JPH0672217B2 - Emulsion type water-based paint for can - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an emulsified water-based paint for cans, and more specifically, to a can that has excellent adhesion to a metal substrate and workability of a coating film. The present invention relates to an emulsion type water-based paint.

(Prior Art) Conventionally, in manufacturing cans for cans, various kinds of paints have been used to coat metal materials and cans themselves in order to prevent metal elution into the contents and to prevent metal corrosion. Has been done. Not only in the case of squeezing iron cans using unpainted metal materials, but also in squeeze cans using coated metal materials and in three-piece cans, the scratches of the coating film that enters during the can manufacturing process are corrected and the top coat is applied. In order to form it, various paints are spray-painted and baked on the canister and the can lid.

From the viewpoints of adhesion to metal substrates, corrosion resistance, flavor characteristics, and coating film processability, paints composed of a combination of an epoxy resin and a curing agent resin and vinyl-based paints are excellent. These paints exhibit good performance of being applied in the form of an organic solvent solution, but during spray painting, the solvent volatilizes into the working environment, causing air pollution and environmental hygiene problems.

In order to eliminate these drawbacks, water-based paints, that is, water-based dispersion paints have already been developed. The first type of such water-based paint is one in which the paint resin is atomized by some means, and a surfactant or a water-soluble or hydrophilic resin is dispersed in water as a dispersant (for example, JP-B-44). −18076
Issue). The second type is modified by reacting a coating having a functional group such as an epoxy resin with a resin having a carboxyl group such as an acrylic resin,
This modified resin is self-emulsified in an aqueous medium by neutralizing with ammonia or amines (for example, JP-A-59-213718).

(Problems to be Solved by the Invention) However, in the former type of water-based coating composition, the dispersion particle size of the coating resin component is generally coarse or uneven, and the water-based coating composition is poor in dispersion stability. However, the performance of the resulting coating film is inferior to that of the solvent type paint.

Further, although the latter type of coating is superior in dispersibility and the like as compared with the former type of coating, it is greatly restricted by the coating resin composition. Since it is difficult to make the content sufficiently large, it is not possible to sufficiently cure the coating film, and therefore, the adhesion of the coating film, the hardness of the coating film, the denseness, the barrier property against corrosive components, etc. are satisfied. The problem arises that it cannot be upgraded to the level that it should be.

The present inventors have studied for producing a water-based paint by subjecting a thermosetting resin containing an epoxy resin component and a curing agent resin component to phase inversion emulsification by utilizing the surface active action of an acrylic resin. In the process, the adhesion of the coating film formed from the water-based paint depends on the kind of amine used for the neutralization of the carboxyl group in the acrylic resin, and the branched chain alkyl group is used as the neutralizing amine. It was found that when at least one amine selected from the group consisting of alkylamines and heterocyclic amines is used, the adhesion of the formed coating film to a metal substrate and the processability of the coating film are significantly improved. .

(Means for Solving Problems) According to the present invention, a thermosetting resin as a coating film forming component containing an epoxy resin component and a curing agent resin component for the epoxy resin component, and a carboxyl group as a polymer dispersant. Containing acrylic resin in the form of a mixture, wherein the mixture has at least one carboxyl group of the acrylic resin in the mixture selected from the group consisting of alkylamines having a branched alkyl group and heterocyclic amine. The emulsion is emulsified by phase conversion simultaneously with neutralization with certain amines, the acrylic resin is present in an amount that results in an oxidation of 2 to 30 based on the coating resin component, and at least the thermosetting resin is an O / W emulsion. There is provided a water-based paint for cans, characterized in that it is present in the form.

(Working) The reason why the water-based paint for cans using an acrylic resin containing a carboxyl group in the form of an amine salt as a dispersant is inferior in adhesion to a metal substrate and processability of a coating film is that amines are different from epoxy resins. This is considered to be due to the high curing rate.

