JPH10259230A - Method for producing aqueous dispersion and aqueous coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an aqueous dispersion of an epoxy group-containing resin, which has excellent storage stability and a small particle diameter, which can provide a film having sufficient curability. And an aqueous coating composition obtained by the method. A carboxylic acid-modified epoxy resin obtained by reacting an epoxy resin (A) with a monomer mixture of an unsaturated carboxylic acid monomer and a radical polymerizable unsaturated monomer or a carboxyl group-containing resin (B). A method for producing an aqueous dispersion, wherein (C) is dispersed in an aqueous medium while adjusting the pH to less than 7.0 in the presence of a basic substance, and an aqueous coating composition obtained by the method. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing an aqueous dispersion containing an epoxy group-containing resin which is applied directly to a metal material or applied on an undercoat, and an aqueous coating composition obtained by the method. About.

[0002]

2. Description of the Related Art Various methods for dispersing an epoxy group-containing resin in an aqueous medium and an aqueous dispersion of an epoxy group-containing resin have been proposed. For example, JP-A-8
JP-A-12932 discloses a method in which a compound obtained by reacting a carboxyl group-containing polymer compound with an epoxy resin is neutralized with a base and dispersed in water.
No. 263 discloses that a phenol resin is added to a dispersion obtained by dispersing a partially bound product of an acrylic resin containing a monobasic carboxylic acid monomer as an essential component and an aromatic epoxy resin in an aqueous medium, and the mixture is stabilized. JP-A-8-208803 discloses a method for producing an aqueous dispersion characterized by stirring until a carboxyl group-containing unsaturated monomer is graft-polymerized onto an epoxy group-containing resin. An aqueous resin composition obtained by seed polymerization of a polymerizable unsaturated monomer in the presence of a combined aqueous dispersion is disclosed in JP-A-7-207221, which discloses a carboxyl group-containing self-emulsifying vinyl polymer-modified epoxy resin. Japanese Patent Application Laid-Open No. 6-179851 discloses an aqueous resin composition containing an epoxy resin, a phenoxy resin and a carboxyl group-containing acrylic polymer. The aqueous coating composition using a reaction product with an aqueous aminoplast fat is disclosed.

[0003]

When an epoxy group-containing resin is converted to an aqueous solution, a mixture of the epoxy resin and the carboxylic acid-containing resin is generally mixed with a basic substance which neutralizes the carboxyl group. Disperses in an aqueous medium below,
Before or during the dispersion, the epoxy group in the resin reacts with the carboxyl group or the epoxy group is hydrolyzed. Therefore, the diameter of the resin particles of the obtained dispersion increases, or the number of epoxy groups remaining in the resin decreases. Aqueous dispersions containing particles with large diameters have poor storage stability, and coatings obtained from dispersions containing resins with a small number of epoxy groups have insufficient curability, water resistance, processability, adhesion, and corrosion resistance. Properties and retort properties are not sufficient. An object of the present invention is to produce an aqueous dispersion of an epoxy group-containing resin, which has excellent storage stability and contains resin particles having a small particle diameter capable of providing a film having sufficient curability. It is an object of the present invention to provide a method and an aqueous coating composition obtained by the method.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object. As a result, when the epoxy group-containing resin is dispersed in an aqueous medium, the pH of the dispersion is adjusted to less than 7.0. The present inventors have found that ring opening due to a reaction between an epoxy group and a carboxyl group or a hydrolysis reaction of an epoxy group can be suppressed, and the present invention has been completed.

That is, the present invention relates to (1) an epoxy resin (A)
A carboxylic acid-modified epoxy resin (C) obtained by reacting a monomer mixture of an unsaturated carboxylic acid monomer and a radical polymerizable unsaturated monomer or a carboxyl group-containing resin (B) with a basic substance A method for producing an aqueous dispersion, wherein the aqueous dispersion is dispersed in an aqueous medium while adjusting the pH to less than 7.0 in the presence of the aqueous dispersion; (2) pH of the obtained aqueous dispersion
Is set to 7.0 to 9.0, (3) the epoxy resin (A),
Is a high molecular weight epoxy resin having a number average molecular weight of 10,000 to 50,000 (A1) and / or a low molecular weight epoxy resin having a number average molecular weight of less than 500 to 10,000 (A
The method for producing the aqueous dispersion according to the above (1), which is 2),
(4) The method for producing an aqueous dispersion according to the above (3), wherein the high molecular weight epoxy resin (A1) has an epoxy equivalent of 7,500 to 75,000, (5) the low molecular weight epoxy resin (A
(2) The method for producing an aqueous dispersion according to the above (3), wherein the epoxy equivalent is 250 to 9,000, (6) the aqueous solution according to the above (1), wherein the component (B) has an acid value of 250 to 650. Production method of dispersion, (7) epoxy resin (A) and (B)
The weight ratio of the components [(A) / (B)] is 75/25 to 95 /
5. The method for producing an aqueous dispersion according to the above (1), which is 5.
(8) The method for producing an aqueous dispersion according to the above (1), wherein the aqueous dispersion further contains a phenol resin and / or an amino resin (D); (9) the phenol resin and / or the amino resin (D) is a carboxylic acid The method for producing the aqueous dispersion according to the above (8), wherein the aqueous dispersion is condensed with the modified epoxy resin (C);
(10) The method for producing an aqueous dispersion according to (1), wherein the aqueous dispersion contains a diol having 2 to 4 carbon atoms as a diluent.
(11) The above (1) wherein the diol is a diol having 4 carbon atoms.
0) The method for producing an aqueous dispersion according to the above, and (12) a monomer mixture of an unsaturated carboxylic acid monomer and a radical polymerizable unsaturated monomer or a carboxyl group-containing resin (B) in the epoxy resin (A). The present invention relates to an aqueous coating composition obtained by dispersing a carboxylic acid-modified phenoxy resin (C) obtained by reacting the above with an aqueous medium in the presence of a basic substance while adjusting the pH to less than 7.0.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The epoxy resin (A) used in the present invention is classified into two types, a high molecular weight epoxy resin (A1) and a low molecular weight epoxy resin (A2), and these can be used alone or as a mixture.

The number average molecular weight of the high molecular weight epoxy resin (A1) is from 10,000 to 50,000, preferably from 10,000 to 30,000, more preferably from 1 to 30,000.
2,000-20,000. The number average molecular weight of the high molecular weight epoxy resin (A1) is 10,000 to 50,000
When it is in the range of 0, satisfactory processability and storage stability are obtained.

The epoxy equivalent of the high molecular weight epoxy resin (A1) (the value obtained by dividing the average molecular weight by the number of epoxy groups per molecule: g / equiv.) Is preferably 7.5.
00 to 75,000, more preferably 15,000 to
50,000, most preferably 20,000 to 40,0
00. Epoxy equivalent of 7,500 to 75,000
If so, satisfactory workability and retortability can be obtained.

