JPH09296148A - Composition for aqueous coating material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition excellent in temporal stability, giving coating films capable of being cured at low temperatures, and useful for coating metals by using an aromatic epoxy resin, etc., as raw materials. SOLUTION: This composition is obtained by chemically reacting (A-1) an aromatic epoxy resin with (B) a monobasic carboxyl group-containing compound and (C) a polybasic carboxyl group-containing compound in the presence (or absence) of ammonia or an amine at a reaction temperature of 70-160 deg.C so that the equivalent ratio of the component B/the component A-1 satisfies 0.2 < the component B/the component A-1<0.8 and that the weight ratio of (the solid content of the component A)/(the solid content of the component C) satisfies 0.5 < the component A-1/the component C<5, mixing (D) the obtained substantially epoxy group-free reaction product with (A-2) an aromatic epoxy resin and/or (E) an aromatic polyol resin in weight ratios of inequalities I, II and III, neutralizing (F) the prepared mixture with (G) a basic compound, and further subjecting the neutralized product to a phase inversion emulsification treatment. The obtained composition emulsion has emulsion particle diameters of <=1.0μm and a viscosity of 1000mPa.s.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based coating composition and a method for producing the same, and particularly to a coating composition excellent as an organic composite-coated steel sheet coating material / PCM steel sheet coating material / can inner surface coating material as a metal coating composition. The present invention relates to a self-emulsifying type aqueous coating composition.

[0002]

2. Description of the Related Art Solvent-based paints using organic solvents have been in the direction of being restricted in use from the viewpoint of resource saving, energy saving, and environmental conservation, and further, there is a shift to paints using water-based solvents. Is desired. In particular, in the case of can paints for coating metal surfaces, the shift to paints using an aqueous solvent has been studied, centering around epoxy resin paints, and various methods have been proposed for making epoxy resins water-soluble. For example, in JP-A-53-1228, a radical initiator such as benzoyl peroxide is used to polymerize an epoxy resin and an acrylic monomer containing a carboxyl group-containing monomer to graft an aliphatic moiety of the epoxy resin. A method is disclosed in which the obtained polymer is dispersed in water using a basic compound such as ammonia or amine.

However, in the above method, it is necessary to increase the graft ratio in order to obtain a highly safe emulsion, and a large amount of a radical polymerization initiator such as benzoyl peroxide, which is expensive and has a high risk of explosion, is produced at the time of production. It had the drawback of having to be used.

Therefore, in JP-A-55-3481 and JP-A-55-3482, an ester is obtained by reacting a carboxyl group-containing vinyl polymer with an epoxy group of an epoxy resin in the presence of an amine catalyst. There is proposed a method in which a carboxyl group-containing vinyl polymer-modified epoxy resin having substantially no epoxy group is obtained, which is neutralized with a base and dispersed in water.

[0005]

However, in the method described in JP-A-55-3481, the esterification is carried out until the epoxy group of the epoxy resin as the main skeleton is substantially completely consumed. The reaction proceeds, and a resin having a high molecular weight or a highly crosslinked structure is produced.
In particular, a can coating material is required to have flexibility to withstand processing as well as hardness of a coating film, but a resin coating material having a high molecular weight or a high cross-linking property is inferior in flexibility of a coating film to be obtained and has poor processability. There's a problem.

Further, when these compositions are applied to a paint for the inner surface of a can, a low molecular weight compound derived from the main component epoxy resin or acrylic resin is eluted in the contents of the can,
There was a problem in food hygiene. Furthermore, in order to prevent the elution of such low molecular weight compounds, it is necessary to completely cure the coating film, and therefore, it is necessary to perform baking at a high temperature, a large amount of energy is required for baking, and the baking speed is also high. There is a problem that it becomes late and causes a decrease in productivity.

On the other hand, paints for organic composite coated steel sheets and paints for PCM steel sheets, which are the same kind of metal surface anticorrosion paints as can paints, are urethane resins, acrylic resins, polyesters for the purpose of shifting to paints using an aqueous solvent. Resins and the like have been studied, and studies on epoxy resins have not been reported so much. For example, in Japanese Patent Laid-Open No. 5-301070,
An example is described in which an epoxy resin is used in the emulsion. However, in the technique disclosed in Japanese Patent Laid-Open No. 5-301070, the epoxy resin is used as a curing agent and cannot be a so-called main binder.

Also, in the technique described in JP-A-6-145559, an epoxy resin is used, but this is also a conventional epoxy emulsion in which a low molecular weight epoxy resin is forcibly emulsified with an emulsifier. Further, the epoxy resin is not used as a main binder because it does not exceed the range of additives or modifiers, which is about 10% of the composition ratio of epoxy to all resins.

Therefore, the object of the present invention is to provide excellent stability over time, to allow the coating film to be cured at a low temperature, and the cured coating film to be obtained to be excellent in adhesion to the metal substrate and to the topcoat paint. Further, it is to provide a composition for an aqueous paint for a metal paint, which is excellent in corrosion resistance, and a method for producing the same.

[0010]

Means for Solving the Problems The inventors of the present invention have recognized the above-mentioned drawbacks of the prior art, and further conducted diligent research to find a composition serving as a main binder. Based on this finding, the present invention has been completed based on the finding that it can be used as an aqueous paint having excellent stability over time, a coating film that can be cured at low temperature, and various physical properties.

That is, the present invention chemically bonds an aromatic epoxy resin (A-1), a compound (B) containing a monovalent carboxyl group and a compound (C) containing a polyvalent carboxyl group. At least the reaction product (D) containing substantially no epoxy group is added to the aromatic epoxy resin (A-
2) and / or aromatic polyol resin (E) is added to obtain a mixture (F), which is neutralized with a basic compound (G) and self-emulsified in water. A water-based coating composition is provided.

The present invention also relates to an aromatic epoxy resin (A-1) as a method for producing the above-mentioned aqueous coating composition,
The reaction temperature of the compound (B) containing a monovalent carboxyl group and the compound (C) containing a polyvalent carboxyl group in the presence or absence of a catalyst of ammonia or amines 7
The equivalence ratio of (B) and (A-1) at 0 to 160 ° C. is 0.2 <
(B) / (A-1) <0.8, and (A-1) and (C)
To a reaction product (D) containing substantially no epoxy group, which is chemically bonded so that the solid content weight ratio of 0.5 <(A-1) / (C) <5. The aromatic epoxy resin (A-2) and / or the aromatic polyol resin (E) is prepared by the following formula: (D) + (E) + (A-2) = 1000 <(E) + ( A-2) ≦ 800 <(A-2) ≦ 80 was prepared by adding a mixture (F) to the mixture so as to have a weight ratio, and the mixture (F) was neutralized with the basic compound (G). Furthermore, the present invention provides a method for producing a water-based coating composition in which emulsion particles have a particle size of 1.0 μm or less and a viscosity of 1000 mPa · s or less by phase inversion emulsification.

Hereinafter, the composition for aqueous paint of the present invention (hereinafter, referred to as
The “composition of the present invention”) and a method for producing the same will be described in detail.