Generally, the curing of an epoxy resin is divided into a curing by the ring opening of the terminal epoxy group and a curing by the reaction of the hydroxyl group in the molecular chain.
There are several types, and the curing of epoxy resin with amines is the former curing by ring opening. Conventionally, in dimethyl-aminoethanol, which is most widely used for neutralizing carboxyl groups, the epoxy resin is cured with amines prior to the original curing due to the reaction between the epoxy resin and the curing agent resin. It seems that workability cannot be achieved as expected.

On the other hand, the alkylamines and heterocyclic amines having a branched chain alkyl group used in the present invention have a low curing rate of the epoxy resin, and therefore, the curing of the coating film is not affected by the epoxy resin component and the curing agent resin component. It is considered that the desired adhesiveness and workability can be obtained because the curing by the reaction with and occurs selectively.

The reason for this is not clear yet, but it is considered as follows. Although the difference in the curing reaction rate of the epoxy resin depending on the type of amines has not been sufficiently clarified, it is believed that the amines used in the present invention slow the curing rate of the epoxy resin due to the steric hindrance effect and the like. Be done.

Further, in the present invention, the epoxy resin component, the curing agent resin component and the carboxyl group-containing acrylic resin component are used in the form of a mixture, and the carboxyl group in the mixture is emulsified by phase conversion by neutralization of specific amines. Since there is no reaction between the epoxy resin component and the carboxyl group-containing acrylic resin component, and the original curing reaction between the epoxy resin and the curing agent resin is effectively performed, the reason why the adhesion and processability are improved it is conceivable that.

(Explanation of preferred embodiments) The water-based paint used in the present invention comprises a thermosetting resin as a coating film-forming component containing an epoxy resin component and a curing agent resin component for the epoxy resin component, and a carboxyl group as a polymer dispersant. Containing acrylic resin.

As the epoxy resin, a bisphenol A type epoxy resin obtained by polycondensation of bisphenols such as bisphenol A and epihalohydrin is suitable, and its epoxy equivalent is generally 400 to 20,000, particularly 1,000 to 5,000.
Range of 0 and number average molecular weight of 1,000 to 20,000, especially 2,000
Those in the range of 0 to 13,000 are preferred.

As a resin curing agent reactive with an epoxy resin, a resin having a functional group reactive with a hydroxyl group or an oxirane ring of the epoxy resin, for example, a hydroxyl group, an amino group, a carboxyl group or the like; Or, a novolac type phenol / formaldehyde resin, urea-formaldehyde resin, melamine / formaldehyde resin, alkyd resin, polyester resin, acrylic resin, polyurethane resin, xylene resin, epoxy ester resin, butyral resin, etc., or a combination of two or more thereof. Is used. Of these, a methylol group-containing thermosetting resin, for example, a phenol resin or an amino resin, particularly a resol type phenol resin is preferable.

The present invention is characterized in that the coating resin can be emulsified and dispersed in a fine dispersed particle size even when the composition ratio of the epoxy resin and the curing agent resin is within an arbitrary range. The ratio of epoxy resin to curing agent resin is generally in the range of 95: 5 to 40:60 by weight, in particular 90:10 to 50:50 by weight.

The acrylic resin as the polymer dispersant is preferably present in an amount such that the acid value is 2 to 30, particularly 5 to 20 based on the coating resin component. If the acid value is below the above range, it becomes difficult to disperse the resin component in the form of an O / W emulsion, and even if the resin component is strongly dispersed, the dispersion stability is poor. On the other hand, when the acid value exceeds the above range, the hot water resistance of the coating film decreases, and the corrosion resistance after retort sterilization decreases.

The acrylic resin used is 35 to 350, especially 70
It is desirable to have an acid value of from 3 to 330, and it is preferable to use this acrylic resin in an amount of 3 to 30% by weight, particularly 5 to 25% by weight, based on the resin as a coating film forming component.

As the acrylic resin, any acrylic resin can be used as long as the acid value is within the above range. This acrylic resin is an ethylenically unsaturated carboxylic acid or an anhydride thereof which gives the resin a carboxyl group having the above-mentioned acid value, an acrylic acid ester or a methacrylic acid ester, and other ethylene copolymerizable therewith. It is composed of a copolymer with an unsaturated monomer. Examples of the ethylenically unsaturated carboxylic acid or its anhydride include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and itaconic anhydride.

