JPH11319042A - Antibacterial reinforced glass article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep antibacterial properties long by coating the surface of a glass article to which physical reinforcing processing is preliminarily applied with a silver-containing soln. and heat-treating the coated article at a glass transition point or higher to diffuse silver into the surface layer part of the reinforced glass article from the surface thereof. SOLUTION: Glass is preliminarily molded into a shape near to that of a final product by a floating, drawing, pressing or blowing method and, when glass reaches a temp. near to its softening temp., cooling air is blown against the glass to quench the same to apply physical reinforcing processing thereto and the obtained reinforced glass article is once cooled to almost room temp. The reinforced glass article is coated with a silver-containing soln. by a dip coating method or a brush coating method and the coated glass article is heat- treated at a glass transition point or higher to diffuse silver into the surface layer part of the reinforced glass article from the surface thereof. By this constitution, the antibacterial effect of the glass article can be kept long against the corrosion of a glass surface caused by an alkali washing soln. or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tempered glass article provided with antibacterial properties, a tempered glass container, or a fire-polished glass container.

[0002]

2. Description of the Related Art A number of technologies relating to articles provided with antibacterial properties and a method for producing the same have been disclosed. For example, stationery, clothing, kitchenware, home appliances, building interior materials, housing equipment, etc. have been put to practical use. Have been. Antibacterial agents that exhibit antibacterial properties include organic synthetic antibacterial agents such as imidanol derivatives, natural antibacterial agents such as wasabi, metallic antibacterial agents such as copper and silver, and oxidizing agents such as titanium oxide. Antibacterial agents are known. In daily necessities, metal-based antibacterial agents using silver are mostly used.

In general, there are roughly three types of methods for applying silver, which is an antibacterial agent, to glass articles. The first method is a method in which silver is mixed with a glass raw material and melt-molded. Since silver existing on the glass surface plays a role in exhibiting antibacterial properties, silver inside the glass has no effect on antibacterial properties. As a result, this method is uneconomical because of the relatively high silver content of the glass.

A second method is to apply a silver-containing coating layer to the surface of a glass article. This method
The amount of silver to be used can be relatively reduced compared to the first method, and it is more economical than the first method. There is a problem that the surface properties of the article are remarkably changed due to the formation of the particles.

[0005] A third method is a method in which a liquid containing silver is applied to the surface of a glass article and heat-treated to diffuse silver from the surface of the glass article into the surface layer of the article.
This is a method that solves the problems of the first and second methods, in which silver is concentrated and distributed on the surface layer of the glass article, and the antibacterial property is depleted in a short time due to abrasion or the like as compared with the second method. And the surface properties of the article are not significantly changed.

The third method is the most excellent of the three methods. However, the glass article into which silver has been introduced by the third method has a problem that the antibacterial property is significantly reduced after alkali cleaning depending on the heat treatment conditions. This is because the glass surface is eroded by the alkaline solution, and silver as an antibacterial agent escapes from the glass article together with the glass component.

[0007]

In order not to significantly reduce the antibacterial properties of the glass article even after the alkali washing, it is necessary to diffuse silver from the surface of the glass article to the inside of the glass article. The general method of countermeasures is to increase the heat treatment temperature and lengthen the heat treatment time.However, these methods have a low diffusion rate for wasting energy and time, and silver is deep inside the glass article. Does not spread. In addition, when heat treatment is performed at a temperature higher than the glass transition point, there is a problem that silver aggregates and the glass is colored yellow.

Although glass is a clean material that does not absorb water, the mouth of the glass container can be directly touched by the mouth of a person, and may be touched by a contaminated solid surface layer during storage. Therefore, it has been desired to impart antibacterial properties particularly to the mouth of the glass container.

[0009]

In the present invention, attention has been paid to tempered glass articles, mouth tempered glass containers, and fire-polished glass containers using silver as an antibacterial agent.

The reason why silver was selected as the antibacterial agent is as follows. Organic antibacterial agents such as organic synthetic antibacterial agents and natural antibacterial agents have a shortcoming of having a short effective period of exhibiting antibacterial properties and lacking heat resistance. Oxide-based antibacterial agents such as titanium oxide have a long-lasting antibacterial effect and are highly safe, but they have the characteristic of exhibiting antibacterial properties only after being irradiated with ultraviolet light, so they are ineffective without irradiation with ultraviolet light Has disadvantages.

Metallic antibacterial agents such as copper and silver maintain antibacterial effects, have high safety, and are excellent in heat resistance. Disadvantageously, copper is slightly less safe and antibacterial than silver. Silver is expensive and may be colored or discolored during processing and use. Zinc is problematic for skin irritation.
As a result of comparing and examining the characteristics of the various antibacterial agents described above, it was concluded that silver was the optimal antibacterial agent.

