JPH0196263A - Aqueous coating compound composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition capable of forming a coating film having excellent taste retention characteristics and adhesiveness in application to metallic materials, by dispersing a specific reaction product and a phenol- formaldehyde resin of resol type. CONSTITUTION:(A) 100pts.wt. reaction product which is a reaction product of an aromatic epoxy resin and a carboxyl group-containing acrylic resin and is obtained by neutralizing excess carboxyl group in the reaction product with a basic compound and (B) 5-50pts.wt., preferably 10-40pts.wt. phenol- formaldehyde resin of resol type which is obtained by reacting a phenol with an aldehyde and is shown by the formula (R is H or 1-12C alkyl; X is H or methyl; a and b are 0-2 with the proviso that sum of a and b is 0.3-2.0 per bisphenol unit on the average) are dispersed into an aqueous medium to give the aimed composition.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to aqueous coating compositions. More specifically, the present invention relates to an aqueous coating composition that can be applied directly to a metal material or on a base coating to form a coating film with excellent flavor retention, adhesive strength, and the like.

BACKGROUND ART Conventionally, in can paints, epoxy resins, which are materials with excellent corrosion resistance, processability, flavor retention, etc., have been mainly used as binders for solvent-based paints. On the other hand, in water-based paints for cans, it is desired to use epoxy resins as binders because of their excellent properties, and various proposals have been made for the use of epoxy resins. Among these, the paint suitable for the inside of cans is a composition in which an epoxy resin is modified with a high acid value acrylic resin, excess carboxyl groups are neutralized with ammonia or amine, and this is dispersed in water. . For example, in JP-A No. 53-1228@, an acrylic nail material containing a carboxyl group-containing material is graft-polymerized on the main chain of an epoxy resin using a radical-generating catalyst such as benzoyl peroxide, and ammonia, amine, etc. A method of dispersing in water using a basic compound such as is disclosed. Also, JP-A-55-348
No. 1 and Japanese Patent Application Laid-Open No. 55-34828 disclose that a high acid value acrylic resin and an epoxy resin, which have been polymerized in advance using a radical generating catalyst such as benzoyl peroxide, are subjected to an ester addition reaction under an esterification catalyst. A composition is disclosed in which excess carboxyl groups of the adduct are neutralized with a basic compound such as ammonia or amine, and the neutralized product is dispersed in water.

However, since the water-dispersed epoxy resin obtained by the above technology does not cure enough by itself during the drying process of ordinary paint for the inside of cans and has poor adhesion to metal, it is necessary to improve both functions. A combination of amino resin and phenol resin is used as the material.

For example, JP-A No. 61-250023 discloses a combination of an acrylic resin containing a basic carboxylic acid monomer and an aromatic epoxy resin, and a phenol resin containing three or four methylol groups per bisphenol molecule. A dispersion in which a phenolic resin containing a basic carboxylic acid monomer is dispersed in an aqueous medium in the presence of ammonia or an amine is disclosed, and JP-A-61-268764 discloses a dispersion in which a phenolic resin containing a -basic carboxylic acid monomer is dispersed in an aqueous medium in the presence of ammonia or an amine. A precondensate of a resin and an aromatic epoxy resin combined with a phenol resin containing a phenol resin having 3 or 4 methylol groups per molecule of bisphenol is dispersed in an aqueous medium in the presence of ammonia or amine. A dispersion comprising the following is disclosed.

However, the dispersions described in these publications all have insufficient adhesive strength, and therefore cannot be used as water-based paints for cans in applications that require strong adhesive strength, such as adhesive cans. Have difficulty.

Means for Solving the Problems In view of the current situation, the present inventor has developed a coating for the inside of cans that can form a coating film that has excellent adhesive strength and flavor retention, and is also excellent in corrosion resistance, workability, hygiene, etc. As a result of intensive research to develop a water-based coating composition, it was discovered that the intended purpose of the present invention could be achieved by using the following specific resol type phenol formaldehyde resin as an essential component. The present invention was completed based on this knowledge.

That is, according to the present invention, (A> a reaction product of an aromatic epoxy resin and a carboxyl group-containing acrylic resin, in which excess carboxyl groups in the reaction product are neutralized with a basic compound) thing 10
0 parts by weight, and (B) made by reacting phenols and aldehydes, -maximum % formula % [wherein R is a hydrogen atom or an alkyl group having 1 to 12 carbon atoms,
X represents a hydrogen atom or a methyl group.

a and b each represent O or an integer of 2 or less. However, a
The sum of and b is on average 0 per unit of bisphenol.
．． It shall be within the range of 3 to 2.0. ] There is provided an aqueous coating composition comprising 5 to 50 parts by weight of a resol type phenol-formaldehyde resin represented by the following formula dispersed in an aqueous medium.

