JPH11278866A - Antibacterial treatment of glass vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out uniform ion exchange to generate no unevenness in coating and to obtain a glass vessel capable of being easily washed with water even if contamination occurs, free from coloring and excellent in antibacterial activity by coating the inner surface of a glass vessel with an aq. soln. contg. silver nitrate and a surfactant and heat-treating the vessel at a temp. at which the ion exchange of alkali metal ions in the surface layer of the vessel for Ag ions is caused. SOLUTION: Silver nitrate has high solubility to water, gives a high concn. uniform soln. and prevents the reduction coloring of silver by its high oxidizing power. The concn. of the silver nitrate used is 5-25 wt.%. The surfactant sufficiently reduces the surface tension of the aq. soln. for ion exchange and enables uniform coating. The concn. of the surfactant used is 0.1-2 wt.%. An organosilver compd. such as silver lactate may be dissolved in place of silver nitrate. The heat treatment temp. is preferably 320-470 deg.C. The glass vessel may be any glass vessel. provided that it contains alkali metal ions. The coating method is not particularly limited and spraying or dipping may be adopted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antibacterial treatment method for a glass container and an antibacterial glass container produced by the treatment method. More specifically, the present invention is a glass container for preventing contamination, deterioration, and decay by microorganisms such as bacteria such as foods, beverages, and drinking water packed in a glass container mainly made of soda-lime glass, and enabling long-term storage. And an antibacterial glass container. In addition, the glass container mentioned here includes glass tableware and vases such as cups and dishes, in addition to glass bottles.

[0002]

2. Description of the Related Art As a method of imparting antibacterial properties to glass products and containers, a method of fusing or coating antibacterial glass, a method of containing silver ions or copper ions in a glass surface layer by ion exchange, and the like have been developed. ing.

As a method for imparting antibacterial properties to a container such as a glass bottle, Japanese Utility Model Publication No. 7-44623 discloses a method in which soluble glass fine particles containing silver ions or copper ions are directly fused to the inner surface of a bottle during molding. Is disclosed. However, in this method, it is extremely difficult to form a uniform antibacterial glass layer because glass particles are mixed with blow air and blown onto the inner surface of the bottle. In addition, the dissolution of the soluble glass into the content may cause the glass layer to peel off.

Japanese Utility Model Application Laid-Open No. 3-64268 discloses a method in which an antimicrobial-soluble glass is adhered to the surface of a container and the glass is covered with a water-permeable film-like object. However, this method is not suitable as a method for imparting antibacterial properties to the inner surface of the glass container.

Japanese Patent Application Laid-Open No. 3-103481 discloses that
A container coated with a paint containing a silver ion-containing controlled-eluting borosilicate glass powder, and a container in which the above-mentioned antibacterial glass powder is further fixed on a coated surface of the container coated with the paint are disclosed. However, this method is not suitable as a method for imparting antibacterial properties to the inner surface of the glass container.

[0006] Japanese Patent Application Laid-Open No. 4-338138 discloses that
A glass having a surface sterilized by immersing glass in an ion exchange solvent composed of an aqueous solution of silver nitrate or an aqueous solution of copper sulfate, drying, and heat-exchanging sodium ions in the glass with silver ions or copper ions by heat treatment is disclosed. I have. However, the germicidal glasses disclosed in the examples are all fine powders, and the germicidal properties of the glass are also all confirmed with the fine powder glass, and it is confirmed whether ion exchange is performed uniformly. It has not been. When the inner surface of the glass container is treated by this method, it is considered extremely difficult to uniformly wet the inner surface of the glass container with the ion exchange solvent.

Further, Japanese Patent Application Laid-Open No. Hei 8-217492 discloses a method for imparting antibacterial properties by exchanging sodium ions and the like of a glass coating layer formed on a substrate with silver ions. However, the coating composition for ion exchange used here is a silver salt such as silver sulfide or silver chloride in water, Aerosil (submicron fine particles of silica) for increasing the strength of a dry film, and a dispersant as a dispersant. Since it is a heterogeneous paste-like composition in which zirconium oxide and chromium oxide as an ion-exchange aid are suspended, it is suitable for glass lining of large-scale equipment such as chemical industry equipment. It is difficult to uniformly ion-exchange the inner surface of an object having a small size.

