JPH04342755A - Aqueous resin composition - Google Patents

Abstract

PURPOSE:To provide the subject aqueous resin composition excellent in safety and sanitary qualities, capable of forming a coating film excellent in adhesion, remarkably excellent in processability and suitable for an interior coating of a can. CONSTITUTION:(A) A self-emulsifiable vinyl-modified epoxy resin having an anionic atomic group (e.g. carboxylic group or sulfonic group) is blended with (B) a polyester resin having <=70 deg.C glass transition temperature and >=10000 number-average molecular weight in a weight ratio of (A/B)=(98/2)-(50/50) on solid matter base. (C) A curing agent (e.g. phenolic resin) is further added thereto as necessary.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to a new and useful aqueous resin composition. More specifically, a composite resin composition containing a specific modified epoxy resin and a polyester resin as essential film-forming components is dispersed in an aqueous medium, and is particularly suitable for use as a paint for the inside of cans. ,
The present invention relates to an extremely useful aqueous resin composition that has excellent processability and adhesion, and can form a coating film that does not require repair after processing.

0002

[Prior Art] Until now, metals such as aluminum, tinplate, and tin-free steel have been used as materials for metal cans, but these metals are usually made of cans in order to prevent corrosion. It is used with a coating film formed on the inside and outside surfaces.

[0003] Among these, epoxy/phenol resin, epoxy/acrylic resin, or epoxy/amino resin are usually used as paints for the inside of cans because of their excellent adhesion and anticorrosion properties. ing.

[0004] However, all of these above-mentioned paints have insufficient processability, and the base metal is often exposed during the can manufacturing process. Therefore, the exposed metal parts are repaired after the can manufacturing process, but such repairs complicate the can manufacturing process, so there is a demand for a paint with excellent workability that does not require such repairs.

[0005] As a paint that satisfies these requirements, a vinyl chloride resin-based organosol paint has been developed. The organosol paint has excellent adhesion to metal materials and processability, and is useful as a paint that does not require repair, but because it uses an organic solvent as a dispersion medium, it has many problems in terms of safety and health.

Furthermore, when used as a paint for metal interior surfaces, the epoxidized oil component, which is a plasticizer or stabilizer, is eluted into the contents during the heat sterilization process, which is unfavorable from a food hygiene perspective. Moreover, not only does it have the problem of changing the flavor of the contents, but it also causes whitening of the paint film and poor opening of the easy-open lid (when opening by pulling the opening tongue on the can lid body). , which indicates the degree of remaining coating film on the inner surface of the opening, and the smaller the remaining coating film, the better the opening property.

[0007] Recently, however, the carcinogenicity of vinyl chloride monomers remaining in vinyl chloride resin has been pointed out, and there has been much discussion about the carcinogenicity of vinyl chloride monomers remaining in vinyl chloride resin. In addition, highly toxic or corrosive chlorine gas and hydrogen chloride gas are generated from the resin, causing environmental pollution and corrosion of extinguishing equipment, which has become a serious social problem. ing.

[0008] Therefore, in order to create a paint that avoids the above-mentioned problems, particularly air pollution, deterioration of the working environment, and the risk of fire and explosion, epoxy resin is modified with acrylic resin to create segments with emulsifying power. In the form introduced into the molecule,
Various methods have been proposed in which so-called self-emulsifying epoxy resins are dispersed in water.

For example, JP-A-53-1228 discloses that a vinyl monomer mixture containing a carboxyl group-containing vinyl monomer is polymerized using a free radical generator such as benzoyl peroxide in the presence of an epoxy resin. A method is disclosed in which the resulting grafted epoxy resin is stably dispersed in an aqueous medium.

[0010] In addition, JP-A No. 55-75460 and JP-A No. 56-109243 disclose a method in which an acrylic resin is reacted with an aromatic epoxy resin having an excess of carboxyl groups and a relatively high molecular weight aromatic epoxy resin. A method is disclosed in which a partial reactant of 1 is stably dispersed in an aqueous medium in the presence of ammonia or amines.

