JPH0953027A - Antibacterial coating composition for external surface of metallic can and metallic can coated therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antibacterial coating composition for the external surface of a metallic can, which is excellent in antibacterial properties and harmlessness to the human body and excellent also in performances as an overvarnish coating material for the external surface of a can top. SOLUTION: This antibacterial coating composition for the external surface of a metallic can is an antibacterial coating composition for coating the body of a metallic can or the external surface of a can top, wherein 0.0001-20 pts.wt. antibacterial zeolite is contained per 100 pts.wt. (in terms of the nonvolatiles) film-forming resin.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to beer, coffee,
The present invention relates to an antibacterial coating composition for the outer surface of a metal can used for coating the outer surface of a metal can body or a can lid filled with beverages such as juice or food, and an antibacterial metal can obtained by coating the same.

[0002]

2. Description of the Related Art Beverage cans such as beer cans, coffee cans, juice cans, and metal cans filled with foods are housed in packaging boxes such as cardboard boxes for transportation and storage. In many cases, it is taken out from the packaging box and left as it is, or left in a shelf, a refrigerator, a vending machine or the like, opened, and then carried to the mouth as it is. For this reason, it is necessary to keep the outer surfaces of the can body and the can lid that are directly in contact with the mouth clean. In this case, safety for the human body is required even when a treatment for keeping the outer surface of the metal can clean.

The outer surface of the main body of the metal can is printed with a printing ink on a base coat usually called a white coat, and a clear coat called an over varnish is applied on the base coat. Solvent-based paints (Japanese Patent Publication No. 6-49845) and water-based paints (JP-A-6-157984, JP-A-3-76771) are used for such clear coats.
No.) and many other paints are known. These clear coats have the processability, retort resistance, adhesion to metal, wet ink suitability, appearance, slipperiness, etc. required for the external coating of the metal can body, but have antibacterial properties. Not not.

As a paint for the outer surface of the can lid, a vinyl chloride resin-based paint (JP-A-2-34648) is mainly used. The vinyl chloride resin-based paint has the processability, retort resistance, and adhesion to metal required for the paint for the outer surface of the can lid, but does not have the antibacterial property.

By the way, in Japanese Patent Publication No. 6-39495,
An antibacterial polymer to be used by mixing with a paint for the inner surface of cans such as beverage cans and food cans is described. However, when this antibacterial polymer is compounded in a clear coat paint to be used on the outer surface of a metal can, the workability required as a paint for the outer surface of the metal can,
There is a problem that suitability for wet ink, appearance, slipperiness and the like are deteriorated.

Further, Japanese Patent Laid-Open No. 63-154746 discloses that
An antibacterial film in which an antibacterial zeolite and a hygroscopic agent are dispersed in a synthetic resin is described. However, this publication does not describe blending the antibacterial zeolite with the coating material for the outer surface of the metal can.

Various antibacterial agents that can withstand the baking temperature of the coating film are known. For example, a metal having an antibacterial property (mainly silver, copper, zinc) is physically adsorbed or chemically adsorbed by an ion exchange reaction. There are inorganic antibacterial agents and the like supported by utilizing. Some inorganic antibacterial agents supporting silver ions are known, and zeolite, carbon fiber, montmorillonite which is a clay mineral, etc. are used as carriers.
However, a coating composition for the outer surface of a metal can body or a can lid, which has been imparted with antibacterial properties by blending such an inorganic antibacterial agent, has not been known so far.

[0008]

An object of the present invention is to provide an antibacterial agent for the outer surface of a metal can which is excellent in antibacterial property and safety for the human body, and which is also excellent in performance as an overburnish paint for the outer surface of a metal can or a can lid. To provide a water-borne coating composition. Another object of the present invention is to provide a metal can excellent in antibacterial property and safety for human body obtained by coating the above-mentioned antibacterial coating composition for external surface of metal can.

[0009]

The present invention provides the following antibacterial coating composition for the outer surface of a metal can and a metal can obtained by coating the same. (1) An antibacterial coating composition for coating an outer surface of a metal can body or a can lid, wherein the metal comprises 0.0001 to 20 parts by weight of antibacterial zeolite with respect to 100 parts by weight of a coating film forming resin solid content. An antibacterial coating composition for the outer surface of a can. (2) The antibacterial zeolite is a powdered antibacterial zeolite carrying one or more metal ions selected from the group consisting of silver ions, copper ions and zinc ions (1) ) An antibacterial coating composition for the outer surface of a metal can as described above. (3) The antibacterial coating composition for the outer surface of a metal can according to the above (1) or (2) is applied to the outer surface of the metal can body or the can lid,
A metal can having an antibacterial coating film formed thereon.

