JPH07138523A - Water-base coating composition - Google Patents

Abstract

PURPOSE:To obtain a water-base coating compsn. which is applied to a primed or unprimed metallic material and baked and which is suitable for can interior coating where esp. high processability and corrosion resistance are required. CONSTITUTION:A self-emulsifiable resin is formed by modifying 10-50wt.% arom. epoxy resin having an epoxy equivalent of 900-4,500 with 10-50wt.% carboxylated acrylic polymer. A water-base coating compsn. is obtd. by dispersing the self-emulsifiable resin, 10-60wt.% high-molecular arom. epoxy resin having at least 0.1 epoxy group per molecule and a number average mol.wt. of 9,000 or higher, and 2-20wt.% resole phenol resin or water-base aminoplast resin in water using ammonia or an amine.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aqueous coating composition. More specifically, directly on the metal material or on the base paint,
Particularly, an aqueous coating composition applied to the inner surface of a metal can which requires high workability and corrosion resistance.

[0002]

2. Description of the Related Art Conventionally, metal cans have usually been provided with a thin synthetic resin protective coating in order to prevent metal materials such as tin plate, tin-free steel and aluminum from directly contacting the contents and corroding.

Epoxy-based paints such as epoxy / phenol, epoxy / amino, and epoxy / acryl are usually used as the inner surface paint because of their excellent adhesion, anticorrosiveness and flavor. However, since the above-mentioned paint is based on a thermosetting resin, it has a drawback of poor workability. Therefore, vinyl chloride resin-based organosol paints have been used for the types and applications of which processability is particularly required, although they are based on thermoplastic resins and have the drawback of having many extracted components and poor flavor.

On the other hand, in recent years, epoxy / acrylic water-based paints have begun to be used in view of work hygiene / environmental measures or safety (dangerous substances). As disclosed so far, an epoxy resin is esterified with an acrylic resin containing a carboxyl group, neutralized with a base and dispersed in water (JP-B-59-37026), an acroyl group Aqueous paint obtained by copolymerizing an epoxy resin with an ethylenic monomer containing acrylic acid or methacrylic acid and dispersing in water in the same manner as above (Japanese Patent Publication No. 62-7213).
A water-based paint prepared by grafting a carboxyl group-containing polymerizable monomer mixture onto an epoxy resin using a free radical generator and dispersing it in water in the same manner as above (Japanese Patent Publication No. Sho 63-178).
No. 69 bulletin) etc. These are self-emulsifying epoxy resin-based water-based paints in which the resin itself exhibits dispersibility,
It contained no surfactant for dispersion in water and was excellent in chemical performance and water resistance.

[0005]

However, the above self-emulsifying type epoxy resin-based water-based coating composition needs to contain at least 10% or more of an acrylic resin as an emulsifying component, resulting in poor processability and a small number of reaction points and a crosslinking density. The corrosion resistance was inferior because of low. The present invention is to provide various water-based coating compositions excellent in processability and corrosion resistance, which are various problems of conventional vinyl chloride resin-based organosol coatings and self-emulsifying epoxy resin-based water-based coatings.

[0006]

In order to solve the above problems, the present invention provides a self-emulsifying resin obtained by modifying an aromatic epoxy resin having an epoxy equivalent of 900 to 4500 with a carboxyl group-containing acrylic polymer, Number average molecular weight is 9
There is provided an aqueous coating composition in which an aromatic polymer epoxy resin of 000 or more and a resol-type phenol resin or an aqueous aminoplast resin are aqueous-dispersed using ammonia or amine.

The epoxy equivalent (A) used in the present invention is 90.
Examples of the aromatic epoxy resin of 0 to 4500 include a bisphenol A type epoxy resin and a bisphenol F type epoxy resin, which have 1.1 to 2.0 epoxy groups in one molecule. Among these epoxy resins, bisphenol A type epoxy resin having a number average molecular weight of 1500 to 9000 or bisphenol F
Type epoxy resins are preferred. Commercially available products include "Epicote 1004" and "Epicote 100" manufactured by Shell Chemical Co., Ltd.
7 "," Epicoat 1009 "," Epicoat 1010 "," Epicoat 4009 "," Epicoat 4010 "and" YDF2004 "manufactured by Tohto Kasei Co., Ltd. and the like. One or more of the above epoxy resins can be selected and used. If the epoxy resin content is less than 10% by weight, the adhesion to the metal base is poor, and if it exceeds 50% by weight, the processability is poor and the content is preferably 10 to 50% by weight, more preferably 20 to 45% by weight.