Furthermore, JP-A-55-3481 and JP-A-55-3482 disclose a method in which a carboxyl group-containing vinyl polymer is esterified with an epoxy resin in the presence of an amine-based esterification catalyst. , discloses a method in which a carboxyl group-containing vinyl polymer-modified epoxy resin, which is based on this epoxy resin and is substantially free of epoxy groups, is neutralized with a basic substance and dispersed in water.

Furthermore, JP-A-57-105418 and JP-A-58-198513 disclose that an aromatic epoxy resin and (meth)acrylic acid are partially reacted, and each molecule contains epoxy resin. A method is disclosed in which a low-molecular compound having an acryloyl group and a monomer mixture containing (meth)acrylic acid is copolymerized, the copolymer is then neutralized with a basic substance, and then dispersed in water. ing.

However, although all of these various aqueous resin compositions are excellent in terms of food hygiene,
It has poor adhesion and openness of the coating film, and is also poor in processability.

[0014]

[Problem to be Solved by the Invention] In other words, a water-based resin composition that poses fewer safety and health problems and has excellent coating film adhesion, openness, and processability has not yet been found. This is the current situation.

[0015] Therefore, the problem to be solved by the present invention is to provide a water-based resin composition for metal coating that has the adhesion and processability of conventional vinyl chloride resin-based organosol paints and also maintains safety and hygiene properties. In addition, the amount of elution of water-soluble resin components present in the coating film is extremely small, even after heat sterilization, so that it can be used as a container for foods, cosmetics, and pharmaceuticals, etc., and has good food hygiene and The object of the present invention is to obtain an aqueous resin composition for metal coating, which has excellent flavor retention and opening properties.

[0016]

[Means for Solving the Problems] Therefore, in view of the above-mentioned circumstances, the inventors of the present invention have focused their efforts on the problems to be solved by the above-mentioned invention, and as a result, have hereby provided a specific When using a novel composite resin type resin composition that combines a self-emulsifying epoxy resin and a polyester resin, water is used as a dispersion medium, which not only improves safety and hygiene, but also improves adhesion. The present invention was completed by discovering that a revolutionary resin composition for metal coating, which is excellent in all of properties, opening properties, and processability, can be obtained.

That is, the present invention contains a vinyl-modified epoxy resin (A) and a polyester resin (B) each having an anionic atomic group and having self-emulsifying properties as essential film-forming components. An object of the present invention is to provide an aqueous resin composition in which a composite resin composition consisting of the following is dispersed in an aqueous medium.

[0018] Here, the anionic atomic group of the vinyl-modified epoxy resin (A) mentioned above refers to a carboxylic acid group,
It refers to an atomic group consisting of a so-called acid group such as a sulfonic acid group or a phosphoric acid group, and also refers to the resin (A)
Self-emulsifying property refers to the self-emulsifying property of
It refers to the property of being emulsifiable in an aqueous medium.

The epoxy-modified epoxy resin (A) is
As mentioned above, any resin that contains an anionic atomic group and has self-emulsifying properties can be used, but for example, a resin manufactured by the following manufacturing method, Particularly representative are those neutralized with a basic compound as necessary.

(1) Aromatic epoxy resin (a-1
), a method of copolymerizing a mixture of copolymerizable monomers essentially containing a monoethylenically unsaturated carboxylic acid in an organic solvent in the presence of a polymerization initiator,
(2) A carboxyl group-containing resin obtained by copolymerizing an aromatic epoxy resin (a-1) and a copolymerizable monomer mixture that essentially includes a monoethylenically unsaturated carboxylic acid in an organic solvent. A method of esterifying vinyl resin (b-1) in an organic solvent at a reactive group concentration such that carboxyl groups are in excess of epoxy groups, or (3) introducing a (meth)acryloyl group. Copolymerizing the aromatic epoxy resin (a-2) and a copolymerizable monomer mixture essentially containing an ethylenically unsaturated carboxylic acid compound in an organic solvent in the presence of a polymerization initiator. There is a method called.

