JPH0718208A - Water-based antibacterial coating material and production thereof - Google Patents

Abstract

PURPOSE:To provide a novel water-based coating material which is self- emulsifiable and self-curing, is excellent in water resistance, heat resistance and hygienic quality, and can reveal an excellent antibacterial effect. CONSTITUTION:A water-based antibacterial coating material having a novel structure and obtained by incorporating under a pH of 7.5 to 9 a water-soluble antibacterial metal salt into a water-base coating material based on a carboxylated acrylic resin neutralized to form an ammonium salt or an amine salt, wherein the concentration of the water-soluble antibacterial metal salt is 0.05-10mmol/100g of the coating material solids.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antibacterial water-based paint and a method for producing the same, and more specifically, a novel antibacterial water-based paint excellent in dispersion stability in water, water resistance, heat resistance and various physical properties of coating film. Antibacterial water-based paint and its manufacturing method.

[0002]

2. Description of the Related Art Conventionally, in the production of cans for canning, various paints were coated on the metal material or the can itself in order to prevent the elution of metal into the contents and to prevent corrosion of the metal.
When an organic paint is used, there is a problem that the working environment is polluted by the volatilization of the solvent. As a solution to such problems, water-based paints that do not use organic solvents are used. As such an aqueous paint, an epoxy resin and its curing agent resin dispersed in water using an anionic or nonionic surfactant have been used, but these have a problem in dispersion stability. At the same time, there is a problem of gelation during storage, and when a large amount of surfactant is used from the viewpoint of dispersibility and storage stability, the surfactant migrates from the formed coating film into the contents. However, there is a problem in that it has an adverse effect on the chemical and mechanical properties of the coating film itself.

Therefore, a self-emulsifying water-based coating material that does not use an emulsifier is desired, and a coating material having a functional group such as an epoxy resin is modified by reacting it with a resin having a carboxyl group such as an acrylic resin. However, a self-emulsifying water-based coating composition has been proposed in which the modified resin is neutralized with ammonia or amines to be self-emulsified in an aqueous medium (JP-A-59-213718).

On the other hand, in a can body containing food and drink, in order to prevent spoilage and deterioration of the contents due to various bacteria,
It is desired that such various paints have antibacterial properties. Particularly in a beverage can, since the drinking mouth is exposed to the outside air, various bacteria are liable to adhere, and such a demand is great from the viewpoint of improving hygiene.

As the antibacterial material, materials containing metal ions such as silver ions, copper ions and zinc ions have been known so far. For example, silver acrylate and / or silver methacrylate is contained as a structural unit. Polymer (Japanese Patent Publication No. Sho 58-43123), a thermomeltable thermoplastic copolymer containing a unit composed of ethylenically unsaturated carboxylic acid or its anhydride, and a polymer composed of silver oxide are known. There is. In order to use these antibacterial polymers in paints, they are used by being dispersed in various paints as powders, but in this case, the antibacterial polymer cannot be sufficiently dispersed, and particularly water-based paints are used. In, the precipitation occurs.

As a solution to such a problem, there is known an antibacterial material composed of a polymer substance containing melamine and / or a melamine derivative and a carboxyl group and containing an antibacterial metal ion chemically bonded to both. (Japanese Patent Publication No. 56-3325).

[0007]

However, even in the above antibacterial material, an emulsifier must be used to obtain an emulsion. Thus, in the water-based paint using the emulsifier, the formed coating film has a problem in hygienic properties and flavor retention, and there is a disadvantage that the chemical and mechanical properties of the coating film itself are adversely affected. Of. Even if it can be formed as a coating film, it is inferior in water resistance and heat resistance due to poor curability, and it is not sufficiently satisfactory as a coating material.

Therefore, an object of the present invention is to provide a novel water-based paint which has self-emulsifying property and self-curing property, is excellent in water resistance, heat resistance and hygienic properties and can exert an excellent antibacterial effect. is there.