In the present invention, component (A>) is a reaction product of an aromatic epoxy resin and a carboxyl group-containing acrylic resin.

Aromatic epoxy resins include, for example, epichlorohydrin and bisphenol condensed to a high molecular weight in the presence of an alkali catalyst, and epichlorohydrin and bisphenol condensed to a low molecular weight epoxy resin in the presence of an alkali catalyst. In addition to those obtained by polyaddition reaction of molecular weight epoxy resin and bisphenol, epoxy ester resins combined with dibasic acids may be used. Here, as the dibasic acid, -maximum % formula % [wherein n represents an integer of 1 to 12]. ] Compounds represented by these are preferably used, and specific examples thereof include succinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, dodecanniic acid, and hexahydrophthalic acid.

As bisphenol, bisphenol A and bisphenol F are preferably used, and a mixture of both may be used.

As a specific example of such an epoxy resin, for example, Epicoat 1004 manufactured by Shell Chemical Co., Ltd.
Number average molecular weight: 1400>, Epicote 1007 (epoxy equivalent: 1700, number average molecular weight: 2900>)
Examples include Epicote 1009 (epoxy equivalent: 3,500, number average molecular weight: 3,750), Epicoat 1010 (epoxy equivalent: 4,500°, number average molecular weight: 5,500).

The number of epoxy groups per molecule of the epoxy resin is not particularly limited, and is appropriately selected depending on the reaction form with the carboxyl group-containing acrylic resin described below. That is,
When the reaction type is an ester reaction, the number of epoxy groups per molecule of the epoxy resin is preferably 0.5 to 2 on average, preferably 0.5 to 1.6. Further, when the reaction form is a graft reaction of an acrylic monomer containing a carboxyl group-containing acrylic monomer by hydrogenation of the epoxy resin main chain, there may be substantially no epoxy group in the epoxy resin.

Further, the number average molecular weight of the above epoxy resin is usually 140.
It is about 0 to 8000, preferably about 2900 to 7000. When the number average molecular weight of the epoxy resin is less than 1400, low molecular weight components originating from the epoxy resin tend to be eluted into the contents of the can during the sterilization process, which is unfavorable from a sanitary standpoint. Conversely, if the number average molecular weight of the epoxy resin is greater than aooo, the viscosity will become too high during reaction with the acrylic resin, making stable emulsification difficult.

As the carboxyl group-containing acrylic resin, the following (a
At least one carboxyl group-containing radically polymerizable unsaturated monomer such as group (b) or, if necessary, a radically polymerizable unsaturated monomer such as group (b) which can be copolymerized with this. The resulting acrylic resin can be exemplified.

(a) α, β-ethylenically inert saturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid, etc. b) ■ 2-Hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxy Hydroxyalkyl esters of acrylic acid or methacrylic acid having 1 to 8 carbon atoms such as propyl acrylate, hydroxypropyl methacrylate, etc.; Methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate , isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, Alkyl or cycloalkyl esters of acrylic acid or methacrylic acid having 1 to 24 carbon atoms, such as stearyl methacrylate, decyl acrylate, etc.; ■Acrylamide, methacrylamide, N-methylacrylamide, N-ethylmethacrylamide, diacetone acrylamide , N-
Functional acrylic or methacrylamide such as methylol acrylamide, N-methylol methacrylamide, N-methoxymethyl acrylamide, N-1 toxymethyl acrylamide, etc.: ■ Styrene, vinyl toluene, vinyl propionate, α
- Vinyl monomers such as methylstyrene, vinyl acetate, acrylonitrile, methacrylate trile, vinyl propionate, vinyl pivalate, beoba monomer (manufactured by Shell Chemical Co., Ltd.); Examples of preferred combinations of the above unsaturated monomers include:
For example, (a) methyl methacrylate/2-ethylhexyl acrylate/acrylic acid, (b) styrene/methyl methacrylate/ethyl acrylate/methacrylic acid, (c) styrene/ethyl acrylate/methacrylic acid, (d) methacrylic acid. Examples include methyl/ethyl acrylate/acrylic acid.

The preparation of these carboxyl group-containing acrylic resins is as follows:
For example, the unsaturated monomers described above can be easily polymerized by solution polymerization in the presence of a radical polymerization initiator.

