JP3453515B2 - Antibacterial tempered glass article - Google Patents

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 mouth tempered glass container, or a fire-polished glass container.

[0002]

2. Description of the Related Art A number of technologies relating to antibacterial articles and methods for producing the same have been disclosed. For example, stationery, clothing, kitchen appliances, home appliances, building interior materials, household equipment, etc. have been put into practical use. Has been done. Antibacterial agents that exhibit antibacterial properties include organic synthetic antibacterial agents such as imidazole derivatives, natural antibacterial agents such as wasabi, metallic antibacterial agents such as copper and silver, and oxidation agents such as titanium oxide. Physical antibacterial agents are known. Most of the daily necessities use a metallic antibacterial agent containing silver.

Generally, there are roughly three methods for applying silver as 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 the silver present on the glass surface plays a role of developing antibacterial properties, the silver inside the glass has no effect on the antibacterial properties. As a result, this method is uneconomical because the glass must be relatively high in silver.

The second method is to apply a coating layer containing silver to the surface of the glass article. This method
Although the amount of silver used can be relatively reduced as compared with the first method and it is more economical than the first method, the coating layer is consumed due to abrasion in a relatively short period of time and the coating layer However, there is a problem that the surface properties of the article are significantly changed due to the formation of the.

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 has improved 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 consumed in a short time due to abrasion etc. as compared with the second method. In addition, the surface properties of the article do not change significantly.

The third method is the best method among the above three methods. However, the glass article introduced with silver by the third method has a problem that the antibacterial property is remarkably reduced after alkali cleaning depending on the heat treatment conditions. This is because the glass surface is eroded by the alkaline liquid, and silver, which is an antibacterial agent, escapes from the glass article together with the glass component.

[0007]

In order not to significantly reduce the antibacterial property of the glass article even after the alkali cleaning, it is necessary to diffuse silver from the surface of the glass article to a deep inside. As a general measure for this, it is common to increase the heat treatment temperature and lengthen the heat treatment time.However, these methods have a slow diffusion rate in spite of wasting energy and time, and the silver does not reach deep inside the glass article. Do not spread. In addition, when heat treatment is performed at a temperature higher than the transition point of glass, there is a problem that aggregation of silver occurs and the glass is colored yellow.

Although glass is a clean material that does not absorb water by nature, the mouth of the glass container may come into direct contact with the mouth of a person and may come into contact with a contaminated solid surface layer during storage. Therefore, it is particularly desired to impart antibacterial properties to the mouth of the glass container.

[0009]

In the present invention, attention was paid to a tempered glass article using silver as an antibacterial agent, a mouth tempered glass container, and a fire-polished glass container.

The reason why silver is selected as the antibacterial agent is as follows. Organic antibacterial agents such as organic antibacterial agents and natural antibacterial agents have a shortcoming that they have a short effective period of exhibiting antibacterial properties and lack heat resistance. Oxidized antibacterial agents such as titanium oxide have a long-lasting antibacterial effect and are highly safe, but on the other hand, they have the characteristic of exhibiting antibacterial properties only after being irradiated with ultraviolet rays, so they have no effect without being irradiated with ultraviolet rays. It has drawbacks.

Metal-based antibacterial agents such as copper and silver have a long-lasting antibacterial effect, are highly safe, and have excellent heat resistance. Individually speaking of the disadvantages, copper is slightly less safe and antibacterial than silver. Silver is expensive and may be colored or discolored during processing and use. Zinc has a problem of skin irritation.
As a result of comparative examination of the characteristics of the above-mentioned various antibacterial agents, it was concluded that silver is the most suitable antibacterial agent.

The present invention has been made in order to solve the above-mentioned problems, and a glass article, a tempered glass container, or a fire-polished glass container (hereinafter referred to as a tempered glass article) which has been subjected to a physical strengthening process in advance is provided. After applying a solution containing silver or a liquid in which fine silver particles are dispersed (hereinafter referred to as a silver-containing solution) to the surface, heat treatment is performed at a temperature not higher than the glass transition point, so that silver is removed from the surface of the tempered glass article to the surface layer portion. The present invention relates to a tempered glass article having antibacterial properties diffused inside.

