JP3428080B2 - Method for producing silver ion-containing glass - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a silver ion-containing glass, and more particularly to a method for producing a silver ion-containing glass composed of an alkali borosilicate glass containing antibacterial silver ions.

[0002]

BACKGROUND OF THE INVENTION It is well known that monovalent silver ions (Ag +) and copper ions (Cu +) are toxic to lower organisms such as microorganisms. In the present specification, microorganisms include bacteria, fungi, viruses, which are microorganisms in a narrow sense, and
It is defined as including broadly defined microorganisms such as protozoa and algae. Further, showing a toxic effect (including an antibacterial effect) on the above-mentioned microorganisms is simply referred to as having antibacterial properties. Up to now, many methods have been proposed in which silver ions (Ag +) are contained in a borosilicate-based soluble glass to impart antibacterial properties (for example, JP-A-2-302).
355 and Japanese Patent Publication No. 4-50878).

[0003]

In the above-mentioned Ag + -containing borosilicate glass, silver colloid and metallic silver are precipitated in the glass. That is, JP-A-2-30235
In Example 5, 20 mol% B ₂ O ₃ and 50 mol% S were used in the examples.
A glass composition of iO ₂ , 30 mol% of Na ₂ O is mentioned, but this composition has the drawbacks described below because metal Ag easily precipitates.

In the glass manufacturing process, platinums are often used for crucibles and pots for melting glass, and for linings of melting furnaces. If silver exists as Ag + in the glass, no problem will occur, but when silver colloid or metallic silver is deposited in the molten glass, this silver forms an alloy with a low melting point with platinum and becomes brittle and becomes a platinum material. It is easy for platinum equipment to have troubles because of cracks in the surface.

Further, Ag in glass has an antibacterial action.
+, And silver present in the glass in a colloidal silver or metallic state cannot be expected to have an antibacterial action. By reducing the precipitation of silver colloid and metallic silver in the glass melt and making most of the silver in the Ag + state as much as possible, a small amount of silver will exhibit an antibacterial effect, reducing the amount of expensive silver used. can do.

As a method of stably containing Ag + in glass, melting in an oxidizing atmosphere (Japanese Patent Laid-Open No. 1-31713)
Although 3) has been proposed, this method is not economical because the precipitation of silver colloid or metallic silver is not sufficiently suppressed and the cost for dissolution increases.

The present invention solves the above problems and eliminates the precipitation of silver colloid or metallic silver, so that the trouble of platinum equipment does not occur and most of the silver used as a raw material is efficiently used. The present invention provides a method for producing a glass composition containing Ag + having a strong antibacterial action.

[0008]

The present invention has been made to solve the above problems. That is, the present invention provides a method for producing an alkali borosilicate glass containing silver ions, which comprises at least 80% by weight of an alkali metal oxide component.
Using alkali metal hydrated borate as raw material , and
Is a method for producing a glass containing silver ions, characterized in that silver nitrate is used as a raw material .

In the present invention, the alkali metal borate used as at least a part of the raw material is a raw material for the alkali metal oxide ( Na ₂ O , K ₂ O, etc.) component and the B ₂ O ₃ component of the borosilicate glass. Becomes Examples of the alkali metal borate include sodium borate such as sodium tetraborate, sodium pentaborate, sodium hexaborate, sodium octaborate and sodium diborate; potassium metaborate, potassium tetraborate, potassium pentaborate, potassium hexaborate and octaborate. Mention may be made of potassium borate, such as potassium borate. Of these, hydrous borate salts of alkali metals, such as hydrous sodium tetraborate, are particularly preferred. The reason for this is that the hydrous borate of an alkali metal, for example, hydrous sodium tetraborate, is used as the raw material for the silver component in the decomposition temperature of silver nitrate (444 ° C).
It becomes a melt below and dissolves silver nitrate well, so Ag
Stabilizes +, and Ag + remains in the glass even at the melting temperature.
It seems to exist as.

[0010] Glauber's salt, which is a sodium sulfate, is generally used as a fining agent for glass, but it also has an oxidizing action in addition to the refining action. It is possible to further oxidize silver and further stably dissolve it as Ag + in the glass by using an alkaline metal borate in combination with Glauber's salt. The preferable amount of Glauber's salt used is 1 to 12% by weight based on the silica sand as the glass raw material.

It is preferred to provide at least 80% by weight, more preferably at least 95% by weight, of the alkali metal oxide component of the Ag + containing borosilicate glass from the alkali metal borate.