Examples of esters of acrylic acid and methacrylic acid include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and (meth ) N-amyl acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate and the like. However, the above-mentioned (meth) acrylic acid means acrylic acid or methacrylic acid.

Examples of the other comonomer that is copolymerized with these monomers include styrene, vinyltoluene, acrylonitrile, methacrylonitrile, and the like.

The acrylic resin used should have a molecular weight sufficient to form a film, and preferably has a molecular weight in the range of 10,000 to 200,000, particularly 20,000 to 150,000. Examples of suitable combinations of acrylic copolymers are (1) methyl methacrylate / 2-ethylhexyl acrylate / acrylic acid, (2) styrene / methyl methacrylate / ethyl acrylate / methacrylic acid, (3) styrene / acrylic. Ethyl acid / methacrylic acid, and (4) methyl methacrylate / ethyl acrylate / acrylic acid.

These acrylic resins can be easily obtained by polymerizing these monomers in an organic solvent in the presence of azobisisobutyronitriles and peroxides.

As the amine having a branched chain alkyl group, isopropylamine, sec-butylamine, tert-butylamine,
A branched chain alkylamine having 3 to 6 carbon atoms, particularly 3 to 4 carbon atoms, such as isoamylamine is used.

As the heterocyclic amine, a saturated heterocyclic amine containing one nitrogen atom such as pyrrolidine, piperidine and morpholine is used.

The amines are preferably used in an amount of at least 0.3 chemical equivalent, particularly 0.7 to 1.3 chemical equivalent based on the carboxyl group of the acrylic resin.

The thermosetting resin O / W type emulsion contains an amine-containing water in an organic solvent solution containing a thermosetting resin and an acrylic resin, or contains a thermosetting resin and an acrylic resin. It can be formed by a so-called phase inversion method in which the amine-containing water is mixed with the melt.

When amine water is added to an organic solvent solution or melt containing a paint resin and an acrylic resin, the viscosity of the system increases at the initial stage of addition, but the viscosity of the system gradually decreases with continued addition. Get started. At this stage, the addition is interrupted, the whole system is homogenized by stirring, and when the addition of the amine water is continued again, the viscosity of the system is rapidly lowered by the addition of a predetermined amount of the amine water. In the initial stage of adding amine water to the resin solution,
The water phase exists in the form of a dispersed phase, but at the stage where the viscosity of the system suddenly drops, the O / W type emulsion in which the aqueous phase is a continuous (dispersion medium) phase and the resin component is a dispersed phase is stable. To generate.

In the case of the solution phase inversion method, an organic solvent solution (I) of a coating resin and an organic solvent solution (II) of an acrylic resin are prepared, and these solutions (I) and (II) are uniformly mixed to prepare a raw material. Use as a solution. Examples of the organic solvent for this solution include aromatic hydrocarbon solvents such as toluene and xylene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohol solvents such as ethanol, propanol, butanol; ethyl cellosolve, One or more of cellosolve solvents such as butyl cellosolve; ester solvents such as ethyl acetate and butyl acetate can be used. The resin component concentration in the raw material solution is
Generally, it should be in the range of 5 to 80% by weight, especially 20 to 70% by weight. If desired, the raw material solution may contain known compounding agents for paints such as plasticizers, lubricants, pigments, fillers and stabilizers.

The amount of water used for phase conversion varies depending on the type of resin and the concentration of the raw material solution, but generally 0.5 to 2.0 times by weight, particularly 0.7 to 1.5 times by weight of water is recommended for the raw material solution. Room temperature is sufficient for mixing the resin solution and the amine water, but it may be heated up to a temperature of about 100 ° C. if desired. The addition and mixing can be performed in a reaction vessel equipped with a usual stirrer, but if desired, a high shear stirring device such as a homomixer or irradiation with ultrasonic vibration can be used.