In the preparation of the composition of the present invention, the aromatic epoxy resin (A
-1) and the aromatic epoxy resin (A-2) mixed with the reaction product (D) of the latter stage have a structural unit derived from an aromatic hydrocarbon in the resin skeleton and have an epoxy group. It is not particularly limited as long as it is one. The aromatic epoxy resin (A-1) and the aromatic epoxy resin (A-2) may be the same or different. Specific examples of the aromatic epoxy resins (A-1) and (A-2) include bisphenol A type epoxy resin, bisphenol AD type epoxy resin, bisphenol F type epoxy resin and novolac type epoxy resin.

The aromatic epoxy resins (A-1) and (A-2) usually have an average of 1.1 to 2.0 per molecule.
It has one epoxy group and has a number average molecular weight of 700 or more, preferably 1400 or more.

When the aromatic epoxy resin (A-1) or (A-2) used in the composition of the present invention has a large molecular weight, phenols, particularly bisphenol, are used. Those consisting of A are useful. For the epoxy group concentration of the raw material epoxy resin,
By using an excessive amount of bisphenol A, it becomes possible to obtain an aromatic epoxy resin (A-1) or (A-2) having a hydroxyl group at the terminal and having a large molecular weight.
Further, if an excessive amount of the raw material epoxy resin is used with respect to the concentration of the hydroxyl group of bisphenol A, an aromatic epoxy resin (A having an epoxy resin at the end and having a large molecular weight) is used.
-1) or (A-2) can be obtained.

The compound (B) containing a monovalent carboxyl group used in the composition of the present invention has a carboxyl group in the molecular skeleton and is not particularly limited. Examples thereof include α, β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and ethylacrylic acid, and dehydrated castor oil fatty acids, fatty acids having a conjugated double bond such as linseed oil fatty acid, and the like. Further, there may be mentioned aliphatic carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, isobutyric acid and isovaleric acid, and aromatic carboxylic acids such as benzoic acid. These may be used alone or in combination of two or more. Among these, acrylic acid and methacrylic acid are preferable because they have a copolymerizability and are effective in improving the anticorrosion property when formed into a coating film and the adhesion of the topcoat.

The polyvalent carboxyl group-containing compound (C) used in the composition of the present invention has a carboxylic acid structural unit in the resin skeleton and is obtained by polymerizing at least two kinds of copolymerizable monomers. (I) carboxyl group-containing vinyl monomer, (ii) aromatic vinyl monomer, and (iii) alkyl ester, hydroxyalkyl ester and N- of α, β-ethylenically unsaturated carboxylic acid
It is obtained by polymerizing at least two kinds of monomers selected from the group consisting of hydroxyalkylamides. For example, these monomers or a mixture thereof are combined so that the resulting polymer has a carboxyl group and / or a hydroxyl group, and a radical polymerization initiator such as azobisisobutyronitrile or benzoyl peroxide is used in an organic solvent. And can be obtained by polymerizing or copolymerizing at a temperature of 60 ° C to 150 ° C.

Examples of the (i) carboxyl group-containing vinyl monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid and fumaric acid.

(Ii) As the aromatic vinyl monomer,
Examples thereof include styrene-based monomers such as styrene, vinyltoluene 2-methylstyrene, t-butylstyrene, and chlorostyrene.

(Iii) Examples of the alkyl ester of α, β-ethylenically unsaturated carboxylic acid include, for example, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-acrylic acid. Amyl, isoamyl acrylate, n-acrylic acid
Acrylic esters such as hexyl, 2-ethylhexyl acrylate, n-octyl acrylate, decyl acrylate, dodecyl acrylate; methyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-methacrylate. Examples thereof include amines, isoamyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, decyl methacrylate, dodecyl methacrylate, and other methacrylate esters.

Examples of the hydroxyalkyl ester of (iii) α, β-ethylenically unsaturated carboxylic acid include hydroxyalkyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and the like. Examples thereof include ester monomers.

Further, (iii) N-hydroxyalkylamides of α, β-ethylenically unsaturated carboxylic acids include
For example, N-methylol (meth) acrylamide, N-
Examples thereof include N-substituted (meth) acrylic monomers such as butoxymethyl (meth) acrylamide.

This polyvalent carboxyl group-containing compound (C)
The content of the (i) carboxyl group-containing vinyl monomer therein is preferably 25 to 75% by weight, more preferably 25 to 75% by weight, since the viscosity of the polyvalent carboxyl group-containing compound (C) is in an appropriate range during production. It is 30 to 60% by weight.
Further, when the content of the (i) carboxyl group-containing vinyl monomer in the polyvalent carboxyl group-containing compound (C) is in this range, the dispersion stability in an aqueous medium is excellent, and the coating is excellent in solvent resistance after coating. A film is obtained, which has a good flavor property when coated on the inner surface of a can, is excellent in water resistance, and can be used as an organic composite coated steel sheet to obtain a coating film having excellent corrosion resistance. Is obtained, which is preferable.

The content of the vinyl monomer having a hydroxyl group as the alkyl ester of (iii) α, β-ethylenically unsaturated carboxylic acid in the compound (C) containing a polyvalent carboxyl group is Since the viscosity of the contained compound (C) at the time of production is in an appropriate range, the production is easy, so that the content is preferably 1 to 5% by weight, and more preferably 2 to 4% by weight. Furthermore, when the content of the hydroxyl group-containing vinyl monomer in the polyvalent carboxyl group-containing compound (C) is in this range, a coating film having excellent dispersion stability in an aqueous medium and excellent solvent resistance can be obtained. In particular, it is preferable because it can be used for an organic composite-coated steel sheet to obtain a coating composition having excellent corrosion resistance, which is a water-based coating composition.

This polyvalent carboxyl group-containing compound (C)
Does not cause gelation during the reaction between the aromatic epoxy resin (A-1) and the monovalent carboxyl group-containing compound (B), and the composition of the present invention is applied to obtain an appropriate crosslinking density. A weight average molecular weight of 3,000 to 50,000, preferably 50, from the viewpoint that a coating film having excellent processability can be obtained.
It is in the range of 00 to 20000. The acid value of the polyvalent carboxyl group-containing compound (C) is 25 to 450 (KOHmg / g) in terms of solid content, preferably 250 to
370 is suitable.

In the present invention, the aromatic epoxy resin (A-1), the compound (B) containing a monovalent carboxyl group, and the compound (C) containing a polyvalent carboxyl group are chemically bound to each other. The reaction product (D) is, for example,
In the presence or absence of a catalyst of ammonia or amines, the equivalent ratio of the aromatic epoxy resin (A-1) and the monovalent carboxyl group-containing compound (B) is 0.2 <
(B) / (A-1) <0.8, and aromatic epoxy resin (A-1) and polyvalent carboxyl group-containing compound (C)
And the solid content weight ratio is 0.5 <(A-1) / (C) <5
The reaction temperature is 70 ° C to 16 ° C.
It can be obtained by reacting at 0 ° C, preferably 90 ° C to 130 ° C.