[0009]

According to the present invention, an acrylic resin-based water-based paint containing a carboxyl group neutralized in the form of an ammonium salt or an amine salt has a pH of 7.5 to 9.
There is provided a method for producing an antibacterial water-based paint, which comprises adding a water-soluble antibacterial metal salt under the conditions of. According to the present invention, an acrylic resin-based water-based paint containing a carboxyl group neutralized in the form of an ammonium salt or an amine salt is also added with p
An aqueous paint obtained by adding a water-soluble antibacterial metal salt under the conditions of H7.5 to 9, wherein the water-soluble antibacterial metal salt is contained in a concentration of 0.05 to 10 mmol per 100 g of the solid content of the paint. An antibacterial water-based coating composition is provided.

[0010]

In the present invention, when a water-soluble antibacterial metal salt is added to an acrylic resin-based water-based paint containing a carboxyl group neutralized in the form of an ammonium salt or an amine salt under the conditions of pH 7.5 to 9, A novel antibacterial water-based paint different from conventional antibacterial water-based paints in which the antibacterial metal is uniformly dispersed in the paint without precipitation and the coating film obtained from this paint has excellent heat resistance and water resistance. Is obtained. It is still unknown whether the antibacterial water-based paint of the present invention has the above-mentioned excellent performance due to the structure, but according to the experiments of the present inventors, the antibacterial water-based paint of the present invention is It is clear that its structure is different from that of the antibacterial material containing the carboxyl group. That is, generally, in an antibacterial material containing a carboxyl group, the carboxyl group is neutralized by a water-soluble metal salt, and the carboxyl group is in a state in which the ions of the antibacterial metal are carried. In water-based paints, carboxyl groups are not neutralized by antibacterial metals.

This means that water is added to the acrylic resin-based water-based paint.
Aqueous paint with a soluble silver salt added dropwise, and in the presence of amines
Water-based paint in which a water-soluble silver salt is added dropwise to a kuriru resin-based water-based paint
To investigate the infrared absorption spectrum (IR) of
Better understood. That is, in the former water-based paint
As shown in Fig. 1, the peak of silver acrylate (1600 cm ^-1
(Near) and silver ions are supported on the carboxyl group.
You can see that it is in the state of being
As shown in Figure 2, the peak for silver acrylate
Is not found, and the silver ion is carried by the carboxyl group.
It is not in a standing state. Thus, the
Bacterial water-based paint has a completely different structure from conventional antibacterial materials
Has an antibacterial metal that does not contain an emulsifier
Can be evenly dispersed in the paint without settling
It becomes Noh.

[0012]

Preferred Embodiment of the Invention

(Preparation of acrylic resin-based water-based paint) The acrylic resin-based water-based paint used in the present invention is a composition containing an epoxy resin component and a carboxyl group-containing acrylic resin component,
Further, a composition comprising an epoxy resin component, a curing agent resin component for the epoxy resin, and a carboxyl group-containing acrylic resin is particularly preferable. Since the epoxy resin component of these compositions is chemically bonded to the acrylic resin, the resulting coating film is stable and has excellent water resistance and heat resistance. Furthermore, since the epoxy group remains at the terminal, it is possible to obtain a coating film having self-crosslinking property and excellent physical properties in combination with the film forming ability of the acrylic resin.

The epoxy resin component and the curing agent resin component therefor are the resin components usually used in can coatings, and are capable of forming a coating film excellent in water resistance, hot water resistance and adhesion to metal. It makes it possible. On the other hand, the carboxyl group-containing acrylic resin is itself a coating film forming resin component and also has a function as a dispersant for emulsifying and dispersing an epoxy resin component and a curing agent resin component.
This self-emulsifying and dispersing action is possible when the carboxyl group in the acrylic resin is ammonium salt or amine salt.

In the present invention, when a compound containing a curing agent resin is used, the advantage that the curing performance is excellent is achieved, and the cured coating film to be formed contains an epoxy resin or acrylic resin component. It is completely crosslinked and cured, and this cured product has the curing agent resin incorporated into the continuous matrix of the coating film by a chemical reaction, so even if it is subjected to high temperature hot water treatment such as retort sterilization, the coating film will be whitened or The advantage of preventing pouring from is also achieved.