Due to the phase inversion, the aqueous dispersion contains both water and an organic solvent. By subjecting this aqueous dispersion to azeotropic vacuum distillation, the organic solvent can be removed azeotropically with water, and the aqueous dispersion can be concentrated. It should be understood that the azeotropic distillation of the organic solvent can be performed while replenishing water from the outside.

Concentration of paint resin solids in final water-based paint is 10 to 70
The content is preferably in the range of 20% to 60% by weight, and the content of the organic solvent in the water-based paint is preferably 15% by weight or less, more preferably 5% by weight or less. Further, for the purpose of improving the dispersion stability of the resin component in the paint, it is acceptable to add a slight amount of a surfactant or a polymer dispersant to the system at any stage.

In the case of the melt phase inversion method, a melt containing a coating resin and an acrylic resin is prepared. The melt viscosity of this melt is generally 10 to 100,000 centipoise, especially 100 to 30,000.
It is suitable to be in the range of centipoise, and if the viscosity is higher than the above range, it may be difficult to uniformly and uniformly knead both. The temperature of the melt is 10 to 150 ° C, especially 2
It is suitable to be 0 to 120 ° C., and if it is higher than the above temperature range, partial gelation or premature gelation (pre-mature) of the coating resin component is likely to occur, which is not preferable.
The organic solvent described above can be used for the purpose of lowering the kneading temperature and lowering the melt viscosity.

The amount of organic solvent used is 30% by weight or less, especially 15% by weight of resin.
It is suitable that the content is less than or equal to weight%. Of course, one or both resin components may be supplied to the kneading in the form of an organic solvent solution.

The melt-kneading can be performed using a kneader, Banbury mixer, single-screw or twin-screw extrusion-type kneader.

The amount of water added and the removal of the organic solvent are the same as in the solution phase conversion method.

The water-based paint according to the present invention has a viscosity suitable for coating and can be used for coating various metal materials, cans, cans and other members. This water-based paint is not only used for ordinary spray paint and electrostatic painting, but also for roller coating,
Brush application, doctor coater, air knife coater,
It can be used for coating work with various coaters such as a reverse coater.

(Effects of the Invention) According to the present invention, a water-based paint is used as a coating film-forming component containing an epoxy resin component and a curing agent resin component as a thermosetting resin, and a carboxyl group-containing acrylic as a polymer dispersant. It is composed of a mixture with a system resin, and this mixture contains the carboxyl group of the acrylic resin in the mixture,
At least one amine salt selected from the group consisting of alkylamines having a branched chain alkyl group and heterocyclic amine is emulsified by phase conversion simultaneously with neutralization in the form of an amine salt, and the acrylic resin is based on the coating resin component. The presence of an acid value of 2 to 30 and at least the thermosetting resin in the form of an O / W emulsion make it possible to obtain excellent adhesion to a metal substrate and processability of a coating film. It is possible to provide an emulsified water-based paint for use.

(Examples) In the examples, parts are by weight unless otherwise specified.
Throughout the examples and comparative examples, the paints or coated plates were evaluated in the following manners, unless otherwise specified.

(1) Stability of paint over time 100 ml of the emulsified water-based paint to be tested was placed in a glass wide-mouthed bottle with an internal capacity of 100 ml, tightly stoppered, stored in a constant temperature bath at 50 ° C for 1 month, and then opened and investigated. The presence or absence of skinning on the liquid surface, the viscosity of the emulsified water-based paint, and the average particle diameter of the resin particles were investigated and compared with those before storage.

(2) Preparation of coated plate, adhesion, retort whitening Emulsion type water-based paint to be tested is coated on electrolytic chromic acid treated steel plate (hereinafter referred to as TFS) using a roll coater and baked at 210 ° C for 10 minutes to cure. It was The coating thickness was about 5 μm.

The coated plate was cut to a width of 5 mm and bonded by pressing with a hot press heated to 200 ° C. for 2 minutes using an adhesive of nylon thread. The peel strength was measured by T-peel, and the initial peel strength immediately after adhesion and the time-dependent peel strength after immersion in warm water at 90 ° C. for 1 week were obtained. Further, a part of this coated plate was subjected to retort treatment at 125 ° C. for 30 minutes, and the presence or absence of whitening of the coating film due to the retort treatment was investigated.