The (A) epoxy resin in the present invention is
Examples of the method (B) for modifying with a carboxyl group-containing acrylic polymer include the above publications (JP-B-59-37026)
62-7213 and JP-B-63-17869) can be applied mutatis mutandis. Specifically, the following method is preferable.

(1) A method of esterifying an epoxy resin with a separately prepared carboxyl group-containing acrylic polymer; the carboxyl group-containing acrylic polymer is acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, etc. A vinyl monomer copolymerizable with one or more carboxyl group-containing vinyl monomers such as, for example, styrene, vinyltoluene, 2-methylstyrene,
Styrenic monomers such as t-butyl styrene and chlorostyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-acrylate
Amyl, isoamyl acrylate, n-hexyl acrylate, n-2 ethylhexyl acrylate, n-acrylate
Acrylic ester type monomers such as octyl, decyl acrylate, dodecyl acrylate; methyl methacrylate,
Ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl methacrylate, n-hexyl methacrylate, n-2 ethylhexyl methacrylate, n-octyl methacrylate, decyl methacrylate. ,
Methacrylic acid ester monomers such as dodecyl methacrylate, lauryl methacrylate; hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxymethyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate; N such as N-methylol (meth) acrylamide and N-butoxymethyl (meth) acrylamide
-One or two of substituted (meth) acrylic monomers
It is obtained by copolymerizing at least one species.

The carboxyl group-containing acrylic polymer is not particularly limited in composition ratio and kind,
Carboxyl group-containing vinyl monomer is 5% by weight or more, especially 30 to 80% by weight of methacrylic acid, and copolymerizable vinyl monomer is 95% by weight or less, especially 20 to 70% of styrene and ethyl acrylate are preferable. Average molecular weight 10,000 ~
200,000 is preferable. The esterification reaction is basically a reaction of a carboxyl group with an epoxy group and / or a hydroxyl group in the acrylic polymer, and an amine-based esterification catalyst can be used. As the amine esterification catalyst,
Examples thereof include dimethylethanolamine, dimethylbenzylamine, ethanolamine, diethanolamine and morpholine.

(2) Epoxy resin, acrylic acid and
(Or) Methacrylic acid is reacted to introduce a (meth) acryloyl group, and then acrylic acid and / or
A method for copolymerizing a vinyl monomer mixture containing methacrylic acid; the reaction ratio of the epoxy resin with acrylic acid and / or methacrylic acid is 1 / 0.1 to 1 / 1.5 (molar ratio)
Is preferred. Specific examples of the vinyl monomer mixture include those described in (1) above, and the composition ratio and type are not particularly limited, but the carboxyl group-containing vinyl monomer is 5% by weight or more, particularly 30 to 80%. Methacrylic acid at 95% by weight, but copolymerizable vinyl monomers at 95% by weight
Below, styrene and ethyl acrylate are particularly preferable at 20 to 70% by weight.

(3) A method of grafting a copolymerizable vinyl monomer mixture containing a carboxyl group-containing vinyl monomer onto an epoxy resin using a free radical generator;
The vinyl monomer mixture is a carboxyl group-containing vinyl monomer alone or a mixture thereof with another vinyl monomer, and specific examples thereof include those described in (1) above. The composition ratio and type of the vinyl monomer mixture are not particularly limited, but 5% by weight or more of the carboxyl group-containing vinyl monomer, particularly 30 to 100% by weight of methacrylic acid, and 95% by weight of the copolymerizable vinyl monomer. Below, styrene and ethyl acrylate are particularly preferable at 0 to 70% by weight.

Among the above methods, (1) the epoxy resin is
A method of esterifying with a separately prepared carboxyl group-containing acrylic polymer, and (2) reacting acrylic acid and / or methacrylic acid with an epoxy resin to introduce a (meth) acryloyl group, and then adding acrylic acid to the group. And / or a method of copolymerizing a vinyl monomer mixture containing methacrylic acid has an ester bond, and since the ester chain length can be increased, the self-emulsifying action is high,
(D) Polymer epoxy resin and (E) Resol-type phenol resin or (F) Aminoplast resin are easily emulsified, which is preferable.