The present invention has been made in order to solve the above-mentioned problems, and is intended to provide a glass article, a mouth-reinforced glass container, or a fire-polished glass container (hereinafter referred to as a tempered glass article) which has been subjected to physical strengthening processing in advance. A silver-containing solution or a liquid in which silver particles are dispersed (hereinafter referred to as a silver-containing liquid) is applied to the surface, and then heat-treated at a temperature equal to or lower than the glass transition point, whereby silver is removed from the surface of the tempered glass article from the surface layer. The present invention relates to a tempered glass article having an antibacterial property diffused inside the glass.

A general physical strengthening method is performed by heating a glass to a softening temperature or the like and then blasting the heated glass with a cool air to rapidly cool the glass. This allows
Only the surface of the glass solidifies and is frozen as it is. Thereafter, when the inside of the softened glass is gradually cooled, a compressive stress layer is formed on the surface of the glass, thereby strengthening the glass article. This tempering method has been put to practical use in window glasses, automobile windshields, tableware glass containers, and the like.

It is generally known that rapidly cooled glass has a lower specific gravity than slowly cooled glass. This means that the quenched glass has a smaller weight per unit volume than the slowly cooled glass, and thus the interatomic distance of the glass is larger. Source (Naruse, “Glass Engineering” 225
-Page 226, Kyoritsu Shuppan, 1990) states that "generally quenched glass is considered to be in a frozen state with a loosened structure at high temperatures." Supplement.

A method in which the mouth of a glass container is fire-polished and is not gradually cooled is generally called a crack-off process. After a glass container near the room temperature is wound around the mouth with a carbide tool such as a scribing wheel, it is cut into a ring by applying thermal and mechanical shocks, chamfered, and polished (or a diamond wheel). Cut the mouth of the container with a carbide cutting disk, etc., go through a chamfering and polishing step) In order to smooth the cut surface, heat it to near the softening temperature with a gas burner etc. and let it cool down to room temperature (slowly) Do not cool). The very thin surface layer at the mouth of the glass container obtained by this method is in a state similar to the mouth surface layer of the mouth-reinforced glass container.

Here, the most common soda lime glass and silver fine particles will be described as an example, but the present invention is not limited to soda lime glass and silver fine particles.

For example, soda lime glass is made of Na2O, CaO
, And SiO2 as a main component, and is configured such that Na and Ca enter into gaps of a network structure formed by SiO2.
To be more precise, Na and Ca cut the Si-O-Si network structure formed by SiO2 to form Si-O-Na or S
It is configured in the form of i-O-Ca. Alkali metal represented by Na is an element that easily moves in glass, and silver that acts as an antibacterial agent in the present invention is introduced into glass by substituting the alkali metal.
In order to diffuse silver from the glass surface to as deep as possible inside the surface layer portion, a method of expanding the network structure formed by SiO2 by physical strengthening and easily replacing silver with an alkali metal is extremely effective.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION There are various types of glass, but any glass can be used as long as it can be physically strengthened.
In addition to the above-mentioned soda-lime glass, a crystal glass containing 24% or more of PbO 2 and a semi-crystal glass containing a little amount of PbO 2 may be used. Of course, glass colored by adding a transition metal oxide or the like may be used.

The glass is formed into a shape close to the final product by a general method such as float, draw, press, blow or the like, and when the glass is at about the softening temperature, it is quenched by blowing cool air, and subjected to physical strengthening. Cool to near room temperature once. The molding process and the physical strengthening process may be continuous,
After the molding step, the material may be gradually cooled to around room temperature, and may be subjected to physical strengthening processing again.

Instead of the physical strengthening method, the glass surface can be kept in a state of low specific gravity by fire-polishing the mouth portion of the glass container during the crack-off process and not gradually cooling the glass container. .

A silver-containing liquid is applied to the tempered glass article by a dip coating method, a brushing method, a spray method, or the like, and subjected to a heat treatment. The heat treatment temperature must be equal to or lower than the glass transition point. If the heat treatment is performed at a temperature higher than this temperature, silver will aggregate and the glass will be colored yellow. The heat treatment temperature is desirably 300 ° C. or higher. 300
If the temperature is lower than 0 ° C., the diffusion rate of silver into the glass is too slow and it takes time, which is not practical.

Heat treatment time (holding time at heat treatment temperature)
Is preferably about 10 minutes to 2 hours. If the time is less than 10 minutes, a satisfactory diffusion effect cannot be obtained, while if the heat treatment is performed for more than 2 hours, it is uneconomical. There is no particular limitation on the heating rate and the cooling rate, but it is necessary to heat and cool the glass at such a speed that the glass is not broken.

[0023]

EXAMPLES (Example 1) A glass plate made of soda lime glass (glass transition point: 550 ° C.) was 100 × 10 mm.
(Thickness: 3 mm), cut with a neutral detergent, and dried. Thereafter, the glass plate was inserted into an electric furnace maintained at 680 ° C. and held for 10 minutes, then quickly taken out of the furnace, and rapidly cooled to room temperature with a blower to perform a physical strengthening process. A silver colloid dispersion prepared by a known method was applied to this physically strengthened glass plate by a dipping method, and heat-treated at 450 ° C. for 80 minutes. The obtained glass plate was colorless and transparent as before the treatment.