In the present invention, as the coating film forming resin,
The coating film forming resin that can be used on the outer surface of the metal can body or the metal can lid can be used without limitation. Specific examples include thermoplastic resins such as vinyl chloride resin, polyester resin and polyamide resin; base resins such as epoxy resin, polyester resin and fluororesin, phenol resin, amino resin, silanol compound, polyisocyanate compound or Examples thereof include thermosetting resins in which a crosslinkable component such as a polyamine compound is combined. These resins can be used alone or in combination of two or more.

Usually, the above-mentioned resin contains, if necessary, a curing accelerator, a leveling agent, a wax, a plasticizer, a filler, a pigment,
It is used as a coating composition by adding a dye or the like. Such a coating composition may be a water-based or solvent-based coating dissolved or dispersed in water and / or an organic solvent,
It may be a powder type paint which does not contain water and / or an organic solvent.

Specific examples of such a coating composition include epoxyamino-based, acrylic-based, alkyd-based, polyester-based, vinylorganosol-based, thermosetting vinyl-based and epoxyester-based coating compositions. To be Among these, epoxyamino-based, acrylic-based, alkyd-based, and polyester-based coating compositions are preferable as the coating for the outer surface of the metal can body, and vinylorganosol-based, thermosetting vinyl-based, epoxy as the coating for the outer surface of the can lid. Ester-based and polyester-based coating compositions are preferred. A commercially available product can also be used as the coating composition, and examples of the coating for the outer surface of the metal can body include RD61003 (I
CI / Paints, trademark, acrylic water-based paint), etc.
As the paint for the outer surface of the can lid, for example, Vitalure 666 (ICI ・ Pa
Ints, trademark, polyester-based solvent-based paint) and the like.

As the antibacterial zeolite used in the present invention, inorganic antibacterial zeolite in which metal ions having antibacterial properties are supported on zeolite can be used. Zeolites are generally aluminosilicates having a three-dimensionally developed skeleton structure, and are generally xM based on Al ₂ O _{3.
2 / n O · Al 2 O} 3 · ySiO 2 · zH 2 O (M is capable of ion exchange, typically a monovalent or divalent metal ion, n represents the valence of M, x, y and z of the components (Representing a molar ratio). Zeolites may be natural or synthetic.

Examples of the metal ion having antibacterial property include silver ion, copper ion, zinc ion, nickel ion, manganese ion, cobalt ion, tin ion, lead ion and bismuth ion. Among these, silver ion, copper ion and zinc ion are preferable, and silver ion is particularly preferable. These metal ions may be supported on the zeolite by one kind alone, or two or more kinds may be supported on the zeolite. The above metal ions have antibacterial activity against general bacteria, fungi, algae, yeasts, etc., and zeolites carrying such metal ions are antibacterial, antifungal, antialgal, yeast resistant, etc. It has antibacterial properties.

Inorganic antibacterial zeolite is excellent in antibacterial property even in powder form by incorporating metal ions into the skeleton structure of the zeolite, the antibacterial property lasts for a long period of time, and is excellent in safety and heat resistance.

[0016] Inorganic antibacterial zeolite has no mutagenicity or primary skin irritation, and its acute toxicity is LD.
It has been confirmed that the ₅₀ value is 5000 mg / kg or more (rat, oral) with low toxicity and high safety, and it is mixed in the paint used on the outer surface of beverage cans such as beer, coffee, juice, etc. that people directly eat. It's safe to do. Also, 55
Since it has heat resistance up to about 0 ° C, even if it is mixed with a baking-type paint for metal cans and baked (for example, 200 ° C, 90 seconds),
It remains as a solid content in the coating film without decomposing, and excellent antibacterial property is maintained for a long time.

The inorganic antibacterial zeolite can be produced by a known method, for example, silver nitrate, copper nitrate, zinc sulfate, silver sulfate, copper sulfate, silver perchlorate, copper perchlorate, zinc perchlorate, A method of supporting by an ion exchange reaction using an aqueous solution of a water-soluble salt such as silver acetate, copper acetate, zinc acetate,
It can be produced by a method of supporting the metal by physical adsorption.

As the antibacterial zeolite, commercially available products may be used. For example, Zeomic (manufactured by Shinagawa Fuel Co., Ltd.,
Trademark) and the like.

The amount of the antibacterial zeolite to be blended is 0.0001 to 20 parts by weight, preferably 0.0005 to 50 parts by weight, as anhydrous zeolite, based on 100 parts by weight of the coating film forming resin solid content.
10 parts by weight, more preferably 0.001 to 10 parts by weight. When the content of the antibacterial zeolite is in the above range, it has sufficient antibacterial properties and has performance as an overburnish paint for the outer surface of the can or the outer surface of the can lid (processability, retortability, metal and ink, etc.). A coating film having excellent adhesiveness and appearance) can be obtained.