The carboxyl group-containing vinyl monomer and the copolymerizable vinyl monomer and the epoxy resin are 8 / 92-50.
The range of / 50 (weight ratio) is preferable, and when the epoxy resin content is less than 50% by weight, the adhesion to the base material, the corrosion resistance, the workability, etc. are deteriorated. On the other hand, if it exceeds 92% by weight, it becomes difficult to make it aqueous. More preferably, the ratio is 10/90 to 30/70.
(Weight ratio)% is good.

The acrylic polymer-modified epoxy resin shown in the above (1) to (3) is mainly one in which a carboxyl group-containing acrylic polymer is bound, and in the solution, a partially unbound carboxyl group is used. In some cases, the containing acrylic polymer and the epoxy resin coexist.

The polymerization catalyst for vinyl monomers used for modifying the acrylic polymer shown in the above (1) to (3), and the catalyst for grafting the carboxyl group-containing vinyl monomer onto the epoxy resin include, for example, organic peroxides, Perfusates, azobis compounds and redox systems combining these with reducing agents can be used. Specifically, benzoyl peroxide, perbutyl octate, t-butyl hydroperoxide, azobisisobutyronitrile, azobisvaleronitrile, 2,2 ^, -azobis (2
-Aminopropane) hydrochloride, etc.
As a free radical generator as a graft catalyst,
Benzoyl peroxide is particularly preferred. They are,
Generally, it can be used in a proportion of 0.3 to 15 parts by weight based on 100 parts by weight of the reaction components.

The acrylic polymer of (1) above and (1) to (3)
The acrylic polymer reaction shown in (1) is preferably carried out in an organic solvent system, and the organic solvent used is a monomer such as vinyl monomer and its copolymer, (A) epoxy resin and (B) high molecular epoxy. A solvent that dissolves a resin or the like and is easily mixed with water is preferable, and examples thereof include alcohol-based, glycol-based, diglycol-based, and acetate-based solvents. Specifically, n-propanol, isopropal,
n-butyl alcohol, isobutyl alcohol, n-amyl alcohol, amyl alcohol, methyl amyl alcohol, ethylene glycol, diethylene glycol,
1,3-butylene glycol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, methyl propylene glycol, methyl propylene diglycol, propyl propylene glycol, propyl propylene diglycol, butyl propylene glycol, ethylene Examples thereof include glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, 3-methoxybutyl acetate, ethylene glycol monobutyl ether acetate and 3-methyl-3-methoxybutyl acetate. Other solvents can be used,
Those which can be removed under reduced pressure until or after the production of the water-based paint are preferable.

The carboxyl group-containing acrylic polymer (B) is inferior in water dispersibility if it is less than 10% by weight, and if it exceeds 50% by weight, workability is deteriorated. More preferably, it is 10 to 30% by weight.

The average of (D) 1 molecule used in the present invention is 0.
An aromatic polymer epoxy resin having 1 or more epoxy groups and a number average molecular weight of 9000 or more has a resin skeleton similar to that of a bisphenol A type epoxy resin or a bisphenol F type epoxy resin, and in one molecule. It has 0.1 or less epoxy groups and is a very high molecular weight resin having a number average molecular weight of 9,000 or more. As a commercial product, Un
Phenoxy PKHH manufactured by ion Carbide Chem., YP-50A, YP-50S manufactured by Tohto Kasei Co., Ltd. are available. If the amount of the polymer epoxy resin is less than 10% by weight, the processability is poor, and if it exceeds 60% by weight, the water dispersibility is poor, and the content is preferably 10 to 50% by weight, more preferably 30 to 50% by weight.

The ammonia or amine used in the present invention is used for neutralizing the carboxyl group of the carboxyl group-containing acrylic polymer shown in the above (1) to (3). Examples of the amine include trimethylamine, triethylamine, There are alkylamines such as butylamine, alcohol amines such as dimethylaminoethanol, diethanolamine and aminomethylpropanol, and volatile amines such as morpholine.

