JPH04134006A - Inorganic antimicrobial agent - Google Patents

Abstract

PURPOSE:To obtain the title antimicrobial agent harmless to man and livestock, capable of imparting synthetic resins, rubbers, coatings, paper, construction materials, etc., with antimicrobial function by calcining a borate of antimicrobial metallic ion such as Ag<+>, Cu<2+>, Zn<2+> or Co<2+> into powder followed by carrying said powder on an inorganic carrier. CONSTITUTION:A reaction is made between (A) an aqueous solution of a soluble borate and (B) another aqueous solution of a soluble metal salt such as silver nitrate under dispersion of an aqueous slurry of an inorganic carrier (e.g. oxide of Ti, Zn, Si, Al or Ca) to deposit a metal borate on the surface of carrier particles, and the resulting product is dried into powder, which is then treated under heating at >=600 deg.C and ground, thus providing the objective antimicrobial agent. The carrier acts as the stabilizer for the metal borate, and in applying to films or rubbers, etc., serves as the essential diluent for uniform dispersion. The metal borate accounts for 0.5-15wt.% of the total amount of it and the carrier. The present agent also gives high antimicrobial powder to various fungi as well as various kinds of bacteria.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inorganic antibacterial agent, and more particularly to an antibacterial agent that is safe for humans and animals and contains borate of an antibacterial metal ion as an active ingredient.

[Prior Art] In the environment surrounding us, a wide variety of fungicides and antibacterial agents are used, for example, in the fields of industry, agriculture, and food additives. Most of these are organic antibacterial agents, but recently antibacterial agents made of aluminosilicate compounds, typified by zeolite A, have attracted attention as inorganic antibacterial agents, and many proposals have been made.

This converts Na” in sodium aluminosilicate into Ag.
``, Cu'', Zn'', etc., which are substituted with metal ions that have a bactericidal effect (Japanese Patent Application Laid-Open No. 60181).
002, JP-A-62-70220, JP-A-82-70221, JP-A-63-265809, etc.).

Also known is a product in which amorphous aluminosilicate, which is a zeolite precursor, supports metal ions having a bactericidal effect (Japanese Patent Laid-Open No. 1-164720).

In addition, inorganic ion exchangers such as natural layered aluminosilicate and titanic acid supported with similar metal ions have also been proposed.

All of the above are inorganic ion exchangers that carry metal ions that have a bactericidal effect, but an antibacterial agent that is supported on an inorganic face t1 is also known.
4, JP-A-2-96508).

Furthermore, antibacterial apatite is also known.

[Problems to be solved by the invention] However, zeolite-based antibacterial agents are not only basic and easily discolored, but also have the influence of residual Na.
When added to synthetic resins, when processed into molded articles or films, there are problems such as discoloration of the resins and inhibition of thermal stability.

In view of the above-mentioned facts, the present inventors conducted intensive research into the development of inorganic antibacterial agents that are safe for humans and animals other than zeolite-based antibacterial agents, and surprisingly found that antibacterial metal salts of boric acid It was discovered that it has an excellent bactericidal effect, and the present invention was completed.

[Means for Solving the Problems] That is, the present invention provides an inorganic antibacterial agent containing borate of an antibacterial metal ion as an active ingredient.

The invention will be described in detail below.

The inorganic antibacterial agent according to the present invention is characterized in that its active ingredient is a sparingly soluble borate of a metal ion having an antibacterial effect.

Although there is no particular limitation on such metal ions, kg"
, Cu2°, Zn'' or co2+ are practically effective, and especially kg'' is the most preferred because it is not only highly safe for humans and livestock but also has excellent bactericidal action.

These metal borates often form poorly soluble metaborates or tetraborates and have bactericidal activity.

For example, silver borate is white by itself, but turns into a gray to black powder when exposed to air.

Therefore, in applications where such a color tone is acceptable, it can be used as an antibacterial agent as it is.

The color fastness of silver borate is better when mixed with other antimicrobial metal ions such as zinc or copper than by itself.

Furthermore, from the viewpoint of color fastness and practicality, it is better to support the dark borate on a desired inorganic carrier.

Such carriers include one or more oxides of titanium, zinc, silicon, cerium, aluminum, calcium or magnesium, silicates, aluminosilicates, phosphates, and others. Activated carbon is mentioned.

Furthermore, the particle state of the inorganic carrier used in the present invention may be in the form of powder, granules, granules, or a molded product having a specific shape, and its appearance differs depending on the use.

However, in many cases, it is in the form of a powder, and the fineness of the powder also depends on the application, but it is best to use a fine powder as much as possible, and in that case, the average particle diameter is preferably within a range of 5 μIll at most.