As the high molecular weight epoxy resin (A1), for example, bisphenol A (4,4'-dihydroxydiphenyl-2,2-propane), bisphenol F (4
4′-dihydroxydiphenylmethane) and condensates obtained by condensing epihalohydrin, β-methylepihalohydrin, etc. with these halogen-substituted products. As such a high molecular weight epoxy resin (A1), a commercially available resin can be used. For example, Epicoat 1255-HX-30 (manufactured by Yuka Shell Epoxy), PKHH, PKHJ, PKHC (manufactured by Phenoxy Associates), phenotote YP-50S, phenotote YP-50, ZX-1356, ZX-139
5, ZX-1449-2, ZX-1449-4 (manufactured by Toto Kasei Co., Ltd.) and the like. These may be used alone or in combination of two or more.

The number average molecular weight of the low molecular weight epoxy resin (A2) is less than 500 to 10,000, preferably less than 3,000 to 10,000. The number average molecular weight of the low molecular weight epoxy resin (A2) is 500 to 10,000
When it is less than the range, satisfactory workability and retortability can be obtained.

The epoxy equivalent of the low molecular weight epoxy resin (A2) is preferably from 250 to 9,000, more preferably from 2,000 to 7,000. When the epoxy equivalent is 250 to 9,000, satisfactory processability and retortability can be obtained.

As the low molecular weight epoxy resin (A2), for example, as in the case of the high molecular weight epoxy resin (A1), those having an epoxy group in the molecule, for example, bisphenol A, bisphenol F, and their halogen-substituted products include epichlorohydrin And condensates obtained by condensing β-methyl epihalohydrin and the like, hydrogenated products of these condensates, polyglycidyl ethers of polyhydric alcohols, and other resins having an epoxy group in the molecule. Further, for example, glycidyl acrylate, glycidyl methacrylate, alicyclic epoxy monomer (for example, Cyclomer M manufactured by Daicel Chemical Industries, Ltd.)
-100, Cyclomer-M-101, etc.) and a radical polymerizable unsaturated monomer having an epoxy group, and a radical polymerizable unsaturated monomer of a monomer mixture (B1) described later. Copolymers and the like obtained from monomers can also be used. Such low molecular weight epoxy resin (A2)
Is commercially available, for example, Epicoat 1
001, 1005, 1007, 1010 (manufactured by Yuka Shell Epoxy), Epotote YD-012, YD-01
4, YD-017, YD-020H, ZX-1373
8 (manufactured by Toto Kasei Co., Ltd.), Denacol EX-212, 30
1, 411 (manufactured by Nagase Kasei) and the like can also be used. These may be used alone or in combination of two or more.

The mixing ratio (weight ratio) of the high molecular weight epoxy resin (A1) and the low molecular weight epoxy resin (A2) is (A1)
/ (A2) = 100/0 to 50/50 is preferable, and 100/0 to 80/20 is more preferable. (A1)
When / (A2) = 100/0 to 50/50, workability is excellent.

[0014] The component (B) for introducing a carboxyl group into the epoxy resin (A) includes a monomer mixture (B1) of an unsaturated carboxylic acid monomer and a radical polymer unsaturated monomer, and Carboxyl group-containing resin (B2)
Is mentioned.

As the unsaturated carboxylic acid monomer which is an essential component of the monomer mixture (B1), for example, acrylic acid,
Monoesters of monocarboxylic acids such as methacrylic acid, maleic acid and itaconic acid or dicarboxylic acids, and monoesters of dicarboxylic acids such as ethyl maleate, butyl maleate, ethyl itaconate and butyl itaconate. Among them, acrylic acid and methacrylic acid are preferred.

As the radical polymerizable unsaturated monomer, a vinyl monomer can be used without any particular limitation. For example, α, β-ethylenically unsaturated aliphatic carboxylic acids such as ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate and 2-ethylhexyl methacrylate Acid alkyl ester monomer; acrylic acid 2
Hydroxyl groups such as -hydroxyethyl, 4-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxyethyl methacrylate, and the reaction product of 2-hydroxyethyl methacrylate with ε-caprolactone Α, β with
An alkyl ester monomer of an ethylenically unsaturated aliphatic carboxylic acid; an amide monomer such as acrylamide, methacrylamide, N-methylol acrylamide, methoxybutyl acrylamide, diacetone acrylamide; an α such as glycidyl acrylate or glycidyl methacrylate; , Β
A glycidyl ester monomer of an ethylenically unsaturated aliphatic carboxylic acid; a vinyl ester monomer of a saturated aliphatic carboxylic acid such as vinyl acetate or vinyl propionate;
Styrene-based monomers such as α-methylstyrene and vinyltoluene are exemplified.

The carboxyl group-containing resin (B2) preferably has a number average molecular weight of 1,000 to 100,000. When the number average molecular weight is in this range, both processability and aqueous dispersion stability are excellent.

Examples of the carboxyl group-containing resin (B2) include a carboxyl group-containing acrylic resin, a carboxyl group-containing polyethylene resin, and a carboxyl group-containing polyester resin. In particular, a carboxyl group-containing acrylic resin is desirable, and a radical polymerizable unsaturated monomer and an unsaturated carboxylic acid monomer exemplified in the monomer mixture (B1) are emulsion-polymerized, solution-polymerized in the presence of a polymerization initiator, Resins obtained by bulk polymerization or the like are preferred.

The acid value of the monomer mixture (B1) and the carboxyl group-containing resin (B2) is preferably from 250 to 65.
0, more preferably 350-600, most preferably 4
60-580. (B) The acid value of the component is 250 to 65.
If it is 0, the aqueous dispersion stability and the storage stability will be improved.

The carboxylic acid-modified epoxy resin (C) is prepared, for example, by adding a monomer of an unsaturated carboxylic acid monomer and a radical polymerizable unsaturated monomer to a solution obtained by dissolving the epoxy resin (A) in an organic solvent. Or a carboxyl group-containing resin (B), and the mixture is heated to a temperature of 40 in the presence of a polymerization initiator.
It is obtained by reacting at ~ 150 ° C for 1-8 hours.

The mixing ratio (A) / (B) of the epoxy resins (A) and (B) is preferably from 75/25 to 5/95 (weight ratio), more preferably from 85/15 to 90/10. is there. When (A) / (B) is in the range of 75/25 to 5/95, satisfactory workability, corrosion resistance, dispersion stability, and storage stability can be obtained.

The organic solvent used for the polymerization is not particularly limited, butanol, isopropanol, ethoxyethanol, ethoxypropanol, methoxypropanol, butoxyethanol, diethylene glycol monobutyl, ethylene glycol, 1,2-butanediol,
Alcohols such as 1,4-butanediol, esters such as butyl acetate and ethyl acetate, hydrocarbons such as toluene and xylene, ethers such as dibutyl ether and ethylene glycol diethyl, ketones such as methyl ethyl ketone and isobutyl methyl ketone And amides such as N-methylpyrrolidone.

The polymerization initiator is not particularly limited either, and organic peroxides such as benzoyl peroxide, di-t-butyl peroxide and t-butyl perbenzoate, azobiscyanovaleric acid,
Organic azo compounds such as azobisisobutyronitrile and the like can be used. The amount of the polymerization initiator depends on the amount of the monomer mixture (B) 10
1 to 15 parts by weight per 0 parts by weight is preferred.

The aqueous coating composition containing the carboxylic acid-modified epoxy resin (C) further comprises a phenolic resin and / or
Alternatively, an amino resin (D) may be included.