Of course, modified epoxy resins (A) containing carboxyl groups and having self-emulsifying properties obtained by other methods can also be used. The above-mentioned aromatic epoxy resin (a-1) is limited to particularly representative examples, such as bisphenol A epoxy resin, bisphenol F epoxy resin, novolak epoxy resin, fatty acid-modified epoxy resin, and phenol These include compound-modified epoxy resins.

Among these aromatic epoxy resins, those having 1.1 to 2.0 epoxy groups in one molecule and having a number average molecular weight of 2,000 or more, preferably 3. 000 or more is appropriate.

Commercially available examples include "Epicoat 152, 154, 1007, 1" manufactured by Yuka Shell Epoxy Co., Ltd.
009, 1010 or 1100L"; or "Epicron 7050, manufactured by Dainippon Ink and Chemicals Co., Ltd.
Examples include 9055 or 9155.

[0024] One or more types of aromatic epoxy resins as described above can be selected and used. Particularly representative monoethylenically unsaturated carboxylic acids include (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid.

Monoalkyl esters of monoethylenically unsaturated dicarboxylic acids, such as monomethyl maleate, monoethyl fumarate, or mono-n-butyl itaconate, may also be used in place of the various monoethylenically unsaturated carboxylic acids listed above. , may be used.

Other copolymerizable monomers include methyl (meth)acrylate, ethyl (meth)acrylate, and (meth)acrylate.
Various types such as propyl acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, and octadecyl (meth)acrylate. (meth)acrylic acid esters;

Various monoethylenically unsaturated aromatic monomers (aromatic vinyl monomers) such as styrene, α-methylstyrene, vinyltoluene, chlorostyrene, and 2,4-dibromustyrene; Various monoethylenically unsaturated nitriles (cyano group-containing vinyl monomers) such as (meth)acrylonitrile; various vinyl esters such as vinyl acetate and vinyl propionate; Various vinylidene halides (vinylidene halides) such as;

2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-methacrylate
Various monoethylenically unsaturated carboxylic acid hydroxyalkyl esters (hydroxyl group-containing vinyl monomers) such as hydroxyethyl; Various monoethylenically unsaturated carboxylic acid glycidyl esters such as glycidyl (meth)acrylate (Glycidyl group-containing vinyl monomers);

Alternatively, various (meth)acrylamide derivatives (vinyl monomers containing amino groups) such as (meth)acrylamide, N-methylol (meth)acrylamide, N-butoxymethylacrylamide, and diacetone acrylamide. Compounds capable of radical polymerization are particularly representative examples.

The amount of monoethylenically unsaturated carboxylic acid used in the above method (1) is 20 parts by weight or more and 80 parts by weight or less when the total weight of the copolymerizable monomers is 100 parts by weight. Within the range is appropriate.

As described above, if the amount of monoethylenically unsaturated carboxylic acid used is 20 parts by weight or more, the dispersion stability of the resin in an aqueous medium, the adhesion of the painted film to metal, the solvent resistance, etc. When used for the inner surface of cans, flavor suitability, etc. tends to be good, so it is preferable.

[0032] The aromatic epoxy resin (a-1) or (a-2) in each method (1) or (2) above and the various copolymerizable monomers as listed above. mixture or carboxyl group-containing vinyl resin (b
-1), the solid content weight ratio is 40/60 to 90/10 when the total weight is 100 parts by weight.
The reactive group concentration is preferably within the range where the carboxyl group is in excess of the epoxy group.

When the proportion of the aromatic epoxy resin (a-1) used is 40 to 90 parts by weight, the coating film has excellent adhesion to metal, and the dispersion stability of the resulting resin (A) is low. This is preferable because it tends to improve.

