JPH0733617A - Antimicrobial granule and production thereof - Google Patents

Abstract

PURPOSE:To provide antimicrobial granules proper in the amount of released silver ions, capable of continuously releasing the silver ions in a certain concen tration over a long period, not causing a vigorous reaction when heated, or stable when heated at high temperatures, and substantially not staining or coloring coatings or synthetic resins, when added to the coatings or synthetic resins. CONSTITUTION:Antimicrobial granules comprising granules produced by fixing silver oxide fine crystals to silica granules in a mixed state and having a size of <=40mum, the contents of the silver oxide and the silica being 1-95wt.% and 5-99wt.%, respectively. Antimicrobial granules produced by heating the granules to reduce the silver oxide into silver. And antimicrobial granules produced by encapsulating either of two kinds of the granules with microcapsules comprising a waterinsoluble porous inorganic compound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a granular silver antibacterial agent and a method for producing the same.

[0002]

2. Description of the Related Art It is known that silver ions have antibacterial properties, but soluble silver salts such as silver nitrate easily elute, so that the consumption of silver ions is large, and a certain amount of silver ions can be consumed over a long period of time. It cannot be released.

In addition, a method of supporting a poorly soluble silver salt has a problem. The following techniques are known as a method for supporting a silver salt.

Japanese Patent Publication No. 60-5359 discloses a method in which a readily soluble silver salt is adsorbed on activated carbon, and then a halogen compound is caused to act thereon to form a sparingly water-soluble silver halide and steam heating. .

Japanese Unexamined Patent Publication No. 63-20090 discloses that a poorly soluble silver salt is supported on a silica / alumina type porous inorganic carrier. This silica / alumina-based porous inorganic carrier has a porous structure of silica gel, zeolite, and perlite. As the sparingly soluble silver salt, an easily soluble silver salt aqueous solution is adsorbed on porous silica gel or the like, and then a halogen compound is allowed to act thereon to form the sparingly soluble silver salt.

Japanese Unexamined Patent Publication (Kokai) No. 3-81209 discloses that finely powdered silica is loaded with an antibacterial metal by absorbing a water-soluble compound as the antibacterial metal. Porous silica having a particle size of 1 to 100 μm is used as the fine powder silica, and the loading of the antibacterial metal is 2 to 10%. The antibacterial metal is required to be water-soluble instead of being a metal such as silver, copper or zinc.

[0007]

The above-mentioned known technique has the following problems.

According to the method disclosed in Japanese Patent Publication No. 60-5359,
Since the carrier is activated carbon, it cannot be used for paints and synthetic resins. Further, since the fixing force is weak only by the adhesion of the silver salt to the activated carbon, there is a problem that the silver halide peels off from the activated carbon during use.

In the method disclosed in Japanese Unexamined Patent Publication No. 63-20090, the more highly dehydrated the porous silica is, the higher the adsorptivity is, but the adsorption of the silver salt on the silica gel is saturated at 2% to 4%. It is said that there is a point, and it is impossible to support a silver salt with a higher concentration than that by the absorption method. Further, some silver halides adsorbed on the surface of silica gel are easily peeled off. Moreover, when it is added to a synthetic resin, there is a problem that the silver halide adsorbed on the silica gel comes into direct contact with the synthetic resin component to cause color contamination or discoloration.

The technique disclosed in Japanese Patent Laid-Open No. 3-81209 is a technique of immersing fine powder silica in an aqueous solution of a metal salt and drying it. Since a water-soluble silver salt or the like is used, it is adsorbed on silica. However, since the water-soluble silver salt is eluted, it cannot be used for a long time. The amount of silver ions released is too large, and it is impossible to continuously maintain a constant silver ion concentration. When it is added to paints or synthetic resins, there arises a problem of significant contamination and discoloration.

As a result of researching such problems of conventional antibacterial agents, the present inventor has found that silver oxide, which has not been conventionally used as an antibacterial agent, can be used as an antibacterial agent.

The solubility of silver oxide is 5.7 × 10 ^-5 mol / L
Since it is (18 ° C.), it can be kept constant with a small amount of dissolution, so that the silver ion can be kept constant. For example, it is possible to maintain silver ions at 50 ppb or less for a long period of time.

Further, the present inventor has previously found that silver oxide having a grain size of 1 μm or less can be produced by utilizing the spray drying technique. Then, it was proposed in Japanese Patent Application No. 5-32825 to encapsulate this and use it as an antibacterial agent. However, silver oxide is a heat-labile compound and tends to react violently with heat to release oxygen. Therefore, it has been found that this antibacterial agent has no problem when it is used for those that do not heat (for example, water treatment), but it is unstable when this antibacterial agent is used for those that heat it.

According to the subsequent research conducted by the present inventor, as will be described later as a reference example, silver oxide having a grain size of 1 μm or less is particularly unstable to heat, and strongly releases oxygen due to heat. Sinter to a mass of metallic silver of 100 μm or more. In addition, there are some remarkable changes in its antibacterial properties. As shown in Table 1, the minimum inhibitory concentration (MIC) against Staphylococcus aureus is 8 ppm.
The MIC of the silver oxide of
It dropped to 0 ppm. Thus, it was found that it is difficult to use silver oxide as it is as an antibacterial agent in a wide range of stable applications.

