flask and stirred, and then the temperature was raised to 100 ° C. to dissolve jER1001. Thereafter, to the flask, "Safonamin L-100" 54.0g was added, and the mixture was held for 2 hours at 100 ° C., to the flask, the amine compound _(a 1 -1) and 23.2 g, the amine compound _{(a 1} - 2) 17.4g was added, it heated up at 120 degreeC, and the solution of the carbonyl group containing modified epoxy resin (A-6) was obtained by hold | maintaining at 120 degreeC for 7.5 hours. Thereafter, a mixture of 9.2 g of acetic acid, 4.7 g of 85% phosphoric acid and 100.0 g of water was added to the solution of the carbonyl group-containing modified epoxy resin (A-6), 1150 g of water was added, and the pressure was reduced. While removing about 930 g of the mixture of the solvent and water by azeotropic distillation and diluting with water so that the solid content is about 30%, an aqueous dispersion of the carbonyl group-containing modified epoxy resin (A-6) ( AD6) was obtained. Regarding the carbonyl group-containing modified epoxy resin (A-6), the carbonyl group concentration is 0.61 mol / Kg (based on the solid content), the amine value is 63 mg-KOH / g (based on the solid content), and weight. The average molecular weight was about 13,000.

[Production Example 10]
The air in a 2 L flask equipped with a stirrer, thermometer, condenser and nitrogen gas inlet was replaced with nitrogen, and 152.0 g of “jER828” and 271.0 g of propylene glycol monomethyl ether were added to the flask. Then, the temperature was raised to 100 ° C. to dissolve jER828. Thereafter, a mixture of 22.6 g of 2-ethylhexylamine and 55.0 g of “Surfonamine L-100” was added to the flask and maintained at 100 ° C. for 2 hours, and then the amine compound (a ₁ −1) was added to the flask. 30.9 g and 10.5 g of diethanolamine were added, the temperature was raised to 120 ° C., and the mixture was held at 120 ° C. for 7.5 hours to obtain a solution of a carbonyl group-containing modified epoxy resin (A-7). . Thereafter, a mixture of 17.1 g of acetic acid, 8.8 g of 85% phosphoric acid, and 100.0 g of water was added to the solution of the carbonyl group-containing modified epoxy resin (A-7), and 1,150 g of water was added. The aqueous dispersion of the carbonyl group-containing modified epoxy resin (A-7) was removed by azeotropic removal of about 950 g of a solvent and water mixture under reduced pressure, and dilution with water to a solid content of about 30%. A body (AD7) was obtained. For the carbonyl group-containing modified epoxy resin (A-7), the carbonyl group concentration is 0.45 mol / Kg (based on solids), the amine number is 118 mg-KOH / g (based on solids), and weight The average molecular weight was about 11,000.

[Production Example 11]
The air in a 2 L flask equipped with a stirrer, thermometer, condenser and nitrogen gas inlet was replaced with nitrogen, and 152.0 g of “jER828” and 277.8 g of propylene glycol monomethyl ether were added to the flask. Then, the temperature was raised to 100 ° C. to dissolve jER828. Thereafter, a mixture of 28.4 g of 2-ethylhexylamine and 55.0 g of “Surfonamine L-100” was added to the flask and maintained at 100 ° C. for 2 hours, and then the amine compound (a ₁ −1) was added to the flask. ) and 19.3 g, the amine compound _(a 1 -3) 23.0 g and the temperature was raised to 120 ° C., and by maintaining at 120 ° C. 7.5 h, a carbonyl group-containing modified epoxy resin (A- A solution of 8) was obtained. Thereafter, a mixture of 15.8 g of acetic acid, 8.1 g of 85% phosphoric acid and 100.0 g of water was added to the solution of the carbonyl group-containing modified epoxy resin (A-8), 1200 g of water was added, and the pressure was reduced. While removing about 1000 g of a mixture of solvent and water by azeotropic distillation and diluting with water to a solid content of about 30%, an aqueous dispersion of a carbonyl group-containing modified epoxy resin (A-8) ( AD8) was obtained. For the carbonyl group-containing modified epoxy resin (A-8), the carbonyl group concentration is 0.62 mol / Kg (based on solids), the amine number is 106 mg-KOH / g (based on solids), and weight The average molecular weight was about 12,000.