A general physical strengthening method is carried out by heating glass to a softening temperature, then blowing cold air onto the heated glass to rapidly cool it. This allows
Only the surface of the glass is solidified and frozen as it is. Then, when the inside of the softened glass is gradually cooled, a compressive stress layer is formed on the glass surface, thereby strengthening the glass article. This strengthening method has been put to practical use in window glasses, windshields of automobiles, glass containers for dining tables, and the like.

It is generally known that the rapidly cooled glass has a smaller specific gravity than the slowly cooled glass. This means that the rapidly cooled glass has a smaller weight per unit volume than the slowly cooled glass, and therefore the interatomic distance of the glass is distant. Document (Naruse, "Glass Engineering" 225
-226, Kyoritsu Shuppan, 1990) states that "generally, quenched glass is considered to be in a frozen state in a relaxed structure at high temperatures," which explains the above theory. I am supplementing.

A method in which the mouth of a glass container is fire-polished and then not gradually cooled is generally called a crack-off process. After scratching the mouth of a glass container near room temperature with a cemented carbide tool such as a scribing wheel in a circular shape, it is cut into a ring shape by applying a thermal mechanical impact, and then chamfered and polished (or a diamond wheel). Cut the mouth of the container with a carbide cutting disk such as, and through a chamfering and polishing process) To smooth the cut surface, heat it to near the softening temperature with a gas burner etc. and let it cool to room temperature (gradually Do not cool). The very thin surface layer of the mouth of the glass container obtained by this method is in a state conforming to the surface layer of the mouth of the tempered glass container.

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

For example, soda lime glass contains Na2O and CaO.
, SiO2 as a main component, and is configured such that Na and Ca enter into the interstices of the network structure formed by SiO2.
To be more precise, Na and Ca cut the Si-O-Si network structure created by SiO2 to produce Si-O-Na or S
It is configured in the form of i-O-Ca. An alkali metal typified by Na is an element that easily moves in glass, and silver acting as an antibacterial agent in the present invention is introduced into glass by substituting with the alkali metal.
In order to diffuse silver from the glass surface to the deepest part inside the surface layer, it is very effective to expand the network structure of SiO2 by physical strengthening to easily replace silver with alkali metal.

[0018]

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

Glass is molded into a shape close to the final product by a general method such as float, draw, press, blow, etc., and when the glass is at a softening temperature, it is rapidly cooled by blowing cold air, and physically strengthened, Cool down 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 then subjected to physical strengthening again.

Instead of the physical strengthening processing method, the glass surface can be kept in a small specific gravity state by a method in which the mouth portion of the glass container in the step of the crack-off process is fire-polished and then not gradually cooled. .

A silver-containing liquid is applied to the tempered glass article by a dip coating method, a brush coating method, a spray method or the like, and a heat treatment is performed. The heat treatment temperature needs to be lower than the glass transition point, and if heat treatment is performed at a temperature higher than this temperature, aggregation of silver occurs and the glass is colored yellow. The heat treatment temperature is preferably 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 10 minutes to 2 hours. If it is less than 10 minutes, a satisfactory diffusion effect cannot be obtained, while if it is heat-treated for more than 2 hours, it is uneconomical. There is no particular restriction on the temperature rising rate and the cooling rate, but it is necessary to heat and cool at a rate that does not break the glass.

[0023]

Example 1 A glass plate made of soda lime glass (glass transition point: 550 ° C.) is 100 × 10 mm.
It was cut to a size (thickness 3 mm), washed with a neutral detergent and then dried. After that, the glass plate was inserted into an electric furnace kept at 680 ° C. and held for 10 minutes, then quickly taken out of the furnace and rapidly cooled to room temperature with a blower for physical strengthening. 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 glass plate obtained was colorless and transparent as before treatment.

Example 2 A press-molded soda lime glass pot (glass transition point: 575 ° C.) was fire-polished immediately after shaping until the surface temperature of the glass pot reached 700 ° C. or higher. Immediately after that, cooling air was strongly blown to the entire pot to rapidly cool the entire pot to 200 ° C. or less, whereby physical strengthening was performed. A silver fine particle dispersion prepared by a known method was applied to this physically strengthened glass pot by a spray method, and the solution was heated at 500 ° C. for 4 hours.
Heat treatment was performed for 0 minutes. The obtained glass pot was colorless and transparent as before treatment.