[0015]

OBJECTS OF THE INVENTION The object of the present invention is to solve the above-mentioned conventional problems, and also to solve the above-mentioned problems in the research and development by the present inventor. An object of the present invention is to provide an antibacterial agent capable of releasing silver ions appropriately and capable of continuously releasing silver ions over a long period of time at a constant silver ion concentration. Also,
Another object of the present invention is to provide an antibacterial agent which does not cause a violent reaction even when heat is applied. Further, it is to provide an antibacterial agent which is stable even when high temperature heat is applied. It is an object of the present invention to provide an antibacterial granular material which is hardly contaminated or discolored even when added to a paint or a synthetic resin. Moreover, it aims at providing the manufacturing method which can manufacture such an antibacterial granular material comparatively cheaply and easily.

[0016]

According to the present invention, fine crystals of silver oxide are fixed to silica particles in a mixed state.
The particle size is less than or equal to μm, and the composition of the particle size is 1 silver oxide.
-95 wt% and silica 5 to 99 wt%, or an antibacterial powder obtained by heat-treating this powder to reduce silver oxide to silver, or the above two types of powder The above object is achieved by an antibacterial powder granule in which any one of the granules is wrapped with a microcapsule made of a water-insoluble porous inorganic compound.

According to the method for producing an antibacterial granular material of the present invention of claim 13, (a) the first step of mixing and stirring the silica sol and the silver nitrate aqueous solution, and (b) the liquid obtained in the first step. Second, a second step of mixing and stirring an aqueous solution of sodium hydroxide to form a colloidal solution of silica sol and silver oxide, (c)
It is characterized in that it comprises a third step of forming the colloidal liquid obtained in the second step into powder particles by spray drying.

According to the method of the present invention as set forth in claim 14, the granular material obtained as described above is further heat-treated to reduce silver oxide to silver.

Further, according to the method of the present invention of claim 16, the powder and granules obtained as described above are encapsulated in microcapsules made of a water-insoluble inorganic compound by an interfacial reaction method.

Alternatively, according to the method of the present invention of claim 18, silica sol and a silver nitrate aqueous solution are mixed without forming a powder by spray drying, and an alkaline aqueous solution is further added to form a slurry, which is subjected to an interfacial reaction method. Microcapsule using.

According to claims 17 and 19, the solid content obtained according to claims 16 and 18 is further heat-treated to reduce silver oxide to silver.

The silica sol used in the present invention is a colloidal solution of silica ultrafine particles having a particle diameter of 5 nm to 20 nm. The particle size of silica is 10-20n
Although a fixing force of 5 to 7 nm is stronger than m, the particle size is not particularly specified in the present invention, and a silica sol having a stable PH in alkali is preferable. A silica sol / silver oxide ratio of 5% or less is not suitable for the present invention because the prevention of sintering when heated is insufficient. Further, when the silver oxide content is 1% or less, the antibacterial effect is lowered, and the antibacterial composition intended to be added in a small amount as an antibacterial agent is poor in practicality.

In a commercially available silica sol, silica solid content is 20 to 40%, sodium oxide is 0.0
Those having a particle size of 1% to 0.6% and a particle size of 5 to 20 nm are used. The commercially available silica sol is Snowtex-20 (silica solid content 2 manufactured by Nissan Chemical Industries, Ltd.).
0%, sodium oxide 0.1-0.35%, particle size 10
~ 20 nm), Snowtex-30 (silica solid content 3)
0%, sodium oxide 0.2-0.6%, particle size 10
20 nm), Snowtex-40 (silica solid content 40
%, Sodium oxide 0.3 to 0.6%, particle size 10 to 2
0 nm), Snowtex-S (silica solid content 30%,
Sodium oxide 0.2-0.6%, particle size 7-9n
m), Snowtex-XS (silica solid content 20%, sodium oxide 0.3 to 0.6%, particle diameter 4 to 6 nm) and the like.

In the present invention, when a commercially available silica sol is used for producing an antibacterial granule by spray drying, if the silica sol is used as it is, the silica concentration is too high and it is difficult to spray. Therefore, the silica sol is diluted with water before use. .

Further, when the silica sol and the silver nitrate aqueous solution are mixed without being made into powder and granules by spray drying, and an alkaline aqueous solution is further added to form a slurry, which is microencapsulated by the interfacial reaction method, the concentration is Use a high silica sol. The silica solid content is preferably 40% or more.