[Production Example 12]
The air in a 2 L flask equipped with a stirrer, thermometer, condenser and nitrogen gas inlet was replaced with nitrogen, 16.9 g diacetone acrylamide, 25.8 g piperazine, and 64.1 g propylene glycol monomethyl ether. Were added to the flask, the temperature in the flask was raised to 100 ° C., and the mixture was stirred at 100 ° C. for 3 hours. Thereafter, 152.0 g of “jER828”, 206.9 g of propylene glycol monomethyl ether, 3.2 g of 2-ethylhexylamine, 55.0 g of “Surfonamine L-100”, and 18.0 g of amine compound (a ₁ −1) Was added to the flask, the temperature in the flask was raised to 120 ° C., and kept at 120 ° C. for 8 hours to obtain a solution of a carbonyl group-containing modified epoxy resin (A-9). Thereafter, a mixture of 24.6 g of acetic acid, 12.6 g of 85% phosphoric acid and 100.0 g of water was added to the solution of the carbonyl group-containing modified epoxy resin (A-9), 1150 g of water was added, and the pressure was reduced. While removing about 950 g of a mixture of solvent and water by boiling, and diluting with water to a solid content of about 30%, an aqueous dispersion of carbonyl group-containing modified epoxy resin (A-9) ( AD9) was obtained. For the carbonyl group-containing modified epoxy resin (A-9), the carbonyl group concentration is 0.62 mol / Kg (based on solids), the amine number is 170 mg-KOH / g (based on solids), and weight The average molecular weight was about 13,000.

[Production Example 13]
The air in a 2 L flask equipped with a stirrer, thermometer, condenser and nitrogen gas inlet was replaced with nitrogen, and 143.6 g of “jER828” and 267.3 g of propylene glycol monomethyl ether were added to the flask. Then, the temperature was raised to 100 ° C. to dissolve jER828. Thereafter, a mixture of 25.8 g of 2-ethylhexylamine, 52.5 g of “Surfonamine L-100” and 4.7 g of isophoronediamine was added to the flask and maintained at 100 ° C. for 2 hours. 40.7 g of the amine compound (a _1-2 ) was added, the temperature was raised to 120 ° C., and the mixture was held at 120 ° C. for 7.5 hours to obtain a solution of the carbonyl group-containing modified epoxy resin (A-10). . Thereafter, a mixture of 13.9 g of acetic acid, 7.1 g of 85% phosphoric acid and 100.0 g of water was added to the solution of the carbonyl group-containing modified epoxy resin (A-10), 1120 g of water was added, and the pressure was reduced. While removing about 910 g of a mixture of solvent and water by azeotropic distillation and diluting with water to a solid content of about 30%, an aqueous dispersion of a carbonyl group-containing modified epoxy resin (A-10) ( AD10) was obtained. For the carbonyl group-containing modified epoxy resin (A-10), the carbonyl group concentration is 0.62 mol / Kg (based on solids), the amine number is 97 mg-KOH / g (based on solids), and weight The average molecular weight was about 11,000.

[Production Example 14]
The air in a 2 L flask equipped with a stirrer, thermometer, condenser and nitrogen gas inlet was replaced with nitrogen, and 143.6 g of “jER828” and 268.1 g of propylene glycol monomethyl ether were added to the flask. Then, the temperature was raised to 100 ° C. to dissolve jER828. Thereafter, a mixture of 31.2 g of 2-ethylhexylamine, 10.5 g of “Surphonamine L-100” and 42.0 g of “Jeffamine ED2003” (trade name, manufactured by Huntsman Corporation, polyoxyalkylenediamine compound) was added to the flask. And then kept at 100 ° C. for 2 hours, 40.7 g of amine compound (a _1-2 ) was added to the flask, heated to 120 ° C., and held at 120 ° C. for 7.5 hours, A solution of a carbonyl group-containing modified epoxy resin (A-11) was obtained. Thereafter, to the solution of the carbonyl group-containing modified epoxy resin (A-11), a mixture of 13.9 g of acetic acid, 7.1 g of 85% phosphoric acid and 100.0 g of water was added, 1130 g of water was added, and the pressure was reduced. While removing about 920 g of a mixture of solvent and water by azeotropic distillation and diluting with water to a solid content of about 30%, an aqueous dispersion of a carbonyl group-containing modified epoxy resin (A-11) ( AD11) was obtained. For the carbonyl group-containing modified epoxy resin (A-11), the carbonyl group concentration is 0.62 mol / Kg (based on solids), the amine number is 97 mg-KOH / g (based on solids), and weight The average molecular weight was about 11,000.