Phenolic resin and amino resin (D)
Has a number average molecular weight of preferably from 100 to 5,000. When the number average molecular weight is within this range, retort resistance and dispersibility are improved.

As the phenolic resin (D), for example,
Resol type phenolic resin (phenol, carbon number 1-1)
Reaction products obtained by reacting phenol, bisphenol A, bisphenol F, or the like substituted with an alkyl group 2 with formaldehyde with an alkali catalyst), novolak-type phenol resin (phenol, having 1 to 12 carbon atoms)
Reaction products obtained by reacting phenol, bisphenol A, bisphenol F, or the like substituted with an alkyl group with formaldehyde with an acid catalyst). As such a phenolic resin (D), a commercially available resin can also be used. For example, Shaunol BKM-2620, CKM-908, CKS-39
4, CKS-380, ARL-080 (manufactured by Showa Polymer Co., Ltd.) and the like.

Examples of the amino resin (D) include dimethylolmelamine, trimethylolmelamine, tetramethylolmelamine, pentamethylolmelamine, hexamethylolmelamine, alkyl ether compounds thereof, urea-formaldehyde condensate, and urea-melamine cocondensation. Objects and the like. Commercially available products include:
Cymel 303, 254, 325, 1128, 1156
(American Cyanamid Co., Ltd.), Mycoat 102,
105, 506 (manufactured by American Cyanamid Co.), Uban 20N, 20SB, 128 (manufactured by Mitsui Toatsu), Sumimar M-50W, M-30W (manufactured by Sumitomo Chemical Co., Ltd.) and the like.

The amount of the resin (D) is preferably [resin (D) / carboxylic acid-modified epoxy resin (C)] × 100, less than 15% by weight, more preferably 0.5 to 10% by weight.

When the phenolic resin and / or amino resin (D) is condensed, for example, the phenolic resin and / or amino resin (D) are uniformly mixed with the epoxy resin, and the mixture is mixed at 80 to 200 ° C., preferably at 80 to 200 ° C. 100 ~
The reaction is carried out at 150 ° C. for 30 minutes to 5 hours, preferably 1 to 5 hours.

The addition (condensation) of the phenolic resin and / or the amino resin (D) to the carboxylic acid-modified epoxy resin (C) can be carried out even before the carboxylic acid-modified epoxy resin (C) is made aqueous (dispersed) as described later. It can be done later.

The aqueous dispersion comprises a carboxylic acid-modified epoxy resin (C) having 30 carboxyl groups of the resin (C).
１２５125 mol%, preferably 59-100 mol%, obtained by dispersing in an aqueous medium in the presence of a basic substance necessary for neutralization. Dispersion is performed using a basic substance.

As the basic substance used, an aliphatic amine compound having 6 or less carbon atoms is preferable. Specifically, ammonia, monomethylamine, dimethylamine, trimethylamine, triethylamine, diisopropylamine,
Tributylamine, triethylamine, monoethanolamine, diethanolamine, cyclohexylamine,
Dimethylethanolamine, methylethanolamine,
Examples thereof include amine compounds such as primary amines such as morpholine, N-methylmorpholine and piperidine, secondary amines and tertiary amines, and particularly preferred are amine compounds having a hydroxyl group such as dimethylethanolamine.

The dispersion is carried out while keeping the pH below 7.0, preferably between 4.0 and 6.9. P at dispersion
When H is 7.0 or more, many occurrences of bumps are observed in the aqueous dispersion, and the particle size of the resin increases. Dispersion methods include, for example, a method of gradually adding an aqueous medium in which an appropriate amount of a basic substance is dissolved to a carboxylic acid-modified epoxy resin (C), and a method of dispersing the carboxylic acid-modified epoxy resin in an aqueous medium in which an appropriate amount of a basic substance is dissolved. There is a method of adding (C) gradually. Dispersion can be performed by a commonly used stirrer. The temperature at the time of dispersion is not particularly limited, but is preferably 40 to 1
00 ° C, more preferably 40 to 70 ° C. When the temperature at the time of dispersion is within the above range, the diameter of the resin particles becomes small, which is preferable.

When a sufficiently good aqueous dispersion is obtained, the above-mentioned basic substance is added to the dispersion, and the pH is adjusted to 7.0 to 9.0.
Preferably, a pH of 7.2 to 9.0 increases the stability of the dispersion.

A diol having 2 to 4 carbon atoms may be added to the aqueous dispersion as a diluent. Specific examples of the diluent include, for example, ethylene glycol, diethylene glycol, propylene glycol, butanediol, and the like. Above all, butanediol is preferred from the viewpoint of workability with less occurrence of armpits. The time of adding the diluent is not particularly limited, and may be added to the aqueous dispersion, may be added to the obtained resin before being dispersed in water, or may be added to the aqueous medium. The addition amount is not particularly limited, either, but it is preferable to add the organic solvent content of the aqueous coating composition so as to be 20% by weight or less.

After dispersing the carboxylic acid-modified epoxy resin (C) in an aqueous medium, the aqueous dispersion may be desolvated under reduced pressure and normal pressure to remove the organic solvent in the dispersion. The final organic solvent content of the aqueous dispersion is preferably 20% by weight or less.

The average particle size of the aqueous dispersion is from 100 to 400.
nm is preferred. The acid value is preferably 25 to 100,
More preferably, it is 25 to 65. Acid value 25-100
If so, the dispersibility, storage stability and retort properties are improved. Further, the epoxy equivalent is preferably 3,000 to 5
000, more preferably 5,000 to 30,000
0.

The solid content in the aqueous dispersion is not particularly limited, but is preferably 25 to 40% by weight, more preferably 28 to 35% by weight.

If necessary, a catalyst such as an inorganic acid such as hydrochloric acid or phosphoric acid or an organic acid such as paratoluenesulfonic acid may be added to the aqueous dispersion thus obtained. The addition amount of the catalyst is preferably 1 part by weight or less based on 100 parts by weight of the solid content of the aqueous coating composition.

Further, a pigment, a rust inhibitor, other water-soluble resins, additives and the like are blended in the aqueous dispersion according to the purpose.
It can also be used as a rust preventive primer, rust preventive paint, water-based printing ink, and the like.

The aqueous dispersion thus obtained can be applied to a substrate to form a film. The object to be coated is not particularly limited, and examples thereof include an aluminum plate; a steel plate; a plated steel plate plated with one or more metals such as zinc, chromium, tin, nickel, and aluminum; Steel plates chemically or electrically treated with zinc phosphate or the like; paper, wood, and the like.

The method of applying the aqueous coating composition to the substrate is not particularly limited, and examples thereof include known methods such as spray coating, roll coater coating, electrodeposition coating, dip coating, and brush coating.

As a curing condition of the coating film, drying at room temperature is possible, but forced drying at a temperature range of 80 to 350 ° C. for 10 seconds to 30 minutes is preferable. The thickness of the coating is preferably 5 to 30 μm.