In the method (3) above, the ratio of aromatic epoxy resin (a-1) and (meth)acrylic anhydride used is based on the total weight of 100 parts by weight of solids. Weight ratio: 90/10 to 99.95/
A value within the range of 0.05 is preferred.

The polymerization initiators used in the various reactions described above are not particularly limited, but include common polymerization initiators such as azobisisobutyronitrile and benzoyl peroxide.

The amount of these polymerization initiators used is not particularly limited, but is 0.01 to 2% of the total weight of the copolymerizable monomers.
The content is preferably within a range of 0% by weight. In addition, to exemplify only particularly representative organic solvents, methanol, ethanol, n-propanol,
Including isopropanol, n-butanol, sec-butanol, tert-butanol, isobutanol, methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol or methyl cellosolve acetate, ethyl cellosolve acetate, etc.

Hydrophilic organic solvents such as dioxane, dimethylformamide, and diacetone alcohol; or lipophilic organic solvents such as ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, toluene, and xylene.

These may be used alone or in combination of two or more, and if necessary, water and the various organic solvents listed above may be combined. As the basic compound that can be used to neutralize the anionic atomic groups in the resin (A) obtained by the above methods (1) to (3), both ordinary inorganic bases and organic bases can be used.

Typical inorganic bases include sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.

On the other hand, particularly representative organic bases include ammonia; alkylamines such as trimethylamine, triethylamine, and butylamine; alcohol amines such as dimethylaminoethanol, diethanolamine, and aminomethylpropanol; and morpholine.

[0041] Polyvalent amines such as ethylene diamine and diethylene triamine can also be used. Among these various basic compounds, it is preferable to use ammonia and volatile amines because they do not remain in the coating film and tend to improve water resistance.

The amount of the basic compound used is preferably such that the pH of the dispersing agent is 5 or more.

[0043] As a method for preparing a composite resin composition constituting the composition of the present invention, the composite resin composition contains an anionic atomic group, and
The vinyl-modified epoxy resin (A
) and polyester resins, especially glass transition temperature (Tg
) is 70℃ or less, and the number average molecular weight is 10,000
The above polyester resin (B) is heated and mixed in the presence of an organic solvent, and the vinyl-modified epoxy resin (B) is mixed with heat in the presence of an organic solvent.
At least a part of the anionic atomic groups contained in A),
What is necessary is to neutralize it with a basic compound and disperse it in an aqueous dispersion.

[0044] In this way, by using the emulsifying power of this self-emulsifying vinyl-modified epoxy resin, it becomes possible to easily disperse the polyester resin, which originally has no affinity for water, in water. .

[0045] In the present invention, since a self-emulsifying vinyl-modified epoxy resin (A) is used, the use of an emulsifier is not particularly necessary, but its use is also prohibited if necessary. There is absolutely nothing to do.

The mixing ratio of the vinyl-modified epoxy resin (A) containing an anionic atomic group and having self-emulsifying properties and the polyester resin (B) is as follows:
The solid content weight ratio, where the total weight with B) is 100 parts by weight, is suitably within the range of (A)/(B) = 98/2 to 50/50.

The proportion of the vinyl-modified epoxy resin (A) containing anionic atomic groups and having self-emulsifying properties is (
When the total weight of A) and (B) is 100 parts by weight,
When the amount is within the range of 98 to 50 parts by weight, the coating film of the resulting aqueous resin composition not only has excellent adhesion and corrosion resistance, but also has particularly good retort resistance and food resistance, which are necessary for can paints. It becomes possible to provide a coating film with excellent hygiene properties.

As the above-mentioned polyester resin (B) constituting the composition of the present invention, any resin can be used, regardless of whether it is crystalline or non-crystalline.
It is appropriate to use one in which the temperature is 70°C or less and the number average molecular weight is 10,000 or more.