The acrylic resin-based water-based paint can be prepared by a method known per se except that the carboxyl group of the acrylic resin is neutralized with an ammonium salt or an amine salt. For example, an epoxy resin component and an acrylic resin component are reacted to form an acrylic resin / epoxy resin partial reaction product having a carboxyl group excess, and the pH of the final composition of the acrylic resin / epoxy resin partial reaction product is 7 to 9, particularly Ammonia or amine in an amount of 7.5 to 8.5 is added and dispersed in the aqueous medium. In this case, the ratio of the epoxy resin component to the carboxyl group-containing acrylic resin component in the paint is preferably 1: 1 to 10: 1, particularly 2: 1 to 9: 1.
Needless to say, a hardener resin component can be added to this coating material if necessary. The compounding amount of the curing agent resin component is preferably in the range of 1 to 20% by weight, particularly 2 to 10% by weight based on the total amount of the epoxy resin component and the carboxyl group-containing acrylic resin component.

In addition to the above-mentioned method, when a hardener resin component is blended, a so-called conversion method is used in which ammonia water or amine-containing water is mixed with an organic solvent solution containing an epoxy resin component, a hardener resin component and an acrylic resin. Can be prepared in. Also, instead of using the above three-component organic solvent solution, a molten mixture thereof can be used. When ammonia water or amine water is added to the organic solvent solution or melt containing the above resin component, the viscosity of the system increases at the initial stage of addition, but the viscosity of the system gradually decreases as the addition continues. start. If the addition is interrupted at this stage and the whole system is homogenized by stirring and the addition of aqueous ammonia or amine water is continued again, the viscosity of the system sharply decreases by the addition of a predetermined amount of aqueous ammonia or amine water. At the initial stage of adding ammonia water or amine water to the resin solution, the aqueous phase exists in the form of a dispersed phase, but at the stage where the viscosity of the system is drastically decreased, the aqueous phase containing the specific resin component is continuously formed. The O / W type emulsion in which the (dispersion medium) phase and the specific other resin component become the dispersion phase is stably generated.

The epoxy resin component in the paint is 20 to 95% by weight, especially 40 to 90% by weight, and the curing agent resin component is 2 to 30% by weight, especially 5 to 20% by weight, based on the three components.
And the acrylic resin component containing a carboxyl group is 10 to 6
It is preferably present in an amount of 0% by weight, especially 15 to 50% by weight.

(Preparation of antibacterial water-based paint) In the present invention
Is an ammonium salt or amine salt as described above.
Acrylic resin-based water containing carboxyl groups neutralized into shape
PH of 7.5 to 9, especially pH 7.7 to 8.
By adding a water-soluble antibacterial silver salt under the conditions of 5
Prepare antibacterial water-based paint. PH conditions outside this range
When water-soluble antibacterial metal salt is added below, its composition becomes clear.
Notwithstanding, precipitation will occur. Sanawa
Then, if the pH becomes 7.5 or less during the addition of the water-soluble silver salt,
A milky white precipitate appears to be high in fat, while
If you add a water-soluble silver salt to a paint with a pH of 9 or more, you can instantly
A black precipitate forms, which in each case is no longer water-based
I can't keep my form. pH adjustment
Depending on the amines added when preparing the resin-based water-based paint
Can be adjusted by adding an antibacterial metal.
It is also possible to add nitric acid or the like to adjust the temperature. Anti
The fungal metal is 100 g of solid content of acrylic resin water-based paint.
Is present in an amount of 0.05 to 10 mmol, preferably 0.1.
Excellent coating when the amount is in the range of 5 to 5 mmol
It is possible to impart antibacterial properties. That is,
If the amount of antibacterial metal is less than the above range, excellent antibacterial effect will be produced.
The amount of antibacterial metal is more than the above range.
Even if the antibacterial effect is the same, the antibacterial silver salt aqueous
The stability of the paint over time is lost.