(Example 2) Immediately after molding, a soda lime glass pot (glass transition point: 575 ° C) formed by press molding was fire-polished until the surface temperature of the glass pot reached 700 ° C or higher. Immediately after that, a physical strengthening process was performed by rapidly blowing cooling air to the entire pot and rapidly cooling the entire pot to 200 ° C. or less. A silver fine particle dispersion prepared by a known method is applied to the physically strengthened glass bowl by a spray method,
Heat treatment was performed for 0 minutes. The obtained glass pot was colorless and transparent as before the treatment.

Example 3 A silver fine particle dispersion prepared by a known method was applied by brushing to a reinforced glass glass tumbler (glass transition point: 465 ° C.) prepared by a known method. 20 at 400 ° C
Heated for minutes. The obtained crystal glass mouth reinforced tumbler was colorless and transparent as before the treatment.

Example 4 The mouth of a goblet made of semi-crystal glass (glass transition point: 500 ° C.) manufactured by a known method was cut by a crack-off process.
After polishing and fire polishing, the mixture was cooled to around room temperature without slow cooling, and a silver colloid dispersion prepared by a known method was applied by a spray method, and heat-treated at 380 ° C. for 60 minutes. The obtained semi-crystal glass goblet was colorless and transparent.

(Comparative Examples 1 to 4) Among the methods shown in Examples 1 to 4, those without physical strengthening or those subjected to slow cooling after fire polishing were prepared, and a silver fine particle dispersion was added to each of them by the respective methods. Antibacterial treatment was performed under each heat treatment condition, and Comparative Examples 1 to 4 were obtained.

(Evaluation of Examples and Comparative Examples) Examples 1-4
And the antibacterial property of the test body produced in Comparative Examples 1-4 was evaluated. First, for each test piece, a commercial automatic dishwasher (pH of the washing solution is 11.5, temperature of the washing solution is 60 ° C., one alkali washing time is 40 seconds, and one rinsing time is 12 hours.
), And those washed 1000 times, 2000 times and 3000 times respectively were separately prepared. 0.1 ml of Escherichia coli was placed on the surface of each test specimen, and the number of surviving bacteria after standing at a temperature of 37 ° C. for 24 hours was measured by an agar plate method. Table 1 shows the results.

[0029]

[Table 1]

From Table 1, it can be seen that, for all examples, 10
The number of surviving bacteria after 24 hours was 100 cfu (colo) in each of the samples washed 00 times, 2000 times, and 3000 times.
nyforming unit) / ml or less, indicating that the antibacterial effect is maintained. On the other hand, those without physical strengthening or those subjected to slow cooling after fire polish (comparative examples) had good antibacterial properties after washing 1000 times, as in the example.
After the 00 washes, the number of surviving bacteria after 24 hours was greater than the number of surviving bacteria after 1000 washes, and after 3000 washes, the number of surviving bacteria was even higher. That is, when the physical strengthening process or the rapid cooling after the fire polish were not performed, the antibacterial effect was reduced when the number of times of washing in the commercial dishwasher was increased.

[0031]

As described above, the antibacterial reinforced glass article according to the present invention, the antibacterial reinforced glass container having the mouth subjected to physical strengthening or the mouth antibacterial which is not gradually cooled after the mouth is fire-polished. Fire polished glass containers can be used on the surface of these glass articles or glass containers.
After applying a solution containing silver or a liquid in which silver fine particles are dispersed, by performing a heat treatment at a temperature equal to or lower than the glass transition point, silver can be diffused deeply into the surface layer from the surface of the article, and alkali Even after repeated washing with the liquid, the antibacterial property can be maintained for a long time.

Claims (3)

[Claims] Claims 1. A silver-containing solution or a liquid in which silver fine particles are dispersed is applied to the surface of a tempered glass article that has been subjected to physical tempering, and then heat-treated at a temperature equal to or lower than the glass transition point to obtain silver. Is spread from the surface of the tempered glass article into the surface layer. 2. The tempered glass article according to claim 1,
A mouth-tempered glass container in which the mouth is physically strengthened, and a solution containing silver or a liquid in which silver fine particles are dispersed is applied to at least the inside and outside surfaces of the mouth of the glass container, and then has a glass transition point or less. A mouth antibacterial reinforced glass container in which silver is diffused from the surface of the glass container to the inside of the surface layer portion by performing a heat treatment at the following temperature. 3. The tempered glass article according to claim 1,
A glass container that is not gradually cooled after fire-polishing the mouth, and a solution containing silver or a liquid in which silver fine particles are dispersed is applied to at least the inside and outside surfaces of the mouth of the glass container, and then heated to a temperature below the glass transition point. An antibacterial fire-polished glass container in which silver is diffused from the surface of the glass container to the inside of the surface layer portion by heat treatment in the above.