Typical polybasic acids used in the preparation of the polyester resin (B) include orthophthalic acid, isophthalic acid, terephthalic acid, terpene-phthalic anhydride adduct, and malonic acid. , succinic acid, adipic acid, sebacic acid, azelaic acid, maleic acid, fumaric acid, itaconic acid, 2,3-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, hexahydroterephthalic acid or trimellitic acid. ,

On the other hand, to exemplify only particularly representative polyhydric alcohols, ethylene glycol, propylene glycol, 1,3-butanediol, 1
, 4-butanediol, 1,4-pentanediol, 1
, 5-pentanediol, 1,6-hexanediol,
1,5-hexanediol, neopentyl glycol,
Diethylene glycol, dipropylene glycol, triethylene glycol, polyethylene glycol, 1,4
- cyclohexanedimethanol, p-xylene glycol, α-methylglucoside, glycerin, pentaerythritol, mannitol or sorbitol.

[0051] By using one type or a combination of two or more of various polybasic acids and polyhydric alcohols as listed above, high It can be easily obtained by the method for preparing molecular weight polyesters.

[0052] To exemplify only typical commercial products of the polyester resin (B), "Vylon 30p, 103, 200," manufactured by Toyobo Co., Ltd.
300, 500, GM400 or GM900".

[0053] The term "aqueous medium" as used in the present invention means at least 10% by weight of water, either alone or as a mixture with a hydrophilic organic solvent. Typical hydrophilic organic solvents that can be used in the present invention include methanol, ethanol,
Various alkyl alcohols such as n-propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, isobutanol; methyl cellosolve, ethyl cellosolve, propyl cellosolve,
Various glycol ethers such as butyl cellosolve, hexyl cellosolve, netyl carbitol, ethyl carbitol, butyl carbitol;

Alternatively, various glycol ether esters such as methyl cellosolve acetate and ethyl cellosolve acetate can be used, as well as dioxane, dimethylformamide, tetrahydrofuran, methyl ethyl ketone, and diacetone alcohol.

Note that there is no problem in using a so-called lipophilic organic solvent, if necessary. When it is necessary to reduce the organic solvent contained in the aqueous resin composition of the present invention, when preparing the vinyl-modified epoxy resin (A) containing the above-mentioned anionic atomic group and having self-emulsifying properties, low boiling point, such as acetone, methyl ethyl ketone, n-butanol or butyl cellosolve;
And, using an organic solvent that is azeotropic with water, the resin (A
) and the polyester resin (B) are dispersed in an aqueous medium and then distilled under normal pressure or reduced pressure to stably and easily obtain an aqueous resin composition with a low content of organic solvent. be able to.

The aqueous composition of the present invention further contains a curing agent (
C) may be added, and as such a curing agent, a phenol resin is preferably used.

Typical examples of such phenol resins include various tetrafunctional phenols such as bisphenol A or bisphenol F; carbolic acid (phenol), m-ethylphenol, 3,5 - trifunctional phenols such as xylenol or m-methoxyphenol; or difunctional phenols such as o-cresol, p-cresol, p-tert-butylphenol, p-ethylphenol or 2,3-xylenol and formaldehyde; A particularly typical example is one obtained by reacting these in the presence of an alkali catalyst.

[0058] Furthermore, some or all of the methylol groups contained in the phenolic resin may be substituted with carbon atoms of 1 to 12 carbon atoms.
It is also possible to use a form etherified with a monohydric alcohol.

[0059] The phenol resin is also used as a base resin, such as the above-mentioned self-emulsifying vinyl-modified epoxy resin (
A) and the polyester resin (B) may be blended within a range of 0 to 20% by weight, preferably 1 to 5% by weight, based on the total solid content of both resins, and if it exceeds 20% by weight, If the amount increases, the processability of the coating film will inevitably deteriorate significantly, so either case is not preferable.