To obtain a silver oxide sol, 10% of silver nitrate is used.
Aqueous solution is mixed with silica sol and stirred for 1 to 3 hours, and then an alkaline aqueous solution is injected with stirring and stirred for 1 to 3 hours. When sodium hydroxide, potassium hydroxide, or ammonia is used as the alkaline aqueous solution, it becomes silver oxide through silver hydroxide. Sodium carbonate as an alkaline aqueous solution,
It is also possible to use sodium hydrogen carbonate, ammonium carbonate, or ammonium hydrogen carbonate to form silver oxide through silver carbonate.
In addition, sodium phosphate, disodium hydrogen phosphate, phosphoric acid 2
It is also possible to use sodium hydrogen, ammonium phosphate, diammonium hydrogen phosphate and ammonium dihydrogen phosphate to form silver oxide through silver phosphate.

In order to enhance the stability of the colloid, PVA or the like is used as a protective colloid substance, for example, 0.001 to 0.1.
% May be added.

When the powder and granules of the present invention are produced by spray drying, when the silica component in the composition is about 10%, fine crystals of sub-micron (1 μm or less) silver oxide are linked in a chain by the silica component. Is doing. When a force is applied by stirring or the like, this breaks the connection by the silica component and becomes a finer powder.

When the amount of silica component in the composition increases, fine particles of submicron silver oxide are surrounded by silica particles,
Silica particles are linked together to form a doughnut-shaped powder (see FIGS. 3 and 4) as a whole, and the particle size is 2 to 40 μm.
m.

For spray drying, a usual spray dryer can be used. For example, with a compact spray dryer manufactured by Anhydro, the spraying conditions are as follows: Nozzle rotation speed 25,0
The spray rate is 250 cc / min at 00 rpm, the internal temperature is 180 ° C, and the outlet temperature is 90 ° C.

The heat treatment in the present invention is carried out to reduce silver oxide to silver. Usually, silver oxide is reduced at about 200 ° C., but the silver oxide of the present invention is a fine crystal of 1 μm or less. It is reduced to silver from around 120 to 130 ° C. The heat treatment is related to temperature and time, and if the granular material is in a dry state, it will be reduced in a few minutes to several tens of minutes, but if the amount of processed material is large or it is in a wet state, it will be reduced uniformly. It is preferable that the heat treatment is performed at 180 ° C. or higher for 1 hour or longer. Further, in the case of encapsulation, the solid content may be washed, and the drying condition may be appropriately selected upon drying, so that this heat treatment can also be performed.

Since silver oxide has a dark brown color and silver has a dark color, according to the present invention, an antibacterial powder or granular material (antibacterial agent) composed of silver oxide and silica or silver and silica is microencapsulated. It can be a white fine powder. Since the size of the produced microcapsules is influenced by the size of the antibacterial agent as the core substance, it is preferable to use an antibacterial agent having a diameter as small as possible in order to obtain a microcapsule having a small diameter. Preferably, an antibacterial agent of 1 μm or less is used as the core substance.

According to the present invention, microencapsulation is carried out by an interfacial reaction method. According to the interfacial reaction method, the capsule grows toward the inside of the foam of the emulsion, so that the particle size of the capsule can be controlled.

In the interfacial reaction method, as the first step of encapsulation, first, an antibacterial agent (that is, an antibacterial powder comprising silver oxide and silica or silver and silica) is added to an aqueous solution of an alkali metal hydroxide. By making a slurry,
The dispersibility of the antibacterial agent in the aqueous solution is improved, and the antibacterial agent can be finally encapsulated with a porous inorganic compound.

As the alkali metal hydroxide compound, for example, an aqueous solution of caustic soda, caustic potash, lithium hydroxide or the like is used, and the concentration of the alkali metal hydroxide compound in the aqueous solution is 0.1 to 10%, preferably 0.
It is about 2 to 3%. The concentration of the antibacterial agent in the obtained slurry is set to 20 to 60% by weight, preferably about 50 to 60% by weight.

Next, in the second step, the slurry is added to the aqueous solution of alkali metal silicate with stirring to form a dispersion liquid.
At this time, the concentration of the antibacterial agent in the dispersion is set to about 10 to 50% by weight. As the alkali metal silicate, silicates such as sodium, lithium and potassium can be used. The addition amount of this silicate is ₂ to in terms of SiO 2.
6.5 mol / L is suitable.

Then, an organic solvent having a water solubility of 7% or less is mixed with the above dispersion liquid to form a W / O type emulsion. Examples of the organic solvent in this case include the following.

<< Aliphatic hydrocarbons >> n-hexane, isohexane, n-heptane, isoheptane, n-octane, isooctane, gasoline, petroleum ether, kerosene, benzine, mineral spirit, etc. << Alicyclic hydrocarbons >> cyclopentane , Cyclohexane, cyclohexene, cyclononane, etc. << Aromatic hydrocarbons >> Benzene, toluene, xylene,
Ethylbenzene, propylbenzene, cumene, mesitylene, tetralin, styrene, etc. <Ethers> Propyl ether, isopropyl ether, etc. <Halogenated hydrocarbons> Methylene chloride, chloroform, ethylene chloride, trichloroethane, trichloroethylene, etc. <Esters> Ethyl acetate, acetic acid -N-propyl, isopropyl acetate, -n-amyl acetate, isoamyl acetate, butyl lactate, methyl propionate, ethyl propionate,
Methyl butyrate, etc. As the organic solvent used at this time, one having a solubility in water of 7% or less is used. The use of more than 7% is not desirable because the emulsion does not become good (uniform).