The number average molecular weight of the carboxyl group-containing acrylic resin is usually about 5,000 to 100,000, and the acid value is usually about 50 to 500 based on the resin solid content.

The reaction product of the aromatic epoxy resin and the carboxyl group-containing acrylic resin can be produced, for example, by the method shown below.

(I> An aromatic epoxy resin and a carboxyl group-containing acrylic resin are subjected to an ester addition reaction in an organic solvent solution in the presence of a tertiary amine.

(n) Graft polymerizing the radically polymerizable unsaturated monomer onto an aromatic epoxy resin in an organic solvent solution in the presence of a radical generator such as benzoyl peroxide.

The intermittent solvent used in the above ester addition reaction and graft polymerization reaction is used to dissolve aromatic epoxy resins and carboxyl group-containing acrylic resins, and to dilute the carboxylic acid salts of these resins with water. Any conventionally known organic solvent can be used as long as it is an organic solvent that is miscible with water and does not interfere with the formation of an emulsion. These organic solvents are, for example, the following - Maximum % formula % (3) [In the above formula, R1 is an alkyl group having 1 to 12 carbon atoms, R2 is an alkyl group having 1 to 6 carbon atoms, and ■ is an alkyl group having 1 to 6 carbon atoms. Indicates an integer from 1 to 6. ]Alcoholic solvents,
Examples include cellosolve-based solvents and carpitol-based solvents. More specifically, such organic solvents include isopropanol, butyl alcohol, 2-hydroxy-4-methylpentane, 2-ethylhexyl alcohol, cyclohexanol, ethylene glycol, diethylene glycol, 1,3-butylene glycol, and ethylene. Examples include glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, and the like. In addition, inert organic solvents other than those mentioned above that do not mix with water can also be used, and examples of such organic solvents include aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and butyl acetate, acetone, Examples include ketones such as methyl ethyl ketone. Further, these organic solvents are desirably those that can be removed by distillation under normal pressure or reduced pressure after the above-mentioned ester addition reaction and graft polymerization reaction.

The tertiary amine used in the above ester addition reaction is -maximum % formula % (6) (wherein R3 and R4 are substituted or unsubstituted monovalent alkyl containing 1 or 2 carbon atoms in the alkyl moiety). The group, R
5 represents a monovalent alkyl group in which the alkyl moiety is substituted or unsubstituted with 1 to 4 carbon atoms. ), N-methylpyrrolidine, N-methylmorpholine, pyridine, N-methylvirol, N-methylpiperidine, etc., which may be used singly or in combination.
Used as a mixture of more than one species.

Specific examples of the amine represented by maximum (6) above include:
Triethylamine, dimethylethanolamine (dimethylaminoethanol), methyljetanolamine, ethylmethylethanolamine, dimethylethylamine,
dimethylpropylamine, dimethyl-3-hydroxy-
Examples include 1-propylamine, dimethylbenzylamine, dimethyl-2-hydroxy-1-propylamine, diethylmethylamine, dimethyl-1-hydroxy-2-propylamine, and the like. Among these, trimethylamine and dimethylethanolamine are particularly preferred.

In the above ester addition reaction, the solid content concentration of the aromatic epoxy resin and carboxyl group-containing acrylic resin used is not particularly limited, and is preferably within a range that provides the optimum viscosity of these resins. Further, the tertiary amine is preferably used in an amount of usually 0.1 to 1 equivalent relative to the epoxy group of the aromatic epoxy resin.

The above ester addition reaction can be carried out by a conventionally known method. For example, after uniformly mixing an organic solvent solution of an aromatic epoxy resin and an organic solvent solution of a carboxyl group-containing acrylic resin, The reaction is preferably carried out in the presence of an aqueous solution at a reaction temperature of usually 60 DEG to 130 DEG C. for about 1 to 6 hours until the epoxy groups are substantially consumed.

In the above graft polymerization reaction, there is no particular restriction on the ratio of the aromatic epoxy resin and the radically polymerizable unsaturated monomer used, but usually the former: the latter = 95 to 70 weight percent: 5 weight range 0 weight It is better to set it as %. In this case, the carboxyl group-containing radically polymerizable unsaturated monomer is preferably used in an amount of 20 to 80 ffiffi% of the total radically polymerizable monomers. The radical generator is preferably used in an amount of usually 3 to 15% by weight based on the radically polymerizable unsaturated monomer.

The above-mentioned graft polymerization reaction can be carried out by a conventionally known method, for example, by uniformly mixing a radical generator into an organic solvent solution of an aromatic epoxy resin heated to 80 to 150°C. The polymer may be added over a period of 1 to 3 hours, and the same temperature may be maintained for another 1 to 3 hours.