As the alkali metal borate, sodium tetraborate is used.
When using thorium, sodium tetraborate isNa
₂ O:B ₂ O ₃ = 1: 2.25 (weight ratio)
Therefore, as described below, borosilicate-based glass containing Ag +
SuB ₂ O ₃ /Na ₂ ORatio (weight ratio) of 2.25 or more
It is preferable to have a composition of That is, the glass composition
ofB ₂ O ₃ /Na ₂ OWhen (weight ratio) is 2.25 or more
In addition to sodium tetraborateB ₂ O ₃ Must be supplied
Therefore, use boric acid or diboron trioxide as the raw material.
ButB ₂ O ₃ Is a component that stabilizes Ag +, so there is a problem
There is no. However, when it becomes less than 2.25, on the contrary,Na ₂ OTo
Must be supplied with raw materials other than sodium tetraborate
But,Na ₂ OCarbonic acid commonly used as a raw material
Salt or nitrate cannot stabilize Ag +
Yes.Na ₂ OAmount of carbonate and nitrate used as raw materials
The total is less than 20% by weight in terms of oxide based on the glass raw materials.
Is preferred.

In the present invention, as the antibacterial glass, S
iO ₂ 25 to 60% by weight, Al ₂ O ₃ 0 to 20% by weight,
Na ₂ O 8 to 26% by weight, B ₂ O ₃ 18 to 60% by weight,
A borosilicate glass containing 0.05 to 2.0% by weight of Ag ₂ O as a main component is preferably used, and sodium borate, particularly hydrous sodium tetraborate is used as a raw material thereof, or in combination with Glauber's salt. Ag by changing the silver
It can be stably dissolved as +.

[0014]

In the above-mentioned borosilicate glass, by using an alkali metal borate as a raw material of an alkali metal oxide, particularly hydrous sodium tetraborate, silver colloid and metallic silver are stably deposited as Ag + without being deposited. Since it dissolves in the glass, it is possible to provide a soluble glass having an antibacterial action without damaging platinum used in equipment.

[0015]

[Example] Silica sand, aluminum oxide, mirabilite, sodium carbonate, so that the target composition of glasses 1 to 5 shown in Table 1 may be obtained.
Potassium carbonate, sodium nitrate, potassium nitrate, sodium tetraborate anhydrous pentahydrate decahydrate (borax), potassium tetraborate tetrahydrate, potassium hexaborate pentahydrate,
Boric acid and silver nitrate were blended to prepare batches as shown in Tables 2-9. Examples 1-5, Comparative Examples 1-4 (Table 2
3) so that the composition of glass 1 is the same as in Example 6,
7, the composition of Comparative Examples 5 and 6 (Table 4) has the composition of glass 2, and the composition of Examples 8 and 9 and Comparative Examples 7 and 8 (Table 5) has the composition of glass 3, The formulations of Examples 10 to 14 and Comparative Examples 9 to 12 (Tables 6 to 7) were adjusted so that the composition of Glass 4 was achieved. Examples 15 to 18 and Comparative Examples 13 and 14 (Tables 8 to 8).
The formulation of 9) is adjusted so that the composition of glass 5 is obtained. The numerical values of the raw materials in the table represent the weight (g) required to make 300 g of glass,
Figures "dissolved to have Ag + amount (%)" of 7,9, amount of silver nitrate is a silver material Ag + amount dissolved in the glass to the (Ag ₂ O amount in terms) (Ag ₂ O Converted to amount, but excludes precipitated metal silver and includes colloidal silver) ratio (%)
(Calculated value). This batch was placed in an alumina crucible if it was predicted that a large amount of metallic silver was precipitated, otherwise placed in a platinum crucible and placed in an electric furnace at 1400.
˜1500 ° C. was heated and melted for 2 hours. The molten glass was poured onto a stainless plate, shaped into a plate, and then gradually cooled.

With respect to these samples, the deposition state of metallic silver and the coloring state of glass were measured by the following methods.・ Precipitation of metallic silver The plate glass after melting and gradually cooling as described above is irradiated with a halogen lamp, and the metal silver having a major axis of 10 μm or more present in the plate glass is magnified 40 times. It is counted using a No. loupe and is expressed as the number per 100 g of glass. When there is no precipitation of metallic silver, ⊚, and the number of metallic silver is 1.
When the number is 0 or less, it is shown by ◯, and when it is more than 10, it is shown by x. Since most of the size (major axis) of metallic silver is 80 μm or less, when the number is 10 or less, the influence on platinum and quality is small, and it is negligible depending on the product type. -In the sample on the colored state of the glass, the case where yellow or brown coloration (coloring due to silver colloid) was not visually observed was marked with O, and the case where coloration was recognized was marked with X. The weight of the silver colloid when coloring is observed corresponds to the weight of metallic silver when the number of metallic silver exceeds 10.