[0060] If necessary, a solvent, a surfactant, an antifoaming agent, etc. can be added to the aqueous resin composition of the present invention in order to improve paintability. It is also possible to add wax, which is a lubricant, to the aqueous resin composition of the present invention for the purpose of preventing damage to the coating film during processing.

The aqueous resin composition of the present invention is particularly useful for coating aluminum, tin-plated steel, pretreated metal or steel, but may also be used as a coating for wood and the like.

The most preferred application is to coat the inner surface of metal containers used for food and drink, but the coating film obtained using the aqueous resin composition of the present invention has water resistance and is suitable for coating. There is no elution of low-molecular compounds from the film into the contents of the can, and the coating film is highly impermeable, so if the composition of the present invention is used, the natural taste or flavor of food and drink stored inside the can can be improved. It does not alter the fragrance, and it can also be expected to have excellent effects on processability and opening properties.

Furthermore, the aqueous resin composition of the present invention does not foam even under high-temperature and short-time baking conditions, allows for thick film coating, and has good processability and corrosion resistance. It is also useful as a weld correction paint for welded cans.

[0064] As a coating method for the aqueous resin composition of the present invention, spray coating such as air spray, airless spray or electrostatic spray is preferred, but dipping coating, roll coater coating, electrodeposition coating, etc. are also possible.

[0065] Also, the baking conditions are 120 to 28
The temperature is preferably 10 seconds to 30 minutes at 0°C. The aqueous resin composition of the present invention can be used with a suitable rust inhibitor,
It can also be used in anticorrosive primers, printing inks, anticorrosive paints, etc. by adding pigments or fillers.

In addition to coatings, the coating composition of the present invention can be used in various fields such as adhesives, fiber treatment agents, and binders.

[0067]

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, Comparative Examples, Applied Examples, and Comparative Applied Examples. In the following, all parts and percentages are based on weight unless otherwise specified. Example 1

[Synthesis of modified epoxy resin containing carboxyl group and having self-emulsifying properties] (1) n-butanol
120 copies (2) “Epicote 101
0” 150 parts (3) Methacrylic acid
25 parts (4)
styrene
10 parts (5) Ethyl acrylate
2 parts (6) Benzoyl peroxide 3 parts (7)
n-butanol
(1) and (
2) was added and heated to dissolve.

A uniform mixture of (3) to (7) was gradually added dropwise to this solution over a period of 2 hours while stirring the flask while maintaining the temperature inside the flask at 100°C. After the dropwise addition was completed, the solution was further stirred at the same temperature for 4 hours to obtain a solution of a carboxyl group-containing self-emulsifying epoxy resin with a solid content of 58%. Hereinafter, this will be abbreviated as resin (A-1).

[Water dispersion of carboxyl group-containing modified epoxy resin] (8) 100 parts of the above carboxyl group-containing modified epoxy resin solution (9) “Vylon GM900”
6 parts (10) dimethylethanolamine
4 parts (11) Ion exchange water
260
(8) and (9) were charged into a four-necked flask filled with nitrogen gas, heated to 110° C., and mixed uniformly.

A mixed solution of (10) and (11) was added dropwise thereto over 30 minutes while stirring to obtain an aqueous dispersion of a carboxyl group-containing vinyl-modified epoxy resin containing a polyester resin. .

Next, 130 parts of n-butanol and water were distilled off by azeotropic distillation under reduced pressure to reduce the nonvolatile content to 2.
Contains 5% solvent-free polyester resin.
An aqueous dispersion (A) of a carboxyl group-containing vinyl-modified epoxy resin was obtained.