One or more of the organic solvents exemplified above are mixed with the dispersion obtained in the second step as described above to form an emulsion. It should be noted that these organic solvents have about 1
Alcohols up to 0% by weight may be mixed. The amount of organic solvent used is W
Although it is not particularly limited as long as it is an / O type, it is usually 50 wt% or more, preferably 70 to 80 wt% of the emulsion.

The emulsion may be prepared by a conventional method such as a stirring method or a shaking method. A known emulsifier may be added at the time of emulsification. As the emulsifier, preferably a nonionic surfactant having an HLB in the range of 3.5 to 6.0 can be used. Examples of this are as follows.

Polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate,
Polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene higher alcohol ether type, polyoxyethylene fatty acid ester type, glycerin fatty acid ester type, polyoxyethylene sorbitol fatty acid ester type and the like.

These emulsifiers are used in an amount of 10 relative to the organic solvent.
It is used in an amount of not more than wt%, preferably 0.01 to 3 wt%.

Then, in a fourth step, an aqueous solution of a compound capable of insolubilizing the alkali metal silicate is added to the W / O type emulsion obtained in the third step, and 20 to 3 is added.
Stir for 0 minutes to react. This reaction is to react an aqueous solution containing an antibacterial agent and an alkali metal silicate with an aqueous solution containing the insolubilizing compound in an emulsion, which becomes an interfacial reaction, and the reaction proceeds around the antibacterial agent, so that the reaction proceeds around the antibacterial agent. The insolubilized inorganic compound is deposited to form a porous inorganic capsule. Since the size of the porous inorganic capsule is influenced by the size of water-based droplets (bubbles) in the emulsion, the size of the droplets in the emulsion is uniform and extremely small (preferably 2 μm or less). Thus, the stirring speed, stirring time, emulsifier, etc. may be appropriately selected.

As the aqueous solution of the compound capable of insolubilizing the alkali metal silicate, sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium hydrogen carbonate, calcium chloride, magnesium chloride, barium chloride or the like can be used.

Then, the inorganic compound deposited around the antibacterial agent is filtered, washed and dried by a conventional method.

The capsule itself (coating material, container portion of the capsule) obtained by this first interfacial reaction method is as follows. (B) Size (particle size) 0.05 to 2.0 μm (b) Capsule thickness 0.02 to 0.5 μm (c) Porosity (whole) 0.1 to 5 cc / g (d) Capsule wall Pore size 20 to 20,000 angstrom (e) Porosity (bulk density) 0.1 to 5 cc / g (f) Average pore radius 20 to 20,000 angstrom Generated by the above reaction to form a capsule coating material. The porous inorganic compound is as follows.

Silicic acid, calcium silicate, magnesium silicate, potassium silicate, barium silicate.

The inclusion rate in the porous inorganic capsule (that is, the ratio of the core substance to the weight of the entire capsule) is 8
When it is 0% or more, the amount of the porous inorganic compound contained is 20.
% And the thickness is thin, the hiding effect of the capsule when mixed with the synthetic resin is reduced. When the encapsulation rate is 10% or less, the content of the porous inorganic compound is 90% or more, the thickness is large, the resistance to the diffusion of silver ions is large, and the antibacterial effect is reduced.

As the porous inorganic compound, silicic acid is somewhat transparent and is well suited for addition to plastics. Magnesium silicate, calcium silicate, barium silicate, titanium oxide, aluminum oxide, and zirconium oxide have excellent hiding power.

[0050]

[Function] Silver nitrate is adsorbed in the state of silica sol, and then an aqueous solution of caustic soda is added to prepare a colloidal solution of silver oxide, and this colloidal solution is solidified by spray drying. In addition, the silver oxide is firmly mixed and fixed in the silica component and does not peel off.

Since silver oxide is supported by the colloidal solution containing silica sol and silver oxide, the silver oxide in the composition can be supported at a high concentration of 95 wt% at maximum. The present invention is capable of fixing a high concentration of silver oxide, and achieves the purpose of antibacterial by using a smaller amount than the prior art. Therefore, the housing of the antibacterial agent for water treatment is small and economical.

Although silver oxide is reduced to silver by heat, according to the present invention, by mixing and fixing fine crystals of silver oxide in silica particles, silver does not sinter during reduction. As a result, fine crystal silver of 1 μm or less can be retained.
The antibacterial effect in this state is an excellent antibacterial level as shown in Table 1.

Furthermore, by encapsulating the antibacterial granules in a water-insoluble porous inorganic capsule, silver oxide or silver and the synthetic resin may come into direct contact when added to paints or synthetic resins. Moreover, since it is controlled to release a small amount of silver ions, no color contamination or discoloration occurs. Even if it does not stain or discolor.