In the present invention, the reactant used as the component (A>) is a reactant of the aromatic epoxy resin and the carboxyl group-containing acrylic resin, and the excess carboxyl group in the reactant is removed with a basic compound. It has been neutralized.

As the basic compound used to neutralize the carboxyl group, a wide variety of conventionally known basic compounds can be used as long as it is normally used for neutralizing carboxyl groups, such as any primary amine, secondary amine, Tertiary amine, monofunctional quaternary
Examples include grade ammonium salts. More specifically, methylamine, ethylamine, n-propylamine, isopropylamine, n-hexylamine, monoethanolamine, propatoolamine, benzylamine, dimethylamine, dibutylamine, dibutylamine, methylethanolamine, jetanol. Amine, triethylamine, diethylethanolamine, dimethylcyclohexylamine, triethanolamine, tributylamine,
Dimethyl n-butylamine, tripropylamine, γ-
These include picoline, tetrahexylammonium hydroxide, and the like. The amount of such a neutralizing agent to be used is preferably 0.1 to 2 neutralization equivalents based on the carboxyl group in the reactant. The treatment with the neutralizing agent can also be carried out by conventionally known methods.

In the present invention, the resol-type phenol-formaldehyde resin used as component (B) is made by reacting phenols and aldehydes, and is formed by reacting phenols with aldehydes, wherein R, X, a, and b are the same as above. ].

In the present invention, the sum of a and b in the above-mentioned maximum (1) is on average 0.3 to 2.0 per unit of bisphenol.
It is essential that it be within the range of 0. When the sum of a and b is less than 0.3 on average per unit of bisphenol, the amount of the phenol resin component that does not substantially have a methylol group increases, so that the phenol resin component is removed from the contents of the can during the sterilization process. It can be eluted into substances, causing unfavorable hygiene conditions. On the other hand, if the sum of a and b exceeds 2.0 on average per unit of bisphenol, the internal stress of the coating will increase, resulting in a tendency for the adhesive strength to decrease, which will impede the intended purpose of the present invention. becomes difficult to achieve. In the present invention, it is particularly desirable that the sum of a and b be within the range of 0.5 to 1.5 on average per unit of bisphenol. In addition, the number of methylol groups is NMR18PLC1GCMAS
It can be easily obtained from S etc.

The resol type phenol-formaldehyde resin (hereinafter simply referred to as "phenol resin") used as component (B) in the present invention is, for example, reacted with phenols in a known reaction medium, preferably an aqueous medium, in the presence of a basic catalyst. Manufactured by reacting with formaldehyde. Examples of phenols include bisphenol A1
Bisphenols such as bisphenol F, phenol,
Trifunctional phenols such as 3,5-xylenol can be mentioned. In addition to the above bisphenols and trifunctional mononuclear phenols, p-cresol, p-tert-
Trifunctional mononuclear phenols such as butylphenol and 2,3-xylenol can also be used in combination. Further, examples of aldehydes include formalin, paraformaldehyde, and Formit E3-IB-M manufactured by Hirome Chemical Co., Ltd. Among these, formalin is preferred. The ratio of phenols and aldehydes used is usually about 0.3 to 2.5 mol, preferably 0.5 to 2.0 mol of the latter per 1 mol of the former.
It is preferable to set it to about mol. As the basic catalyst, any of the basic catalysts conventionally used in the production of resol-type phenol-formaldehyde resins can be used, but in order to obtain a phenol resin that can exhibit the desired effects of the present invention, it is necessary to use an alkaline catalyst. Preference is given to using metal hydroxides, alkaline earth metal hydroxides or amines as catalysts.

Specific examples of basic catalysts include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide, etc., and alkaline earth metal hydroxides such as magnesium hydroxide, barium hydroxide, etc. The amines include triethylamine and the like. The amount of basic catalyst that should be present in the reaction medium is
In the case of alkali metal hydroxides, phenol 1
About 0.01 to 1.0 mol, preferably 0.01 to 1.0 mol.
In the case of alkaline earth metal hydroxides, the amount is usually about 0.01 to 2.0 mol, preferably 0.05 to 1.0 mol, per 1 mol of phenol.
It is best to set it to about 0 mol, and in the case of amines,
Usually, the amount is about 0.01 to 0.5 mol, preferably about 0.05 to 0.1 mol, per 1 mol of phenol.