In the production of this reaction product (D), examples of ammonia or amines used as a catalyst include alkylamines such as ethylamine, butylamine, diethylamine, trimethylamine, triethylamine and butylamine; 2-dimethylaminoethanol, Alcohol amines such as diethanolamine, triethanolamine, aminomethyl propanol and dimethylaminomethyl propanol; morpholine; and polyamines such as ethylenediamine and diethylenetriamine. When this ammonia or amines is used as a catalyst, the amount thereof is usually the aromatic epoxy resin (A-1), the compound (B) containing a monovalent carboxyl group, and the polyvalent carboxyl. In the reaction with the group-containing compound (C), the amount is about 0.1 to 10 times the amount of the residual carboxyl group when the carboxyl group and the epoxy group present in the reaction mixture theoretically react. Yes, and preferably about 0.5 to 0.95 times.

Next, in the present invention, an aqueous coating composition can be obtained according to the following methods (1) to (3). Reaction product (D) and aromatic epoxy resin (A-
The mixture (F-1) with 2) is neutralized with the basic compound (G) and self-emulsified in water to produce the mixture. Reaction product (D) and aromatic epoxy resin (A-
The mixture (F) with 2) and the aromatic polyol resin (E) is neutralized with the basic compound (G) and self-emulsified in water to produce the mixture.

The composition of the present invention may be prepared by any of the above-mentioned methods (1) to (3) without any particular limitation. In particular, among these methods, the method (1) is preferable in that the emulsification can be easily performed because the increase in viscosity until reaching the phase inversion point is small when self-emulsifying in water.

The aromatic polyol resin (E) used in the above-mentioned method has a primary hydroxyl group in the resin skeleton and substantially no epoxy group, and is an epoxy of an aromatic epoxy resin. It is obtained by modifying the group with a terminal stopper. The aromatic epoxy resin as a raw material is not particularly limited as long as it has a structural unit derived from aromatic hydrocarbon in the resin skeleton. Examples thereof include bisphenol A type epoxy resin, bisphenol AD type epoxy resin, bisphenol F type epoxy resin, and novolac type epoxy resin.
The aromatic epoxy resin usually has an average of 1.1 to 2.0 epoxy groups in one molecule and a number average molecular weight of 700 or more, preferably 1400 or more.

Examples of the terminal stopper used for modifying the epoxy group of the aromatic epoxy resin include phenols, carboxylic acids, primary amines, secondary amines, mercaptans, alcohols, Those having a reactive hydrogen atom such as water, or alkyl halides,
Those having no reactive hydrogen atom such as Grignard reagent and nucleophiles such as alkyllithium can be used.

Examples of the mercaptans include methyl mercaptan, ethyl mercaptan propyl mercaptan, isopropyl mercaptan, n-butyl mercaptan, acrylic mercaptan, benzyl mercaptan and the like. Examples of alcohols include methyl alcohol, ethyl alcohol, n-propyl alcohol, n-butyl alcohol, n-pentyl alcohol,
Examples thereof include benzyl alcohol, methyl cellosolve, ethyl cellosolve, propyl cellosolve, and methyl carbitol. Examples of the alkyl halides include methyl chloride, ethyl chloride propyl chloride,
Examples include methyl bromide and ethyl bromide.
Examples of the Grignard reagent include methyl magnesium bromide, ethyl magnesium bromide, propyl magnesium bromide, and henzyl magnesium bromide. As alkyl lithium, etc.,
For example, methyl lithium, ethyl lithium, propyl lithium, n-butyl lithium and the like can be mentioned.

Examples of the phenols used as the terminal terminator include bisphenol A, alkyl monophenol, resorcinol and the like.

The carboxylic acids include, for example, benzoic acid, palmitic acid, lauric acid, myristic acid, stearic acid, etc., castor oil fatty acid, soybean oil fatty acid, and carboxylic acid.
Monocarboxylic acid compounds such as animal oil and plant oil fatty acids such as oleic oil fatty acid, flaxseed oil fatty acid, cottonseed oil fatty acid, glutaric acid, maleic acid, adipic acid, succinic acid, trimellitic acid, pyromellitic acid, glyco-acrylic acid, tartaric acid, etc. Examples thereof include polycarboxylic acid compounds.

Examples of primary amines or secondary amines include hydroxylamines such as ethanolamine and diethanolamine, and alkylamines such as propylamine, ethylamine, dipropylamine and diethylamine. .

When it is necessary to increase the molecular weight of the aromatic epoxy resin, phenols, particularly bisphenol A, are effective as the terminal terminator. By using an excessive amount of bisphenol A with respect to the concentration of the epoxy group of the raw material aromatic epoxy resin, it is possible to increase the molecular weight and seal the epoxy group of the aromatic epoxy resin. Also, when it is not necessary to increase the molecular weight, a monocarboxylic acid compound,
The use of secondary and secondary amines is effective because of their high reactivity with epoxy groups.

In the preparation of the aromatic polyol resin (E), the terminal terminating agent for modifying the epoxy group of the aromatic epoxy resin may be only one kind or a combination of two or more kinds. May be.

The end-capping agent has an aromatic polyol resin (E) having a number average molecular weight of 350 to 40,000.
The epoxy groups are used in an amount of 0 to 0.2 on average in one molecule, and 0.01 to 4.0 on average of primary hydroxyl groups in one molecule. When the amount of the epoxy group of the aromatic polyol resin (E) is within this range, it is possible to prevent destabilization of the aqueous dispersion and deterioration of the coating film due to the ring-opening reaction of the epoxy group, which is more preferable. When the primary hydroxyl group in the aromatic polyol resin (E) is in this range, generation of a microgel body having a network structure due to excessive esterification reaction can be suppressed, which is more preferable.

In the present invention, the weight ratio of the reaction product (D), the aromatic epoxy resin (A-2) and the aromatic polyol resin (E) in the mixture (F) is represented by the following formula. Adjusted to be within range. (D) + (E) + (A-2) = 100 0 <(E) + (A-2) ≦ 80 0 <(A-2) ≦ 80 Preferably, 1 ≦ (E) + (A-2 ) ≦ 80 1 ≦ (A-2) ≦ 80 More preferably, 30 ≦ (E) + (A-2) ≦ 70 20 ≦ (A-2) ≦ 70, and (E) is preferably. , 0 ≦ (E) ≦ 50, and more preferably 0 ≦ (E) ≦ 40.

In preparing the mixture (F), the aromatic epoxy resin (A-2) and / or the aromatic polyol is used.
If the resin (E) is added to and mixed with the reaction product (D), the amount of the polyvalent carboxyl group-containing compound (C) used in the preparation of the reaction product (D) can be reduced, and the composition of the present invention can be reduced. When the content in the product is reduced, the free carboxyl groups after the curing reaction of the coating film formed by applying the composition of the present invention are reduced, and the gel fraction is increased. Therefore, the coating film physical properties such as water resistance, chemical resistance, and adhesion are improved, which is preferable.

In the preparation of the composition of the present invention, the mixture (F) comprises the reaction product (D), the aromatic epoxy resin (A-2) and / or the aromatic polyol resin (E) as described above. Are mixed with each other, and further neutralized with the basic compound (G) to be self-emulsified in water to form an emulsion. Reaction product (D) and aromatic epoxy resin (A
-2) and / or mixing with the aromatic polyol resin (E) is not particularly limited, and for example, a stirring blade such as a turbine blade, a ribbon blade, a paddle blade, or a propeller blade is used in a batch reactor. It can be carried out according to a method such as stirring and mixing.