The powder and granules obtained by spray-drying the colloidal solution of silica sol and silver oxide according to the present invention can be stabilized with submicron fine particles. Therefore, the particle size of the porous inorganic capsule can be made smaller than 2 μm.

[0055]

EXAMPLES The present invention will be described in detail below with reference to examples, but in order to facilitate understanding of the present invention, the case of only silver oxide will be described as a reference example.

[0056]

Reference Example 1 400 g of silver nitrate was dissolved in 3 L (liter) of water, and 10 g of sodium hydroxide was added to the silver nitrate aqueous solution.
A solution prepared by dissolving 0 g in 1 L of water was injected and stirred for 2 hours. The liquid was spray-dried with a compact type spray dryer manufactured by Anhydro at a spray rate of 250 cc / min in an atmosphere of 200 ° C. to obtain brown powder A-1. An electron micrograph (30,000 times) of the powder and granules is shown in FIG. FIG. 9 shows the analysis result of the components of the powdery granules A-1 by the X-ray diffractometer. From FIG. 9, it is apparent that this powder / grain A-1 is silver oxide.

[0057]

Reference Example 2 The powder of A-1 was heat-treated at 200 ° C. for 1 hour to obtain a powder of A-2. The electron micrograph (1,000 times) is shown in FIG. X of this powder A-2
The analysis results of the components by the line diffractometer are shown in FIG. Figure 10
From this, it is clear that this powder A-1 is silver.

[0058]

Example 1 366 g of silver nitrate was dissolved in 3 L of water, and this silver nitrate aqueous solution was added to Snowtex-20 (silica sol:
Solid content 20 wt% Nissan Chemical Industries Ltd. product) 1500
Water was added to g to make a 3 L solution, and the mixture was stirred for 2 hours. Then, a solution prepared by dissolving 92 g of sodium hydroxide in 1 L of water was poured into the mixed solution and stirred for 2 hours. The liquid was spray-dried with a compact type spray dryer manufactured by Anhydro at a spray rate of 250 cc / min in an atmosphere of 200 ° C. to obtain brown powder B-1.

An ordinary electron microscopic photograph (5,000 times) of the obtained granular material B-1 is shown in FIG. Furthermore, when the powder and granules are directly taken in an electron micrograph, the silver component is shining,
It was confirmed that in this granular material, fine crystals of silver oxide were fixed to silica particles in a mixed state. This powder B
FIG. 11 shows the analysis result of the components by the X-ray diffractometer of -1. As is clear from FIG. 11, the one fixed by silica in this granular material B-1 is silver oxide. The proportion of silver oxide in this composition was calculated to be about 45.
wt%.

[0060]

[Example 2] The powder B-1 obtained in Example 1 was mixed with 2
It heat-processed at 00 degreeC for 1 hour, and the granular material B-2 was obtained. The electron micrograph (5,000 times) is shown in FIG. FIG. 12 shows the analysis results of the components of this powder B-2 using an X-ray diffractometer.
Shown in. As is clear from FIG. 12, this powder B-2
Fixed inside by silica is silver.

From the analysis results of the components by the X-ray diffractometer of the above Reference Examples 1 and 2 and Examples 1 and 2, it was silver oxide when the heat treatment was not performed, and the silver oxide was heat treated at 200 ° C. for 1 hour. It was confirmed that 100% silver was reduced.

[0062]

Example 3 246 g of Snowtex-20 (silica sol: solid content 20%, product of Nissan Chemical Industries, Ltd.) was diluted twice with water. To this silica sol diluting solution, add silver nitrate 60
A solution prepared by dissolving 0 g in 6 L of water was injected with stirring and stirred for 2 hours. Then, a solution prepared by dissolving 140 g of sodium hydroxide and 10 g of polyvinyl alcohol in 3 L of water was injected and stirred for 2 hours. The solution was spray-dried with a compact type spray dryer manufactured by Anhydro at a spray rate of 250 cc / min in an atmosphere of 200 ° C. to give a brown powder D-1.
Got An electron micrograph (1,000 times) of the powder and granules is shown in FIG. The proportion of silver oxide in this composition is calculated to be about 90 wt%.

[0063]

Example 4 The powder D-1 obtained in Example 3 was used as 2
It heat-processed at 00 degreeC for 1 hour, and the powder-form D-2 was obtained. The electron micrograph (1,000 times) is shown in FIG.

[0064]

Example 5 D-1 powder and granules 4 obtained in Example 3
0 g was added to a solution prepared by dissolving 0.2 g of sodium hydroxide in 40 g of water to give a slurry. Then, this slurry was added to 180 cc of sodium silicate (6.5 mol / L) with stirring and treated with ultrasonic waves for 2 minutes to improve dispersibility. Polyoxyethylene sorbitan trioleate 15 was added to this dispersion.
Normal hexane and cyclohexane containing g / L of 1:
600 cc of the mixed solution of 1 was added and stirred at 6000 rpm for 1 minute to obtain a W / O type emulsion. Into this W / O type emulsion, ammonium hydrogen carbonate (1.5 mol /
L) 1 L was mixed and stirred at room temperature for 30 minutes to form porous capsules. Then, the mixture was filtered, washed with water, washed with ethanol, and dried at 80 ° C. for 12 hours to obtain about 80 g of white powdery or granular material EL-1. The porous capsule powder thus obtained contains silver oxide and the encapsulation rate is 50%. An electron micrograph (2,00
0 times) is shown in FIG.

