JP2001097735A - Antibacterial glass and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an antibacterial glass and to provide its production method capable of inexpensively producing a high-performance antibacterial glass by utilizing a sol-gel process. SOLUTION: This antibacterial glass is obtained by mixing a hydrolysable organic silicone compound, a hydrolysable metal M compound (M is a metal atom having a valence in its oxide <= coordination number), an antibacterial metal salt, an alkali catalyst and water and then braking the mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antibacterial glass suitably used for sterilizing fibers, building materials, plastics, paints, water and the like, and a method for producing the same.

[0002]

2. Description of the Related Art As one of manufacturing methods of antibacterial glass,
The sol-gel method is known. In the sol-gel method, a gel body is prepared by hydrolyzing a reaction product of a metal alkoxide compound such as tetraethyl silicate and an Ag coordination compound obtained by coordinating an alkoxy group-containing compound such as trimethoxysilylpropyldiethylenetriamine. Ag coordination compound is produced by mixing an Ag salt obtained by dissolving an Ag salt in a non-aqueous organic solvent and an alkoxy group-containing compound in a non-aqueous organic solvent such as ethanol. It is. By the way, in the conventional sol-gel method, Ag is present not in an ionic state but in a colloidal particle state in the glass, so that the obtained antibacterial glass is colored, and its use is limited. Heat treatment cannot be performed, and dense and stable glass cannot be obtained.
There is a problem that the release rate of Ag is not slow.

[0003] To solve these problems,
The present inventors have disclosed in Japanese Patent Application Laid-Open No. Hei 9-110463 that a hydrolyzable organic silicon compound and a hydrolyzable metal M compound (however, when M is an oxide, its valence is smaller than the coordination number) A metal solution), a raw material solution containing an antibacterial metal salt, an acid catalyst, and water are mixed and gelled, and then calcined, whereby Ag is contained in the glass in an ion state. Has been proposed. The antibacterial glass obtained by this method is a bulk material, and is used for actual use after being crushed and classified.

[0004]

The antibacterial glass obtained by the above method is characterized in that the antibacterial metal is dispersed in the glass in an ionic state, so that the glass is not colored. It has the feature that the Ag release rate is continuous and slow. However, among the antibacterial metals contained in glass, only those present on the surface of the glass contribute to the antibacterial performance, and expensive antibacterial metals are not effectively used.

An object of the present invention is to provide an antibacterial glass which can be produced by using a sol-gel method, can effectively utilize an antibacterial metal, and can exhibit antibacterial performance efficiently, and a method for producing the same. It is.

[0006]

The antimicrobial glass of the present invention is an antimicrobial glass having a surface layer formed on a substrate, characterized in that antimicrobial metal ions are contained only in the surface layer. And Further, the method for producing the antibacterial glass of the present invention comprises a hydrolyzable organosilicon compound, a hydrolyzable metal M compound (however, when M is an oxide, its valence is smaller than the coordination number. (Indicating an atom), an antibacterial metal salt, an alkali catalyst, and water, followed by baking.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The antibacterial glass of the present invention is prepared by mixing a hydrolyzable organosilicon compound, a hydrolyzable metal M compound, and an antibacterial metal salt with an alkali solvent containing an alkali catalyst and water, and then baking the mixture. be able to.

Here, the organosilicon compound is not particularly limited as long as it has hydrolyzability. For example, silicon alkoxide such as tetraethoxysilane (TEOS) can be used. The metal M compound is not particularly limited as long as it has hydrolyzability and the valence of the metal M when converted to an oxide is smaller than the coordination number. For example, aluminum triisopropoxide (Al Aluminum alkoxides such as (OPr) ₃ ) can be used. As an antibacterial metal salt, silver nitrate (AgNO
₃ ) etc. can be used. A preferred combination of the metal M and the antibacterial metal is M for Al and the antibacterial metal for Ag. Ammonia (NH ₃ ) is suitable as the alkali catalyst.

When an organosilicon compound or a metal M compound is mixed with water, each compound undergoes hydrolysis, condenses and gels. At this time, if an alkali is used as a catalyst, negative charges are charged on the surface of the initially generated gel fine particles, and the Coulomb repulsion prevents the bonding between the fine particles, and as a result,
The subsequent pulverizing step becomes unnecessary. When an acid catalyst such as nitric acid is used as in the conventional method, the fine particles are combined (aged) with the progress of gelation to form a bulk body, and a pulverizing step for pulverization is required. .

When an antibacterial metal salt is added to a solvent, antibacterial metal ions are uniformly dispersed in the gel during the hydrolysis and condensation processes. Further, since the metal M contained in the gel has a valence n smaller than the coordination number z, an excess oxygen atom having a negative charge without being electrically neutralized by the charge (n ⁺ ) of the metal M becomes Metal M
Which neutralizes and stabilizes with antibacterial metal ions. Therefore, the antibacterial metal can be stably and uniformly dispersed in an ion state after firing.

In mixing each component with a solvent, first, only a certain amount of an organosilicon compound is added to an alkaline solvent, and then a separately prepared hydrolyzable organosilicon having a vitrizable composition is added. It is preferable to add a compound, a hydrolyzable metal M compound and an antibacterial metal salt.

When only an organosilicon compound is added to a solvent, highly condensed silica gel fine particles serving as a nuclide (Seed) are formed, and the solution becomes cloudy. Silica gel particles
By setting it as “ed”, the antibacterial metal ions can be efficiently present on the surface portion of the glass. By adjusting the concentration of the organosilicon compound to be added first, the particle size of the obtained microspherical glass can be controlled.

After the seed is formed, a separately prepared hydrolyzable organosilicon compound having a vitrizable composition, a hydrolyzable metal M compound and an antibacterial metal salt are added to the solution. surface layer made of SiO ₂ -MxOy system glass containing antimicrobial metal ions is formed on the surface, grow as a single particle. The thickness of the surface layer can be adjusted or its composition can be changed stepwise by changing the number of times and the ratio of addition of the organosilicon compound, the metal M compound and the antibacterial metal salt.

Thereafter, the mixture is stirred for a predetermined time, dried, and
When calcined at a temperature of about 1000 ° C., SiO ₂ -Mx containing antibacterial metal ions
A microsphere antibacterial glass of submicron to micron order having a surface layer made of Oy glass is formed.
Note that the drying step is not always necessary.

The antibacterial glass thus obtained is
Since the antibacterial metal is dispersed in an ionic state, the glass is not colored, and a dense glass can be obtained by firing at a high temperature. And even if the antibacterial metal ions are released from the glass surface and consumed, the antibacterial metal inside the surface layer diffuses toward the surface in an ionic state, so the release rate of the antibacterial metal from the glass surface is continuous and It is moderate. Moreover, the gradient of the antibacterial metal release rate-time graph can be controlled by the ratio of the metal M to the antibacterial metal and the total amount of the antibacterial metal. Further, by changing the process, the composition of the surface layer can be freely changed, and an antibacterial agent suitable for various uses can be designed.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments.
Tables 1 to 4 show the manufacturing conditions of each example, and Table 5 shows the glass composition of the obtained sample. Tetraethoxysilane (TEO) as a raw material for silica, alumina and silver oxide
S), aluminum triisopropoxide (Al (OP
For r) ₃ ) and silver nitrate, the amount that theoretically yielded the composition shown in Table 5 was calculated and used as the total amount used.

(1) Preparation of Sample [Example 1] Preparation of Silica Fine Particle (Seed) -Dispersed Cloudy Liquid First, a Teflon container is charged with ethanol as a solvent and an aqueous NH ₃ solution as an alkali catalyst. As water required for hydrolysis, water in an aqueous NH ₃ solution was used. Then S
Tetraethoxysilane (TEOS) for eed production
Was added in three portions of 8%, 16% and 16% of the total amount used by weight, and the mixture was stirred in that state. The addition of TEOS was performed every one hour.

TEOS was added to the turbid liquid prepared in the step of preparing the microspherical glass at 15% of the total amount used, and then aluminum triisopropoxide (Al
(OPr) ₃ ) in 25% of the total amount used, silver nitrate (AgN
O ₃ ) was also added at 25% of the total used amount, and this series of operations was repeated every hour for a total of four times. In each of the following examples, the repetitive work was performed every hour.

Aging, drying, heat treatment After completion of the above operation, stirring is continued for about 20 hours, then dried at room temperature for 5 hours and at 40 ° C. for 1 day to completely remove the solvent, and then at 1000 ° C. for 2 hours. A heat treatment was performed at a temperature rise of 100 ° C./hour to obtain a glass sample having an average particle size of about 1 μm.