The (E) resol type phenol resin used in the present invention is a resin obtained by condensing an arbitrary phenol component and formaldehyde in the presence of a basic catalyst. Further, as the phenol component constituting the resol-type phenol resin, o-cresol, p-cresol,
p-tert-butylphenol, p-ethylphenol,
2,3-xylenol, 2,5-xylenol, p-te
Bifunctional phenols such as rt-aminophenol, p-nonylphenol, p-phenylphenol, p-cyclohexylphenol, carboxylic acid, m-cresol, m-
Trifunctional phenols such as ethylphenol, 3,5-xylenol and m-methoxyphenol, monofunctional phenols such as 2,4-xylenol and 2,6-xylenol, bisphenol A: bisphenol B, bisphenol F and the like. Tetrafunctional phenols etc. alone or 2
Combinations of more than one type are used. As a basic catalyst,
For example, ammonia, amine, hydroxide of alkaline earth metal, oxide of alkali metal, oxide of alkaline earth metal and the like can be used. Resol-type phenolic resins with less than 2% by weight have low crosslink density and poor corrosion resistance.
On the other hand, if the amount exceeds 5% by weight, the crosslink density becomes too high and the workability deteriorates. Therefore, 2 to 20% by weight is preferable.

The aqueous aminoplast resin (F) used in the present invention includes any of those which are alkyl-etherified with an alcohol by addition-condensing an arbitrary amino component and formaldehyde in the presence of a basic catalyst.
As the amino component, there are melamine, benzoguanamine, acetoguanamine, urea, spiroguanamine, phthaloguanamine, and the like, and one or a combination of two or more types is used. Examples of the alcohol include methanol, ethanol, isobutanol, n-butanol and the like, and a single kind or a combination of two or more kinds is used. Preferred are melamine or benzoguanamine resins etherified with methanol or ethanol. As commercially available products, Cymel 300 manufactured by Mitsui Cyanamid Co.,
There are 303, 325, 701, 1123, 1170, My Court 101 and the like. If the amount of the aqueous aminoplast resin is less than 2% by weight, the crosslinking density is low and the corrosion resistance is poor, and if it exceeds 20% by weight, the crosslinking density is too high and the processability is lowered.

In the present invention, the resol type phenol resin and the aminoplast resin may be used in combination, and the total amount of the combination is preferably 2 to 20% by weight for the same reason as above.

It is possible to add a solvent, a surfactant or a defoaming agent for improving the coating property to the water-based coating composition of the present invention, if necessary. It is also possible to add a wax, which is a lubricant, to the water-based coating composition of the present invention after forming a coating film to prevent scratches on the coating film during processing and transportation.

As a base material to be applied, a metal plate of a treated or untreated one such as an aluminum plate, a steel plate, a zinc steel plate, a tin plate, etc. is suitable, and an epoxy-based or vinyl-based undercoat is used. Even on the primer,
It may be directly on the metal material. As a coating method, various methods known in this field, such as roll coater coating, spray coating, dip coating, and electrodeposition coating, can be applied, and among them, roll coater coating and spray coating are preferable.
The drying and curing conditions are preferably 150 to 230 ° C for 1 to 30 minutes or 240 to 300 ° C for 15 to 60 seconds.

[0026]

The aqueous coating composition of the present invention comprises (A) 10 to 5 aromatic epoxy resins having an epoxy equivalent of 900 to 4500.
A number average molecular weight of (C) self-emulsifying resin obtained by modifying 0% by weight of (B) a carboxyl group-containing acrylic polymer in an amount of 10 to 50% by weight, and (D) having an average of 0.1 or more epoxy groups per molecule. 10 to 60% by weight of an aromatic polymer epoxy resin having a content of 9000 or more, and (E) a resole type phenol resin or (F) an aqueous aminoplast resin 2
Aqueous dispersion of about 20% with ammonia or amine, which contains an unmodified linear high molecular weight epoxy resin to impart internal plasticity effective processability, epoxy resin skeleton, resol type phenol resin Alternatively, by including the aminoplast resin, the crosslink density is increased, the adhesion to the base is improved, and the corrosion resistance can be imparted.

[0027]

EXAMPLES Next, the present invention will be described more specifically by way of examples. In the examples, "parts" and "%" indicate "parts by weight" and "% by weight", respectively.

Production Example 1 Production of Epoxy Resin (A) (1) Epicoat 1009 (manufactured by Yuka Shell Epoxy Co., Ltd.) 600.0 parts (2) Ethylene glycol monoethyl ether 400.0 parts In a four-necked flask (1)- (2) is charged and 100 under a nitrogen stream.
It was heated to ℃ and completely dissolved to obtain 60% of epoxy resin (A).