(3) Evaluation of actual water For some emulsified water-based paints, the test water-based paint was applied on one side of the TFS with a roll coater and baked at 210 ° C for 10 minutes.
After drying, the other side was similarly coated and baked to prepare a double-sided coated plate. The thickness of each coating film was about 4 μm. Using this paint board and nylon adhesive, create a 202 diamond adhesive canister (both ends are necked into 200 diamonds), double-tighten the canopy, and then add consomme soup. After filling, the bottom lid was double-wound to make a consommé soup. Fill this consommé soup at 90 ° C for 90 minutes.
It was sterilized by retort for minutes, cooled, air-dried, and stored in a warehouse. After being stored for 6 months, it was opened and examined for abnormalities such as whitening of the coating film and internal corrosion.

Also, for some emulsion-type water-based paints, the above double-sided coated plate is molded into a 200-diamond can lid, and double-tightened to one end of an adhesive canister made using solvent-based paint, and the consomme soup is prepared. After filling, the same lid was double wrapped around the other end to fill the consommé soup. This can was retort treated in the same manner as the above can, and stored for 6 months, then opened and examined for abnormalities such as whitening of the coating film on the can lid, internal corrosion, and deterioration of adhesion. In this case, the adhesiveness was evaluated by the amount of the area where the coating film was peeled from the substrate when the cellophane tape was attached to the surface to be tested and the tape was peeled off.

Example 1 480 parts by weight of a bisphenol A type epoxy resin having a number average molecular weight of about 3,750 and an epoxy equivalent of about 3,000 was added to butyl cellosolve 4
A solution dissolved in 80 parts was prepared, and a resol type phenol resin derived from bisphenol A, paracresol, and formaldehyde using an ammonia catalyst (bisphenol A / paracresol = 80/20, number average molecular weight 650).
A solution having 120 parts by weight dissolved in 240 parts of a mixed solvent of xylene, methyl isobutyl ketone and cyclohexanone (xylene / methyl isobutyl ketone / cyclohexanone = 1/1/1) was prepared and mixed with the above epoxy resin solution.

On the other hand, prepare a mixture of 20 parts of ethyl acrylate, 20 parts of methyl methacrylate, 40 parts of methacrylic acid, 20 parts of styrene and 1 part of tert-butyl hydroperoxide, and stirrer, thermometer, dropping funnel, reflux condenser and A flask equipped with an active gas inlet was charged with 50 parts of ethyl cellosolve and 25 parts of the above mixture, heated to 90 ° C. with stirring under a nitrogen stream, and then the monomer mixture in a flask maintained at the same temperature. Was added dropwise over 3 hours for copolymerization, and tert-butyl hydroperoxide 0.6
Then, 50 parts of ethyl cellosolve was added and cooled to complete the reaction. The obtained acrylic resin had a weight average molecular weight of about 120,000, an acid value of 124, and a solid content of the resin solution was about 50%.

On the one hand, to 220 parts of the above mixed solution of epoxy resin and phenol resin, 20 parts of the above acrylic resin solution was added and stirred to uniformly mix, and on the other hand, to 250 parts of deionized water, Table 1 Amine water was prepared by dissolving each of the six amines shown in 1) in an amount of 1 equivalent per carboxyl group in 20 parts of the acrylic resin solution. Amine water was gradually added dropwise with vigorous stirring of a mixed solution of the above-mentioned epoxy resin, phenol resin, and acrylic resin, and the viscosity of the system increased at the beginning of the addition of amine water to form a white cream. As the addition of amine water proceeded, the viscosity of the system began to gradually decrease. At this stage, the addition of the amine water was interrupted, the stirring was continued, and the addition of the amine water was restarted after the whole was in a state of being uniformly dispersed. As a result, the viscosity of the system rapidly decreased. The addition of amine water was continued under stirring, and a safe O / W type emulsion was formed after the entire amount of the addition was completed.