Therefore, the antibacterial agent of the present invention is preferably one in which a metal salt of boric acid having an antibacterial effect is supported on an inorganic carrier that is insoluble or sparingly soluble in water, but these metal salts of boric acid may also be used. It is not limited to one type, but two or more types may be supported at the same time, and if necessary, antibacterial zeolite, silver phosphate, etc. may be used in combination to support the support.

Thus, in the antibacterial agent according to the present invention, the carrier acts as a stabilizer for the metal borate having antibacterial properties;
On the other hand, the antibacterial effect varies depending on the composition ratio and content of metal ions in the metal borate, but since it exhibits antibacterial activity in very small amounts, the inorganic carrier that supports it can be applied to films, synthetic resins, rubber, etc. In this case, it is essential for uniform dispersion and acts as a diluent for the metal borate.

In the antibacterial agent of the present invention, the ratio of the inorganic carrier to the metal borate varies depending on the use, composition, etc., but the metal borate is preferably 0.1 to 30% by weight based on the total weight. 0.5-15% by weight is suitable. However, depending on the application, this composition ratio can also be varied.

Further, the antibacterial agent according to the present invention includes a fired powder obtained by heat-treating the above-mentioned porate salt or a product supporting the same.

The heating conditions are not particularly limited, but are 300°C or higher, preferably 600°C or higher, and the temperature can be set arbitrarily up to a practically high temperature that melts the borate to form glass, and heating is performed multiple times. You can.

It is possible to control the elution of antibacterial metal ions due to such heat treatment, and eliminate discoloration due to exposure to silver ions, further improving so-called color fastness, making it possible to provide a more practical antibacterial agent that can be applied to a wide range of applications. .

The antibacterial agent according to the present invention can be produced by the following method, but is not particularly limited to the following method.

■ A method based on the reaction of an aqueous solution of a soluble borate with an aqueous solution of a soluble metal salt such as silver nitrate.

■ A method in which metal borates are deposited on the surface of carrier particles under the dispersion of an aqueous slurry of an inorganic carrier.

■ Dry powder of ■ or ■ at 300℃ or higher, preferably 6
A method of pulverizing after heat treatment at a temperature of 00°C or higher.

In the present invention, the method according to the above method (2) is particularly preferable. In addition, since sintering occurs between particles when the heat-treated fired product is pulverized, it is desirable to use a pulverizer such as a jet mill to pulverize it as finely as possible.

[Production use] The antibacterial agent according to the present invention is "AFI" which has antibacterial properties.

It is a metal borate of Cu”, Z n”, Co2+,
Furthermore, such a metal borate has an antibacterial metal borate supported on an inorganic carrier that is insoluble or sparingly soluble in water, and has excellent antibacterial activity. In particular, silver borate is excellent.

The details of the mechanism by which metal borates have antibacterial activity are unknown, but it is likely that BO
- It is thought that they act synergistically to exert remarkable antibacterial activity.

Further, the carrier supporting the metal borate maintains the stability of the metal borate, thereby increasing the practicality of the antibacterial agent according to the present invention.

The antibacterial agent according to the present invention has a wide antibacterial spectrum, and surprisingly has strong antibacterial activity against not only various bacteria but also various molds.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 Lithium metaborate tetrahydrate (NaBO2.4 H2
0) Dissolve 278 g in 1ρ pure water (liquid A).

Silver nitrate (AfIN Oa) 34011 is dissolved in pure water 11 (solution B).

Next, solution B was added to solution A to perform a precipitation reaction, followed by washing with water, separation, drying, and pulverization to obtain 300 g of silver metaborate.
(hereinafter referred to as "antibacterial agent A").

Example 2 Sodium tetraborate (N a2B 40 ? 10
H20) To a solution of 38.14& in pure water 11, a solution 100a+N in which silver nitrate 34FI was dissolved in pure water was added to perform a precipitation reaction, and then post-treated in the same manner as in Example 1 to obtain silver tetraborate. To obtain approximately 25ii, this will hereinafter be referred to as "antibacterial agent B").

Example 3 To 1 g of the same sulfur and lithium metaborate aqueous solution as in Example 1,
255 g of silver nitrate and zinc nitrate [Z n (N O3)2
・1 p of a mixed solution of 4 g of 6H2017 dissolved in 11 of pure water was added to perform a precipitation reaction, and the same post-treatment was then performed to obtain 213 g of zinc silver metaborate (hereinafter referred to as "antibacterial agent C"). ).