Conditions for the reaction between phenols and aldehydes are not particularly limited and can be appropriately selected from a wide range, but generally 50 to 90°C, preferably 60 to 70°C.
C. for about 1 to 8 hours, preferably about 2 to 3 hours.

The phenolic resin thus produced is isolated and purified from the reaction mixture by means known per se.

The aqueous coating composition of the present invention is obtained by dispersing the above (A> component and (B) component) in an aqueous medium. (A>
The mixing ratio of component and component (B) is usually 10% of the former.
5 to 50 parts by weight, preferably 1 part by weight of the latter per 0 parts by weight
The amount is preferably 0 to 40 parts by weight. If the amount of component (B) is less than 5 parts by weight, the hardness of the coating film formed from the composition will not be sufficient, and corrosion resistance, water resistance, and gel fraction will tend to decrease, and the adhesive strength will improve. The effect is not as expected. On the other hand, if the amount of component (B) exceeds 50 parts by weight, the hardness of the coating film becomes too high, resulting in a decrease in adhesive strength and workability, and also tends to be poor in hygiene. Components (A) and (B) are preferably blended so that the resin solid content in the composition of the present invention is typically in the range of 15 to 40%.

The water-based paint composition of the present invention has a swelling value determined by the following formula (2) when the water-based paint composition is baked and dried, the paint film is peeled off, and the film is immersed in cyclohexanone at 30°C for 4 days. rate of 20-200%, preferably 40-16
It is desirable that it be 0%.

k= (W2 Wl)X100/W+ (2)
[Here, k is the cyclohexanone swelling ratio, Wl is the weight of the coating before dipping, and W2 is the weight of the coating after dipping. ] If the swelling ratio is less than 20% or more than 200%, it becomes difficult to obtain sufficient adhesive strength. Although the reason for this is not clear, it is thought that in order to maintain strong adhesive strength, the hardness of the coating film must be within an appropriate range.

In addition, in the present invention, there is a correlation between the swelling rate and the amount of phenol resin blended, and between the swelling rate and the total number of a and b in general formula (1), for example, the amount of phenol resin blended is larger. The larger the total number of a and b is, the smaller the swelling ratio becomes.

The aqueous coating composition of the present invention may further contain a solvent, but from the viewpoint of environmental pollution, it is desirable that the amount of the solvent is 5% by weight or less.

Furthermore, the composition of the present invention may appropriately contain commonly used additives such as anti-agglomeration agents, flow control agents, pigments, etc., if necessary.

The aqueous coating compositions of the present invention can be applied to a variety of substrates by a variety of techniques known in the art. For example, the compositions of the invention may be used in the can manufacturing industry which uses primarily metal cans, many of which are cylindrical, made from aluminum, tin-free steel, electro-tin plate, rolled sheet, etc., among others. can be used. Cans used to package and ship food, coffee, beer, and other beverages are primarily of the three-piece or two-piece die-cut and iron-on (D&I) variety. Cans made from three pieces (body, lid and bottom) can be roll coated before the metal sheet is formed into the shape of the can, or can be spray coated after the parts are formed. D&I type cans, in which a sheet of metal is stamped to produce a closed cylinder at one end, are commonly spray coated. After the coating, it is generally dried at a temperature of about 90 DEG to 330 DEG C. for about 5 seconds to about 30 minutes.

Effects of the Invention The aqueous coating composition of the present invention is capable of forming a coating film that is excellent in flavor retention and adhesive strength, and is also excellent in corrosion resistance, processability, sanitary properties, and the like.

First generation of large family Examples are given below to further clarify the present invention.

In the following, "part" and "1%" mean "part by weight" and "% by weight," respectively.

<Production of carboxyl group-containing acrylic resin solution> Production Example 1 400 parts of 1 tanoyl was weighed into a 4-tubular flask equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel, and a nitrogen inlet. Next, 174 parts of methacrylic acid, 87 parts of styrene,
29 parts of ethyl acrylate and 14.5 parts of benzoyl peroxide (75% water wet) were weighed into a beaker,
The mixture was thoroughly mixed and stirred to prepare a premix.

The temperature of the butanol in the flask was heated to 105° C., and at this temperature the premix was added dropwise from the dropping funnel over a period of 3 hours. The temperature was maintained for an additional 2 hours to complete the copolymerization reaction. Then 2-butoxethanol29
0 parts added, viscosity 370 centipoise, resin acid value 39
A carboxyl group-containing acrylic resin solution (hereinafter referred to as "acrylic resin solution A") with a solid content of 30% was obtained.