When the aqueous coating composition is used for coating the inner surface of a can, it is usually preferable to apply the composition using a roll coater. Food and beverage cans usually include a three-piece can consisting of a lid part, a cylindrical peripheral part, and a bottom part, and a two-piece can consisting of a lid part and other parts. When the aqueous composition is applied, the lid part and the cylindrical peripheral part of the three-piece can can be applied by a roll coater. In the case of coating the cylindrical peripheral portion, bottom portion, etc. of a two-piece can, spray coating is preferred.

The aqueous coating composition of the present invention can be suitably applied particularly to so-called end materials such as lids of cans. However, it does not apply only to the inner surface of the can,
For example, it can be applied to building materials, home electric appliances, automobile parts, and the like.

According to the method of the present invention, when the carboxylic acid-modified epoxy resin is dispersed in water, the pH of the dispersion is set to less than 7.0, in other words, by setting the dispersion to the acidic side,
It is considered that the decomposition of the epoxy group and the reaction with the acid were suppressed. Therefore, the resin constituting the obtained aqueous dispersion contains many epoxy groups, and the particle size of the dispersion becomes small. Such compositions have good curability without the use of a curing agent, and the resulting coatings therefore exhibit excellent processability, retort properties and corrosion resistance.

[0047]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 255 parts by weight of Epicoat EP-1256 (manufactured by Yuka Shell Epoxy Co., Ltd., high molecular weight epoxy resin, hereinafter the same) was added to a reaction vessel, 77 parts by weight of diethylene glycol monobutyl ether, and methoxypropanol 305.
Parts by weight, and the temperature was gradually increased while stirring.
The phenoxy resin was dissolved at 2 ° C. for 2 hours. Methacrylic acid 21 parts by weight, styrene 12 parts by weight, ethyl acrylate 12 parts by weight, benzoyl peroxide 4 parts by weight, toluene 15
A monomer solution consisting of parts by weight was added dropwise to the solution of the phenoxy resin at 105 to 110 ° C. over 2 hours,
Stirring was continued at 110 ° C. for 3 hours. Reaction solution at 70 ° C
Dimethylethanolamine 10.5 parts by weight,
An aqueous solution consisting of 622 parts by weight of deionized water was added dropwise to the reaction solution at 70 ° C. for 2 hours while stirring to carry out dispersion. Thereafter, stirring was further continued for 1 hour to obtain an aqueous dispersion having a pH of 6.8. To stabilize the dispersion, 10.5 parts by weight of dimethylethanolamine was gradually added, and the solvent and water were removed under reduced pressure. The aqueous coating composition had a nonvolatile content of 35%, a pH of 7.98 and an average particle diameter of 350 nm. I got Table 1 shows the raw materials and amounts of the resins in the composition, the average particle size of the obtained composition, and the solvents used in the reaction. In Table 1, MAA is methacrylic acid, ST is styrene, EA is ethyl acrylate,
BDG is diethylene glycol monobutyl ether, M
P represents methoxypropanol. The obtained aqueous coating composition was treated with 1,2-butanediol (solid content 10% in the composition).
10 parts by weight for 0 parts by weight).
An aluminum plate having a thickness of 12 mm was coated with a bar coater so as to have a dry film thickness of 12 μm, and baked at 250 ° C. for 30 seconds.
A test piece having a length of 5 cm and a width of 10 cm was cut from the baked film. The storage stability of the aqueous coating composition and the retort resistance, workability, and corrosion resistance of the baked film were evaluated by the following test methods. Table 3 shows the results.

Storage Stability of Aqueous Coating Composition Diluted with 10 times the volume of deionized water,
After 30 days, the presence or absence of sedimentation was examined. ：: No sedimentation after 30 days ○: No sedimentation after 20 days, sedimentation after 30 days △: No sedimentation after 10 days, sedimentation after 20 days ×: Sedimentation after 10 days

Ion-exchanged water was placed in a retort-resistant autoclave, and the test piece was
C. for 30 minutes, and the degree of whitening of the film was visually determined. ◎: no whitening ○: slight whitening △: slight whitening ×: considerable whitening

[0051] As shown in workability Figure 1, the coating 3 of the test piece 1 to the outside, the test piece 1 as thick as in the aluminum plate 2 so as to sandwich one specimen 1 (0.3 mm) Was bent, tightened with a bias, and the degree of cracking of the processed portion 4 was determined using a 50-fold loupe. ◎: No cracks ○: Slight cracks △: Slight cracks ×: Significant cracks

Corrosion Resistance A test piece whose back surface was sealed with a polyester tape was immersed in boiling 3% saline to determine the degree of corrosion of the coated surface. ：: No corrosion ○: Slightly corroded △: Slightly corroded ×: Significantly corroded

The average particle diameter was measured by a laser scattering method using a laser light scattering ELS-800 manufactured by Otsuka Electronics Co., Ltd.

Example 2 270 parts by weight of Epicoat EP-1010 (manufactured by Yuka Shell Epoxy Co., Ltd., low molecular weight epoxy resin), 77 parts by weight of diethylene glycol monobutyl ether, and 305 parts by weight of methoxypropanol were charged into a reaction vessel and gradually stirred. And the epoxy resin was dissolved at 110 ° C. for 2 hours. Methacrylic acid 21 parts by weight, styrene 6 parts by weight, ethyl acrylate 3 parts by weight, benzoyl peroxide 4
A monomer solution consisting of 15 parts by weight of toluene and 15 parts by weight of toluene was added dropwise to the epoxy resin solution at 105 to 110 ° C. for 2 hours, and stirring was continued at 105 to 110 ° C. for 3 hours. The reaction solution was cooled to 70 ° C., and an aqueous solution consisting of 10 parts by weight of dimethylethanolamine and 539 parts by weight of deionized water was added dropwise to the reaction solution at 70 ° C. for 2 hours while stirring to carry out dispersion. After that, continue stirring for another 1 hour,
An aqueous dispersion having a pH of 6.88 was obtained. To stabilize the dispersion, 10 parts by weight of dimethylethanolamine was gradually added, and the solvent and water were removed under reduced pressure to obtain a nonvolatile content of 35% and a pH of 8.0.
3. An aqueous coating composition having an average particle diameter of 395 nm was obtained. Table 1 shows the raw materials and amounts of the resins in the composition, the average particle size of the obtained composition, and the solvents used in the reaction. A film was obtained from the obtained aqueous coating composition in the same manner as in Example 1.
In the same manner as in Example 1, the stability of the obtained aqueous coating composition and the retort resistance, workability, and corrosion resistance of the baked film were evaluated. Table 3 shows the results.