Production Example 2 Production of polymer epoxy resin solution (B) (1) Phenoxy PKHH (manufactured by Union Carbide Chem.) 500.0 parts (2) Ethylene glycol monoethyl ether 500.0 parts In a four-necked flask (1)- (2) is charged and 100 under a nitrogen stream.
50% phenoxy resin solution completely dissolved by heating to ℃
I got (B).

Production Example 3 Production of carboxyl group-containing acrylic polymer (C) (1) Styrene 180.0 parts (2) Ethyl acrylate 150.0 parts (3) Methacrylic acid 270.0 parts (4) Benzoyl peroxide 12.0 parts (5) n -Butanol 386.0 parts (6) Benzoyl peroxide 1.0 part (7) Benzoyl peroxide 1.0 part Charge (5) into a 4-necked flask, heat to 100 ° C under a nitrogen stream, and mix (1) to (4). The solution was added dropwise at 100 ° C over 3 hours, 1 hour after the addition of (6), and 1 hour later.
(7) was added, and the mixture was kept at the same temperature for 2 hours to obtain a 60% carboxyl group-containing acrylic polymer solution (C).

Production Example 4 Production of Resol-type Phenolic Resin Solution (D) (1) p-cresol 417.7 parts (2) formalin 40% n-butanol solution 580.1 parts (3) magnesium hydroxide 2.2 parts 4 neck flask ( Charge 1) to (3) and 100 under a nitrogen stream.
After reacting at ℃ for 2.5 hours, neutralized with phosphoric acid, xylene / n-butanol / cyclohexanone = 1/1/1
A large amount of water was added and the mixture was allowed to stand for 5 hours, the aqueous layer containing the produced salt was separated and removed, and further azeotropic dehydration was performed to obtain a 35% resol type phenol resin solution (D).

Production Example 5 Production of aqueous aminoplast resin solution (E) (1) Cymel 1123 350.0 parts (2) Ethylene glycol monoethyl ether 650.0 parts (1) to (2) were charged into a 4-necked flask and a nitrogen stream was introduced. Under 30 ℃
To obtain a 35% aqueous aminoplast resin solution (E).

Example 1 (1) Epoxy resin solution (A) 145.8 parts (2) Carboxyl group-containing acrylic polymer (C) 83.3 parts (3) Dimethylaminoethanol 18.6 parts (4) Polymeric epoxy resin solution (B) 175.0 parts (5) Resol type phenolic resin solution (D) 71.4 parts (6) Dimethylaminoethanol 4.7 parts (7) Ion-exchanged water 501.2 parts (1)-(2) were charged in a 4-necked flask and under a nitrogen stream. Add (3) with stirring to add 8 to the content of carboxyl groups.
After performing 0 mol% neutralization, the internal temperature was raised to 80 ° C., the mixture was stirred at this temperature for 60 minutes, and then cooled to room temperature. The reduction rate of oxirane% was 70%, and the viscosity was also thicker than that before cooking. After cooking, (4) to (5) were added with stirring while cooling to 50 ° C or lower, and after adding (6) and stirring, (7) was added little by little to obtain an aqueous dispersion having a solid content of 25%. .

Examples 2 to 4 Epoxy resin solution (A) and carboxyl group-containing acrylic polymer solution having the formulations shown in Table 1 were prepared in the same manner as in Example 1.
Cooking (C), and further polymer epoxy resin solution (B)
, Resol type phenol resin solution (D) or aqueous aminoplast resin solution (E) and ion-exchanged water were added to obtain an aqueous dispersion having a solid content of 25%.