The MIC of the obtained porous capsule powder for Staphylococcus aureus was 8 ppm.

2% of the porous capsule powder was added to a two-liquid water type acrylic epoxy resin to obtain a coating material. A broth suspension of Staphylococcus aureus was smeared on a polyester plate coated with the paint, and the viable cell count was measured after culturing at 37 ° C for 24 hours. The bacterial count of the non-treated sample for comparison was 1.4 × 10 ⁹ cells / ml, whereas the bacterial count of the paint-coated sample was zero.

[0067]

Example 6 The powdery granules EL-1 obtained in the above Example 5 was heat-treated at 200 ° C. for 1 hour to obtain white powdery granules EL-2 in which the encapsulated silver oxide was reduced to silver. The electron micrograph (20,000 times) is shown in FIG.

MI of this granule against Staphylococcus aureus
C was 16 ppm.

Polyester of the porous capsule powder
%, Polyester was heated and melted at 260 ° C., and a plastic plate having a size of 50 mm × 100 mm × 2 mm was molded by an extruder. This polyester plate had no abnormalities such as discoloration, contamination and deterioration. Staphylococcus aureus was smeared on the molded polyester plate with a broth suspension having a bacterial count of 5 × 10 ⁴ , and the bacterial count after culturing at 37 ° C. for 24 hours was zero, resulting in an excellent antibacterial effect. was gotten.

Reference Examples 1 and 2 and Example 1 described above
Table 6 shows the results of measurement of the minimum inhibitory concentration (MIC) against Staphylococcus aureus for the powders and granules obtained by
It was shown to.

[0071]

[Table 1] The following can be seen from the above description and Table 1. As can be seen from FIG. 1, by utilizing the spray drying technique,
It is possible to produce silver oxide having a grain size of μm or less. However, silver oxide is a heat-labile compound and tends to react violently with heat to release oxygen. For this reason, silver oxide having a grain size of 1 μm or less is particularly unstable to heat, and violently releases oxygen due to heat, and as shown in FIG. 2, sinters into a mass of metallic silver of several hundred μm or more. In addition, the antibacterial property is significantly changed, and as shown in Table 1, the minimum inhibitory concentration (MIC) of 8 ppm of silver oxide against Staphylococcus aureus was reduced to 2000 ppm by heat treatment at 250 ° C. (from practical use) Has a MIC value of preferably 250 ppm or less). Thus, it was found that it is difficult to use silver oxide as it is as an antibacterial agent in a wide range of stable applications.
On the other hand, as shown in Table 1, the antibacterial powder of the present invention does not cause a violent reaction even when heat is applied, and as is clear from FIGS. 3 to 8, there is no sintering of silver crystals, As shown in Table 1, the antibacterial property is still maintained.

[0072]

Example 7 80 g of silver nitrate was dissolved in 1 L of water, and this silver nitrate aqueous solution was added to Snowtex-20 (silica sol:
Solid content 20 wt% Nissan Chemical Industries Ltd. product) 3000
Water was added to g to make a 6 L solution, and the mixture was stirred for 2 hours. Then, a solution prepared by dissolving 25 g of sodium hydroxide in 1 L of water was injected and stirred for 2 hours. The liquid is 250 with an Anhydro compact spray dryer.
It was spray-dried in an atmosphere of 200 ° C. with a spray rate of cc / min to obtain a granular material. The MIC of this granular material is 64 ppm as shown in Table 2. The calculated silver oxide in the composition is about 8 wt%.

[0073]

Example 8 32 g of silver nitrate was dissolved in 1 L of water, and this silver nitrate aqueous solution was added to Snowtex-20 (silica sol:
Solid content 20 wt% Nissan Chemical Industries Ltd. product) 3000
Water was added to g to make a 6 L solution, and the mixture was stirred for 2 hours. Next, a solution prepared by dissolving 12 g of sodium hydroxide in 1 L of water was injected and stirred for 2 hours. The liquid is 250 with an Anhydro compact spray dryer.
The powder was obtained by spray drying in an atmosphere of 200 ° C. with a spray rate of cc / min. The MIC of this powder is as shown in Table 2,
It was 125 ppm. The silver oxide in the composition is calculated to be about 3.5 wt%.

[0074]

Example 9 16 g of silver nitrate was dissolved in 1 L of water, and this silver nitrate aqueous solution was added to Snowtex-20 (silica sol:
Solid content 20 wt% Nissan Chemical Industries Ltd. product) 3000
Water was added to g to make a 6 L solution, and the mixture was stirred for 2 hours. Next, a solution prepared by dissolving 5 g of sodium hydroxide in 1 L of water was injected and stirred for 2 hours. 250cc of this liquid with a compact type spray dryer manufactured by Anhydro
The powder was obtained by spray-drying in an atmosphere of 200 ° C. at a spray rate of / min. The MIC of this powder is 1 as shown in Table 2.
It was 25 ppm. The silver oxide in the composition is calculated to be about 1.7 wt%.