<Production of epoxy resin solution> Production example 2 Epicoat 828 (epoxy resin manufactured by Yuka Shell Co., Ltd., epoxy equivalent 184-194, viscosity 120-150 poise,
25°C), 286 parts of bisphenol A, 0.5 part of tri-n-butylamine, and 88 parts of methyl isobutyl ketone were placed in a reaction vessel and heated to 135°C under a nitrogen stream, and the contents generated heat to 180°C. This product was cooled to 160°C and reacted for about 3 hours, resulting in an epoxy value of 0.025 and a solution viscosity (resin content of 40°C at 25°C).
Gardner-Holdt viscosity of butylcarpitol solution in %)
A 90% epoxy resin solution of No. 24 (hereinafter referred to as "epoxy resin solution B") was obtained.

Production Example 3 Epicoat 807 (epoxy resin manufactured by Yuka Shell Co., Ltd., epoxy equivalent 168-178, viscosity 120-150 poise,
25°C), 274 parts of bisphenol F, 0.5 part of tri-n-butylamine, and 82 parts of methyl isobutyl ketone were placed in a reaction vessel and heated to 135°C under a nitrogen stream, and the contents generated heat to 180°C. This product was cooled to 160°C and reacted for about 3 hours to obtain an epoxy value of 0.024 and a solution viscosity (resin content of 40°C at 25°C).
Gardner-Holdt viscosity of butylcarpitol solution in %)
A 90% epoxy resin solution of No. 22 (hereinafter referred to as "epoxy resin solution C") was obtained.

<Production of phenol resin solution> Production example 4 228 parts of bisphenol A, 122 parts of a 37% formaldehyde aqueous solution, and 2 parts of caustic soda were charged into a reaction vessel equipped with a stirrer and a reflux condenser, and the temperature was raised to 60°C and reacted for 3 hours. Ta. Next, 2.45 parts of sulfuric acid was added to this, and further n
-Add 228 parts of butanol and reduce pressure to 650 mmHg
The mixture was heated and azeotropically dehydrated. After reducing the pressure to 80% concentration,
It was diluted to 60% with n-butanol to obtain a phenol resin solution (hereinafter referred to as "phenol resin solution D") containing 60% monomethylol, 30% dimethylol, and an average degree of methylolation of 1.2 per unit of bisphenol A. .

Production Example 5 A reaction vessel equipped with a stirrer and a reflux condenser was charged with 228 parts of bisphenol A, 122 parts of a 37% formaldehyde aqueous solution, and 5.1 parts of triethylamine, heated to 60° C., and reacted for 3 hours. Next, 228 parts of n-butanol was added and heated at a reduced pressure of 650 mmug to perform azeotropic dehydration. After reducing the pressure to a concentration of 80%, dilute to 60% with n-butanol to obtain 60% monomethylol and 30% dimethylol.
%, average degree of methylolation 1 per unit of bisphenol A
．． A phenol resin solution of No. 2 (hereinafter referred to as [phenol resin solution E]) was obtained.

Production Example 6 A reaction vessel equipped with a stirrer and a reflux condenser was charged with 228 parts of bisphenol A, 324 parts of a 37% formaldehyde aqueous solution, and 2 parts of caustic soda, heated to 60°C, and reacted for 3 hours. Next, 2.45 parts of sulfuric acid was added to this, and further n
-Add 228 parts of butanol and reduce pressure to 650 mmHg
The mixture was heated and azeotropically dehydrated. After reducing the pressure to 80% concentration,
Diluted to 60% with n-butanol, 10% monomethylol, 50% dimethylol, 30% trimethylol.
%, average degree of methylolation per unit of bisphenol A 2
．． A phenol resin solution (hereinafter referred to as "phenol resin solution F") was obtained.

Production Example 7 A reaction vessel equipped with a stirrer and a reflux condenser was charged with 228 parts of bisphenol A, 486 parts of a 37% formaldehyde aqueous solution, and 70 parts of caustic soda, heated to 60° C., and reacted for 3 hours. Next, 2.45 parts of sulfuric acid was added to this, and further n
-Add 228 parts of butanol and reduce pressure to 650 mmHg
The mixture was heated and azeotropically dehydrated. After reducing the pressure to 80% concentration,
A phenolic resin solution diluted to 60% with n-butanol and containing 30% trimethylol and 40% tetramethylol as main components (average degree of methylolation 3.0 per unit of bisphenol A, hereinafter referred to as "phenol resin solution G") ) was obtained.

Production Example 8 228 parts of bisphenol A, 24.3 parts of a 37% formaldehyde aqueous solution, 97.7 parts of water, and 2 parts of caustic soda were placed in a reaction vessel equipped with a stirrer and a reflux condenser, and the temperature was raised to ζ60°C and reacted for 3 hours. .