Example 4 To the same sodium metaborate aqueous solution 11 as in Example 1, 255 g of silver nitrate and copper nitrate [Cu(N O3) 2 .3
H20] Mixture 11 in which 60 g was dissolved in 1N pure water
was added to cause a precipitation reaction, and then the same post-treatment was performed to obtain copper silver metaborate (hereinafter referred to as "antibacterial agent D").
).

Example 5 An aqueous slurry in which 70y of titanium dioxide was uniformly well dispersed in 11% pure water was subjected to a reaction in an amount such that 1.8 g of silver metaborate was deposited under stirring in accordance with Example 1 to support silver metaborate. Titanium dioxide was obtained (hereinafter referred to as "antibacterial agent E").
).

Next, this powder was fired in an electric furnace at 1000° C. for 2 hours, and then finely pulverized to obtain a white powder (hereinafter referred to as "antibacterial agent F").

Example 6 Using 70 g of wet process silica powder, zinc silver metaborate 2. A silica powder supporting silver metaborate (hereinafter referred to as "antibacterial agent G") was obtained by carrying out the same operation as in Example 5, except that O9 was set to be deposited.

Furthermore, this was calcined in the same manner as in Example 5 to obtain a white powder (hereinafter referred to as "antibacterial agent (■-■)").

Example 7 Zinc white supporting silver metaborate was obtained by carrying out the same operation as in Example 5 except that 70 g of zinc white was used (hereinafter, this will be referred to as "antibacterial agent (■)").

Furthermore, this was calcined in the same manner as in Example 5 to obtain a white powder (hereinafter referred to as "antibacterial agent J").

Antibacterial activity test Samples prepared in Examples 1 to 7 were mixed with 0.59% of pre-prepared bacterial contaminated water (Note 1) or mold diluted water (Note 2).
m+! The mixture was then slowly stirred using a magnetic cooler for 10 minutes. This liquid was measured using a simple microorganism measuring instrument Easy Calto TTC [for testing aerobic bacteria, fungi, and yeasts: manufactured by San-Ai Sekiyu Co., Ltd.] and Easy Cal l--M [fungi,
A culture test (Note 3) was conducted using a product manufactured by San-Ai Sekiyu Co., Ltd. for testing enzymes and Q-types. The results are shown in Table 1.

(Note 1): River water diluted with sterile water to bring the number of bacteria to 105...For total bacterial testing (Note 2) 1g of black mold-infested wall soil diluted with 100 sterile water...Fungi For testing (Note 3): Culture was carried out in an incubator at 27-30°C for 2 days (total introduction bacteria) or 4 days (fungi).

11 - Regression % (Note 2): The total number of strokes was evaluated based on the relationship between the degree of colony development and the number of bacteria roughly determined in advance. 0 is the case where no colony development is observed.

(Note 3): The degree of fungal contamination was determined using a four-step method, where - means no contamination, + means mild contamination, moderate contamination for samurai, and severe contamination for samurai.

Antibacterial test (2) Potato 100g, glucose 10g, agar 12.5i
? Then, prepare a potato agar medium containing 500 parts pure water and place it in a chalet (15-20 ml) to cool and solidify.

Next, a filter paper (30 mm x 30 m1) was impregnated with a solution in which 0.59 of a sample of each antibacterial agent was dispersed in 50 m1 of pure water, and the filter paper was brought into close contact with the culture medium to remove mold (Hureobasidium Pollulams).
Spread the supernatant of the FERM S-9) (*) containing liquid evenly over the entire spray medium, cover with a lid, and culture at 28°C ± 2°C. Thereafter, the degree of contamination of the paper was evaluated after 4 weeks. The results are shown in Table 2.

Note*: Subphylum Deuteromycota, Deuteromycota, Reticulata Moniliata, Aueo
It has a wide range of criteria for determining the genus basidium and has a strong bactericidal effect.

Therefore, it can be applied to synthetic resins, rubber, paints, paper, building materials, etc. to impart antibacterial functions to these materials and increase their value.

[Effect of the invention]

Claims (1)

[Claims] 1. An inorganic antibacterial agent containing borate of an antibacterial metal ion as an active ingredient. 2. Antibacterial metal ions are Ag^+, Cu^2^+, Zn
The inorganic antibacterial agent according to claim 1, which is one or more metal ions selected from ^2^+ and Co^2^+. 3. The inorganic antibacterial agent according to claim 1 or 2, wherein the inorganic antibacterial agent is a fired powder. 4. An inorganic antibacterial agent comprising the inorganic antibacterial agent according to any one of claims 1 to 3 supported on an inorganic carrier.