[0017]

[Table 1] ================================= Composition Glass 1 Glass 2 Glass 3 Glass 4 Glass 5 (weight %) (% By weight) (% by weight) (% by weight) (% by weight) −−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−− _{- SiO 2 55.0 55.0 55.0 40.0 55.0} Al 2 O 3 9.0 9.0 9.0 0 10.0 Na 2 O 10.0 0 0.3 10.0 20. 0 K ₂ O 0 10.0 9.7 0 0 B ₂ O ₃ 26.0 26.0 26.0 50.0 15.0 Ag ₂ O 0.4 0.4 0.4 0.4 1.5 0.4 ==================================

[0018]

[Table 2]

[0019]

[Table 3]

[0020]

[Table 4]

[0021]

[Table 5]

[0022]

[Table 6]

[0023]

[Table 7]

[0024]

[Table 8]

[0025]

[Table 9]

As is clear from Tables 2 to 9, in all the glasses of Examples, metallic silver was not deposited at all, or was negligibly small, and there was no fear of coloring. On the other hand,
The glass of the comparative example has the following drawbacks. Comparative Example 1,
In 2,5,6,9,10,13,14, a very large amount of metallic silver is deposited and the glass is colored. In other comparative examples, the glass is not colored, but a large amount of metallic silver is deposited.

It should be noted, for all the comparative examples of the calculation of the Ag + amount dissolved in the glass (translated at Ag ₂ O amount), 80-98% of the silver nitrate is dissolved in the glass as Ag + It was found that 200cc of Comparative Example 1 was actually
As a result of melting once using the platinum crucible of No. 3 (thickness: 0.5 mm) under the above melting conditions, platinum became brittle and cracks occurred.

Finally, in the examples in which no metallic silver was deposited, the platinum crucible was not embrittled even if it was melted several tens of times in the platinum crucible under the above melting conditions.

[0029]

INDUSTRIAL APPLICABILITY As described above, the silver ion-containing glass of the present invention is cost-effective by using an alkali metal borate, particularly hydrous sodium tetraborate, as a raw material for an alkali metal oxide of a borosilicate glass. It is possible to manufacture a glass containing silver ions, which is advantageous to the above and has excellent antibacterial properties.

Continuation of the front page (56) References JP-A-3-146436 (JP, A) edited by Sakuo Saku et al., Glass Handbook, Asakura Shoten Co., Ltd., September 30, 1975, p. 297 (58) Fields surveyed (Int.Cl. ⁷ , DB name) C03C 1/00-14/00 A01N 59/16 WPI

Claims (6)

(57) [Claims] 1. A method for producing an alkali borosilicate glass containing silver ions, wherein a hydrated borate of an alkali metal is used as a raw material of at least 80% by weight of an alkali metal oxide component, and silver nitrate is used as a raw material of silver. A method for producing a glass containing silver ions, comprising: 2. Of the raw materials of the alkali metal oxide component,
The method for producing a silver ion-containing glass according to claim 2, wherein Glauber's salt is used as the remaining raw material other than the one obtained by using the hydrous borate of the alkali metal. 3. The method for producing a silver ion-containing glass according to claim 1, wherein the hydrous borate of an alkali metal is sodium tetraborate containing crystal water. 4. The alkali borosilicate glass is SiO ₂
25-60% by weight, Al ₂ O ₃ 0-20% by weight, Na ₂ O
8 to 26% by weight, B ₂ O ₃ 18 to 60% by weight, Ag ₂ O
The method for producing a silver ion-containing glass according to claim 1, which is a composition containing 0.05 to 2.0% by weight as a main component. 5. The alkali borosilicate glass is B ₂ O ₃ /
The silver according to claim 4, wherein Na ₂ O (weight ratio) has a component ratio of 2.25 or more, and sodium tetraborate containing water of crystallization is used as a raw material of 100% of the alkali metal oxide component. Method for producing ion-containing glass. 6. The borosilicate alkali glass is B ₂ O ₃ /
Na ₂ O (weight ratio) is one having a component ratio of less than 2.25, among the raw materials of an alkali metal oxide components, as the rest of materials other than those due to sodium tetraborate containing the crystal water, Glauber's salt The method for producing a silver ion-containing glass according to claim 4, wherein: