JPH10120518A - Antimicrobial agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an antimicrobial agent high in stability, being hardly influenced by light, heat, pressure, chemical substances, etc., by using inorganic powder containing metal silver fine particles having particle diameters equal to or smaller than a fixed value. SOLUTION: This antimicrobial agent uses inorganic powder containing metal silver fine particles having <=10nm particle diameters. Preferably, the antimicrobial agent is prepared by using inorganic powder having an inclusion lattice. The inorganic powder having the inclusion lattice has properties of holding molecules in a part of a structure having a fine layered or a basket-like void and the extremely fine metal particles can be produced by taking advantage of the properties. Zeolite, layer phosphate, layer clay mineral, transition metal chalcogenide, graphite, etc., may be cited as the inorganic power having the inclusion lattice. The antimicrobial agent is used for drinking water treatment and providing a polymer molding material with antimicrobial properties.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antibacterial agent used for drinking water treatment or for imparting antibacterial properties to a polymer molding material by adding it to an antibacterial agent, which is affected by light, heat, pressure, chemical substances and the like. It relates to a hardly stable antibacterial agent.

[0002]

2. Description of the Related Art Attempts have been made to obtain an antibacterial molded article by adding an antibacterial agent to various polymer molding materials, and many antibacterial agents for this purpose have been developed. Among these, an antibacterial zeolite in which silver ions as antibacterial metal ions are supported on zeolite which is a crystalline aluminosilicate (JP-A-60-181002), and an antibacterial agent in which silver ions are supported on zirconium phosphate (see (Japanese Unexamined Patent Publication No. 3-83905) has been proposed and is known to be excellent in safety and antimicrobial durability. Antimicrobial agents may be affected by light, heat, pressure, chemicals, etc. when undergoing various processes and in the final use. Physical properties such as coloring, discoloration, and mechanical strength were sometimes reduced. In particular, antibacterial agents containing silver ions have extremely high antibacterial performance, but have a drawback that they are easily affected by light, heat, pressure and chemical substances.

[0003]

Accordingly, it is an object of the present invention to provide light,
An object of the present invention is to provide an antibacterial agent which has no or little reduction in antibacterial action and physical properties such as coloring, discoloration and mechanical strength due to heat, pressure, chemical substances and the like.

[0004]

As a result of various studies conducted by the present inventors to solve the above-mentioned problems, it has been found that metallic silver fine particles having a particle diameter of 10 nm or less are chemically very stable, and that the antibacterial performance is high. Found to be comparable to those carrying
The present invention has been completed. The present invention has a particle diameter of 10 n.
The present invention provides an antibacterial agent characterized by being an inorganic powder containing metallic silver fine particles of m or less. Silver particles are physicochemically stable, are less susceptible to physical effects such as light, heat, and pressure, and are also stable to chemical substances. However, a silver particle having a general particle size of 0.5 μm has almost no antibacterial action and is not suitable as a practical antibacterial agent.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. It is very difficult to pulverize metallic silver particles to obtain a large amount of uniform particles of 10 nm. For this reason, in order to prepare an inorganic powder containing metal silver fine particles having a particle diameter of 10 nm or less used in the present invention, it is desirable to use an inorganic powder having an inclusion lattice. The inclusion lattice is a gap that allows atoms and molecules to enter, and the inorganic powder having this inclusion lattice has the property that molecules can be trapped in the part of the structure that has minute layered or cage-shaped cavities. Utilizing the properties, uniform and very fine metallic silver particles can be produced. As the inorganic powder having an inclusion lattice used in the present invention, zeolite, layered phosphate, layered viscosity mineral, transition metal chalcogenide, graphite, transition metal oxide, and layered oxyacid salt At least one selected

The zeolites include synthetic zeolites and natural zeolites, such as A-type zeolites, X-type zeolites, Y-type zeolites, T-type zeolites, high silica zeolites, sodalite, mordenite, analcyme, clinoptilolite, Chabasite, Erio Knight and the like can be mentioned. As the layered phosphate,
Zirconium phosphate, titanium phosphate and the like can be mentioned. Examples of the layered clay mineral include montmorillonite, vermiculite, kaolinite, beidellite, sepiolite and the like. Transition metal chalcogenides include titanium, zirconium, hafnium, molybdenum, tungsten, niobium, tantalum, vanadium,
Transition metals such as manganese and nickel, and sulfur, selenium,
Compound containing a chalcogen element such as tellurium, for example, Ta
S ₂ , TaSe ₂ , NbS ₂ , VPS ₃ , MnPS ₃ ,
NiPSe _{3 and the} like.