(Epoxy Resin Component) As the epoxy resin, a bisphenol type epoxy resin obtained by polycondensation of bisphenols such as bisphenol A and epihalohydrin is suitable, and its epoxy equivalent is generally 4
00 to 20000, especially 1000 to 5000, and its number average molecular weight is 1000 to 20000,
Those in the range of 2000 to 13000 are particularly preferable.

(Acrylic resin component) The acrylic resin component to be used preferably has an acid value of generally 1 to 400, especially 5 to 350. Among these, the solvent type is 1
Although it may have a relatively low acid value of 1 to 150, in the case of the self-emulsifying type, since excess carboxyl groups other than the silver salt form become ammonium salts or amine salts, self-emulsifying property occurs, Those having a relatively high acid value of 30 to 400 are preferable.

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 that gives a carboxyl group having the above-mentioned acid value to the resin, an acrylic acid ester or a methacrylic acid ester, and other ethylene type copolymerizable with them. It consists of a copolymer with an unsaturated monomer. As the ethylenically unsaturated carboxylic acid or its anhydride, methacrylic acid, acrylic acid, crotonic acid, itaconic acid, fumaric acid,
Maleic acid, maleic anhydride, itaconic anhydride and the like can be mentioned, and these can be used alone or in combination of two or more kinds.

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

Other comonomers copolymerized with these monomers include styrene, vinyltoluene, acrylonitrile, methacrylonitrile, acrylamide and the like.

The weight average molecular weight of the acrylic resin used is generally 5,000 to 200,000, and particularly 10,000.
It is desirable to have a molecular weight within the range of 150,000. Examples of suitable combinations of acrylic copolymers are:
(1) Methyl methacrylate / 2-ethylhexyl acrylate / acrylic acid, (2) Styrene / Methyl methacrylate /
Examples are ethyl acrylate / methacrylic acid, (3) styrene / ethyl acrylate / 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.

(Curing Agent Resin Component) The curing agent resin component used in the present invention forms a cured product with an epoxy resin, and is not limited to this, but a methylol group such as a phenol resin or an amino resin is used. A resin containing an etherified methylol group can be preferably used. As the phenol resin, a resol type phenol resin or an etherified product thereof is used. This resol-type phenol resin contains a phenol such as p-substituted phenol and formaldehyde or a functional derivative thereof in the presence of an alkali metal catalyst or an alkaline earth metal catalyst at a ratio of 2 mol or more of formaldehyde per 1 mol of the phenol. It is obtained by reacting and etherifying if necessary. The resol type phenol resin used is generally 200
It is preferable to have a number average molecular weight of 1 to 1500, particularly 250 to 1300.

As the amino resin, melamine-formaldehyde resin, benzoguanamine-formaldehyde resin, urea-formaldehyde resin and the like are used. These resins are preferably etherified with alcohols such as ethanol and butanol. This amino resin can be obtained by reacting a corresponding nitrogen-containing compound with formaldehyde or a functional derivative thereof in the presence of an alkali metal catalyst or an alkaline earth metal catalyst and, if necessary, etherification. The amino resin used is generally 2
It preferably has a number average molecular weight of 00 to 2000, particularly 250 to 1500.

(Antibacterial Metal) Examples of the water-soluble antibacterial metal salt include silver salts such as silver nitrate and silver acetate, copper salts such as copper chloride, copper sulfate, copper nitrate and copper acetate, zinc chloride and zinc sulfate. , And zinc salts such as zinc nitrate and zinc acetate may be used alone or in combination of two or more kinds. Among them, silver is particularly preferable because it has excellent antibacterial activity.

(Organic solvent solution) As an organic solvent containing an epoxy resin component, a curing agent resin component and an acrylic resin, an aromatic hydrocarbon solvent such as toluene or xylene;
Ketone solvents such as acetone, methyl ethyl ketone, meryl isobutyl ketin, cyclohexanone; ethanol,
Alcohol solvents such as propanol and butanol; cellosolve solvents such as ethyl cellosolve and butyl cellosolve; ester solvents such as ethyl acetate and butyl acetate 1
One kind or two or more kinds can be used. The concentration of the resin component in the raw material solution is generally 5 to 80% by weight, particularly 20 to 7%.
It is preferably in the range of 0% by weight. This raw material solution contains
If desired, known compounding agents for paints such as plasticizers, lubricants, pigments, fillers, stabilizers and the like may be added.