Example 3 In a reaction vessel, 282 parts by weight of ZX-1449-4 (manufactured by Toto Kasei Co., Ltd., phenoxy resin), 77 parts by weight of diethylene glycol monobutyl ether, and methoxypropanol 30 were used.
5 parts by weight were charged, and the temperature was gradually increased while stirring.
The phenoxy resin was dissolved at 2 ° C. for 2 hours. A monomer solution consisting of 15 parts by weight of methacrylic acid, 1.5 parts by weight of styrene, 1.5 parts by weight of ethyl acrylate, 2 parts by weight of benzoyl peroxide and 15 parts by weight of toluene was added to a solution of a phenoxy resin at 105 to 110 ° C. for 2 hours. And then add 10
Stirring was continued at 5 to 110 ° C. for 3 hours. Reaction solution 7
After cooling to 0 ° C., an aqueous solution consisting of 7.5 parts by weight of dimethylethanolamine and 625 parts by weight of deionized water was added at 70 ° C.
The mixture was added dropwise to the reaction solution over 2 hours with stirring to perform dispersion.
Thereafter, stirring was further continued for 1 hour to obtain an aqueous dispersion having a pH of 6.82. To stabilize the dispersion, 7 parts by weight of dimethylethanolamine was gradually added, and the solvent and water were removed under reduced pressure. The nonvolatile content was 35%, the pH was 8.10, and the average particle size was 280.
nm aqueous coating composition was obtained. Table 1 shows the raw materials and amounts of the resins in the composition, the average particle size of the obtained composition, and the solvents used in the reaction. A film was obtained from the obtained aqueous coating composition in the same manner as in Example 1. In the same manner as in Example 1, the stability of the obtained aqueous coating composition and the retort resistance, workability, and corrosion resistance of the baked film were evaluated. Table 3 shows the results.

Example 4 Phenotote YP-50S (manufactured by Toto Kasei Co., Ltd.,
Phenoxy resin) 135 parts by weight, ZX-1449-4
135 parts by weight of phenoxy resin (manufactured by Toto Kasei Co., Ltd.), 77 parts by weight of diethylene glycol monobutyl ether, and 305 parts by weight of methoxypropanol were charged, and the temperature was gradually increased while stirring, and the phenoxy resin was dissolved at 110 ° C. for 2 hours. 24 parts by weight of methacrylic acid, 3 parts by weight of styrene,
A monomer solution consisting of 3 parts by weight of ethyl acrylate, 3 parts by weight of benzoyl peroxide, and 15 parts by weight of toluene was dropped into the solution of the phenoxy resin at 105 to 110 ° C. for 2 hours, and further stirred at 105 to 110 ° C. for 3 hours. Continued. Further, 18 parts by weight of Shonor CKS-394 (manufactured by Showa Polymer Co., Ltd., resol type phenol resin) was added to the above reaction solution, and the mixture was reacted at 120 ° C. for 3 hours to precondensate the phenol resin. The reaction solution was cooled to 70 ° C., and an aqueous solution consisting of 12 parts by weight of dimethylethanolamine and 643 parts by weight of deionized water was added dropwise to the reaction solution at 70 ° C. for 2 hours while stirring to carry out dispersion. Thereafter, stirring was further continued for 1 hour to obtain an aqueous dispersion having a pH of 6.88. 13 parts by weight of dimethylethanolamine was gradually added to stabilize the dispersion, and the solvent and water were removed under reduced pressure.
An aqueous coating composition having a pH of 8.03 and an average particle diameter of 203 nm was obtained. Table 1 shows the raw materials and amounts of the resins in the composition, the average particle size of the obtained composition, and the solvents used in the reaction. A film was obtained from the obtained aqueous coating composition in the same manner as in Example 1. In the same manner as in Example 1, the stability of the obtained aqueous coating composition, the retort resistance of the baked film, the workability,
The corrosion resistance was evaluated. Table 3 shows the results.

Example 5 Epotote YD-020H (manufactured by Toto Kasei Co., Ltd.)
270 parts by weight of a low molecular weight epoxy resin), 77 parts by weight of diethylene glycol monobutyl ether, and 305 parts by weight of methoxypropanol were charged, and the temperature was gradually increased while stirring, and the epoxy resin was dissolved at 110 ° C. for 2 hours. 18 parts by weight of methacrylic acid, 6 parts by weight of styrene, 6 parts by weight of ethyl acrylate, 4 parts by weight of benzoyl peroxide,
A monomer solution consisting of 15 parts by weight of toluene is dropped into the solution of the epoxy resin at 105 to 110 ° C. for 2 hours,
Further, stirring was continued at 105 to 110 ° C. for 3 hours. The reaction solution was cooled to 70 ° C., and an aqueous solution consisting of 9.5 parts by weight of dimethylethanolamine and 623 parts by weight of deionized water was added dropwise to the reaction solution at 70 ° C. for 2 hours while stirring to carry out dispersion. Thereafter, stirring was continued for another 1 hour, and
62 aqueous dispersions were obtained. To stabilize the dispersion, 10 parts by weight of dimethylethanolamine was gradually added, and the solvent and water were removed under reduced pressure to obtain an aqueous coating composition having a nonvolatile content of 35%, a pH of 7.88, and an average particle diameter of 367 nm. Table 1 shows the raw materials and amounts of the resins in the composition, the average particle size of the obtained composition, and the solvents used in the reaction. A film was obtained from the obtained aqueous coating composition in the same manner as in Example 1. In the same manner as in Example 1, the stability of the obtained aqueous coating composition and the retort resistance, workability, and corrosion resistance of the baked film were evaluated.
Table 3 shows the results.

Example 6 A phenotote YP-50S (manufactured by Toto Kasei Co., Ltd.,
(Phenoxy resin) 144 parts by weight, ZX-1449-4
96 parts by weight (manufactured by Toto Kasei Co., Ltd., phenoxy resin), 77 parts by weight of diethylene glycol monobutyl ether, and 305 parts by weight of methoxypropanol were charged, and the temperature was gradually increased while stirring, and the phenoxy resin was dissolved at 110 ° C. for 2 hours. 24 parts by weight of methacrylic acid, 18 parts by weight of styrene,
A monomer solution consisting of 18 parts by weight of ethyl acrylate, 6 parts by weight of benzoyl peroxide, and 15 parts by weight of toluene is dropped into the solution of the phenoxy resin at 105 to 110 ° C. for 2 hours, and further stirred at 105 to 110 ° C. for 3 hours. Continued. Further, 18 parts by weight of Shaunol CKS-394 (manufactured by Showa Polymer Co., Ltd., resol type phenol resin) was added to the above reaction solution, and reacted at 120 ° C. for 3 hours to precondensate the phenol resin. The reaction solution was cooled to 70 ° C., and an aqueous solution consisting of 10 parts by weight of dimethylethanolamine and 642 parts by weight of deionized water was added dropwise to the reaction solution at 70 ° C. for 2 hours while stirring to carry out dispersion. Thereafter, stirring was further continued for 1 hour to obtain an aqueous dispersion having a pH of 6.87. To stabilize the dispersion, 9 parts by weight of dimethylethanolamine was gradually added, and the solvent and water were removed under reduced pressure.
H7.89 and an aqueous coating composition having an average particle diameter of 183 nm were obtained. Table 1 shows the raw materials and amounts of the resins in the composition, the average particle size of the obtained composition, and the solvents used in the reaction.
A film was obtained from the obtained aqueous coating composition in the same manner as in Example 1. In the same manner as in Example 1, the stability of the obtained aqueous coating composition and the retort resistance, workability, and corrosion resistance of the baked film were evaluated. Table 3 shows the results.