[0075]

[Table 2] As is clear from Table 2, the granular material of the present invention has a large antibacterial property even when the silver oxide component is about 1%.

[0076]

Example 10 Water was added to 1200 g of Snowtex S (silica sol: fine particle type, silica solid content 30%) to make 3 L. A solution prepared by dissolving 40 g of silver nitrate in 1 L of water was injected into this silica sol diluted solution, and the mixture was stirred for 3 hours. Next, a solution prepared by diluting 200 g of ammonia (20%) in 2 L of water was poured into the silica sol-silver nitrate solution while stirring, and was stirred at high speed for 2 hours with a homomixer to obtain a colloidal solution of silica sol and silver oxide. . The colloidal solution was spray-dried with a compact spray dryer manufactured by Anhydro at a spray rate of 250 cc / min to give a donut-shaped silver oxide content with an average particle diameter of 10 μm (calculated value). To obtain a granular material. The MIC of the powder and granules for Staphylococcus aureus was 125 ppm.

50 parts of granules produced in the same manner as above,
40 parts of acetate flakes and 10 parts of butyrolactone were mixed and processed into pellets having a diameter of 2 mm and a length of 10 mm by a granulating machine disk pelleter manufactured by Fuji Paudal Co., Ltd. A 15-ton factory cooling water stock water tank was provided with a bypass circulation water pipe separately from the water pipe, and 1.5 kg of the pellet was provided in a cartridge filter type in the middle of the pipe, and 100 L / min of water was circulated by a pump. The number of bacteria in water was measured every 5 days and continued for 6 months. Partial work on the cooling water piping in the factory was done twice in 6 months, and both times just after the construction, the number of general bacteria was 2 x 1 due to bacterial contamination with new pipes.
Although it showed 0 ³ cells / mL, the number of general bacteria could be kept at zero from the next day.

[0078]

Example 11 Water was added to 1393 g of Snowtex S (silica sol: fine particle type, silica solid content 30%) to make 3 L. A solution prepared by dissolving 40 g of silver nitrate in 1 L of water was injected into this silica sol diluted solution, and the mixture was stirred for 3 hours. Then, a solution prepared by dissolving 30 g of sodium hydroxide in 2 L of water was poured into the silica sol-silver nitrate solution while stirring to obtain 2
High-speed stirring was carried out with a homomixer for an hour to obtain a colloidal solution of silica sol and silver oxide. The colloidal solution was heated to 250 by an Anhydro compact spray dryer.
Spray drying with a spray rate of cc / min to obtain an average particle size of 10μ
A doughnut-shaped powder of m was obtained. The MIC of the granules against Staphylococcus aureus was 64 ppm.

The powder and granules were mixed with activated carbon of 40 mesh in an amount of 1% and put into a household water purifier at a rate of 50 g. As a result of soaking in water for 2 weeks, general bacteria were 5 × 10 ³ / m in normal activated carbon.
Although it was L, the number of bacteria was zero when the powder and granules were used, and the silver concentration in water was 42 ppb.

[0080]

Example 12 Water was added to 12.6 g of silver nitrate to prepare a 20 g aqueous solution. This silver nitrate aqueous solution is Snowtex-5
It was added to 64 g of 0 (silica sol: 50 wt% solids, manufactured by Nissan Chemical Industries, Ltd.) and stirred for 2 hours. Then, a solution prepared by adding water to 3 g of sodium hydroxide and dissolving it in 16 g to make the total amount 100 g was stirred for 2 hours. The silver component of the dispersion liquid is 8%, and the silica component is 32% slurry liquid. 100 g of the slurry liquid was added to 180 cc of sodium silicate (6.5 mol / L) with stirring and treated with ultrasonic waves for 2 minutes. To this dispersion was added 600 cc of a 1: 1 mixture of normal hexane and cyclohexane containing 15 g / L of polyoxyethylene sorbitan trioleate, and the mixture was stirred at 6000 rpm for 1 minute to obtain a W / O type emulsion. To this W / O type emulsion, 1 L of ammonium hydrogen carbonate (1.5 mol / L) was mixed and stirred at room temperature for 30 minutes to carry out a reaction for encapsulating a porous capsule.
Then, it was filtered, washed with water and washed with ethanol, and dried at 80 ° C. for 12 hours to obtain about 80 g of powdery particles. The porous capsule powder thus obtained contained silver oxide and had an encapsulation rate of 50% and was a white powdery granule having a particle diameter of 2 μm or less.