Next, to 100 parts of this aqueous dispersion (A), 6 parts of hexyl cellosolve and "EP-560" (
Manufactured by Monsanto, partially butyl etherified,
resol type phenolic resin; non-volatile content = 72%).
65 parts of the aqueous resin composition was added to form a paint, thereby obtaining a paint which is one form of the aqueous resin composition of the present invention. Examples 2 and 3 Aqueous dispersions were obtained in the same manner as in Example 1, except that the raw materials shown in Table 1 were used in predetermined proportions, and then made into a paint. Example 4

[Example of preparation of carboxyl group-containing vinyl resin] (a)
n-butanol 67
0 parts (b) Styrene
180 parts (c) Ethyl acrylate 45 parts (d)
Methacrylic acid 225
Part (e) Benzoyl peroxide
First, (a) was charged into a four-necked flask that had been purged with 9 parts nitrogen gas, and heated to 100°C while stirring and dissolving.
A mixed solution of (b) to (e) was gradually added dropwise thereto over a period of 2 hours.

After the addition was completed, stirring was continued for 3 hours at the same temperature to obtain a solution of carboxyl group-containing vinyl resin with a solid content of 40%.

[Synthesis of modified epoxy resin containing a carboxyl group and having self-emulsifying properties] (f) “Epicote 1010”
150 parts (g) 238 parts of the above carboxyl group-containing vinyl resin solution
(h) n-butanol
250 copies (i)
dimethylethanolamine
4 in which 20 parts (f) to (h) were replaced with nitrogen gas
The mixture was charged into a neck flask and stirred at 100°C for 2 hours to completely dissolve it, and then cooled to 80°C.

Next, (i) was added to this solution, and 1
By stirring for a certain period of time, a solution of a carboxyl group-containing vinyl-modified epoxy resin having a solid content of 48% was obtained. Hereinafter, this will be abbreviated as resin (A-2).

[Water dispersion of carboxyl group-containing vinyl-modified epoxy resin] (j) The above carboxyl group-containing vinyl-modified epoxy resin solution


100 copies (k) “Byron 300”
12 parts
(l) Ion exchange water
Charge (j) and (k) into a four-necked flask filled with 256 parts of nitrogen gas,
These were heated to 110°C and mixed uniformly.

Next, while stirring, the mixture was heated for 30 minutes (l
) was added dropwise to obtain an aqueous dispersion of a carboxyl group-containing vinyl-modified epoxy resin containing a polyester resin and having a solid content of 16.3%.

Furthermore, n-butanol and water were distilled off by azeotropic distillation under reduced pressure to obtain a polyester resin-containing carboxyl group-containing vinyl-modified epoxy resin with a nonvolatile content of 25%. An aqueous dispersion was obtained.

[0081] Thereafter, the same procedure as in Example 1 was carried out except that this aqueous dispersion was used, to form a paint, thereby obtaining a paint which is one form of the aqueous resin composition of the present invention.

Examples 5 and 6 Aqueous dispersions were obtained in the same manner as in Example 1, except that the raw materials shown in Table 1 were used in predetermined proportions, and then made into a paint. I forced it.

[0083]

[Table 1]

Comparative Examples 1 and 2 Example 1 and 2 except that the respective vinyl-modified epoxy resins obtained in Examples 1 and 4 were used, and the use of polyester resin was completely omitted. A control aqueous dispersion was obtained in the same manner.

Next, coatings were prepared in the same manner as in Example 1, except that the respective aqueous resin compositions were used to obtain control coatings.

[0086] Obtained in each of the above examples and comparative examples,
Evaluation of each paint was performed in the following manner. The results are summarized in Table 2.

[Evaluation of dispersion stability over time of aqueous resin composition]
Each paint was sealed in a 200 ml glass container and left to stand at room temperature for 20 days, after which the dispersion state of the aqueous resin composition was evaluated according to the following three criteria.

○...Presence of precipitate is not observed at all △...Precipitate is slightly observed ×...Precipitate is very much present

[Creation of painted board for test] Thickness: 0.32m
The weight of the dry coating film is 120 m on an aluminum plate.
Each coating was applied separately using a bar coater so that the coating composition had the following properties: g/dm2, baked in an oven at 260°C for 30 seconds, and then cooled to room temperature to obtain a coated board for testing.