Example 2 Preparation of Silica Fine Particle (Seed) -Dispersed Cloudy Liquid First, a Teflon container was charged with ethanol as a solvent and an aqueous NH ₃ solution as an alkali catalyst. As water required for hydrolysis, water in an aqueous NH ₃ solution was used. next,
For the production of Seed, TEOS is used at a time,
% (Weight ratio), and the mixture was stirred in that state. In the same manner as in Example 1, TEO was added to the cloudy liquid prepared in
S, aluminum triisopropoxide (Al (OP
r) ₃ ), silver nitrate (AgNO ₃ ) was added. Aging, drying, and heat treatment After the above operation, stirring, drying, and heat treatment were performed in the same manner as in Example 1 to obtain a glass sample having an average particle size of about 1.2 μm.

Example 3 Preparation of a Silica Fine Particle (Seed) -Dispersed Cloudy Liquid In the same manner as in Example 1, a silica fine particle (Seed) -dispersed cloudy solution was prepared. 15% of the total amount of TEOS was added to the cloudy liquid prepared in the preparation of microspherical glass, and the mixture was stirred for 1 hour, and this operation was repeated twice in total. Thereafter, TEOS was added at 15% of the total usage, then aluminum triisopropoxide (Al (OPr) ₃ ) was added at 50% of the total usage, and silver nitrate (AgNO ₃ ) was also added at 50% of the total usage, followed by stirring. This series of operations was repeated twice in total. Aging, drying and heat treatment After completion of the above operations, stirring, drying and heat treatment were carried out in the same manner as in Example 1 to obtain a glass sample having an average particle size of about 1 μm.

Example 4 Preparation of Opaque Dispersion of Silica Fine Particles (Seed) A turbid solution of silica fine particles (Seed) was prepared in the same manner as in Example 1. TEOS was added to the white turbid liquid prepared in the preparation of the microspherical glass at 15% of the total used amount, and the mixture was stirred for 1 hour. This operation was repeated three times in total. Thereafter, 15% of the total amount of TEOS was added, and then aluminum triisopropoxide (Al (OPr) ₃ ) and silver nitrate (AgNO ₃ ) were added and stirred. Aging, drying, and heat treatment After the above operation, stirring, drying, and heat treatment were performed in the same manner as in Example 1 to obtain a glass sample having an average particle size of about 1 μm.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

[Table 4]

[0027]

[Table 5]

(2) Evaluation method for chemical durability of glass In order to evaluate the chemical durability and sustained release of Ag of the obtained glass, elution of Si and Ag from the glass into water in the following manner. The amount was checked. First, 0.1 g of the glass prepared above was weighed, individually placed in a polypropylene container, 20 ml of distilled water was added, the container was placed in a thermostat at 37 ° C., and the container was vibrated at a rotation frequency of 100 rpm. After immersing the glass in water for a predetermined period while applying vibration, the container was taken out of the constant temperature bath, filtered to separate the glass and the solution, and the concentrations of Si and Ag in the solution were measured by high-frequency inductively coupled plasma emission analysis. . The measurement results of the Si concentration and the Ag concentration are shown in FIGS.

Evaluation of Chemical Durability As shown in FIG. 1, in each of the examples, the elution amount of Si increased at a constant rate as the immersion time became longer, and the elution amount in two weeks after immersion was about 5 ppm. This indicates that the elution amount of Si from the glass is about 0.1%, which indicates that the chemical durability is extremely high. When the elution of Al was measured in the same manner, almost no elution of Al was confirmed.

Evaluation of sustained release of Ag From FIG. 2, it can be seen from FIG. 2 that the amount of Ag eluted at a substantially constant rate with respect to the immersion time in each of the examples, and the amount of Ag eluted about 2 ppm two weeks after immersion. . The antibacterial performance largely depends on the amount of Ag eluted, and even in Example 4 in which the Ag amount was reduced to 1/4, almost the same amount of eluted amount can be obtained by making the Ag content ratio of the glass surface layer the same. It was confirmed that.

(3) Evaluation method of antibacterial property of glass The antibacterial property of the produced glass was evaluated. The evaluation was performed using the minimum growth inhibitory concentration (MIC) method based on the liquid medium dilution method, and measured according to the following procedure. 1) Preparation of bacterial solution Escherichia coli is prepared in a Mueller Hinton (MHB) liquid medium. (Bacterial count: 1.0 to 5.0 × 10 ⁴ / ml) 2) Preparation of sample Heat sterilization at 160 to 180 ° C. for 120 minutes or more. 3) Preparation of test medium A sample of 6400 μg / ml is added to the MHB medium, and a 1 / 2-fold dilution is sequentially performed based on the sample to prepare a sample medium. 4) Inoculation of bacterial solution The adjusted bacterial solution is inoculated into the test medium diluted in each. 5) Culture The sample inoculated with the bacterial solution is placed in a water bath and cultured with shaking. (35-37 ° C, 24h)

Judgment Table 6 shows the MIC values of the samples prepared by the MIC method.

[Table 6]

As shown in Table 6, all of the prepared samples passed the antibacterial performance standard of 800 ppm.
Further, Example 4 in which the Ag amount was reduced to 1/4 also showed sufficient antibacterial properties, and has the possibility of cost reduction. Further, by changing the thickness of the surface layer and the Ag content ratio, glasses having various antibacterial properties can be easily designed.

[0034]

As described above, the antibacterial glass of the present invention comprises:
It is a colorless and dense material, and has excellent chemical durability and sustained release of antibacterial substances, and exhibits good antibacterial performance.
Therefore, long-term stable antimicrobial continuity can be expected in various places that require antimicrobial properties, and it is suitable as an antimicrobial material. Moreover, since the antibacterial metal is contained only in the surface layer, the expensive antibacterial metal can be effectively used.
Further, by changing the process, it is possible to design an antibacterial agent suitable for various uses.

If the obtained glass is a bulk material as in the conventional method, a pulverizing step is required to use the glass as an antibacterial agent, which increases the production cost. In addition, deterioration of antibacterial performance becomes a problem due to contamination due to abrasion of the pulverizing mill or the like. In order to further improve the antibacterial property, it is preferable that the particles are spherical, the particle size is fine, and the particle size is uniform. However, if the particles are crushed and classified, the particles become crushed. In addition, the cost is increased if the size is adjusted to be fine. On the other hand, since the antibacterial glass produced by the method of the present invention has a fine spherical shape, there is no need to perform pulverization and classification. Further, the adjustment of the particle size is easy. Therefore, a microsphere antibacterial glass excellent in antibacterial performance can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a graph showing the elution amount of Si.

FIG. 2 is a graph showing the elution amount of Ag.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 1/50 531 C02F 1/50 531E C03C 12/00 C03C 12/00 (72) Inventor Shoichi Kawashita Kyoto 13-1 Tamiyamonmaecho, Sanaka-ku, Kyoto-shi, Japan 310 Matsuya Residence Hyakumanbe 310 (72) Inventor Noriaki Masuda 2-7-1, Hararashi, Otsu-shi, Shiga Prefecture Nippon Electric Glass Co., Ltd. (72) Inventor Shibuya Takehiro F-term (reference) 4-7 FH01 FJ01 FK01 FL01 GA01 GA10 GB01 GC01 GD01 GE01 HH01 HH03 HH04 HH05 HH07 HH09 HH11 HH13 HH17 HH20 JJ01 JJ03 JJ05 JJ07 JJ10 KK01 KK03 KK05 KK07 KK10 MM15 NN4 0 4H011 AA02 BB18 BC18 DA01 DD07

Claims (10)

[Claims] An antibacterial glass comprising a substrate and a surface layer formed thereon, wherein the antibacterial metal ion is contained only in the surface layer. 2. The antibacterial glass according to claim 1, wherein the substrate is made of silica fine particles. 3. The method according to claim 1, wherein the surface layer is made of Si containing antibacterial metal ions.
_{2. The} antibacterial composition according to claim 1, wherein the glass is made of an O2-MxOy glass (where M is a metal atom whose valence is smaller than the coordination number, and x and y indicate the atomic ratio of M to O, respectively). Glass. 4. The antibacterial glass according to claim 3, wherein M is Al. 5. The antibacterial glass according to claim 1, wherein the antibacterial metal is Ag. 6. A hydrolyzable organosilicon compound, a hydrolyzable metal M compound (where M represents a metal atom whose valence is smaller than the coordination number when formed into an oxide), an antibacterial property A method for producing an antibacterial glass, which comprises mixing a metal salt, an alkali catalyst, and water and then firing. 7. A first mixing step in which the mixing comprises preparing a pre-mixed liquid containing a predetermined amount of a part of the organosilicon compound, an alkali catalyst and water, and adding a predetermined amount of the remaining organosilicon compound to the pre-mixed liquid. A second mixing step of adding and mixing the compound, the metal M compound, and the antibacterial metal salt. 8. The method for producing an antibacterial glass according to claim 6, wherein M is Al. 9. The method for producing antibacterial glass according to claim 6, wherein the antibacterial metal is Ag. 10. The method for producing antibacterial glass according to claim 6, wherein the alkali catalyst is ammonia.