[0035]

[Table 1]

Example 5 (1) Epoxy resin solution (A) 145.8 parts (2) Methacrylic acid 0.5 part (3) Sodium hydroxide 0.05 part (4) n-Butanol 79.2 parts (5) Styrene 15.0 parts (6) Acrylic Ethyl acid 12.5 parts (7) Methacrylic acid 22.5 parts (8) Benzoyl peroxide 1.5 parts (9) Benzoyl peroxide 0.1 parts (10) Benzoyl peroxide 0.1 parts (11) Polymer epoxy resin solution (B) 175.0 parts (12) ) Resol type phenol resin solution (D) 71.4 parts (13) Dimethylaminoethanol 23.3 parts (14) Ion-exchanged water 453.1 parts (1) to (3) were charged in a 4-neck flask and the internal temperature was 120 to 13
Raise the temperature to 0 ° C and proceed the reaction under a nitrogen stream to obtain an acid value of 0.
When the temperature becomes 2 or less, cool and add (4) at 90 ° C,
The mixture of (5) to (8) was added dropwise over 2 hours with stirring at 90 ° C, and (9) was added 1 hour after the addition.
After 1 hour, (10) was added, and the mixture was stirred for 1 hour while maintaining the same temperature and cooled to 50 ° C. Subsequently, (11) to (13) were added, and (14) was added little by little while stirring to obtain an aqueous dispersion having a solid content of 25%.

Example 6 (1) Epoxy resin solution (A) 104.2 parts (2) Methacrylic acid 0.22 parts (3) Sodium hydroxide 0.04 parts (4) n-Butanol 70.8 parts (5) Styrene 15.0 parts (6) Acrylic Ethyl acid 12.5 parts (7) Methacrylic acid 22.5 parts (8) Benzoyl peroxide 2.5 parts (9) Benzoyl peroxide 0.2 parts (10) Benzoyl peroxide 0.2 parts (11) Polymeric epoxy resin solution (B) 250.0 parts (12) ) Resol type phenol resin solution (D) 35.7 parts (13) Dimethylaminoethanol 23.3 parts (14) Ion-exchanged water 463.8 parts (1) to (3) are charged into a 4-necked flask and the internal temperature is 120 to 13
Raise the temperature to 0 ° C and proceed the reaction under a nitrogen stream to obtain an acid value of 0.
When the temperature becomes 2 or less, cool and add (4) at 90 ° C,
The mixture of (5) to (8) was added dropwise over 2 hours with stirring at 90 ° C, and (9) was added 1 hour after the addition.
After 1 hour, (10) was added, and the mixture was stirred for 1 hour while maintaining the same temperature and cooled to 50 ° C. Subsequently, (11) to (13) were added, and (14) was added little by little while stirring to obtain an aqueous dispersion having a solid content of 25%.

Examples 7 to 9 In the same manner as in Example 5, the epoxy resin solution (A), methacrylic acid and sodium hydroxide having the composition shown in Table 2 were charged and reacted, and then a vinyl monomer and benzoyl peroxide were mixed. Dropping the liquid, followed by polymer epoxy resin solution
(B), resol type phenolic resin solution (D), or aqueous aminoplast resin solution (E), and dimethylaminoethanol are added, and ion-exchanged water is added little by little while stirring to form an aqueous dispersion having a solid content of 25%. Obtained.

[0039]

[Table 2]

Example 10 (1) Epoxy resin solution (A) 145.8 parts (2) n-butanol 79.2 parts (3) Styrene 15.0 parts (4) Ethyl acrylate 12.5 parts (5) Methacrylic acid 22.5 parts (6) Benzoyl Peroxide 3.5 parts (7) Benzoyl peroxide 0.3 parts (8) Benzoyl peroxide 0.3 parts (9) Polymer epoxy resin solution (B) 175.0 parts (10) Resol type phenolic resin solution (D) 71.4 parts (11) Dimethyl Aminoethanol 23.3 parts (12) Ion-exchanged water 451.2 parts A 4-necked flask was charged with (1) to (2), the internal temperature was raised to 120 ° C, and the mixture was stirred under a nitrogen stream (3) to (6). The mixture solution of was added dropwise over 2 hours, and 1 hour after the addition, (7) was added,
After a further 1 hour, (8) was added, and after 1 hour, the mixture was cooled to 50 ° C. After continuously adding (9) to (11), (12) was further added little by little to obtain an aqueous dispersion having a solid content of 25%.

Examples 11 to 13

In the same manner as in Example 10, a mixture of vinyl monomer and benzoyl peroxide was added dropwise to the epoxy resin solution (A) having the composition shown in Table 3 to prepare a polymer epoxy resin solution (B) and a resol-type phenol. The resin solution (D) or the aqueous aminoplast resin solution (E) and dimethylaminoethanol were added, and ion-exchanged water was added little by little to obtain an aqueous dispersion having a solid content of 25%.