The neutralization with the basic compound (G)
The excess carboxyl groups present in mixture (F) are carried out as ammonium or amine salts using ammonia or amines as basic compound (G). This neutralization is preferably carried out by adding ammonia or amines in such an amount that the pH of the aqueous coating composition of the present invention becomes 5 to 11.

Examples of the amines used as the basic compound (G) include ethylamine, butylamine,
Alkylamines such as diethylamine, trimethylamine, triethylamine, butylamine; alcohol amines such as 2-dimethylaminoethanol, diethanolamine, triethanolamine, aminomethylpropanol, dimethylaminomethylpropanol; morpholine; polyvalent ethylenediamine, diethylenetriamine, etc. Examples include amines.

Further, the emulsification of the neutralized mixture (F) is carried out by dropping water or warm water in a conventional apparatus while stirring at the optimum temperature of the phase inversion point, usually in the range of 50 to 90 ° C. It can be performed according to the method of. Alternatively, a commercially available emulsifier capable of high stirring may be used. The composition of the present invention obtained by this emulsification has a particle size of 1.0.
having emulsion particles of less than μm and having a viscosity of 100
It has a particle size of 0 mPa · s or less, preferably 0.7 μm or less, and a viscosity of 500 mPa · s or less.

The composition of the present invention is used as an aqueous paint by adding and dispersing an aqueous medium. Here, the aqueous medium means water alone in which at least 10% by weight or more is water, or a mixture of water and a hydrophilic organic solvent. As the hydrophilic organic solvent, for example, methanol, ethanol,
Alkyl alcohols such as isopropanol, n-butanol, sec-butanol, tert-butanol, and isobutanol, ether alcohols such as methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, methyl carbitol and ethyl carbitol, methyl cellosolve acetate, Ether esters such as ethyl cellosolve acetate, oxane,
Dimethylformamide, diacetone alcohol and the like are used.

In the composition of the present invention, the mixture ratio of the neutralized mixture (F) / water is usually about 25/75, and after emulsification, it is distilled under reduced pressure depending on the purpose of use and the conditions of use. The amount of the aqueous medium used may be reduced by increasing the amount of the aqueous medium used, or the amount of the aqueous medium may be increased by additional addition. For example, the ratio of the neutralized mixture (F) / aqueous medium is good. In order to obtain a stable aqueous coating composition, preferably 5/95 to 70 /
30 and more preferably 20/80 to 50/50.

The aqueous coating composition of the present invention can be used as an aqueous coating by adding a pigment. The pigment used is not particularly limited, and various known pigments can be used. Further, the composition of the present invention, as long as not impairing the above properties as an aqueous coating, if necessary, for example, hexamethoxymethylmelamine, methylolated benzoguanamine resin, aqueous aminoplast resin such as methylolated urea resin. , Block tolylene diisocyanate, block diphenyl diisocyanate, block hexamethylene diisocyanate and other block isocyanates,
Further, a curing agent such as a phenol resin or a surfactant for improving the coating property, a defoaming agent, etc. can be added.

The object to be coated on which the composition of the present invention is applied to form a coating film is not particularly limited. In particular, the composition of the present invention is suitable as a paint for forming a cured coating film by coating a treated steel plate such as an untreated steel plate, a zinc nickel steel plate, a zinc iron plate, and a tin plate. The coating method is not particularly limited, and for example, any method such as spray coating such as air spray, airless spray, electrostatic spray, dip coating, roll coater coating, and electrodeposition coating is possible and is not particularly limited. The baking conditions for forming the cured coating film can be selected preferably from a temperature range of 100 ° C to 240 ° C and a time range of 10 seconds to 30 minutes.

[0050]

The present invention will be described below with reference to examples and comparative examples. In addition, "part" and "%" in a sentence show "weight part" and "weight%", respectively. Throughout the examples and comparative examples, the paints or paint plates were evaluated according to the following methods, unless otherwise specified. The results are shown in Table 1.

(Evaluation of Painted Plate) (1) Evaluation of Corrosion Resistance Preparation of Painted Plate A water-based coating composition obtained in each of Examples and Comparative Examples was mixed with water to prepare a resin varnish having a solid content of 10%. Prepare. This resin varnish is applied to the surface of a galvanized steel sheet having a thickness of 0.8 mm by using a No. 5 bar coater,
After 20 seconds, the steel plate is baked at 120 ° C. to cure the resin varnish to produce a coated plate having a cured coating film with a thickness of about 1 to 2 μm. Evaluation A part of this coated plate was treated with 5% saline solution at 35 ° C.
After being subjected to a continuous salt spray test for 0 hours, it is evaluated according to the following criteria. No abnormalities ……………… ◎◎ Slightly corroded… ○ Significantly corroded …… △ Whole corroded …… ×

(2) Evaluation of Adhesion Adhesion of a Painted Plate A melamine alkyd resin was prepared by using a No. 60 bar coater on a cured coating film of the same paint plate used for the evaluation of corrosion resistance. Is applied and baked at 130 ° C for 20 minutes to cure the melamine alkyd resin to a thickness of about 3
A coating sample is prepared by forming a coating film of 5 to 40 μm.
(Hereinafter, this coated sample is referred to as "melamine alkyd-no treatment")

Water is added to the aqueous coating composition obtained in the Examples or Comparative Examples to prepare a solid content of 10%. Using a No. 5 bar coater,
It is applied on a galvanized steel sheet having a thickness of 0.8 mm, and after 20 seconds, the steel sheet is baked and cured at 120 ° C. to produce a coated plate having a cured coating film having a thickness of about 1 to 2 μm. Furthermore, on the cured coating film, using an electrostatic coating device,
A polyester-based powder coating material is applied and baked and cured at 180 ° C. for 20 minutes to form a coating film having a thickness of about 35 to 40 μm, and a coated sample is prepared. (Hereinafter, this coated sample is referred to as "non-treated polyester")

Water is added to the aqueous coating composition obtained in the Examples or Comparative Examples to prepare a solid content of 10%. Using a No. 5 bar coater,
It is applied on a galvanized steel plate having a thickness of 0.8 mm, and after 20 seconds, the plate is baked and cured at 120 ° C. to manufacture a coated plate having a cured coating film having a thickness of about 1 to 2 μm.
Furthermore, an epoxy polyester-based powder coating material is applied onto the cured coating film by using an electrostatic coating device, and 165 ° C x 20
A coating sample is prepared by baking and curing for a minute to form a coating film having a thickness of about 35 to 40 μm. (Hereinafter, this coated sample is referred to as "no epopoly-treated")

Water is added to the aqueous coating composition obtained in the Examples or Comparative Examples to prepare a solid content of 10%. Using a No. 5 bar coater,
It is applied on a galvanized steel sheet having a thickness of 0.8 mm, and after 20 seconds, the steel sheet is baked and cured at 120 ° C. to produce a coated plate having a cured coating film having a thickness of about 1 to 2 μm. 60% of this coated plate in 2% sodium silicate solution
After soaking at 30 ° C. for 30 seconds, it is washed with ion-exchanged water and dried with nitrogen gas. Then, a melamine alkyd resin was applied onto the cured coating film using a No. 60 bar coater, and baked and cured at 130 ° C. for 20 minutes to give a thickness of about 35.
A coating sample is prepared by forming a coating film of -40 μm.
(Hereinafter, this coated sample is referred to as "melamine alkyd-treated")