Example 3 A crystal glass mouth reinforced tumbler (glass transition point: 465 ° C.) prepared by a known method was coated with the silver fine particle dispersion prepared by a known method by brush coating, 20 at 400 ° C
Heat treatment was performed for a minute. The obtained crystal glass-reinforced mouth tumbler was colorless and transparent as before treatment.

Example 4 The mouth of a semi-crystal glass goblet (glass transition point: 500 ° C.) produced 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, 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 not physically strengthened or those which were gradually cooled after fire polishing were prepared, and silver fine particle dispersion liquids were applied to them respectively. 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 to 4
And the antibacterial property of the test body produced in Comparative Examples 1 to 4 was evaluated. First, for each test sample, an automatic dishwasher for commercial use (the pH of the cleaning liquid was 11.5, the temperature of the cleaning liquid was 60 ° C., the alkaline cleaning time was 40 seconds, and the rinsing time was 12 times).
Sec.), 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 body, and the number of surviving bacteria after standing at a temperature of 37 ° C. for 24 hours was measured by the agar plate method. The results are shown in Table 1.

[0029]

[Table 1]

From Table 1, for all examples, 10
The number of viable cells after 24 hours was 100 cfu (col
It was revealed that the antibacterial effect was sustained, as the antibacterial effect was maintained. On the other hand, the one which was not subjected to physical strengthening or the one which was gradually cooled after fire polishing (Comparative Example) had a good antibacterial property as in the Example after washing 1000 times.
After 00 washes, the number of surviving cells after 24 hours was higher than that after 1000 times of washing, and after 3000 times of washing, the number of surviving cells was even higher. That is, when physical strengthening or quenching after fire polishing was not performed, it was observed that the antibacterial effect decreased as the number of times of washing in the commercial dishwasher increased.

[0031]

INDUSTRIAL APPLICABILITY As described above, the antibacterial tempered glass article according to the present invention, the mouth antibacterial tempered glass container in which the mouth is physically strengthened, or the mouth antibacterial property which is not slowly cooled after the mouth is fire-polished The fire-polished glass container is the surface of these glass articles or glass containers,
After applying a solution containing silver or a liquid in which fine silver particles are dispersed, by heat-treating at a temperature not higher than the glass transition point, silver can be diffused from the surface of the article to a deep inside of the surface layer portion. The antibacterial property can be maintained for a long time even after repeated washing with a liquid.

Continuation of the front page (56) Reference JP 10-15041 (JP, A) JP 8-207202 (JP, A) JP 8-245240 (JP, A) JP 7-165478 (JP , A) JP-A-9-67143 (JP, A) JP-A-8-217492 (JP, A) JP-A-6-24756 (JP, A) JP-A-51-18719 (JP, A) JP-A- 57-67035 (JP, A) JP 49-121686 (JP, A) JP 11-228186 (JP, A) JP 4-209870 (JP, A) JP 7-33617 (JP, A) JP-A-4-134008 (JP, A) JP-A-3-245893 (JP, A) JP-A-9-48625 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) ) A61L 2/16 C03C 21/00

Claims (3)

(57) [Claims] 1. A silver-containing solution or a liquid in which fine silver particles are dispersed is applied to the surface of a physically strengthened tempered glass article, and then heat-treated at a temperature not higher than the glass transition point to obtain silver. An antibacterial tempered glass article in which is diffused from the surface of the tempered glass article to the inside of the surface layer portion. 2. The tempered glass article according to claim 1,
A mouth-strengthened glass container having a physical strengthening process applied to the mouth, and after applying a solution containing silver or a liquid in which fine silver particles are dispersed to at least the inner and outer surfaces of the mouth, the glass transition point or less A mouth antibacterial tempered glass container in which silver is diffused from the surface of the glass container to the inside of the surface layer by heat treatment at the temperature. 3. The tempered glass article according to claim 1,
A glass container that is not gradually cooled after fire-polishing the mouth, and after applying a solution containing silver or a liquid in which silver fine particles are dispersed to at least the inner and outer surfaces of the mouth of the glass container, the temperature is not higher than the glass transition point. A mouth antibacterial fire-polish glass container in which silver is diffused from the surface of the glass container to the inside of the surface layer by heat treatment.