Example 7 A reaction vessel was charged with 270 parts by weight of Epototo EP-1007 (a low molecular weight epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd.), 77 parts by weight of diethylene glycol monobutyl ether, and 305 parts by weight of methoxypropanol, and gradually stirred. The temperature was raised, and the epoxy resin was dissolved at 110 ° C. for 2 hours. 18 parts by weight of methacrylic acid, 6 parts by weight of styrene, 6 parts by weight of ethyl acrylate, benzoyl peroxide 3
A monomer solution consisting of 15 parts by weight of toluene and 15 parts by weight of toluene was added dropwise to the epoxy resin solution at 105 to 110 ° C. for 2 hours, and stirring was continued at 105 to 110 ° C. for 3 hours. Further, 18 parts by weight of Shaunol CKS-394 (a resol-type phenol resin manufactured by Showa Polymer Co., Ltd.) was mixed. The mixture was cooled to 70 ° C., and an aqueous solution consisting of 9 parts by weight of dimethylethanolamine and 646 parts by weight of deionized water was added dropwise to the reaction solution at 70 ° C. for 2 hours while stirring to carry out dispersion. Then, stirring was continued for another 1 hour,
A water dispersion of 6.88 was obtained. For stabilizing the dispersion, 9 parts by weight of dimethylethanolamine was gradually added, and the solvent and water were removed under reduced pressure to obtain an aqueous coating composition having a nonvolatile content of 35%, a pH of 7.88, and an average particle diameter of 299 nm. Table 1 shows the raw materials and amounts of the resins in the composition, the average particle size of the obtained composition, and the solvents used in the reaction. A film was obtained from the obtained aqueous coating composition in the same manner as in Example 1. In the same manner as in Example 1, the stability of the obtained aqueous coating composition and the retort resistance, workability, and corrosion resistance of the baked film were evaluated.
Table 3 shows the results.

Example 8 In a reaction vessel, 270 parts by weight of ZX-1449-4 (Phenoxy resin, manufactured by Toto Kasei Co., Ltd.), 77 parts by weight of diethylene glycol monobutyl ether, and methoxypropanol 305 were used.
Parts by weight, and the temperature was gradually increased while stirring.
The phenoxy resin was dissolved at 2 ° C. for 2 hours. Methacrylic acid 21 parts by weight, styrene 6 parts by weight, ethyl acrylate 3
1 part by weight of a monomer solution consisting of 3 parts by weight of benzoyl peroxide and 15 parts by weight of toluene in a phenoxy resin solution.
0.5 to 110 ° C., dropwise for 2 hours, and
Stirring was continued at 0 ° C. for 3 hours. Shownor C
6 parts by weight of KS-394 (manufactured by Showa Polymer Co., Ltd., resol type phenol resin) was added to the above reaction solution, and the mixture was reacted at 120 ° C. for 3 hours to precondensate the phenol resin. The reaction solution was cooled to 70 ° C., and an aqueous solution consisting of 11 parts by weight of dimethylethanolamine and 644 parts by weight of deionized water was cooled to 70 ° C.
After dropwise addition to the reaction solution over 2 hours, stirring was continued for another 1 hour to obtain an aqueous dispersion having a pH of 6.87. To stabilize the dispersion, 11 parts by weight of dimethylethanolamine was gradually added, and the solvent and water were removed under reduced pressure.
8.11, an aqueous coating composition containing particles having an average particle diameter of 236 nm was obtained. Table 1 shows the raw materials and amounts of the resins in the composition, the average particle size of the obtained particles, and the solvents used in the reaction. A film was obtained from the obtained aqueous coating composition in the same manner as in Example 1. In the same manner as in Example 1, the stability of the obtained aqueous coating composition and the retort resistance, workability, and corrosion resistance of the baked film were evaluated. Table 3 shows the results.

Example 9 (Synthesis of Epoxy Resin) A reaction vessel was charged with 100 parts by weight of diethylene glycol monobutyl ether and 350 parts by weight of methoxypropanol, and gradually stirred for 110 hours.
The temperature was raised to ° C. A monomer solution consisting of 75 parts by weight of styrene, 75 parts by weight of methyl methacrylate, 75 parts by weight of ethylhexyl acrylate, 51 parts by weight of n-butyl acrylate, 21 parts by weight of glycidyl methacrylate, and 7 parts by weight of t-butyl peroxy-2-ethylhexanate was added to 11
The mixture was added dropwise to the reaction vessel at 0 ° C. for 3 hours, and stirring was further continued to obtain an epoxy resin having a nonvolatile content of 40.2% and a number average molecular weight of 10,000.

(Synthesis of Carboxyl Group-Containing Resin) A reaction vessel was charged with 100 parts by weight of diethylene glycol monobutyl ether and 350 parts by weight of methoxypropanol, and the temperature was gradually raised to 110 ° C. with stirring. Styrene 12
A monomer solution consisting of 0 parts by weight, 60 parts by weight of ethyl acrylate, 120 parts by weight of methacrylic acid, and 7 parts by weight of t-butylperoxy-2-ethylhexanate was heated at 110 ° C. for 3 hours.
The mixture was dropped into the reaction vessel over a period of time, and stirring was further continued to obtain a carboxyl group-containing resin having a nonvolatile content of 40.8% and a number average molecular weight of 12,000.

(Production of Aqueous Dispersion) In a reaction vessel, 559 parts by weight of an epoxy resin and 184 parts by weight of a carboxyl group-containing resin were charged and mixed. The temperature of the mixed solution was raised to 70 ° C.
Dimethylethanolamine 11 parts by weight, deionized water 74
An aqueous solution consisting of 5 parts by weight was added dropwise to the reaction solution at 70 ° C. for 2 hours while stirring to carry out dispersion. Thereafter, stirring was further continued for 1 hour to obtain an aqueous dispersion having a pH of 6.87. To stabilize the dispersion, 15 parts by weight of dimethylethanolamine was gradually added, and the solvent and water were removed under reduced pressure.
%, PH 8.11, and an average particle diameter of 398 nm. Table 1 shows the raw materials and amounts of the resins in the composition, the average particle size of the obtained composition, and the solvents used in the reaction. A film was obtained from the obtained aqueous coating composition in the same manner as in Example 1. In the same manner as in Example 1, the stability of the obtained aqueous coating composition and the retort resistance, workability, and corrosion resistance of the baked film were evaluated. Table 3 shows the results.

Example 10 (Epoxy resin solution) In a reaction vessel, 260 parts by weight of the epoxy resin used in Example 9, 150 parts by weight of ZX-1449-4 (manufactured by Toto Kasei Co., Ltd., phenoxy resin), and 50 parts by weight of diethylene glycol monobutyl ether , 175 parts by weight of methoxypropanol, and gradually stirred while stirring.
The temperature was raised to 0 ° C. to dissolve.

(Synthesis of Carboxyl Group-Containing Resin) A reaction vessel was charged with 100 parts by weight of diethylene glycol monobutyl ether and 350 parts by weight of methoxypropanol, and heated to 110 ° C. while gradually stirring. Styrene 10
A monomer solution consisting of 0 parts by weight, 80 parts by weight of ethyl acrylate, 120 parts by weight of methacrylic acid, and 7 parts by weight of t-butylperoxy-2-ethylhexanate was heated at 110 ° C. for 3 hours.
The mixture was dropped into the reaction vessel over a period of time, and the stirring was further continued to obtain a carboxyl group-containing resin having a nonvolatile content of 40.5% and a number average molecular weight of 12,000.