Water is added to the aqueous coating composition obtained in the Examples or Comparative Examples to prepare a solid content of 10%. Using a No. 5 bar coater,
It is applied on a galvanized steel sheet having a thickness of 0.8 mm, and after 20 seconds, the steel sheet is baked and cured at 120 ° C. to produce a coated plate having a cured coating film having a thickness of about 1 to 2 μm. 60% of this coated plate in 2% sodium silicate solution
After soaking at 30 ° C. for 30 seconds, it is washed with ion-exchanged water and dried with nitrogen gas. After that, the polyester powder coating is applied on the cured coating film using an electrostatic coating device, and the temperature is 180 ° C.
Is baked and cured for 20 minutes to form a coating film having a thickness of about 35 to 40 μm to prepare a coated sample. (Hereinafter, this coated sample is referred to as "polyester-treated")

Water is added to the aqueous coating composition obtained in the Examples or Comparative Examples to prepare a solid content of 10%. Using a No. 5 bar coater,
It is applied on a galvanized steel sheet having a thickness of 0.8 mm, and after 20 seconds, the steel sheet is baked and cured at 120 ° C. to produce a coated plate having a cured coating film having a thickness of about 1 to 2 μm. 60% of this coated plate in 2% sodium silicate solution
After soaking at 30 ° C. for 30 seconds, it is washed with ion-exchanged water and dried with nitrogen gas. Then, using an electrostatic coating device, coat the epoxy polyester powder coating on the cured coating,
It is baked and cured at 165 ° C for 20 minutes to a thickness of about 35-4.
A coated sample is prepared by forming a 0 μm coating film. (Hereinafter, this coated sample is referred to as "with Epopoly-treated")

Evaluation-1 (Cross-cut test) A coated sample having a width of about 1 mm was used on the coated surface of the coated sample.
Eleven cuts are made in each of the vertical and horizontal directions to form 100 cross-cuts. Next, after a cellophane adhesive tape having a width of 24 mm was adhered to this coating surface, the cellophane adhesive tape was strongly peeled off, and 100 was used as a denominator, and the unpeeled number of the grid was a numerator. Show as an index. (Hereafter referred to as "primary")

Evaluation-2 A part of the coated sample was dipped in boiling water for 2 hours, and then the cross-cut test of Evaluation-1 was performed to determine the condition of the blister. (Hereinafter referred to as "secondary")

(Example 1) -Preparation of polyvalent carboxyl group-containing compound (C) solution-A four-necked flask purged with nitrogen gas was charged with 500 parts of ethylene glycol monobutyl ether, and 150-1 was used.
Styrene 104 is heated to 60 ° C and kept at that temperature.
Parts, 50 parts of ethyl acrylate, 311 parts of methacrylic acid,
A homogeneous solution in which 32 parts of hydroxyethyl methacrylate and 5.5 parts of dicumylper oxide were mixed was gradually put into a four-necked flask for 2 hours for reaction.
After the completion of the appropriate period, the reaction was continued by stirring at a temperature for 6 hours, and then ethylene glycol monobutyl ether and unreacted vinyl monomer were distilled off from the reaction mixture under reduced pressure. Then, the reaction mixture was cooled to room temperature,
A solution of a polyvalent carboxyl group-containing compound having an acid value (converted to 100% of resin) of 307 KOH mg / 1 g and a solid content of 52.1% was obtained. The weight average molecular weight of the produced polyvalent carboxyl group-containing compound was about 8,000, and the content of carboxylic acid units was 47%.

-Preparation of Aromatic Polyol Resin (E) Solution- 1000 parts of bisphenol A type epoxy resin (number average molecular weight: about 3200, epoxy equivalent: about 2700 g / eq) was placed in a four-necked flask substituted with nitrogen gas. And 200 parts of xylene are charged and gradually heated to an internal temperature of 120 ° C.
The reaction mixture was completely dissolved by stirring for 1 hour and then gradually heated to 150 ° C. Internal temperature is 15
After reaching 0 ° C, 38.9 parts of diethanolamine was added to 1
The temperature was lowered over a period of time, and the reaction was continued for 6 hours. Then, to the reaction mixture, ethylene glycol monobutyl ether 4 was added.
After adding and dissolving 92.6 parts, the mixture was cooled to room temperature to obtain a solution of an aromatic polyol resin having an epoxy equivalent of 30,000 g / eq or more and a solid content of 60%.
The number average molecular weight of the produced aromatic polyol resin is 3,300, and the average number of epoxy groups per molecule is 0.1.
Or less.

-Preparation of water-based coating composition-In a four-necked flask whose inside was replaced with nitrogen gas, the number average molecular weight was about 3700 and the epoxy equivalent was about 2250 g /
eq of bisphenol A type epoxy resin 360 parts, methacrylic acid 6.9 parts, polyvalent carboxyl group-containing compound solution (solid content 52.1%) 345 parts obtained above, and ethylene glycol monobutyl ether 375 parts. After charging, the mixture was gradually heated to raise the internal temperature to 130 ° C. and stirred for 1 hour to completely dissolve it. Then, it was gradually cooled to 110 ° C. After the internal temperature reached 110 ° C., 74.2 parts of dimethylaminoethanol was added. In addition, 110
The reaction was carried out at 3 ° C. for 3 hours. The acid value (converted to 100% of resin) of the reaction mixture at this time was measured to be 92 KOHmg /
1 g. Next, 420 parts of a bisphenol A type epoxy resin having a number average molecular weight of about 3700 and an epoxy equivalent of about 2250, 400 parts of the aromatic polyol resin solution (solid content 60%) obtained above, and propylene glycol monomethyl ether. -380 parts of ter was mixed and stirred for 1 hour while maintaining the temperature to prepare a completely dissolved solution. This solution is added to the above reaction mixture and 100
After holding at 0 ° C. for 1 hour, 3720 parts of ion-exchanged water was gradually added and emulsified using a disperser. At this time,
A milky white dispersion having a solid content of 20% was obtained. Thereafter, the solvent ethylene glycol monobutyl ether and propylene glycol monomethyl ether were distilled off together with water under reduced pressure, and the solid content was 30% until the total amount of the solvent was reduced to 2.7 times the solid content. Ion-exchanged water was added every time the temperature was exceeded, and the mixture was distilled off under reduced pressure to prepare an aqueous coating composition. The resulting water-based coating composition had a solid content of 27.7% and a viscosity of 82.
0 mPa · s, solvent content 9% or less, average particle size 0.36
It was one of μm. In addition, the composition for water-based coating,
It was stored at room temperature for 3 months, but no abnormality was observed.