[Production Example 15]
Air in a 2 L flask equipped with a stirrer, thermometer, condenser and nitrogen gas inlet was replaced with nitrogen, and 94.1 g of “jER1001” and 201.6 g of propylene glycol monomethyl ether were added to the flask. Then, the temperature was raised to 100 ° C. to dissolve jER1001. Thereafter, a mixture of 15.9 g of 2-ethylhexylamine and 52.8 g of “Surfonamine L-100” was added to the flask and maintained at 100 ° C. for 2 hours, and then the amine compound (a _1-2 ) was added to the flask. ) 38.8 g, “jER154” (trade name, manufactured by Japan Epoxy Resin Co., Ltd., phenol novolac type epoxy resin) 56.3 g and propylene glycol monomethyl ether 56.3 g were added, and the temperature was raised to 120 ° C. And the solution of a carbonyl group containing modified epoxy resin (A-12) was obtained by hold | maintaining at 120 degreeC for 7.5 hours. Thereafter, a mixture of 10.1 g of acetic acid, 5.2 g of 85% phosphoric acid and 100.0 g of water was added to the solution of the carbonyl group-containing modified epoxy resin (A-12), 1100 g of water was added, and the pressure was reduced. Meanwhile, about 900 g of a mixture of solvent and water was removed by azeotropic distillation, and diluted with water so that the solid content was about 30%, an aqueous dispersion of a carbonyl group-containing modified epoxy resin (A-12) ( AD12) was obtained. Regarding the carbonyl group-containing modified epoxy resin (A-12), the carbonyl group concentration is 0.62 mol / Kg (based on the solid content), the amine value is 73 mg-KOH / g (based on the solid content), and weight. The average molecular weight was about 13,000.

[Comparative Production Example 1]
The air in a 2 L flask equipped with a stirrer, thermometer, condenser and nitrogen gas inlet was replaced with nitrogen, and 152.0 g of “jER828” and 253.7 g of propylene glycol monomethyl ether were added to the flask. Then, the temperature was raised to 100 ° C. to dissolve jER828. Thereafter, a mixture of 38.8 g of 2-ethylhexylamine, 50.0 g of “Surfonamine L-100” and 12.9 g of dibutylamine was added to the flask, the temperature was raised to 120 ° C., and the mixture was heated at 120 ° C. for 5 hours. By holding, a solution of a modified epoxy resin (A-13) containing no carbonyl group was obtained. Thereafter, a mixture of 13.5 g of acetic acid, 6.9 g of 85% phosphoric acid, and 100.0 g of water is added to the solution of the modified epoxy resin (A-13), 1100 g of water is added, and the solvent is reduced under reduced pressure. And about 900 g of a mixture of water and azeotropically removed and diluted with water to a solids content of about 30% to obtain an aqueous dispersion (AD13) of a modified epoxy resin (A-13) containing no carbonyl groups Got. The amine value of the modified epoxy resin (A-13) was 100 mg-KOH / g (based on solid content), and the weight average molecular weight was about 11,000.

[Production of aqueous primer composition]
[Example 1]
283.3 parts (85 parts solids) of an aqueous dispersion (AD1) of the carbonyl group-containing modified epoxy resin (A-1) obtained in Production Example 4 and 5 parts of vanadium pentoxide as a rust preventive pigment (C) 5 parts of calcium phosphate, 5 parts of Shieldex C303 (manufactured by WR Grace & Co., trade name, calcium ion exchanged silica), and 30 parts of titanium white pigment [TS-6200 (manufactured by DuPont)] as a coloring pigment, Were mixed in a container, and then the mixture was dispersed in a pigment until the tub (particle diameter of the coarse pigment particles) became 15 μm or less. Next, 15 parts of Cymel 701 (manufactured by Nippon Cytec Industries, Ltd., methylated melamine resin) as a cross-linking agent (B) is added to the above mixture, mixed uniformly, and a viscosity of about 25 with deionized water. By adjusting to the second (Ford Cup # 4/25 ° C.). 1 was obtained.

[Examples 2 to 22 and Comparative Examples 1 to 3]
Except that the formulation was changed as shown in Tables 1 and 2, the aqueous primer composition No. 2 to 25 were obtained.
Note that (Note 1) to (Note 10) in the table are as follows.
(Note 1) Cymel 701: manufactured by Nippon Cytec Industry, methylated melamine, solid content 82%
(Note 2) Duranate WT30-100: manufactured by Asahi Kasei Chemicals Co., Ltd., water-dispersible isocyanate compound, solid content 100%, this was blended after being diluted with water so that the effective solid content was 30% immediately before blending.
(Note 3) PR-55317: manufactured by Sumitomo Bakelite Co., Ltd., resol type phenol resin, solid content 50%
(Note 4) Hardener SC: Asahi Kasei Chemicals, semicarbazide-based curing agent, concentration 50%
(Note 5) ADH: adipic acid dihydrazide, solid content 100%
(Note 6) Bihijoule VPLS2310: manufactured by Sumika Bayer Urethane Co., Ltd., blocked polyisocyanate compound with water dispersibility, solid content 38%
(Note 7) Shieldex C303: W.W. R. Grace & Co. Calcium ion exchanged silica (Note 8) Gasil 200DF: Crossfield, silica fine powder (Note 9) K-White G105: Teica, phosphate metal salt compound (Note 10) TS-6200: DuPont Titanium white pigment