Examples of the transition metal oxide include tungsten oxide, rhenium oxide, ruthenium oxide, and vanadium oxide. Examples of the lamellar oxyacid salts include alkali metal salts and alkaline earth metal salts of titanic acid, uranic acid, niobic acid, tungstic acid, molybdic acid, and vanadic acid, for example, sodium titanate, sodium uranate, potassium uranate, and niobium. Potassium acid, sodium tungstate, magnesium molybdate, calcium molybdate, potassium vanadate and the like can be mentioned. Other examples of the inorganic powder supporting silver particles include silica gel, alumina gel, activated carbon, and glass.

In the present invention, the particle diameter of the inorganic powder is preferably in the range of 0.1 to 20 μm from the viewpoint that it can be easily used in various processes. The average particle diameter of the inorganic powder is 0.3 to 12 μm, preferably 0.5 to 4 μm.
μm is appropriate. In the present invention, the specific surface area of the inorganic powder is 80 from the viewpoint that a large amount of metallic silver fine particles can be contained.
It is preferably at least m ² / g, and the upper limit is not particularly limited, but is usually at most 900 m ² / g.

In the present invention, the fine metal silver particles having a particle diameter of 10 nm or less formed on the inorganic powder can be prepared, for example, by bringing a solution of a silver salt compound into contact with the inorganic powder particles and reducing the particles. As the silver compound used in the preparation of the antibacterial agent in the present invention, a water-soluble silver compound is preferable, for example, silver nitrate, silver sulfate, silver acetate, silver chlorate, silver perchlorate, silver hexafluorophosphate, tetrafluoroborane Silver acid, diammine silver sulfate and the like.
As a method for reducing the silver salt contacted and attached on the inorganic powder, there are a thermal decomposition method and a reducing agent reaction method. The thermal decomposition method is a method of heating at a temperature higher than the thermal decomposition temperature of the silver compound. For example, the thermal decomposition temperature of silver nitrate is 444 ° C, the thermal decomposition temperature of silver acetate is 240 ° C, and the thermal decomposition temperature of silver tetrafluoroborate is 200 ° C. The reducing agent reaction method is a method in which various reducing agents are allowed to act on a silver compound, and this is reduced to metallic silver. Reducing agents that can be used include sugars, aldehydes,
Hydroquinone, formic acid, oxalic acid, ascorbic acid, nitrites, divalent chromium salts, divalent iron salts, monovalent copper salts,
Examples thereof include tetravalent uranium salts, divalent vanadium salts, sulfurous acid gas, nitrous acid gas, and carbon monoxide.

In the present invention, the silver particles in the antibacterial agent are 10n.
m or less preferably account for 60% by weight or more, more preferably 80% by weight or more of the total silver particles. The particle size of the silver particles can be measured with an electron microscope (point: EM-002A, etc.) having a point resolution of 0.5 nm or less.
In the present invention, the average particle size of the silver particles in the antibacterial agent,
1 to 10 nm, preferably 4 to 10 nm is appropriate.
The antibacterial agent comprising the inorganic powder of the present invention preferably contains silver particles in an amount of 0.7% by weight or more, more preferably 1.4% by weight or more of the weight of the antibacterial agent from the viewpoint of antibacterial performance. The antibacterial agent of the present invention can be used in various fields where antibacterial action is required. For example, it can be used in the field of drinking water treatment, the field of food packaging, the field of medical products, the field of home cooking products for business use, the field of bathrooms, the field of toilets, and the like.

[0011]

The antibacterial agent of the present invention is hardly affected by light, heat, pressure, chemical substances and the like, and can exhibit a highly stable antibacterial action for a long period of time.

[0012]

【Example】

Examples 1 to 5 A-type zeolite powder (Na ₂ O.Al ₂ O _3.
1.9 SiO ₂ .xH ₂ O: average particle size 1.5 μm, specific surface area 720 m ²
/ G), zirconium phosphate powder (average particle size 0.6 μm,
Specific surface area 240 m ² / g), sepiolite (average particle size 80
An antibacterial agent powder was prepared from a mesh, a specific surface area of 110 m ² / g) and sodium titanate (average particle size of 3.7 μm, a specific surface area of 85 m ² / g) by a thermal decomposition method using silver acetate as a silver compound. . For the preparation, a predetermined amount of inorganic powder and silver acetate fine powder were mixed with a small amount of water, and then heated at 280 to 300 ° C. for 1 hour. Table 1 shows the formulation amount, the silver content of the prepared antibacterial agent powder, and other measured values.

Examples 6 and 7 Y-type zeolite powder (Na ₂ O.Al ₂ O _3.
2.4 SiO ₂ xH ₂ O: average particle size 0.5 μm, specific surface area 840 m ²
/ G), montmorillonite powder (average particle size 100mesh,
A specific surface area of 280 m ² / g) was immersed in an aqueous solution of silver nitrate to deposit silver ions on the surface. After washing this with water,
A 10% aqueous solution of ascorbic acid was added to reduce silver ions to metal salts. After filtration and drying at 100 ° C., an antibacterial agent was prepared. Table 2 shows the silver content of the prepared antibacterial agent powder and other measured values.