Example 2 Preparation of Polyvalent Carboxyl Group-Containing Compound (C) Solution-A four-necked flask internally purged with nitrogen gas was charged with 500 parts of ethylene glycol monobutyl ether and charged with 140 parts.
Styrene 1 while heating to ~ 150 ° C and maintaining that temperature
04 parts, ethyl acrylate 50 parts, methacrylic acid 311
Solution, 32 parts of hydroxyethyl methacrylate, and 5.5 parts of dicumylper oxide were mixed to prepare a uniform solution,
The reaction was carried out by gradually lowering it into a four-necked flask over 2 hours. After completion of the appropriate temperature, the temperature was maintained and the mixture was stirred for 6 hours to continue the reaction, and then ethylene glycol was removed from the reaction mixture under reduced pressure.
Rumonobutyl ether and unreacted vinyl monomer were distilled off. Next, when the reaction mixture was cooled to room temperature, the acid value (converted to 100% of resin) was 328 KOHmg / 1.
A solution of a polyvalent carboxyl group-containing compound having a solid content of 47.0% was obtained. The weight average molecular weight of the produced polyvalent carboxyl group-containing compound was about 14,000, and the carboxylic acid unit was 50%.

-Preparation of water-based coating composition-In a four-necked flask internally purged with nitrogen gas, the number average molecular weight was about 3700 and the epoxy equivalent was about 2250 g / e.
The bisphenol A type epoxy resin (q) (360 parts), methacrylic acid (6.9 parts), the polyvalent carboxyl group-containing compound (solid content 47.0%) 383 parts, and ethylene glycol monobutyl ether (337 parts) were charged. ,
The mixture was gradually heated to raise the internal temperature to 130 ° C. and stirred for 1 hour to completely dissolve it. Then, it was gradually cooled to 110 ° C. After the internal temperature reached 110 ° C., 79.0 parts of dimethylaminoethanol was added and reacted. In addition, 11
The reaction was performed at 0 ° C. for 3 hours. The acid value (converted to 100% of resin) of the reaction mixture at this time was measured to be 96 KOHm.
It was g / 1g. Next, 420 parts of a bisphenol A type epoxy resin having a number average molecular weight of about 3700 and an epoxy equivalent of about 2250, 400 parts of the aromatic polyol resin solution (solid content 60%) obtained in Example 1, and propylene glycol. -380 parts of rumonomethyl ether was added, and the mixture was stirred for 1 hour while maintaining the temperature to prepare a completely dissolved solution. Add this solution to the above reaction mixture,
After holding at 100 ° C. for 1 hour, 3720 parts of ion-exchanged water was gradually added to emulsify using a disperser. At this time, a milky white dispersion liquid having a solid content of 20% was obtained. Then, under reduced pressure, the solvent ethylene glycol monobutyl ether was added.
Tellurium and propylene glycol monomethyl ether were distilled off together with water, and ion-exchanged water was added every time the solid content exceeded 30% until the total amount of the solvent decreased to 2.7 times the solid content, and the pressure was reduced. Then, the aqueous coating composition was prepared. The obtained water-based coating composition had a solid content of 27.0%,
The viscosity was 420 mPa · s, the solvent content was 9% or less, and the average particle size was 0.32 μm. Further, this aqueous coating composition was stored at room temperature for 3 months, but no abnormality was observed.

(Example 3) -Preparation of water-based coating composition-A four-necked flask whose inside was replaced with nitrogen gas had a number average molecular weight of about 3700 and an epoxy equivalent of about 2250 g /
eq of bisphenol A type epoxy resin 600 parts, methacrylic acid 11.5 parts, polyvalent carboxyl group-containing compound solution obtained in Example 1 (solid content 52.1%) 460 parts,
And ethylene glycol monobutyl ether 620
I prepare the part and heat gradually and raise internal temperature to 130 degrees Celsius,
It was stirred for 1 hour and completely dissolved. Then, it was gradually cooled to 110 ° C. After the internal temperature reached 110 ° C., 96.7 parts of dimethylaminoethanol was added. In addition, 1
The reaction was carried out at 10 ° C for 3 hours. The acid value (converted to 100% of resin) of the reaction mixture at this time was measured to be 72 KOHm.
It was g / 1g. Next, 360 parts of a bisphenol A type epoxy resin having a number average molecular weight of about 3700 and an epoxy equivalent of about 2250, and 240 parts of propylene glycol monomethyl ether were added, and the mixture was stirred for 1 hour while maintaining the temperature to complete the addition. A dissolved solution was prepared. This solution was added to the above reaction mixture, kept at 100 ° C. for 1 hour, and then emulsified using a disperser while gradually adding 3720 parts of ion-exchanged water. At this time, a milky white dispersion liquid having a solid content of 20% was obtained. Thereafter, the solvent ethylene glycol monobutyl ether and propylene glycol monomethyl ether were distilled off together with water under reduced pressure, and the solid content was 30% until the total amount of the solvent was reduced to 2.7 times the solid content. Ion-exchanged water was added every time the temperature was exceeded, and the mixture was distilled off under reduced pressure to prepare an aqueous coating composition. The obtained aqueous coating composition had a solid content of 26.5%, a viscosity of 120 mPa · s,
The solvent content was 9% or less and the average particle size was 0.34 μm. Further, this aqueous coating composition was stored at room temperature for 3 months, but no abnormality was observed.

(Example 4) -Preparation of water-based coating composition-In a four-necked flask whose inside was replaced with nitrogen gas, the number average molecular weight was about 3700 and the epoxy equivalent was about 2250 g /
eq of bisphenol A type epoxy resin 600 parts, methacrylic acid 11.5 parts, polyvalent carboxyl group-containing compound solution obtained in Example 1 (solid content 52.1%) 460 parts,
And ethylene glycol monobutyl ether 620
I prepare the part and heat gradually and raise internal temperature to 130 degrees Celsius,
It was stirred for 1 hour and completely dissolved. Then, it was gradually cooled to 110 ° C. After the internal temperature reached 110 ° C., 96.7 parts of dimethylaminoethanol was added. In addition, 1
The reaction was carried out at 10 ° C for 3 hours. The acid value (converted to 100% of resin) of the reaction mixture at this time was measured to be 72 KOHm.
It was g / 1g. Next, 240 parts of a bisphenol A type epoxy resin having a number average molecular weight of about 3700 and an epoxy equivalent of about 2250, 200 parts of the aromatic polyol resin solution (solid content 60%) obtained in Example 1, and propylene glycol. -160 parts of rumonomethyl ether was added, and the mixture was stirred for 1 hour while maintaining the temperature to prepare a completely dissolved solution. Add this solution to the above reaction mixture,
After holding at 100 ° C. for 1 hour, 3720 parts of ion-exchanged water was gradually added to emulsify using a disperser. At this time, a milky white dispersion liquid having a solid content of 20% was obtained. Then, under reduced pressure, the solvent ethylene glycol monobutyl ether was added.
Tellurium and propylene glycol monomethyl ether were distilled off together with water, and ion-exchanged water was added every time the solid content exceeded 30% until the total amount of the solvent decreased to 2.7 times the solid content, and the pressure was reduced. Then, the aqueous coating composition was prepared. The obtained aqueous coating composition had a solid content of 26.8%,
The viscosity was 80 mPa · s, the solvent content was 9% or less, and the average particle size was 0.33 μm. Further, this aqueous coating composition was stored at room temperature for 3 months, but no abnormality was observed.