[0008]

The above-mentioned conventional antibacterial treatment method involves problems such as restrictions on food hygiene, detachment of glass powder, and process problems in mass production when an antibacterial soluble glass is adhered to the inner surface of a glass container. Had. In addition, when ion exchange is performed and antibacterial ions are contained in the surface layer of the inner surface of the glass, it is difficult to perform uniform ion exchange, and furthermore, the amount of adhesion due to non-uniform application of the ion exchange treatment agent, dripping, etc. The portion more than the other portions was liable to cause stains considered to be derived from silver nitrate after the heat treatment, and had a problem that the stains were not removed even after washing with water, resulting in a defective product.

Therefore, the present invention solves the above-mentioned problems and uses an ion exchange method free from problems such as peeling, and makes the surface layer on the inner surface of the glass container uniformly contain silver ions by an easy process.
An object of the present invention is to find an antibacterial treatment method for a glass container that can easily remove dirt by washing with water after heat treatment.

[0010]

According to the present invention, an inner surface of a glass container is coated with an aqueous solution containing silver nitrate and a surfactant, and then coated at a temperature at which ion exchange between alkali metal ions and silver ions in the surface layer occurs. Provided is an antibacterial treatment method for a glass container, wherein heat treatment makes the inner surface layer of the glass container substantially uniformly contain an antibacterial amount of silver ions.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The antibacterial treatment method for a glass container according to the present invention comprises applying an aqueous solution containing silver nitrate and a surfactant to the inner surface of the glass container and subjecting the solution to heat treatment, and converting the alkali metal ions on the surface layer on the inner surface of the glass container with silver ions. It is characterized by ion exchange. By dissolving the surfactant in the treatment aqueous solution, the surface tension of the treatment aqueous solution is reduced, so that the treatment aqueous solution can be uniformly coated without being repelled on the inner surface of the glass container, and the silver ion is contained in the surface layer more uniformly than before. As a result, the degree of soiling due to nitric acid before washing was significantly reduced. In addition, the addition of the surfactant makes the deposits containing silver and sodium and the above-mentioned stains remaining on the glass surface due to the burning out (burnout) of the organic components during the heat treatment porous and simultaneously solidifies the glass surface. It is thought to have the effect of weakening the adhesive force, facilitates the next step of washing with water, and enables the production of antibacterial glass containers at a high yield. As the type of surfactant, anionic,
Both cationic and nonionic types can be used,
A polymer having a large molecular weight, that is, a material whose burning temperature is as close as possible to the heat treatment temperature for ion exchange is effective for preventing stains and easily cleaning.

Since silver nitrate has high solubility in water and is oxidizing, it is preferably used as a silver compound to be dissolved in an ion exchange treatment aqueous solution. That is, a uniform solution having a high concentration can be obtained, thereby facilitating uniform ion exchange, and preventing strong reduction of silver due to strong oxidizing property.

The concentration of silver nitrate is preferably 5 to 25% by weight. If the amount is less than 5% by weight, the antibacterial effect may not be sufficiently obtained. Conversely, if it exceeds 25% by weight, antibacterial properties are high, but dirt frequently occurs, and cleaning becomes difficult. The concentration of silver nitrate is more preferably 9 to 20% by weight in consideration of antibacterial properties, detergency and the like.

The concentration of the surfactant depends on the kind thereof, but it is usually preferably 0.1 to 2% by weight. About 0.05% by weight is enough to sufficiently lower the surface tension of the ion exchange treatment aqueous solution so that the treatment aqueous solution can be uniformly coated without being repelled on the inner surface of the glass container. 0.1 to increase
It is preferable to dissolve it by weight percent or more. 2% by weight
When dissolved in excess, the coloration of the bottle tends to occur, which is thought to be due to the reduction of silver ions. The concentration of the surfactant is more preferably 0.2 to 1% by weight in consideration of washing properties, coloring problems, and the like.

An organic silver compound other than silver nitrate can be dissolved as the silver compound. As the kind of the organic silver, those which can be made into a uniform aqueous solution are preferable, and specifically, silver lactate, silver acetate and the like are preferably used. When these organic silver compounds are dissolved, the same effect as a surfactant is brought about by burning off the organic components at the time of heat treatment, and the stain can be more easily removed by washing with water in the next step. The concentration of these organic silver compounds is preferably 0.1 to 5% by weight, and the total concentration with silver nitrate is preferably 5 to 25% by weight. When the concentration of the organic silver compound is less than 0.1% by weight, the effect of addition is hardly observed. Conversely, even if added in an amount exceeding 5% by weight, the effect is not changed, but it is difficult to dissolve in water, which is economically disadvantageous. Furthermore, reduction coloring of silver ions also easily occurs. The total concentration of the organic silver is more preferably 0.2 to 2.5% by weight in consideration of washing properties, coloring problems, and the like.