(Amines) Examples of amines used for neutralizing acrylic resin-based paint include alkylamines such as trimethylamine, triethylamine and butylamine;
Alcohol amines such as dimethylaminoethanol, diethanolamine, triethanolamine, aminomethylpropanol, and morpholine are used. Also, polyamines such as ethylenediamine and diethylenetriamine can be used. Ammonia and amines are preferably used in an amount of 0.3 to 1.3 chemical equivalents to the carboxyl group of the acrylic resin.

The amount of the aqueous medium used for the phase inversion varies depending on the type of resin and the concentration of the raw material solution, but is generally 0.5 to 2.0 times by weight, particularly 0.7 to 1.5 times the weight of the raw material solution. It is recommended to use twice the weight of water. Mixing the resin solution with ammonia or amine water is sufficient at room temperature,
If desired, the temperature may be increased to about 100 ° C.
The addition and mixing can be carried out in a reaction tank equipped with an ordinary stirrer, but if desired, a high shear stirring device such as a homomixer can be used, or irradiation with ultrasonic vibration can be used. Both the water and the organic solvent are contained in the aqueous dispersion obtained by the phase inversion. By subjecting this aqueous dispersion to azeotropic distillation under reduced pressure, 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 supplementing water from the outside.

The concentration of the coating resin solid content in the final water-based paint is preferably 10 to 70% by weight, particularly 20 to 60% by weight, and the content of the organic solvent in the water-based coating is 15% by weight or less. It is particularly desirable that the amount is 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 1
0 to 100,000 centipoise, especially 100 to 30
It is suitable to be in the range of 000 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 15
It is suitable to be 0 ° C., particularly 20 to 120 ° C., and if it is higher than the above temperature range, partial gelation or premature gelation 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 the organic solvent used is suitably 30% by weight or less, particularly 15% by weight or less, based on the resin content. 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, a Banbury mixer, a 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.

In the present invention, the aqueous medium means water alone having at least 10% by weight or more of water or a mixture with a hydrophilic organic solvent, and examples of the hydrophilic organic solvent include methanol, ethanol, n-propanol and isopropanol. , N-butanol, sec-butanol, isobutanol, and other alkyl alcohols, methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, methyl carbitol, ethyl carbitol, and other ether alcohols, methyl cellosolve acetate, ethyl cellosolve acetate, etc. Other ether esters of dioxane, dimethylformamide, diacetone alcohol, tetrahydrofurfuryl alcohol and the like are used.

The antibacterial water-based paint according to the present invention is known per se after being directly applied to a metal plate such as a tin plate, an aluminum plate, a treated steel plate or the like, or after an undercoat is applied thereto, or after the metal plate is molded. In addition to being used for brush coating, spray coating and electrostatic coating, it can be used for roller coating, brush coating, coating with various coaters such as a doctor coater, an air knife coater and a reverse coater. Even if the formed coating film is washed with water, the antibacterial metal does not fall off,
Antibacterial effect continues.

[0035]

INDUSTRIAL APPLICABILITY The water-based paint of the present invention can be suitably used especially as a can-making paint. By applying it not only to the inner surface of the can but also to the outer surface, the contents can be effectively prevented from rotting or deteriorating. Especially, there is a possibility that bacteria and the like will adhere to the outer surface exposed to the outside air, so that the bacteria and the like are prevented from growing and the bacteria and the like are mixed in the contents. When attached, it is possible to prevent bacteria and the like from entering the mouth. Further, even when stored in a refrigerated state, the coating film made of the antibacterial water-based paint of the present invention has excellent water resistance, so that the antibacterial performance is stably maintained for a long period of time. In addition, antibacterial water-based paints containing a hardener resin component have excellent curing performance, and even when the formed cured coating film is subjected to high temperature hot water treatment such as retort sterilization, it causes whitening or coating. The pouring from the membrane is effectively prevented.