These emulsions were concentrated by a rotary evaporator, and 100 parts of water and 120 parts of organic solvent were collected to obtain a solid content of 40%.
The emulsified water-based paint of These emulsion type water-based paints contain about 3.5% organic solvent per paint,
The average particle size of the resin particles is shown in Table 1.

Table 1 shows the results of evaluation of various properties of these six types of emulsion-type water-based paints.

Comparative Example 1 Five types of emulsion-type water-based paints were produced in accordance with Example 1 except that the five types of amines shown in Table 2 were used, and the results of evaluation of various properties are shown in Table 2.

Example 2 15 parts of ethyl acrylate, 15 parts of methyl methacrylate,
A mixture of 40 parts of methacrylic acid, 30 parts of styrene and 1 part of tert-butyl hydroperoxide was prepared, and an acrylic resin was synthesized according to the method shown in Example 1. The acrylic resin thus obtained had a weight average molecular weight of about 130,000, an acid value of 124, and a solid content of the resin solution of about 50%. This acrylic resin solution was gradually added to 500 parts of deionized water under vigorous stirring to precipitate a solid content, and the obtained solid acrylic resin was further vacuum dried.

Next, the epoxy resin and the phenol resin shown in Example 1, hexyl cellosolve, and 6 parts of the amines shown in Table 3 in 150 parts of deionized water were added in an amount of 1 per 1 carboxyl group in 10 parts of the acrylic resin. An amine water having an equivalent amount dissolved therein was prepared.

Into a kneader stored at 80 ° C, 80 parts of the epoxy resin and 20 parts of the phenol resin, and 10 parts of the above solid acrylic resin were added and mixed, and further, 15 parts of hexyl cellosolve were added and mixed. Then, after forming a uniform concentrated solution, the above amine water kept at 80 ° C. was gradually added dropwise.
With the addition of amine water, the system becomes a white cream,
The viscosity of the system decreased sharply as the addition of amine water proceeded. When the dropping of the amine water was continued, a stable O / W type emulsion was formed after the dropping of the entire amount was completed.

These emulsions contained about 4.3% of organic solvent per paint, and the average particle size of the resin particles is shown in Table 3.

Table 3 shows the results of evaluation of various properties of these five types of emulsion type water-based paints.

Comparative Example 2 Five kinds of emulsified water-based paints were produced in accordance with Example 2 except that the five kinds of amines shown in Table 4 were used, and various properties thereof were evaluated. Table 4 shows the results.

Example 3 Six epoxy resins having a molecular weight and an epoxy equivalent as shown in Table 5 were prepared, and the same phenol resin solution, acrylic resin solution and morpholine as those used in Example 1 were used, According to the method of Example 1, 6 types of emulsion type water-based paints were prepared.

Apply these 6 types of emulsion type water-based paint on both sides of TFS
It was molded into a diamond can lid and evaluated. The results are shown in Table 5.

Example 4 Four types of emulsified aqueous solutions were prepared according to the method shown in Example 1 by using the four types of curing agent resins shown in Table 6, the epoxy resin of Example 1, the acrylic resin, and sec-butylamine. A paint was made.

These emulsion-type water-based paints were applied to both sides of TFS, molded into a 200 diamond can lid, and evaluated. The results are shown in Table 6.

Example 5 Using the epoxy resin and the phenol resin, the acrylic resin and the morpholine of Example 1, the epoxy resin and the phenol resin were blended at the ratios shown in Table 7, and 6 kinds of the epoxy resin and the phenol resin were prepared according to the method shown in Example 1. An emulsion type water-based paint was prepared.

Table 7 shows the results of evaluation of the performance of can lids manufactured using these six types of emulsion-type water-based paints.

Example 6 Epoxy resin, phenol resin of Example 1, and Table 8
An emulsified water-based paint was prepared in accordance with Example 1 except that 8 kinds of acrylic resin having an acid value as shown in Table 1 and morpholine were used, and the amount of acrylic resin as shown in Table 8 was added. .

Table 8 shows the results of evaluating the stability of these emulsion-type water-based paints and the performance of the can lids produced using the same.