With respect to the above surfactant and organic silver compound, it should be noted that the container may be colored as long as it can be uniformly coated without coating unevenness, and as long as the washing property and the antibacterial property are satisfied. It is.

The heat treatment temperature is preferably from 320 to 470 ° C. If the temperature is lower than 320 ° C., the amount of silver ions penetrating into the surface layer on the inner surface of the glass container by ion exchange decreases, so that antibacterial properties may be insufficient. Conversely, if the temperature exceeds 470 ° C., not only is the contamination after the heat treatment increased, making it difficult to wash in the next step, but also, the penetration depth of silver ions from the surface layer on the inner surface of the glass container becomes too deep, which is effective for expressing antibacterial properties. It becomes difficult to maintain a high silver ion concentration near the surface. The heat treatment temperature is 350 to 450 ° C. in consideration of the absolute amount of silver ions entering the surface layer and the silver ion concentration near the surface.
Is more preferable. One hour is sufficient for the heat treatment time within this temperature range, but can be changed as appropriate according to the temperature.

The method for applying the ion exchange treatment aqueous solution to the inner surface of the glass container is not particularly limited.
Any method can be used as long as coating can be performed uniformly, such as by brush coating or a rotation method.

In order to adjust the surface tension of the ion exchange aqueous solution, ethanol, methanol, acetone,
A water-soluble organic solvent such as IPA may be added.

The glass container subjected to the antibacterial treatment is not particularly limited as long as it is a glass containing not only soda-lime glass but also alkali metal ions such as borosilicate glass.

[0021]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

In the examples and comparative examples, evaluation and judgment were performed by the following methods. (1) Application unevenness After coating the inner surface of a glass container with an ion exchange treatment aqueous solution by a spray method, the presence or absence of repelling and unevenness was visually determined. 〇: No repelling, no unevenness ×: Repelling, non-uniformity (2) Washability After spraying, drying, and heat treatment, the inside of the glass container was washed while gently rubbing with a brush while spraying water, and evaluated for ease of dirt removal. Δ: Stain easily removed Δ: Stain removed ×: Stain not removed (3) Coloring After heat treatment and washing, the presence or absence of brown coloring on the inner surface of the glass container was visually judged. 〇: No color ×: Colored XX: Colored (4) Antibacterial property Evaluated by a film adhesion method. A 50 × 50 mm sample was cut out from the glass container subjected to the ion exchange treatment, and a bacterial solution of Escherichia coli (the number of bacteria: 10 ⁵ / ml) was dropped on the sample, and a polyethylene film was placed over the sample and adhered. This was allowed to stand still at 35 ° C. and a relative humidity of 90% or more, and the viable cell count after 24 hours was measured. As a control sample, the same measurement as above was performed on a glass container not subjected to the antibacterial treatment. 〇: Viable cell count is 1/1000 or less of control ×: Viable cell count is more than 1/1000 of control

Example 1 Silver nitrate concentration and nonionic surfactant (manufactured by Lion Corporation)
An aqueous solution of ion exchange treatment was prepared such that the liponox TL) concentrations were 5.0% by weight and 0.5% by weight, respectively. This is spray-coated on the inner surface of a colorless and transparent soda-lime glass-based glass bottle.
For 1 hour to perform ion exchange. When the obtained glass bottle was evaluated according to the above method, coating unevenness,
It was a non-colored product with excellent detergency and high antibacterial properties.

COMPARATIVE EXAMPLE 1 An ion exchange treatment aqueous solution having a silver nitrate concentration of 10.0% by weight and containing no surfactant was prepared, and the same treatment as in Example 1 was performed. Although a glass bottle having no coloring and having high antibacterial properties was obtained, application unevenness was observed and cleaning properties were poor.

Examples 2 to 4 and Comparative Examples 2 to 4 The same treatment as in Example 1 was performed except that the concentration of silver nitrate was changed in the range of 1.0 to 30.0% by weight. In Comparative Example 2 having a silver nitrate concentration of 1.0% by weight and Comparative Example 3 having a silver nitrate concentration of 3.0% by weight, sufficient antibacterial properties were not obtained, and the silver nitrate concentration was 30.0% by weight.
Comparative Example 4 was inferior in washability. On the other hand, in Examples 2, 3 and 4 where the silver nitrate concentrations were 10.0, 15.0 and 25.0% by weight, good results were obtained as in Example 1.