(Production of Aqueous Dispersion) A reaction vessel was charged with 637 parts by weight of an epoxy resin solution and 111 parts by weight of a carboxyl group-containing resin, and mixed. The mixture was heated to 70 ° C., and 7 parts by weight of dimethylethanolamine and 7 parts of deionized water were added.
An aqueous solution consisting of 45 parts by weight was added dropwise to the reaction solution at 70 ° C. for 2 hours while stirring to carry out dispersion. Thereafter, stirring was further continued for 1 hour to obtain an aqueous dispersion having a pH of 6.77. To stabilize the dispersion, 8 parts by weight of dimethylethanolamine was gradually added, and the solvent and water were removed under reduced pressure.
%, PH 8.22, and an average particle size of 385 nm. Table 1 shows the raw materials and amounts of the resins in the composition, the average particle size of the obtained composition, and the solvents used in the reaction. A film was obtained from the obtained aqueous coating composition in the same manner as in Example 1. In the same manner as in Example 1, the stability of the obtained aqueous coating composition and the retort resistance, workability, and corrosion resistance of the baked film were evaluated. Table 3 shows the results.

Example 11 (Synthesis of Epoxy Resin) A reaction vessel was charged with 100 parts by weight of diethylene glycol monobutyl ether and 350 parts by weight of methoxypropanol, and gradually stirred for 110 hours.
The temperature was raised to ° C. A monomer solution consisting of 75 parts by weight of styrene, 75 parts by weight of methyl methacrylate, 75 parts by weight of ethylhexyl acrylate, 51 parts by weight of n-butyl acrylate, 21 parts by weight of glycidyl methacrylate, and 7 parts by weight of t-butyl peroxy-2-ethylhexanate was added to 11
The mixture was added dropwise to the reaction vessel at 0 ° C. for 3 hours, and stirring was further continued to obtain an epoxy resin having a nonvolatile content of 40.2% and a number average molecular weight of 10,000.

(Synthesis of Carboxyl Group-Containing Resin) A reaction vessel was charged with 100 parts by weight of diethylene glycol monobutyl ether and 350 parts by weight of methoxypropanol, and the temperature was gradually raised to 110 ° C. with stirring. Styrene 12
A monomer solution consisting of 0 parts by weight, 60 parts by weight of ethyl acrylate, 120 parts by weight of methacrylic acid, and 7 parts by weight of t-butylperoxy-2-ethylhexanate was heated at 110 ° C. for 3 hours.
The mixture was dropped into the reaction vessel over a period of time, and stirring was further continued to obtain a carboxyl group-containing resin having a nonvolatile content of 40.8% and a number average molecular weight of 12,000.

(Production of Aqueous Dispersion) In a reaction vessel, 559 parts by weight of an epoxy resin, 184 parts by weight of a carboxyl group-containing resin, and Cymel 235 (manufactured by American Cyanimid Co., Ltd.)
(Melamine resin) 10 parts by weight were charged, and the mixture was heated to 80 ° C. and reacted for 1 hour. The reaction solution was cooled to 60 ° C., and an aqueous solution composed of 11 parts by weight of dimethylethanolamine and 745 parts by weight of deionized water was added dropwise to the reaction solution at 60 ° C. for 2 hours while stirring to carry out dispersion. Then one more
Stirring was continued for an hour to obtain an aqueous dispersion having a pH of 6.77. To stabilize the dispersion, 15 parts by weight of dimethylethanolamine was gradually added, and the solvent and water were removed under reduced pressure to obtain an aqueous coating composition having a nonvolatile content of 35%, a pH of 8.01, and an average particle diameter of 378 nm. Raw material and amount of resin in the composition,
Table 1 shows the average particle size of the obtained composition and the solvent used for the reaction. A film was obtained from the obtained aqueous coating composition in the same manner as in Example 1. In the same manner as in Example 1, the stability of the obtained aqueous coating composition and the retort resistance, workability, and corrosion resistance of the baked film were evaluated. Table 3 shows the results.

Comparative Example 1 A reaction vessel was charged with 270 parts by weight of Epicoat EP-1010 (Epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd.), 77 parts by weight of diethylene glycol monobutyl ether, and 305 parts by weight of methoxypropanol. After heating, the epoxy resin was dissolved at 110 ° C. for 2 hours.
A monomer solution composed of 21 parts by weight of methacrylic acid, 6 parts by weight of styrene, 3 parts by weight of ethyl acrylate, 4 parts by weight of benzoyl peroxide, and 15 parts by weight of toluene was dropped into the epoxy resin solution at 105 to 110 ° C. for 2 hours. One more
Stirring was continued at 05-110 ° C for 3 hours. The reaction solution was cooled to 70 ° C., and after stirring for 2 minutes at 21.7 parts by weight of dimethylethanolamine, an aqueous solution composed of 539 parts by weight of deionized water was added dropwise to the reaction solution at 70 ° C. for 2 hours while stirring, and dispersed. Was. Thereafter, when stirring was continued for another 1 hour, the aqueous dispersion (pH: 8.20) was aggregated and settled. Table 2 shows the raw materials and amounts of the resins in the dispersion and the solvents used in the reaction.

Comparative Example 2 A reaction vessel was charged with 270 parts by weight of Epicoat EP-1010 (epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd.), 77 parts by weight of diethylene glycol monobutyl ether, and 305 parts by weight of methoxypropanol. After heating, the epoxy resin was dissolved at 110 ° C. for 2 hours.
A monomer solution composed of 21 parts by weight of methacrylic acid, 6 parts by weight of styrene, 3 parts by weight of ethyl acrylate, 4 parts by weight of benzoyl peroxide, and 15 parts by weight of toluene was dropped into the epoxy resin solution at 105 to 110 ° C. for 2 hours. One more
Stirring was continued at 05-110 ° C for 3 hours. The reaction solution was cooled to 70 ° C., and an aqueous solution consisting of 21.7 parts by weight of dimethylethanolamine and 539 parts by weight of deionized water was added to 70 parts by weight.
The mixture was added dropwise to the reaction solution with stirring at 2 ° C. for 2 hours to perform dispersion. Thereafter, stirring was further continued for 1 hour to obtain an aqueous dispersion having a pH of 8.58. Further, the solvent and water were removed under reduced pressure to obtain an aqueous coating composition having a nonvolatile content of 35%, a pH of 8.44, and an average particle diameter of 808 nm. Table 2 shows the raw materials and amounts of the resin in the composition, the average particle size of the obtained composition, and the solvent used for the reaction. Example 1 was obtained from the obtained aqueous coating composition.
A coating was obtained in the same manner as described above. In the same manner as in Example 1, the stability of the obtained aqueous coating composition and the retort resistance, workability, and corrosion resistance of the baked film were evaluated. Table 3 shows the results.