[0036]

EXAMPLES The present invention will be described in more detail below with reference to examples. Example 1 (Preparation of Acrylic Resin Solution Containing Carboxyl Group) (1) Methacrylic acid 48 parts Styrene 24 parts Methyl methacrylate 24 parts Ethyl acrylate 24 parts Benzoyl peroxide 2 parts (2) Butylcellosolobe 200 parts n-Butanol 80 parts 4 mouths Charge the flask with 1/4 of (1) and the whole amount of (2),
After the temperature was raised to 110 ° C., the remaining amount of (1) was dropped into the flask over 2 hours. After the dropping is completed, the inside of the flask is kept at 11
The temperature was kept at 0 ° C. to obtain an acrylic resin. The weight average molecular weight of the resin was about 50,000 and the acid value was 250.

(Preparation of Phenolic Resin Solution) 108 g of p-cresol, 324 aqueous 37% formaldehyde solution
g, and mixed with 133 g of a 30% sodium hydroxide aqueous solution,
After reacting at 50 ° C. for 2 hours, the temperature is raised to 70 ° C., and the reaction is continued at this temperature for 4 hours. Then, it is diluted with a double amount of water, cooled to room temperature, and then neutralized in a 15% aqueous acetic acid solution. The generated precipitate was collected by filtration and washed with water to obtain a pale yellow powder. The number average molecular weight of this product was about 250. This pale yellow powder was mixed with a mixed solvent (40 parts of methyl isobutyl ketone, 20 parts of xylene).
Parts, cyclohexanone 20 parts, methyl isobutyl carbitol 10 parts, methyl ethyl ketone 10 parts) and a solid content of 3
It was dissolved so as to be 0% to obtain a phenol resin solution.

(Preparation of water-based paint) 400 parts of Epicoat 1009 and butyl cellosolve 200 were placed in a four-necked flask.
Parts, 300 parts of n-butanol and 100 parts of xylene were added and heated to 50 ° C. to completely dissolve the epoxy resin.
The epoxy resin solution is mixed with the phenol resin solution such that the epoxy resin / phenol resin is 95/5 in terms of solid content, and the acrylic resin solution is 80/20 epoxy resin / acrylic resin in terms of solid content. As mixed. After holding the mixed liquid at 110 ° C. for 2 hours, the liquid temperature was lowered to 80 ° C. and 25 parts of dimethylethanolamine was mixed. This mixed solution was kept at 80 ° C. for 30 minutes to obtain an acrylic resin / epoxy resin partial reaction product. 2000 g of ion-exchanged water was added dropwise to this resin solution with high speed stirring to obtain an aqueous dispersion. The obtained dispersion was distilled under reduced pressure at 50 ° C. to remove a part of the solvent, and ion-exchanged water was added again to obtain an aqueous coating material having a solid content of 30%. The pH of the paint was 7.9. (Preparation of antibacterial water-based paint) To 500 parts of the above-mentioned water-based paint, an aqueous silver nitrate solution having a concentration of 0.05 mol / liter was dropped. The pH of the paint was 7.8 and no precipitation was observed.

Example 2 An aqueous silver acetate solution having a concentration of 0.05 mol / liter was added dropwise to 500 parts of the aqueous coating material having a pH of 7.9 prepared in Example 1.
The pH of the paint was 7.8 and no precipitation was observed.

Comparative Example 1 500 parts of the antibacterial water-based coating material prepared in Example 1 was added with a concentration of 0.
Further, 90 parts of a 05 mol / liter silver nitrate aqueous solution was added dropwise. The pH of the paint was 7.4, and a large amount of milky white precipitates were formed.

Comparative Example 2 A water-based paint having a pH of 7.9 prepared in Example 1 had a concentration of 0.0.
The pH was adjusted to 7.3 by the dropwise addition of 5 mol / liter dilute nitric acid. To 500 parts of this water-based paint, 30 parts of a 0.05 mol / liter silver nitrate aqueous solution was dropped. The pH of the paint was 7.2, and a large amount of milky white precipitates were formed.