Next, 2.45 parts of sulfuric acid was added thereto, and further 228 parts of n-1 tanol were added thereto, followed by heating and azeotropic dehydration at a reduced pressure of 650 mmHc+. After reducing the pressure to a concentration of 80%, diluted to 60% with n-butanol, 20% monomethylol,
Average degree of methylolation per unit of bisphenol A: 0.2
phenolic resin solution (hereinafter referred to as "phenolic resin solution H")
) was obtained.

<Manufacture of water-based coating composition> Example 1 Formulation (1) Acrylic resin solution A 150 parts (2
) Epoxy resin solution B 283 parts (3) n-
7Tanol 86 parts (4) 2-Butoxychetanol 47 parts (5) Deionized water
3.2 parts (6) dimethylaminoethanol 5.3 parts (7) dimethylaminoethanol
9.5 parts (8) Phenol resin solution D 1
50 parts (9) Deionized water 566 parts Total 1300 parts Put the above (1) to (4) into a reaction container, and add 115 parts of deionized water under a nitrogen stream.
It was heated to ℃ to dissolve the resin component. 105℃ after melting
Add (5) to (6) in this order, and heat at 105℃ for 3
Holds time. The reaction product has a solid content weight ratio of acrylic resin/epoxy resin of 15/85. The reaction was tracked by measuring the acid value, and the acid value was 51 at the end of the reaction. Then, after 3 hours, (7) was added, and after 5 minutes, (8) was added, followed by hot blending at 105°C for 30 minutes.

Then, (9) was added over a period of 30 minutes to obtain a solid content of 3
A 0% stable water-based paint was obtained.

Example 2 A water-based paint was obtained in the same manner as in Example 1, except that the same amount of phenol resin solution E was used instead of the phenol resin solution.

Example 3 A water-based paint was obtained in the same manner as in Example 1, except that the same amount of epoxy resin solution C was used instead of epoxy resin solution B.

Example 4 Blend (1) Epoxy resin solution 8 283 parts (2) n
-Butanol 121 parts (3) 2-butoxyshetanol 117 parts (4) Methacrylic acid
27 parts (,5) styrene
13.5 parts (6) Ethyl acrylate
4.5 parts (7) Benzoyl peroxide
3 parts (8) dimethylamine ethanol 14.8
Part (9) 150 parts of phenolic resin solution D (
10) 566.2 parts deionized water
A total of 1300 parts of the above (1) to (3) were placed in a reaction vessel and heated to 115°C under a nitrogen stream to dissolve the resin components. Then (4) to (7)
A mixture of the above was added dropwise over 1 hour, and the mixture was further reacted at 115°C for 2 hours. Thereafter, the mixture was cooled to 105°C, and (8) was added. After 5 minutes, (9) was added, and hot blended at 105°C for 30 minutes. Thereafter, (10) was added every 30 minutes to obtain a stable water-based paint with a solid content of 30%.

Comparative Example 1 A water-based paint was obtained in the same manner as in Example 1, except that the phenolic resin solution was not used.

Comparative Example 2 A water-based paint was obtained in the same manner as in Example 1, except that 90 parts of Cymel 1156 (melamine formaldehyde resin, manufactured by American Cyanamid Co., Ltd.) was used instead of the phenolic resin solution.

Comparative Example 3 A water-based paint was obtained in the same manner as in Example 1, except that the same amount of phenolic resin solution F was used instead of the phenolic resin solution.

Comparative Example 4 A water-based paint was obtained in the same manner as in Example 1, except that the same amount of phenolic resin solution G was used instead of the phenolic resin solution. This corresponds to the dispersion described in JP-A-61-250023M.

Comparative Example 5 A water-based paint was obtained in the same manner as in Example 1, except that the same amount of phenolic resin solution H was used instead of the phenolic resin solution.

Comparative Example 6 A water-based paint was obtained in the same manner as in Example 1, except that 255 parts of phenolic resin 6 liquid was used.

<Coating film performance test> The water-based paints obtained in Examples 1 to 5 and Comparative Examples 1 to 6 above were coated with Tin Free Steel (manufactured by Toyo Kohan Co., Ltd., plate thickness 0.2
3 mm> with a dry film thickness of 4 to 5 microns per coat, and then coated with a roll at an ambient temperature of 200'C.
Dry for 0 minutes.