A glass piece was cut out from the glass bottle obtained in Example 2 and the cross section was subjected to EPMA analysis. As a result, it was found that silver ions were distributed at a high concentration at a depth of about 20 μm from the surface. I understood.

Examples 5 to 12 Except that the concentrations of silver nitrate and organic silver were variously changed as shown in Table 1, the same treatments as in Example 1 were performed. Was done.

Comparative Examples 5 and 6 An ion exchange treatment aqueous solution containing no silver nitrate and containing the same amount of silver lactate and the same surfactant as in Example 1 was prepared. In Comparative Example 5 in which the concentration of silver lactate was 5.0% by weight, it was difficult to dissolve in water, so that application unevenness was caused. In addition, the atmosphere became reductive, and it was colored dark brown. Silver lactate concentration is 1.
Comparative Example 6 at 0% by weight not only colored brown but also had insufficient antibacterial properties.

Examples 13 to 17, Comparative Example 7 The silver nitrate concentration was 10.0% by weight, and the concentration and type of the surfactant were variously changed (concentration: 0.1 to 2.5% by weight, type:
Example 1 In addition to the nonionic surfactant used in Example 1, anionic surfactant sodium alkyl ether sulfate) was used, and the same treatment as in Example 1 was performed. When the same nonionic surfactant as in Example 1 was used, the desired effect could be almost obtained although the cleaning property was slightly inferior in Example 13 having a concentration of 0.1% by weight. Nonionic surfactant concentration of 0.2
Sufficient effects were obtained with 5% by weight of Example 14, 1.0% by weight of Example 15 and 2.0% by weight of Example 16.
Example 17 in which an ion exchange treatment aqueous solution was prepared under the same conditions as in Example 14 except that the type of surfactant was changed to an anionic surfactant, also exhibited the desired effects. On the other hand, in Comparative Example 7 in which the concentration of the nonionic surfactant was 2.5% by weight, the atmosphere became reductive and was colored brown.

Examples 18 and 19, Comparative Examples 8 and 9 The same treatment as in Example 2 was performed except that the heat treatment temperature was changed to 250 to 500 ° C. In Example 18 where the heat treatment temperature was 350 ° C. and Example 19 where the heat treatment temperature was 450 ° C., similar favorable results were obtained as in Example 2. On the other hand, the heat treatment temperature is 250 ° C,
Comparative Examples 8 and 9 at 300 ° C. had insufficient antibacterial properties.

[0031]

[Table 1]

As shown in Table 1, according to the antibacterial treatment method for the inner surface of the glass container of the present invention shown in Examples 1 to 19,
It is possible to easily obtain an antibacterial glass container having high antibacterial properties, which is excellent in washability without coating unevenness and coloring.

On the other hand, Comparative Examples 1 to 10 outside the scope of the present invention do not satisfy at least one of the above-mentioned four evaluation items.

[0034]

According to the method for antibacterial treatment of a glass container of the present invention, a suitable amount of surfactant is dissolved together with silver nitrate in an aqueous solution of ion exchange treatment, so that uniform ion exchange can be performed without coating unevenness. Even if stains are generated, a glass container which can be easily washed by water washing in the next step, has no coloring, and has excellent antibacterial properties can be produced at a high yield.

Further, by coexisting an organic silver compound such as silver lactate and silver acetate, a desired glass container can be manufactured more efficiently.

Claims (5)

[Claims] An inner surface of a glass container is coated with an aqueous solution containing silver nitrate and a surfactant, and then heat-treated at a temperature at which ion exchange between alkali metal ions and silver ions in a surface layer occurs. An antibacterial treatment method for a glass container, wherein the surface layer contains an antibacterial amount of silver ions substantially uniformly. 2. The method according to claim 1, wherein the concentration of silver nitrate in the aqueous solution is 5 to 25% by weight and the concentration of surfactant is 0.1 to 2% by weight. 3. The aqueous solution further contains silver lactate and / or silver acetate at 0.1 to 5% by weight, the total silver salt concentration with silver nitrate is 5 to 25% by weight, and the surfactant concentration is The method according to claim 1, wherein the amount is 0.1 to 2% by weight. 4. The method according to claim 1, wherein said temperature is from 320 to 470 ° C. 5. A glass container which has been subjected to antibacterial treatment by the method according to claim 1.