Example 7 Epoxy resin, phenolic resin of Example 1 and Table 9
Emulsified water-based paints of eight types according to Example 1 except that three types of acrylic resins having an acid value as shown in Table 1 and morpholine are used and the amount of acrylic resin shown in Table 9 is added. Was produced.

Table 9 shows the results of evaluating the stability of these emulsion-type water-based paints and the performance of the can lids produced using the same.

Example 8 Epoxy resin, phenolic resin of Example 1, and Table 10
Emulsified water-based paints of eight types according to Example 1 except that four kinds of acrylic resins having an acid value as shown in Table 1 and morpholine are used, and the amount of acrylic resin shown in Table 10 is added. Was produced.

Table 10 shows the results of evaluating the stability of these emulsion-type water-based paints and the performance of the can lids produced using the same.

Comparative Example 3 220 parts of the mixed solution of the epoxy resin solution and the phenol resin solution of Example 1 and 20 parts of the acrylic resin solution of Example 1 were mixed, heated to 100 ° C. under stirring, and stirred at the same temperature for 2 hours. Continued. Then, the system was cooled to 80 ° C., 2 equivalents of dimethylaminoethanol per carboxyl group in the acrylic resin was added dropwise over 15 minutes, and stirring was continued for 30 minutes at the same temperature, then 500 parts of deionized water was added under stirring. Gradually throw in.
When the addition of deionized water was completed, the system became a milky white dispersion. The average particle size of the resin particles was 0.19 μm. This dispersion (emulsion) was concentrated by a rotary evaporator to obtain an emulsified water-based paint having a solid content of 40%.

This paint was applied to an electrolytic chromic acid treated steel plate (TFC) using a roll coater, and baked at 210 ° C for 10 minutes to cure. The coating thickness was about 5 μm.

The above-mentioned coated plate was cut into a width of 5 mm, and a nylon-based adhesive was used to press for 2 minutes with a hot press heated to 200 ° C. to adhere the plate. The peel strength was measured by T-peel, and the initial peel strength immediately after adhesion and the time-dependent peel strength after immersion in warm water at 90 ° C. for 1 week were obtained.

The results are shown in Table 11 in comparison with the results of paint No. 10.

Continuation of the front page (56) Reference JP-A-60-215015 (JP, A) JP-A-59-213718 (JP, A) JP-A-61-218663 (JP, A) JP-A-62-201971 (JP , A) JP-A-63-43966 (JP, A) JP-A-63-108078 (JP, A)

Claims (7)

[Claims] 1. A thermosetting resin as a coating film-forming component containing an epoxy resin component and a curing agent resin component therefor, and a carboxyl group-containing acrylic resin as a polymer dispersant, in the form of a mixture. However, the mixture has a phase in which the carboxyl group of the acrylic resin in the mixture is simultaneously neutralized with at least one amine selected from the group consisting of alkylamines having a branched chain alkyl group and heterocyclic amine. The can is characterized in that it is emulsified by the conversion, the acrylic resin is present in an amount that gives an acid value of 2 to 30 based on the coating resin component, and at least the thermosetting resin is present in the form of an O / W emulsion. Water-based paint. 2. An epoxy resin component is a bisphenol A type epoxy resin having an epoxy equivalent of 400 to 20000 and a number average molecular weight of 1000 to 20000.
Aqueous paint for can according to the item. 3. The water-based paint for cans according to claim 1, wherein the curing agent resin is a resole-type phenol resin or an amino resin. 4. Epoxy resin and hardener resin 95: 5 to 4
The water-based can paint according to claim 1, which is contained in a weight ratio of 0:60. 5. A water-based can paint for a can according to claim 1, wherein the acid value of the acrylic resin is within the range of 35: 350 and is present in the range of 3 to 30% by weight based on the thermosetting resin. 6. An O / W type emulsion of a thermosetting resin is formed by mixing an amine-containing water with an organic solvent solution containing a thermosetting resin and an acrylic resin. Aqueous paint for cans according to claim 1. 7. An O / W emulsion of thermosetting resin is formed by kneading an amine-containing water with a melt containing a thermosetting resin and an acrylic resin. Aqueous paint for cans according to claim 1.