Comparative Examples 1 to 3 As comparative examples, zirconium phosphate powder containing no silver particles (average particle size: 0.6 μm, Comparative Example 1), silver ion-substituted zirconium phosphate powder (silver ion content: 3.1) %, An average particle diameter of 0.6 μm, Comparative Example 2), and silver particles having an average particle diameter of 10 μm (Comparative Example 3).

Test Example 1 (Antibacterial activity test) The antibacterial activity of the particles obtained in Examples and Comparative Examples was determined by measuring the minimum inhibitory concentration (MIC) and the minimum killing concentration (MBC) according to the standard method of the Japanese Society of Chemotherapy. The evaluation was performed by measuring each of the bacterial species of Streptococcus and Pseudomonas aeruginosa. Table 3 shows the results. Test Example 2 (Durability Test for Light, Heat, and Chemical Substances) In order to evaluate the various durability of the particles obtained in the examples and comparative examples, the following treatments were performed, and then the minimum value was determined according to the standard method of the Japanese Society of Chemotherapy. The growth inhibitory concentration (MIC) and the minimum kill concentration (MBC) were measured for S. aureus. The results are shown in Tables 4 and 5. Treatment A: Two UV lamps (20 W) at a distance of 10 cm
Irradiated for 1000 hours. Treatment B: heated at 800 ° C. for 96 hours in a nitrogen atmosphere. Treatment C: The substrate was immersed in a 1N aqueous solution of sodium hydroxide at 20 ° C. for 96 hours and then washed with water. Treatment D: 20% aqueous solution of sodium hypochlorite at 1N concentration
After immersion at 96 ° C for 96 hours, it was washed with water.

[0016]

[Table 1] Table 1 Example Inorganic powder containing metallic silver fine particles Antibacterial agent type Silver content Silver particles having a silver particle diameter of 10 nm or less (%) Content of uniform diameter (nm) (% by weight) 1 A-type zeolite 2.5 8.0 70 2 A-type zeolite 0.75 5.5 90 3 Zirconium phosphate 2.8 5.8 704 Sepiolite 1.2 7.0 805 Sodium titanate 5.8 9.5 60

[0017]

[Table 2] Example 2 Inorganic powder containing metallic silver fine particles Antibacterial agent Type Silver content Silver particles having a particle size of 10 nm or less (%) Content of uniform diameter (nm) (% by weight 6 Y-type zeolite 1.4 9.0 707 Montmorillonite 2.6 9.0 70

[0018]

Table 3 Unit: ppm ─────────────────────────────────── Sample Staphylococcus aureus Green pus Bacteria MIC MBC MIC MBC Example 1 250 500 250 500 Example 2 62 500 62 250 Example 3 62 500 125 500 Example 4 250 1000 250 250 Example 5 250 250 125 125 500 Example 6 62 250 250 500 Example 7 62 250 125 250 Comparative Example 1 2000 or more 2000 or more 2000 or more 2000 or more Comparative Example 2 250 1000 500 2000 Comparative Example 3 2000 or more 2000 or more 2000 or more 2000 or more

[0019]

Table 4 ─────────────────────────────────── MIC, MBC ( ppm) Treatment A Treatment B Treatment C Treatment D MIC MBC MIC MBC MIC MBC MIC MBC Example 1 250 500 250 500 250 500 250 500 Example 2 62 250 62 500 62 250 62 500 Example 3 62 250 62 500 62 500 62 500 Example 4 250 1000 250 1000 250 500 250 500 Example 5 62 250 62 250 62 250 62 250 Example 6 62 250 62 250 62 250 62 250 Example 7 62 250 62 250 62 250 62 250 Comparative example 1 2,000 or more -2,000 or more-2,000 or more-2,000 or more-Comparative Example 2 2,000 or more-2,000 or more-2,000 or more-2,000 or more- Comparative Example 3 2,000 or more-2,000 or more-2,000 or more-2,000 or more-* 2,000 or more are MIC values.

[0020]

[Table 5] 処理Color change treatment A of sample antibacterial agent Process B Process C Process D Example 1 White White White White White Example 2 White White White White White Example 3 White White White White White Example 4 White White White White White Example 5 White White White White White Example 6 White White White White White Example 7 White White White White White Comparative Example 1 White White White White White Comparative Example 2 Yellow White Gray Color Gray-white Yellow-brown Comparative Example 3 Gray-white Gray-white Gray-white Gray-white

Claims (2)

[Claims] 1. An antibacterial agent which is an inorganic powder containing metal silver fine particles having a particle size of 10 nm or less. 2. The inorganic powder is selected from the group consisting of zeolite, layered phosphate, layered clay mineral, transition metal chalcogenide, graphite, transition metal oxide, and layered oxyacid having an inclusion lattice. The antibacterial agent according to claim 1, which is at least one kind.