The antibacterial coating composition of the present invention can be produced by blending the antibacterial zeolite with the finished product of the coating composition containing the coating film-forming resin and uniformly dispersing the mixture with a paint conditioner or the like. It is also possible to add antibacterial zeolite at an arbitrary timing during the production of the coating composition containing the coating film-forming resin.

The antibacterial coating composition for the outer surface of a metal can of the present invention is a beverage can such as beer, coffee or juice; an outer surface of a metal can main body or a can lid for filling food such as a food can such as a can for canning. It can be used as a paint. When the coating layer is laminated on the outer surface of the metal can body or the can lid, the antibacterial coating composition for the outer surface of the metal can of the present invention is used as a coating material for forming the outermost coating layer.

The metal material for the can body or the can lid is not particularly limited, and an aluminum plate, a TFS plate (Tin Free S
Steel plate such as steel; steel plate surface plated with zinc, tin, chromium, aluminum, etc .; steel plate surface treated with chromic acid, iron phosphate, zinc phosphate, etc .; A treated aluminum plate whose surface is treated with chromic acid, a zircon compound or the like can be used.

The antibacterial coating composition of the present invention can be applied to an object to be coated by a coating method such as roller coating, spray coating, airless spray coating, bar coater coating or dip coating. In this case, it is preferable that the film thickness is usually 3 to 100 μm. When coating on the outer surface of the main body of the beverage can or the lid of the can, it is preferable to coat the film on a film thickness of about 3 to 30 μm.

The baking of the paint can be carried out at a baking temperature and for a time suitable for the film-forming resin, and generally about 150.
~ 310 ° C, preferably about 180-290 ° C, about 5-5
It is performed for 600 seconds, preferably 7 to 300 seconds.

The coating film thus formed has excellent antibacterial properties, can inhibit the sterilization or growth of microorganisms adhering to the surface of the coating film, and is also excellent in human safety. Therefore, it is possible to maintain the cleanliness of a portion that directly touches the mouth, such as beverage cans such as coffee, beer and juice, and metal cans such as food cans, and it is safe.

The antibacterial metal can of the present invention is obtained by applying the antibacterial coating composition for external surfaces of the metal can of the present invention onto a metal material for a can main body and / or a can lid, and applying a coating film as described above. It is a formed can. Since the antibacterial coating film is formed on the metal can of the present invention, the outer surfaces of the metal can main body and the can lid are kept clean for a long period of time and are safe.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described with reference to Examples. In each example, Zeomic (trademark, manufactured by Shinagawa Fuel Co., Ltd.) was used as the antibacterial zeolite. This Zeomic is a zeolite in which a metal ion such as a silver ion, a copper ion or a zinc ion is supported by ion exchange, and has an average particle diameter of 0.6 to 2 μm and a specific surface area of about 60.
It is an antibacterial zeolite having 0 m ² / g.

Example 1 1) Preparation of antibacterial coating composition 270 parts by weight of resin for external coating of can RD61003 (trademark of ICI Paints, trademark, acrylic clear water-based coating composition, solid content 37%) (as resin solid content) To 100 parts by weight), 0.001 part by weight of Zeomic as an antibacterial zeolite was dispersed with a paint conditioner to prepare an antibacterial coating composition. This antibacterial coating composition was applied to an aluminum plate (JIS H5052 material, 0.3 mm) with a bar coater and then baked at 200 ° C. for 4 minutes to form a 7 μm coating film. This aluminum plate was cut into a piece of 3 cm × 3 cm, and this was used as a test piece to perform the following antibacterial test.

2) Antibacterial Property Test The antibacterial property was tested as follows. 2-1) Test bacteria As test bacteria, Aspergillus niger Cladosporium cladosporioides Gliocladium virens Penicillium funiculosum and Aureobasidium pullu
A bacterium mixed with lans was used.

2-2) Preparation of Bacterial Mixture Dioctyl sodium sulfosuccinate was dissolved in water to a concentration of 0.005% by weight. 200 ml of this solution was placed in a 300 ml Erlenmeyer flask and then sterilized by an autoclave. One platinum loop of the spores of the test bacterium in which the above-mentioned bacterium was mixed was sampled and shaken well to sufficiently disperse the spores. Next, this was passed through a filter paper that had been sterilized by dry heat to remove the insoluble matter to obtain a bacterial mixture. This bacterium mixture was sealed in a sterilized 300 ml Erlenmeyer flask until the following test was carried out to prevent bacterium contamination.