Example 3 To the aqueous paint of pH 7.9 prepared in Example 1, dimethylethanolamine was further added to adjust the pH of the aqueous paint to 8.6. Concentration 0.05 mol / in 500 parts of this water-based paint
30 parts of an aqueous silver nitrate solution was added dropwise. PH of paint
Was 8.5, but no precipitation was observed.

Comparative Example 3 The pH of the aqueous paint was adjusted to 9.2 by further adding dimethylethanolamine to the aqueous paint of pH 7.9 prepared in Example 1. Concentration 0.05 mol / in 500 parts of this water-based paint
30 parts of an aqueous silver nitrate solution was added dropwise. With this paint, a black precipitate was formed at the same time when the aqueous silver nitrate solution was dropped.

Example 4 400 parts of Epicoat 1009, 200 parts of butyl cellosolve, 300 parts of n-butanol and 100 parts of xylene were placed in a four-necked flask and heated to 50 ° C. to completely dissolve the epoxy resin. The phenol resin solution prepared in Example 1 was mixed with the epoxy resin solution so that the epoxy resin / phenol resin was 90/10 in terms of solid content, and 110
Hold at 2 ° C for 2 hours. After cooling this resin solution to room temperature, the acrylic resin used in Example 1 was mixed so that the epoxy resin / acrylic resin ratio would be 80/20 in terms of solid content. While stirring this resin solution at high speed using a homogenizer, 28 parts of 28% ammonia water was added, and further 1200 parts of ion-exchanged water was gradually added to obtain an O / W type emulsion. This emulsified dispersion was distilled under reduced pressure at 50 ° C. to remove a part of the solvent, and then ion-exchanged water was added,
An aqueous paint having a solid content of 30% was obtained. The pH of the water-based paint is 8.
It was 7. To 500 parts of this water-based paint, 90 parts of a 0.05 mol / liter silver nitrate aqueous solution was dropped. P of paint
H was 8.4, but no precipitation was observed.

Example 5 To 500 parts of the aqueous coating material having a pH of 8.6 prepared in Example 3, 30 parts of a 0.5 mol / liter silver nitrate aqueous solution was dropped. The pH of the paint was 7.7, but some fine black precipitate was observed in the paint.

Example 6 To 500 parts of the aqueous coating composition having a pH of 7.9 prepared in Example 1 was added dropwise 9 parts of an aqueous silver nitrate solution having a concentration of 0.05 mol / liter. The pH of the paint was 7.9, which was unchanged and no precipitation was observed.

Example 7 To 500 parts of the aqueous paint having a pH of 7.9 prepared in Example 1 was added dropwise 30 parts of an aqueous solution of silver acetate having a concentration of 0.005 mol / liter. The pH of the paint was 7.9, which was unchanged and no precipitation was observed.

Comparative Example 4 To 500 parts of the aqueous coating composition having a pH of 7.9 prepared in Example 1, 9 parts of an aqueous solution of silver nitrate having a concentration of 0.005 mol / liter was dropped. The pH of the paint was 7.9, which was unchanged and no precipitation was observed.

Comparative Example 5 An aqueous paint was prepared in the same manner as in Example 1 except that the silver nitrate aqueous solution was not added dropwise. Comparative Example 6 An aqueous coating material was prepared in the same manner as in Example 4 except that the silver nitrate aqueous solution was not added dropwise.

The antibacterial effect of the water-based paints of the above Examples and Comparative Examples was examined by the following method. In addition, Comparative Examples 1 to 3
With regard to the paint of, it cannot be painted due to precipitation,
The antibacterial effect could not be investigated. (Preparation of Painted Plate for Antibacterial Property Evaluation) Each of the aqueous paints of Examples and Comparative Examples was applied to a TFS plate by a # 14 bar coater, and baked and cured at 200 ° C. for 1 minute in a gas oven. The obtained coated plate was cut into a piece of 5 cm × 5 cm, and the cut edge portion was corrected with the paint of Comparative Example 1, and then the piece was again cut into 2 pieces.
Baking was performed at 00 ° C. for 1 minute to cure the coating material on the cut edge portion. After this 5 cm × 5 cm coating test piece was subjected to retort sterilization treatment (130 ° C.-30 minutes), the antibacterial effect was evaluated using Escherichia coli.