(Example 5) -Preparation of aqueous coating composition-A four-necked flask whose inside was replaced with nitrogen gas had a number average molecular weight of about 3700 and an epoxy equivalent of about 2250 g /
bis bisphenol A type epoxy resin 360 parts, methacrylic acid 6.9 parts, polyvalent carboxyl group-containing compound solution (solid content 52.1%) 690 parts obtained in Example 1, and ethylene glycol monobutyl ether 390. Charge the parts and gradually heat to raise the internal temperature to 130 ° C. 1
It was stirred for a time to completely dissolve it. Then, it was gradually cooled to 110 ° C. After the internal temperature reached 110 ° C., 155 parts of dimethylaminoethanol was added. In addition, 110
The reaction was carried out at 3 ° C. for 3 hours. The acid value (converted to 100% of resin) of the reaction mixture at this time was measured to be 140 KOHmg.
It was / 1g. Next, 300 parts of a bisphenol A type epoxy resin having a number average molecular weight of about 3700 and an epoxy equivalent of about 2250, 300 parts of the aromatic polyol resin solution (solid content 60%) obtained in Example 1, and propylene glycol. -Adding 240 parts of rumonomethyl ether,
A solution was prepared by maintaining the temperature and stirring for 1 hour to completely dissolve it. Add this solution to the above reaction mixture and
After holding at 00 ° C. for 1 hour, 3720 parts of ion-exchanged water was gradually added to emulsify using a disperser. At this time, a milky white dispersion liquid having a solid content of 20% was obtained. Then, under reduced pressure, the solvent ethylene glycol monobutyl ether was added.
Tellurium and propylene glycol monomethyl ether were distilled off together with water, and ion-exchanged water was added every time the solid content exceeded 30% until the total amount of the solvent decreased to 2.7 times the solid content, and the pressure was reduced. Then, the aqueous coating composition was prepared. The resulting aqueous coating composition had a solid content of 27.1%,
The viscosity was 100 mPa · s, the solvent content was 9% or less, and the average particle size was 0.30 μm. Further, this aqueous coating composition was stored at room temperature for 3 months, but no abnormality was observed.

(Example 6) -Preparation of polyvalent carboxyl group-containing compound (C) solution-A four-necked flask whose inside was replaced with nitrogen gas was charged with 500 parts of ethylene glycol monobutyl ether and charged with 15 parts.
After heating to 0 to 160 ° C., while maintaining the temperature, a homogeneous solution obtained by mixing 123 parts of styrene, 70 parts of ethyl acrylate, 307 parts of methacrylic acid and 5.5 parts of dicumylperoxide was gradually added over 2 hours. The reaction was carried out appropriately.
After completion of the appropriate temperature, the mixture was stirred for 6 hours while maintaining the temperature, and then 250 parts of ethylene glycol monobutyl ether was added and dissolved. Next, when the reaction mixture was cooled to room temperature, the acid value (resin 100% conversion) 278 KOHmg /
A solution of the polyvalent carboxyl group-containing compound having 1 g and a solid content of 40% was obtained. The polyvalent carboxyl group-containing compound produced has a weight average molecular weight of about 5,000 and a carboxylic acid unit of 4
It was 3%.

-Preparation of water-based coating composition-In a four-necked flask whose inside was replaced with nitrogen gas, the number average molecular weight was about 3700 and the epoxy equivalent was about 2250 g /
bis bisphenol A type epoxy resin 360 parts, methacrylic acid 6.9 parts, a solution of the polyvalent carboxyl group-containing compound obtained above (solid content 40.0%) 450 parts, and ethylene glycol monobutyl ether 270 parts Was charged and gradually heated to raise the internal temperature to 130 ° C., and stirred for 1 hour to completely dissolve it. Then, it was gradually cooled to 110 ° C. After the internal temperature reached 110 ° C., 66.6 parts of dimethylaminoethanol was added. In addition, 110
The reaction was carried out at 3 ° C. for 3 hours. At this time, the acid value (converted to 100% of resin) of the reaction mixture was measured and found to be 80 KOHmg /
1 g. Next, 420 parts of a bisphenol A type epoxy resin having a number average molecular weight of about 3700 and an epoxy equivalent of about 2250, 400 parts of the aromatic polyol resin solution (solid content 60%) obtained above, and propylene glycol monomethyl ether. A solution was prepared by adding 380 parts of Teru and stirring for 1 hour while maintaining the temperature to completely dissolve it. This solution is added to the above reaction mixture and 100
After holding at 0 ° C. for 1 hour, 3720 parts of ion-exchanged water was gradually added and emulsified using a disperser. At this time,
A milky white dispersion having a solid content of 20% was obtained. Thereafter, the solvent ethylene glycol monobutyl ether and propylene glycol monomethyl ether were distilled off together with water under reduced pressure, and the solid content was 30% until the total amount of the solvent was reduced to 2.7 times the solid content. Ion-exchanged water was added every time the temperature was exceeded, and the mixture was distilled off under reduced pressure to prepare an aqueous coating composition. The obtained aqueous coating composition had a solid content of 27.3% and a viscosity of 90.
mPa · s, solvent content 9% or less, average particle size 0.36μ
It was m. Further, this aqueous coating composition was stored at room temperature for 3 months, but no abnormality was observed.

(Comparative Example 1) -Preparation of composition for aqueous coating composition-A four-necked flask whose inside was replaced with nitrogen gas had a number average molecular weight of about 3700 and an epoxy equivalent of about 2250 g /.
eq of bisphenol A type epoxy resin 960 parts, methacrylic acid 18.4 parts, polyvalent carboxyl group-containing compound solution obtained in Example 1 (solid content 52.1%) 460 parts,
And ethylene glycol monobutyl ether 860
I prepare the part and heat gradually and raise internal temperature to 130 degrees Celsius,
It was stirred for 1 hour and completely dissolved. Then, it was gradually cooled to 110 ° C. After the internal temperature reached 110 ° C., 90 parts of dimethylaminoethanol was added. In addition, 110
The reaction was carried out at 3 ° C. for 3 hours. The acid value (converted to 100% of resin) of the reaction mixture at this time was measured to be 51 KOHmg /
1 g. After that, 3720 parts of ion-exchanged water was gradually added and emulsified using a disperser. At this time,
A milky white dispersion having a solid content of 20% was obtained. Next, the solvent ethylene glycol monobutyl ether was distilled off together with water under reduced pressure, and ion exchange was carried out every time the solid content exceeded 30% until the total amount of the solvent decreased to 2.7 times the solid content. Water was added and the mixture was distilled off under reduced pressure to prepare an aqueous coating composition. The obtained aqueous coating composition had a solid content of 26.8%,
The viscosity was 530 mPa · s, the solvent content was 9% or less, and the average particle size was 0.39 μm. Further, this aqueous coating composition was stored at room temperature for 3 months, but no abnormality was observed.