Also, apply 8-10% of the above water-based paint on one side of 100μ aluminum foil.
It was coated so as to have a thickness of μ and then dried at an ambient temperature of 200'C for about 30 seconds. Furthermore, apply the above water-based paint on the back side.
Apply the coating to a thickness of ~10 μ, and then reduce the ambient temperature to 200 μm.
A test panel for aqueous extract flavor test was prepared by drying at 'C for about 10 minutes.

Also #50ETP (manufactured by Nippon Steel Corporation, plate thickness 0.24m
m>, apply the above water-based paint to a dry film thickness of 20~
Paint to a thickness of 30 μm, then reduce the ambient temperature to 200 μm.
'C for about 10 minutes to prepare a test panel for cyclohexanone swelling rate.

Various test methods are shown below.

(1) Adhesion strength A test panel painted on tin-free steel with a width of 5 mm.
, cut into 25 cm long pieces, stack the two sheets with the coated side inside, and place a 9 cm long nylon film (manufactured by Ohcell Co., Ltd., Diamid Film, count #40, thickness 40μ) between them.
sandwiched two sheets, fused the nylon film at 200'C for 60 seconds in a hot press, and then heated at 200'C for 3 seconds.
A test piece was prepared by pressure bonding for 0 seconds at a pressure of 5 rkg, cm2. The test piece was autographed (manufactured by Shimadzu Corporation).
T-beer peeled at a tensile speed of 100 mm/min.
The peel strength at that time was defined as the adhesive strength.

The value was the average value of 5 times.

The untreated adhesive strength was measured using the press-bonded test piece as it was.

The water resistant adhesive strength is 0.4% at 90℃ for the crimped test piece.
Measurements were taken after immersion in a citric acid aqueous solution for one week.

(2) Using a special engineered fold-type DuPont impact tester, a painted sample of tin-free steel folded in half was placed at the bottom, and a steel weight weighing 1 kCI with a flat contact surface was placed at a high height. 5Qc
The length of cracks in the coating film at the bent portions that occur when dropped from m.m was measured.

020-10mm1Δ: 10-20mm.

x: 20mm or more.

(3) Chloroform extraction amount Test panel painted on tin-free steel is 10 cm
Cut into 10 cm x coated area and 1 c of chloroform
It was immersed in boiling chloroform at a ratio of m2/1 m2. After treatment with boiling chloroform for 1 hour,
The ratio of the amount extracted after treatment to the weight of the coating film before treatment on the test panel was expressed as a percentage.

(4) Place 100μ aluminum foil coated with various water-based paints with water extract flavor into a heat-resistant glass bottle so that the applied area is 1 Cff12:1 mQ of tap water treated with activated carbon, and cover with a lid.]22
After sterilization at 5°C-30, flavor test of the liquid contents is conducted.

O: Not much change, Δ: Slight change, X: Significant change.

(5) Potassium permanganate consumption Amount of water extract The liquid obtained in the flavor test was measured according to the test method described in the Food Sanitation Act (Ministry of Health and Welfare No. 434). The consumption amount was expressed in ppm.

(6) Cyclohexanone swelling rate From the #50ETP test panel coated with various water-based paints, the paint film was peeled off using the mercury-algum method, immersed in cyclohexanone at 30°C for 4 days, and cyclohexanone was applied according to the above formula (2). The swelling ratio was determined.

Claims (1)

[Scope of Claims] [1] (A) A reaction product of an aromatic epoxy resin and a carboxyl group-containing acrylic resin, wherein excess carboxyl groups in the reaction product are neutralized with a basic compound. It is made by reacting 100 parts by weight of the reactant, and (B) phenols and aldehydes, and has a general formula ▲ Numerical formula, chemical formula, table, etc. ▼ (1) (In the formula, R is a hydrogen atom or a carbon number of 1 to 12 an alkyl group,
X represents a hydrogen atom or a methyl group. a and b each represent 0 or an integer of 2 or less. However, the sum of a and b shall be within the range of 0.3 to 2.0 on average per unit of bisphenol. 1. An aqueous coating composition comprising 5 to 50 parts by weight of a resol-type phenol-formaldehyde resin represented by the following formula dispersed in an aqueous medium. [2] After baking and drying the above water-based paint composition,
Peel off the paint film and soak it in cyclohexanone at 30℃ for 4 hours.
The composition according to claim 1, which has a swelling ratio of 20 to 200% as determined by the following formula (2) when immersed for one day. K=(W_2-W_1)×100/W_1(2) [Here, K is the cyclohexanone swelling ratio, W_1 is the weight of the coating before immersion, and W_2 is the weight of the coating after immersion. ]