[Evaluation of foaming properties during baking] The surface of each coated test plate obtained as described above was visually observed and evaluated on the following three scales.

○…No foaming occurs △…Small foaming occurs ×…Big foaming occurs on the front side

[Adhesion] Using a cutter, cut 10 squares of 1 x 1 mm into the coating film formed on the test painted board.
After making 0 pieces and pasting adhesive tape on that part, the adhesive tape was rapidly peeled off, and the state of peeling of the coating film was observed and evaluated according to the following three grades.

○…No peeling at all △…1 to 30% of the whole peeled off ×...31 to 100% of the entire area was peeled off

[Workability] The coated test plate was processed into a lid under the conditions that the press temperature was 20°C and the coated plate temperature was 20°C. In order to examine the degree of damage to the paint film after processing, we used an enamellator (current testing machine) on the painted surface of the lid, filled the top of the lid with 1% saline, and used the lid as an anode. A cathode was inserted into the saline solution, and the current value was measured and evaluated according to the following three stages.

○...Current value is less than 0.3mA △...Current value is 0.3 or more and 3mA or less ×...Current value is 3
exceeding mA

[Openability] A lid manufactured in the same manner as in the workability test was boiled at 100°C for 30 minutes, and then the opening tongue was pulled and the inner surface of the opening was opened. The degree of persistence of the coating film was evaluated according to the following three levels.

○...No paint film remains △...A little paint film remains ×...A lot of paint film remains

[Elution test] In 100 ml of purified water, 1
The above test coated plate with an area of 60 cm2 was immersed and boiled at 100°C for 1 hour.The consumption of potassium permanganate in the purified water was measured and evaluated according to the following three levels. .

○...Consumption amount is 5 ppm or less △...Consumption amount exceeds 5 ppm but is 10 ppm or less ×...Consumption amount exceeds 10 ppm

[Flavor test (taste test)] Diameter is 5
A hard glass rod of mm was immersed in each paint obtained in each example and comparative example, pulled out, and after no spontaneous dripping was observed, it was placed in an oven at 260 ° C.
Baking was performed for 30 seconds.

[0101] After taking it out and cooling it, it was immersed in purified water at a rate of 100 ml per 100 cm2 of the coating surface, kept in a tightly stoppered state, boiled for 30 minutes, and then cooled to 20°C.

[0102] As a control test (blank test), the same glass rod was treated in the same way, except that it was baked for 30 seconds in an oven at 260°C without being immersed in the paint. Water was prepared, and the odor and taste of the test water in this case were compared and evaluated on the following three scales.

○...Substantially no difference in both odor and taste △
…Suspicious differences (minor differences) are observed in odor and taste×…Obvious differences (remarkable differences) are observed in odor and taste

[0104]

[Table 2]

[0105]

[Effects of the Invention] The aqueous resin composition of the present invention has the following properties: ■ There is little fear of fire or pollution, and it is excellent in safety and hygiene.
It has excellent paint film adhesion and extremely good processability.Moreover, when used as a paint for the inside of cans, it has very low water extractability from the paint film. , has excellent food hygiene, and ■
The opening properties are also extremely good.

Claims (4)

[Claims] Claim 1: A composite resin composition comprising a vinyl-modified epoxy resin (A) having an anionic atomic group and self-emulsifying properties and a polyester resin (B) is dispersed in an aqueous medium. An aqueous resin dispersion characterized by being obtained. 2. A composite resin composition comprising a vinyl-modified epoxy resin (A) having an anionic atomic group and having self-emulsifying properties, a polyester resin (B), and a curing agent (C), An aqueous resin dispersion characterized in that it is obtained by dispersing it in an aqueous medium. 3. The polyester resin (B) described above is 70%
The aqueous resin composition according to claim 1 or 2, which has a glass transition temperature of .degree. C. or lower and a number average molecular weight of 10,000 or more. 4. The aqueous resin composition according to claim 1 or 2, wherein the curing agent (C) is a phenol resin.