[Preparation of test plate]
An aqueous primer composition was applied to a 55% aluminum-zinc plated steel sheet (galvalume steel sheet, plate thickness 0.35 mm, plating AZ150) subjected to chemical conversion treatment with a bar coater so that the dry film thickness was 5 μm. The primer coating film was formed by drying for 45 seconds so that the maximum material temperature of the steel sheet reached 200 ° C., and then the primer coating film was similarly formed on the opposite surface of the steel sheet. On one side of the previously formed primer coating, KP color 1555 brown full gloss (manufactured by Kansai Paint Co., Ltd., polyester / melamine paint, glass transition temperature 50 ° C.) was applied so that the dry film thickness was about 15 μm, and PMT Was baked for 45 seconds to reach 220 ° C. to form a top coating film, and a test coating plate was prepared. The test coating plate was prepared from the aqueous primer composition Nos. Obtained in Examples 1 to 22 and Comparative Examples 1 to 3. Each of 1 to 25 was prepared.
Each obtained coating plate for a test was tested according to the following test conditions. A result is combined with Table 1 and Table 2, and is shown.

[Machinability (4T processability)]
The test coating plate cut into a size of 6 cm × 12 cm at room temperature of 20 ° C. was subjected to 4T folding so that the length of the bent portion was 6 cm. The crack resistance of the coating film in the bent portion and the adhesion of the coating film in the bent portion were evaluated according to the following criteria. As for the adhesion of the coating film in the bent portion, a degree of peeling of the coating film in the bent portion when a cellophane (registered trademark) adhesive tape was applied to the bent portion and the tape was peeled off instantaneously was evaluated.
In this specification, the 4T bending process means that the corrosion test coating plate is formed in a vise so that the top coating film forming surface of the test coating plate faces the outside with four steel plates having the same thickness sandwiched therebetween. It means a process of bending 180 degrees.

[Draft resistance of the coating film in the bent part]
○: No cracking of the coating film is observed in the processed part, or a slight cracking of the coating film is observed in the processing part. Δ: A considerable cracking of the coating film is observed in the processing part. Is markedly observed [Adhesion of the coating film in the bent portion]
○: Peeling of the coating film is not recognized in the processed part or slight peeling of the coating film is recognized in the processed part. Δ: Peeling of the coating film is considerably recognized in the processed part. Peel off

[Composite cycle corrosion test (CCT test)]
The test was conducted according to JASO M609-91 (automobile material corrosion test 1991). Specifically, the test coating plate is formed such that one of the both sides in the longitudinal direction forms burrs on the top coating film forming surface (surface) side, and the other of the both sides in the longitudinal direction forms the top coating film non-forming surface ( It was cut into a size of 6 cm × 12 cm so as to form burrs on the back surface side. Next, a cross cut having a narrow angle of 30 degrees and a line width of 0.5 mm was placed in the center of the cut surface of the test coating plate using the back side of the cutter knife so as to reach the steel plate. Next, 6 cm, which is one end portion in the longitudinal direction of each of the cut test coating plates, was sealed with a rust preventive paint to form a 4T bent portion, thereby forming a corrosion test coating plate.
The corrosion test coating plates were prepared from the aqueous primer composition Nos. Obtained in Examples 1 to 22 and Comparative Examples 1 to 3. Each of 1 to 25 was prepared.

On each coating plate for corrosion test, (cycle 5% saline spray at 35 ° C for 2 hours)-(drying at 60 ° C for 4 hours relative humidity 95%)-(wet at 50 ° C for 2 hours relative humidity 95%) as one cycle, The corrosion test was conducted for 150 cycles (total of 1200 hours). The state of the 4T bent portion, the cross cut portion, and the edge portion of the corrosion test coating plate after the corrosion test was evaluated according to the following criteria.