Comparative Example 3 Phenotote YP-50S (manufactured by Toto Kasei Co., Ltd.)
Phenoxy resin) 135 parts by weight, ZX-1449-4
135 parts by weight of phenoxy resin (manufactured by Toto Kasei Co., Ltd.), 77 parts by weight of diethylene glycol monobutyl ether, and 305 parts by weight of methoxypropanol were charged, and the temperature was gradually increased while stirring, and the phenoxy resin was dissolved at 110 ° C. for 2 hours. 24 parts by weight of methacrylic acid, 3 parts by weight of styrene,
A monomer solution consisting of 3 parts by weight of ethyl acrylate, 3 parts by weight of benzoyl peroxide, and 15 parts by weight of toluene was dropped into the solution of the phenoxy resin at 105 to 110 ° C. for 2 hours, and further stirred at 105 to 110 ° C. for 3 hours. Continued. Further, 18 parts by weight of CKS-394 (manufactured by Showa Polymer Co., Ltd., resol type phenol resin) was added to the above reaction solution, and the mixture was reacted at 120 ° C. for 3 hours to precondensate the phenol resin. The reaction solution was cooled to 70 ° C., and an aqueous solution consisting of 25 parts by weight of dimethylethanolamine and 1250 parts by weight of deionized water was added dropwise to the reaction solution at 70 ° C. for 2 hours while stirring to carry out dispersion. Thereafter, stirring was further continued for 1 hour to obtain an aqueous dispersion having a pH of 7.85. The solvent and water were removed under reduced pressure to obtain an aqueous coating composition having a nonvolatile content of 35%, a pH of 7.82, and an average particle size of 796 nm. Table 2 shows the raw materials and amounts of the resin in the composition, the average particle size of the obtained composition, and the solvent used for the reaction. A film was obtained from the obtained aqueous coating composition in the same manner as in Example 1. In the same manner as in Example 1, the stability of the obtained aqueous coating composition and the retort resistance, workability, and corrosion resistance of the baked film were evaluated. Table 3 shows the results.

Comparative Example 4 Phenotote YP-50S (manufactured by Toto Kasei Co., Ltd.)
(Phenoxy resin) 210 parts by weight, 77 parts by weight of diethylene glycol monobutyl ether, and 305 parts by weight of methoxypropanol were charged, and the temperature was gradually increased while stirring.
The phenoxy resin was dissolved at 10 ° C. for 2 hours. A monomer solution composed of 45 parts by weight of methacrylic acid, 24 parts by weight of styrene, 21 parts by weight of ethyl acrylate, 7 parts by weight of benzoyl peroxide, and 15 parts by weight of toluene was dropped into the solution of the phenoxy resin at 105 to 110 ° C. for 2 hours. 10 more
Stirring was continued at 5 to 110 ° C. for 3 hours. Furthermore, CK
18 parts by weight of S-394 (manufactured by Showa Polymer Co., Ltd., resol type phenol resin) was added to the above reaction solution, reacted at 120 ° C. for 3 hours, and the phenol resin was precondensed. The reaction solution was cooled to 70 ° C., and an aqueous solution comprising 17 parts by weight of dimethylethanolamine and 1250 parts by weight of deionized water was cooled to 70 ° C.
The mixture was added dropwise to the reaction solution with stirring at 2 ° C. for 2 hours to perform dispersion. Thereafter, stirring was further continued for 1 hour to obtain an aqueous dispersion having a pH of 6.85. To stabilize the dispersion, 25 parts by weight of dimethylethanolamine was gradually added, and the solvent and water were removed under reduced pressure to obtain an aqueous coating composition having a nonvolatile content of 35%, a pH of 7.82, and an average particle diameter of 387 nm. Table 2 shows the raw materials and amounts of the resin in the composition, the average particle size of the obtained composition, and the solvent used for the reaction. A film was obtained from the obtained aqueous coating composition in the same manner as in Example 1. In the same manner as in Example 1, the stability of the obtained aqueous coating composition and the retort resistance, workability, and corrosion resistance of the baked film were evaluated. Table 3 shows the results.

[0074]

[Table 1]

[0075]

[Table 2]

[0076]

[Table 3]

[0077]

According to the method for producing an aqueous dispersion of the present invention, the resin constituting the aqueous dispersion contains many epoxy groups and has a small particle diameter. Therefore, the resulting dispersion has excellent storage stability, and the coating obtained without using a curing agent has good curability, excellent processability,
Shows retort and corrosion resistance. Such an aqueous coating composition can be widely applied to building materials, home appliances, automobile parts, and the like, including so-called end materials such as lids of cans.

[Procedure amendment]

[Submission date] June 26, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Added

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a method for testing the workability of a coating film.

[Description of Signs] 1 Test piece 2 Aluminum plate 3 Coating 4 Processing part

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tamio Iimure 4-1-1-15 Minamishinagawa, Shinagawa-ku, Tokyo Japan Paint Co., Ltd. Tokyo Office

Claims (12)

[Claims] 1. A carboxylic acid-modified epoxy obtained by reacting an epoxy resin (A) with a monomer mixture of an unsaturated carboxylic acid monomer and a radical polymerizable unsaturated monomer or a carboxyl group-containing resin (B). A method for producing an aqueous dispersion, comprising dispersing the resin (C) in an aqueous medium while adjusting the pH to less than 7.0 in the presence of a basic substance. 2. The pH of the obtained aqueous dispersion is adjusted to 7.0 to 7.0.
The method according to claim 1, wherein the aqueous dispersion is 9.0. 3. The epoxy resin (A) has a number average molecular weight of 1
0000 to 50,000 high molecular weight epoxy resin (A
1) and / or a number average molecular weight of 500 to 10,000
2. A low molecular weight epoxy resin (A2) having a molecular weight of less than 0.
A method for producing the aqueous dispersion as described above. 4. The process for producing an aqueous dispersion according to claim 3, wherein the high molecular weight epoxy resin (A1) has an epoxy equivalent of 7,500 to 75,000. 5. The method for producing an aqueous dispersion according to claim 3, wherein the epoxy equivalent of the low molecular weight epoxy resin (A2) is from 250 to 9,000. 6. The method for producing an aqueous dispersion according to claim 1, wherein the acid value of the component (B) is from 250 to 650. 7. The method for producing an aqueous dispersion according to claim 1, wherein the weight ratio [(A) / (B)] of the epoxy resin (A) and the component (B) is 75/25 to 95/5. 8. The method for producing an aqueous dispersion according to claim 1, wherein the aqueous dispersion further contains a phenol resin and / or an amino resin (D). 9. The method for producing an aqueous dispersion according to claim 8, wherein the phenol resin and / or the amino resin (D) is condensed with the carboxylic acid-modified epoxy resin (C). 10. The aqueous dispersion as a diluent has 2 to 2 carbon atoms.
The method for producing an aqueous dispersion according to claim 1, comprising the diol of (4). 11. The method for producing an aqueous dispersion according to claim 10, wherein the diol is a diol having 4 carbon atoms. 12. A carboxylic acid-modified epoxy obtained by reacting an epoxy resin (A) with a monomer mixture of an unsaturated carboxylic acid monomer and a radical polymerizable unsaturated monomer or a carboxyl group-containing resin (B). An aqueous coating composition obtained by dispersing the resin (C) in an aqueous medium while adjusting the pH to less than 7.0 in the presence of a basic substance.