2-3) Test procedure The test piece of 1) above is attached to the center of the PDA plate medium in a petri dish, and 1 ml of the bacterial mixture solution of 2-2) above is evenly spread over the surface of the medium and the surface of the test piece. Then, the dish was put on the dish, and the dish was placed in a constant temperature bath adjusted to 28 ± 2 ° C. and cultured for one week. Then, the antibacterial property was visually evaluated according to the evaluation criteria in Table 1. Table 2 shows the results of tests repeated three times. The PDA plate medium was potato dextrose agar 3
After dissolving 9 g in 1000 ml of distilled water, it was sterilized by an autoclave and poured into a petri dish to be solidified.

[0032]

[Table 1]

Example 2 Example 2 was repeated except that the amount of Zeomic was changed to 10 parts by weight. Table 2 shows the results.

Comparative Example 1 The can outer surface paint RD6100 without the addition of Zeomic.
A test piece was obtained in the same manner as in Example 1 except that 3 was used alone. Using this test piece, an antibacterial test was conducted in the same manner as in Example 1. Table 2 shows the results.

Example 3 Paint for external surface of can lid Vitalure666 (trademark, manufactured by ICI Paints Co., Ltd.)
Polyester solvent type clear coating composition, solid content 30
%) 333 parts by weight (100 parts by weight as a resin solid content), and the above Zeomic 0.0 as an antibacterial zeolite.
02 parts by weight were dispersed with a paint conditioner to prepare an antibacterial coating composition. This antibacterial coating composition was applied to the same aluminum plate as in Example 1 by a bar coater and then baked at 280 ° C. for 25 seconds to form a 7 μm coating film. This aluminum plate was cut into a piece of 3 cm × 3 cm, and this was used as a test piece to perform an antibacterial test in the same manner as in Example 1. Table 2 shows the results.

Example 4 Example 4 was repeated except that the amount of Zeomic was changed to 5 parts by weight. Table 2 shows the results.

Comparative Example 2 The above-mentioned paint Vita for the outer surface of the can lid without the addition of Zeomic
A test piece was obtained in the same manner as in Example 3 except that lure666 was used alone. Using this test piece, an antibacterial test was conducted in the same manner as in Example 3. Table 2 shows the results.

[0038]

[Table 2]

Example 5 Using the same test piece as in Example 1, the antialgal property was tested as follows. That is, the test piece was attached to the center of the Dettmel medium, and 1 ml of a mixed solution of green algae, cyanobacteria and diatom
Was evenly sprinkled on the surface of the medium and the surface of the test piece, covered with a Petri dish lid, and cultured in a room (25 ° C.) sufficiently exposed to sunlight for 4 weeks. Then, the anti-algal property was visually determined according to the evaluation criteria in Table 1. Table 3 shows the results of tests repeated three times. The composition of Detmel medium is as follows. Dettomeru _{medium: Ca (NO 3) 2 ·} 4H 2 O; 1.0g MgSO 4 · 7H 2 O; 0.25g KCl; 0.25g KH 2 PO 4; 0.25g FeCl 3; traces of agar; 15 g distilled water; 1000 ml

Examples 6 to 8 and Comparative Examples 3 to 4 In Example 5, except that the test piece of Example 1 was replaced by a test piece similar to those of Examples 2 to 4 and Comparative Example 1 or 2. The same procedure as in Example 5 was performed. The results are shown in Table 3.

[0041]

[Table 3]

[0042]

The antibacterial coating composition for the outer surface of a metal can of the present invention contains a specific amount of antibacterial zeolite, and therefore has excellent antibacterial properties and safety to the human body, and is an overburnish paint for the outer surface of a can. Is also excellent in performance. Since the metal can of the present invention is coated with the above-mentioned antibacterial coating composition, the outer surfaces of the metal can body and the can lid are kept clean for a long period of time and are safe.

Claims (3)

[Claims] 1. An antibacterial coating composition for coating an outer surface of a metal can body or a can lid, wherein the antibacterial zeolite is contained in an amount of 0.0001 to 20 parts by weight based on 100 parts by weight of a solid content of a film forming resin. Antibacterial coating composition for external surfaces of metal cans. 2. The antibacterial zeolite is a powdered antibacterial zeolite carrying one or more metal ions selected from the group consisting of silver ions, copper ions and zinc ions. Item 1. An antibacterial coating composition for the outer surface of a metal can according to Item 1. 3. A metal can, wherein the antibacterial coating composition for the outer surface of a metal can according to claim 1 or 2 is applied to the outer surface of a metal can body or a can lid to form an antibacterial coating film.