[Evaluation criteria for 4T machined parts]
◎: Generation of rust is not observed. ○: Generation of white rust is recognized, but the length of the rust portion along the processed portion is less than 20 mm. Δ: The length of white rust along the processed portion is 20 mm or more. And less than 40 mm x: The length of white rust along the processed part is 40 mm or more, or occurrence of red rust is observed

[Evaluation criteria for cross-cut part]
◎: No white rust or swelling is observed ○: Slight white rust is observed, but no swelling is observed △: Clear white rust is observed, or white rust is slight Occurrence of bulge is observed around the object ×: White rust is generated on the whole, and bulge is generated in the periphery

[Evaluation criteria for edge part]
The average value of the edge creep widths on the left and right long sides of the coated plate was determined and evaluated according to the following criteria.
◎: Corrosion width is less than 5 mm ○: Corrosion width is 5 mm or more and less than 10 mm △: Corrosion width is 10 mm or more and less than 20 mm ×: Corrosion width is 20 mm or more

[Examples 23 to 38 and Comparative Examples 4 to 8]
Except that the formulation was changed as shown in Table 3 and Table 4, the aqueous primer composition No. 26-46 were obtained.
Next, the 55% aluminum-zinc plated steel plate (galvalume steel plate, plate thickness 0.35 mm, plating AZ150) subjected to chemical conversion treatment was subjected to aqueous primer composition No. 5 so that the dry film thickness was 5 μm. 26 was applied with a bar coater and baked for 30 seconds so that the PMT reached 120 ° C. to form a primer coating film, and then a primer coating film was similarly formed on the opposite surface of the steel plate. On one side of the previously formed primer coating, KP color 1555 brown full gloss (manufactured by Kansai Paint Co., Ltd., polyester / melamine paint, glass transition temperature 50 ° C.) was applied so that the dry film thickness was about 15 μm, and PMT Was baked for 45 seconds to reach 220 ° C. to form a top coating film, and a test coating plate was prepared. Aqueous primer composition No. With respect to 27 to 46, test coating plates were prepared in the same manner as described above except that a primer coating film was formed according to the PMTs shown in Tables 3 and 4.
The results are also shown in Table 3 and Table 4.

[Weatherability]
In accordance with JIS H 8602 5.12 (1992) (water spray time 12 minutes, black panel temperature 60 ° C.), tested for 750 hours with a carbon arc lamp type accelerated weathering tester (Sunshine Weatherometer), test plate The gloss before and after the test was measured to determine the gloss retention, and evaluated according to the following criteria.
A: 60 degree gloss retention is 90% or more B: 60 degree gloss retention is 70% or more and less than 90% Δ: 60 degree gloss retention is 30% or more and less than 70% X: 60 degree gloss retention is less than 30%

Claims

An aqueous primer composition comprising a carbonyl group-containing modified epoxy resin (A), a crosslinking agent (B) and a rust preventive pigment (C),
The carbonyl group-containing modified epoxy resin (A) has at least one active hydrogen bonded to a nitrogen atom and an amine compound (a 1 ) having a carbonyl group, and two epoxy groups in one molecule. Produced by reacting with the epoxy resin (a 2 ) having the above,
The aqueous primer composition.
The amine compound (a 1 ) is produced by a Michael addition reaction between diacetone acrylamide and an amine compound (a 11 ) having two or more active hydrogens bonded to a nitrogen atom in one molecule. An aqueous primer composition.
The aqueous primer composition according to claim 1 or 2, wherein the carbonyl group-containing modified epoxy resin (A) has at least one hydrophilic group selected from the group consisting of an anionic group, a cationic group and a nonionic group. .
The crosslinking agent (B) is at least one crosslinking agent selected from the group consisting of isocyanate compounds, blocked isocyanate compounds, amino resins, phenol resins, hydrazide compounds, and semicarbazide compounds. The aqueous primer composition according to Item.
The aqueous primer composition according to any one of claims 1 to 4, wherein the crosslinking agent (B) comprises a hydrazide compound and / or a semicarbazide compound.
The aqueous primer according to any one of claims 1 to 5, wherein the rust preventive pigment (C) contains a vanadium compound (c 1 ), a silicon-containing compound (c 2 ), and a phosphoric acid compound (c 3 ). Composition.
A step (1) of forming a cured primer coating by coating the aqueous primer composition according to any one of claims 1 to 6 on a metal material and then drying the composition, and the cured primer A step (2) of forming a top coating film by applying a top coating material on the coating film and then drying it so as to reach a maximum material temperature of 180 ° C. to 300 ° C.
A method for forming a multilayer coating film comprising:
The crosslinking agent (B) contains a hydrazide compound and / or a semicarbazide compound, and is dried so as to reach the maximum material temperature not lower than 10 ° C. and lower than 180 ° C. in the step (1). The method according to claim 7, wherein forming.
A coated article formed by coating the aqueous primer composition according to any one of claims 1 to 6 on a metal material, or by the method according to claim 7 or 8.