(Comparative Example 2) -Preparation of water-based coating composition-A four-necked flask whose inside was replaced with nitrogen gas had a number average molecular weight of about 3700 and an epoxy equivalent of about 2250 g /
eq bisphenol A type epoxy resin 360 parts, methacrylic acid 6.9 parts, polyvalent carboxyl group-containing compound solution (solid content 52.1%) 345 parts obtained in Example 1, and ethylene glycol monobutyl ether 375. Charge the parts and gradually heat to raise the internal temperature to 130 ° C. 1
It was stirred for a time to completely dissolve it. Then, it was gradually cooled to 110 ° C. After the internal temperature reached 110 ° C., 74.2 parts of dimethylaminoethanol was added. In addition, 11
The reaction was performed at 0 ° C. for 3 hours. The acid value (converted to 100% of resin) of the reaction mixture at this time was measured to be 92 KOHm.
It was g / 1g. Next, 1100 parts of the aromatic polyol resin solution (solid content 60%) obtained in Example 1 and 100 parts of propylene glycol monomethyl ether were added, and the mixture was stirred for 1 hour while maintaining the temperature to completely dissolve it. To prepare a solution. When this solution was added to the above reaction mixture and kept at 100 ° C. for 30 minutes, the resin solution rolled up in a stirrer and became in a gel state.

Comparative Example 3 Preparation of Aromatic Polyol Resin (E) Solution In a four-necked flask whose inside was replaced with nitrogen gas, a bisphenol A type epoxy resin (number average molecular weight: about 3200,
Epoxy equivalent: about 2700 g / eq) 1000 parts and xylene 200 parts were charged and gradually heated to an internal temperature of 120 ° C.
The mixture was stirred up for 1 hour to completely dissolve it, and then gradually heated to 150 ° C. After the internal temperature reached 150 ° C., 37.4 parts of diisopropylamine was appropriately added over 1 hour, and the reaction was further performed for 6 hours. The reaction mixture is then added to ethylene glycol monobutyl ether 492.6.
Parts were added and dissolved, and then cooled to room temperature,
Epoxy equivalent is 30,000 g / eq or more and solid content is 6
A 0% solution of aromatic polyol resin was obtained. The number average molecular weight of the produced aromatic polyol resin is 3200,
The average number of epoxy groups per molecule was 0.1 or less.

-Preparation of water-based coating composition-In a four-necked flask whose inside was replaced with nitrogen gas, the number average molecular weight was about 3700 and the epoxy equivalent was about 2250 g /
eq bisphenol A type epoxy resin 360 parts, methacrylic acid 6.9 parts, polyvalent carboxyl group-containing compound solution (solid content 52.1%) 345 parts obtained in Example 1, and ethylene glycol monobutyl ether 375. Charge the parts and gradually heat to raise the internal temperature to 130 ° C. 1
Stir for a period of time to completely dissolve. Then, it was gradually cooled to 110 ° C. After the internal temperature reached 110 ° C., 74.2 parts of dimethylaminoethanol was added. In addition, 1
The reaction was carried out at 10 ° C for 3 hours. The acid value (converted to 100% of resin) of the reaction mixture at this time was measured to be 92 KOHm.
It was g / 1g. Next, 420 parts of a bisphenol A type epoxy resin having a number average molecular weight of about 3700 and an epoxy equivalent of about 2250, 400 parts of the aromatic polyol resin solution (solid content 60%) obtained above, and propylene glycol monomethyl ether. A solution was prepared by adding 380 parts of Teru and stirring for 1 hour while maintaining the temperature to completely dissolve it. This solution was added to the above reaction mixture and 10
After holding at 0 ° C. for 1 hour, 3720 parts of ion-exchanged water was gradually added to emulsify using a disperser. At this time, a milky white dispersion liquid having a solid content of 20% was obtained. Then, under reduced pressure, the solvent ethylene glycol monobutyl ether was added.
Tellurium and propylene glycol monomethyl ether were distilled off together with water, and ion-exchanged water was added every time the solid content exceeded 30% until the total amount of the solvent decreased to 2.7 times the solid content, and the pressure was reduced. Then, the aqueous coating composition was prepared. The resulting aqueous coating composition had a solid content of 27.6%,
The viscosity was 720 mPa · s, the solvent content was 9% or less, and the average particle size was 0.35 μm. Further, this aqueous coating composition was stored at room temperature for 3 months, but no abnormality was observed.

[0074]

[0075]

[Table 1]

[0076]

EFFECT OF THE INVENTION The aqueous coating composition of the present invention has excellent stability over time, can cure a coating film at a low temperature, and can be applied to a metal substrate to obtain a cured coating film having excellent adhesion and corrosion resistance. be able to. Therefore, the aqueous paint composition of the present invention is suitable as a main component of an aqueous paint for metal paints.

Claims (7)

[Claims] 1. An aromatic epoxy resin (A-1), a compound (B) containing a monovalent carboxyl group, and a polyvalent carboxyl group-containing compound (C) are chemically bound to each other. Reaction product (D) containing substantially no epoxy group
An aromatic epoxy resin (A-2) and / or an aromatic polyol resin (E) are added to the mixture to obtain a mixture (F), and the mixture (F) is mixed with the basic compound (G) to form a mixture. A composition for water-based paints, which is prepared by blending and self-emulsifying in water. 2. The aromatic epoxy resins (A-1) and (A-2) have an average of 1.1 to 2.0 epoxy groups in one molecule and a number average molecular weight of 700 or more. The composition for water-based paints according to claim 1, which is 3. The amount of the compound (B) containing a monovalent carboxyl group is 0.1 to 0.9 mol% of the epoxy group of the aromatic epoxy resin (A-1). The aqueous coating composition according to claim 1. 4. The polyvalent carboxyl group-containing compound (C)
Has a weight average molecular weight of 3,000 to 50,000 and an acid value of 25 to
The aqueous coating composition according to claim 1, which contains 450, 25% by weight or more of a carboxylic acid unit and 1 to 5% by weight of a hydroxyl group. 5. The aromatic polyol resin (E) has a number average molecular weight of 350 to 40,000 and an average of 0.01 to 4.0 primary hydroxyl groups in one molecule, and substantially has an epoxy group. The aqueous coating composition according to claim 1, which is not contained above. 6. An aromatic epoxy resin (A-1), a compound (B) containing a monovalent carboxyl group, and a compound (C) containing a polyvalent carboxyl group are used as a catalyst for ammonia or amines. In the presence or absence of the reaction temperature 70 ~
At 160 ° C., the equivalent ratio of (B) and (A-1) is 0.2 <
(B) / (A-1) <0.8, and (A-1) and (C)
To a reaction product (D) containing substantially no epoxy group, which is chemically bonded so that the solid content weight ratio of 0.5 <(A-1) / (C) <5. The aromatic epoxy resin (A-2) and / or the aromatic polyol resin (E) is prepared by the following formula: (D) + (E) + (A-2) = 1000 <(E) + ( A-2) ≦ 800 <(A-2) ≦ 80 was prepared by adding a mixture (F) to the mixture so as to have a weight ratio, and the mixture (F) was neutralized with the basic compound (G). Further, a method for producing a composition for water-based coating composition in which the particle size of emulsion particles is 1.0 μm or less and the viscosity is 1000 mPa · s or less by phase inversion emulsification. 7. The mixture ratio of the neutralized mixture (F) and the aqueous medium is such that the weight ratio of the solid resin of (F) / the weight ratio of the aqueous medium is 5/95 to 70/30. A method for producing an aqueous coating composition.