(Antibacterial Evaluation Test) Escherichia
coli IAM 1239) suspension and test bacteria number 2-4x
Dilution was prepared so as to be 10 6 cells / ml. 0.1 ml of this test bacterial solution was dropped onto a retort-treated 5 × 5 (cm ² ) cut coated plate and allowed to act at 37 ° C. for 24 hours while being held. 24 hours later, sterilized saline 3
After washing with 0 ml, the number of surviving bacteria in the washing solution was measured by a membrane filter method. The culture was carried out at 37 ° C. for 24 hours using a broth medium for general bacteria (manufactured by Nissui Pharmaceutical Co., Ltd.). Table 1 shows the properties of the paint and the results of evaluation of antibacterial properties. In the evaluation of antibacterial properties in Table 1, ◯: number of gold after action / initial number of bacteria <10 ^-2 Δ: 10 ^-2 ≤ number of bacteria after action / initial number of bacteria <10 ^-1 ×: 10 ^-1 ≤ action Subsequent bacterial count / initial bacterial count.

[0052]

[Table 1]

[Brief description of drawings]

FIG. 1 is a chart of infrared absorption spectrum (IR) of a water-based paint obtained by dropping water-soluble silver on an acrylic resin-based water-based paint under the absence of amines.

FIG. 2 is a chart of infrared absorption spectrum (IR) of a water-based paint obtained by dropping water-soluble silver on an acrylic resin-based water-based paint in the presence of amines.

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[Procedure amendment]

[Submission date] July 12, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

(Preparation of water-based paint) 400 parts of Epicoat 1009 and butyl cellosolve 200 were placed in a four-necked flask.
Parts, 300 parts of n-butanol and 100 parts of xylene were added and heated to 50 ° C. to completely dissolve the epoxy resin.
The epoxy resin solution is mixed with the phenol resin solution such that the epoxy resin / phenol resin is 95/5 in terms of solid content, and the acrylic resin solution is 80/20 epoxy resin / acrylic resin in terms of solid content. As mixed. After holding the mixed liquid at 110 ° C. for 2 hours, the liquid temperature was lowered to 80 ° C. and 25 parts of dimethylethanolamine was mixed. This mixed solution was kept at 80 ° C. for 30 minutes to obtain an acrylic resin / epoxy resin partial reaction product. 2000 g of ion-exchanged water was added dropwise to this resin solution with high speed stirring to obtain an aqueous dispersion. The obtained dispersion was distilled under reduced pressure at 50 ° C. to remove a part of the solvent, and ion-exchanged water was added again to obtain an aqueous coating material having a solid content of 30%. The pH of the paint was 7.9. (Preparation of antibacterial water-based paint) To 500 parts of the above-mentioned water-based paint, 30 parts of an aqueous solution of silver nitrate having a concentration of 0.05 mol / liter was dropped. The pH of the paint was 7.8 and no precipitation was observed.

[Procedure amendment 0]

[Document name to be amended] Statement

[Correction target item name] 0039

[Correction method] Change

[Correction content]

Example 2 To 500 parts of the water-based paint having a pH of 7.9 prepared in Example 1, 30 parts of an aqueous solution of silver acetate having a concentration of 0.05 mol / liter was dropped. The pH of the paint was 7.8 and no precipitation was observed.

Claims (2)

[Claims] 1. A water-soluble antibacterial metal salt is added to an acrylic resin-based water-based paint containing a carboxyl group neutralized in the form of an ammonium salt or an amine salt under conditions of pH 7.5 to 9. Antibacterial water-based paint manufacturing method. 2. An aqueous solution obtained by adding a water-soluble antibacterial metal salt to a water-borne acrylic resin coating containing a carboxyl group neutralized in the form of an ammonium salt or an amine salt under conditions of pH 7.5 to 9. An antibacterial water-based paint, characterized in that the water-soluble antibacterial metal salt is contained in a concentration of 0.05 to 10 mmol per 100 g of the solid content of the paint.