[0043]

[Table 3]

Comparative Examples 1 to 6 A water dispersion having a solid content of 25% was prepared in the same manner as in Example 1 except that the formulations shown in Tables 4 to 5 were changed in the same manner as in Example 1 above. Obtained.

[0045]

[Table 4]

[0046]

[Table 5]

Comparative Examples 7 to 8 The same procedure as in Example 5 was repeated, except that the formulation shown in Table 6 was changed to obtain a solid content of 25.
% Aqueous dispersion was obtained.

[0048]

[Table 6]

Comparative Examples 9 to 10 In the same manner as in Example 5 above, except that the formulation shown in Table 7 was changed, the same procedure as in Example 10 was carried out.
% Aqueous dispersion was obtained.

[0050]

[Table 7]

[0051]

[Paint preparation] The organic solvent contained in the aqueous dispersions obtained in the above-mentioned Examples and Comparative Examples was removed under reduced pressure so that the content rate was 15% in the paint at a solid content of 25%. I adjusted it.

[0052]

[Performance test] The storage stability test results of the water-based coating compositions obtained in Examples 1 to 13 and Comparative Examples 1 to 10 were applied on a 0.30 mm aluminum plate with a bar coater so that the thickness was 10 μm.
Tables 8 to 9 show the results of evaluation of various physical properties by baking and drying at 5 ° C for 5 minutes to prepare a test panel.

The various test methods in Tables 8 to 9 are as follows. (1) Storage stability of paint: Stored in a thermostat at 50 ° C and periodically evaluated the appearance and properties. Good storage stability ・ ・ ・ ・ ○ Abnormalities such as gelation, sedimentation, and separation occurred during storage ・ ・ ・ ・ ×

(2) Adhesion: Approximately using a knife on the coating surface
Make a width of 1.5 mm and make 11 cuts in each of the vertical and horizontal directions. The number of unpeeled parts of the crevices when strongly peeled off with a 24 mm width cellophane adhesive tape is shown in the molecule.

(3) Water resistance: Treated in water at 125 ° C. for 40 minutes,
Determine the surface condition of the coating film.

(4) Workability: The coated plate was cut into a size of 40 mm × 50 mm, the coating film was placed outside, and the test site was folded in two so that the test site was 40 mm, and between the two folded test pieces. thickness
After sandwiching two 0.30 mm aluminum plates and dropping a load of 3 kg from the height of 45 cm to the bending part, 6.
The current value of 2 cm width of the processed part was measured after applying 0 V × 10 seconds.

(5) Corrosion resistance: using a knife on the coated surface x
The test piece with the notch is marked at 125 ℃ in 1% saline solution.
Treat for 40 minutes and store at 50 ° C for 1 week, and judge the degree of corrosion near the X mark. No abnormality ・ ・ ・ ・ ○ Mark slightly corroded ・ ・ ・ ・ △ mark Marked corrosion ・ ・ ・ ・ × mark

(6) Flavor: Test piece coating film applied area 1c
Put 1 ml of tap water treated with activated carbon per m ² into a heat-resistant glass bottle filled with the treated water, cover with a lid, sterilize at 125 ° C for 45 minutes, and then use the Hoover of the content liquid.
The change in (flavor) was judged. No change ・ ・ ・ ・ ○ mark Slight change ・ ・ ・ ・ △ mark Significant change ・ ・ ・ ・ × mark

[0059]

[Table 8]

[0060]

[Table 9]

Claims (2)

[Claims] 1. A self-emulsifying method wherein (A) 10 to 50 wt% of an aromatic epoxy resin having an epoxy equivalent of 900 to 4500 is modified with 10 to 50 wt% of a carboxyl group-containing acrylic polymer (B). The number average molecular weight of epoxy resin is (D) having an average of 0.1 or more epoxy groups per molecule of 9000.
The above aromatic polymer epoxy resin 10 to 60% by weight, and (E) resole type phenol resin and / or (F) aqueous aminoplast resin 2 to 20% by weight were aqueous dispersed using ammonia or amine. An aqueous coating composition characterized by the above. 2. The aqueous solution according to claim 1, wherein (C) the self-emulsifying resin has an ester bond of (A) epoxy resin and (B) carboxyl group-containing acrylic polymer. Coating composition.