[0081]

EFFECTS OF THE INVENTION According to the present invention, the amount of silver ions released is appropriate, and moreover, silver ions can be continuously released for a long period of time at a constant silver ion concentration, and a vigorous reaction occurs even when heat is applied. Of antibacterial granules that are stable or stable even when exposed to high temperature heat and that do not cause contamination or discoloration when added to paints or synthetic resins, and such antibacterial granules can be manufactured relatively inexpensively and easily. A possible method is provided.

The antibacterial effect of the antibacterial composition of the present invention is semi-permanent and not only harms the human body, but is also expected to be used as a medicine. It is possible to obtain antibacterial and antifungal effects for the following applications over a long period of time.

1. It is applied to the following uses as an antibacterial fiber by mixing it with synthetic fiber and recycled fiber acetate.
White coat, mask, sheets, cloth, towel, bedding, pantyhose, socks, gauze, gloves, wrapping cloth, cotton swab, cosmetic cotton, toilet seat cover, carpet, filter, especially for hospital sewing products, sanitary materials, as an antibacterial measure It is valid.

2. It is applied to the following applications by mixing it with molded products, sheets and films. Cooking plate, tableware, containers,
Caps, packings, labels for bottles, food films, slippers, toothbrushes, condoms, PVC and latex gloves, bath mats, washing sponges, water disinfection pellets for industrial water and swimming pool water treatment, food preservatives , Effective for imparting antibacterial properties to cosmetic puffs and the like.

3. It is processed into paper and non-woven fabric and used for the following purposes. It is effective for antibacterial and antifungal wallpaper, wall cloth, acne pat to remove acne bacteria in non-woven fabric, wet tissue in non-woven fabric, anti-bacterial hair cover.

4. It is effective in the following as an antibacterial and antifungal paint when mixed with paint. Antibacterial floor paints, wall paints, floor waxes, water tank paints, anti-algae paints for cooling towers, antibacterial paints for drain pans, disinfectant paints for humidifiers, disinfectant paints inside water pipes, and medical covering materials.

5. It is processed into a cushion material and is effective as an antibacterial mat for beds.

6. It is processed into activated carbon and is effective as an antibacterial activated carbon for water purification.

7. Effective for antibacterial toothpaste and deodorant deodorant.

8. Addition to emulsion or wax is effective for drugs for skin diseases and drugs for fever.

9. Effective for sterilization when added to planting media and hydroponics.

10. The antibacterial composition according to the present invention comprises an MRS
It is effective in preventing nosocomial infections caused by A and the like, and is also effective as a sterilizing material for clean rooms in food factories and pharmaceutical factories.

11. By adding the antibacterial composition of the present invention to an emulsion or a wax, it is effective as a therapeutic agent for atopic skin diseases, and also effective as a therapeutic agent for burns without leaving keloids on the skin.

12. Since the antibacterial composition of the present invention does not cause inactivation of antibacterial by a surfactant, unlike an antibacterial agent by an organic compound which has been conventionally used,
A soap having antibacterial properties can be obtained by adding it to soap.

[Brief description of drawings]

FIG. 1 is an electron micrograph (30,000 times) of powder A-1 obtained in Reference Example 1.

FIG. 2 is an electron micrograph (1,000 times) of powder A-2 obtained in Reference Example 2.

FIG. 3 is a granule B-1 obtained according to Example 1 of the present invention.
3 is an electron micrograph (5,000 times) of FIG.

FIG. 4 is an electron micrograph (5,000 times) of powder B-2 obtained in Example 2 of the present invention.

FIG. 5: Granules D-1 obtained according to Example 3 of the present invention
3 is an electron micrograph (1,000 times) of the above.

FIG. 6 is an electron micrograph (× 1,000) of powder D-2 obtained in Example 4 of the present invention.

FIG. 7: Granules EL- obtained according to Example 5 of the present invention
1 is an electron micrograph (20,000 times).

FIG. 8 is an electron micrograph (20,000 times) of a powder or granule EL-2 obtained in Example 6 of the present invention.

FIG. 9 is a diagram showing the results of analysis of components by X-ray diffraction of the powder or granule A-1 obtained in Reference Example 1.

10 is X of sample A-2 obtained in Reference Example 2. FIG.
It is a figure which shows the analysis result of the component by a line diffraction.

FIG. 11: Granule B-obtained according to Example 1 of the present invention
It is a figure which shows the analysis result of the component by the X-ray diffraction of 1.

FIG. 12 is a diagram showing a result of analysis of components by X-ray diffraction of the powdery or granular material B-2 according to Example 2 of the present invention.

Claims (20)

[Claims] 1. An antibacterial powdery granule comprising fine particles of silver oxide fixed to silica particles in a mixed state and having a particle size of 40 μm or less. 2. A fine grain of silver oxide having a fine particle size of 40 μm or less fixed in a state of being mixed with silica particles, the composition of the fine grain being 1 to 95 wt% of silver oxide and 5 to 5 of silica. 99
Antibacterial granules characterized by being wt%. 3. The antibacterial powder according to claim 1, wherein the fine crystals of silver oxide have a size of 1 μm or less. 4. The antibacterial powder or granule according to claim 1 or 2, wherein the powder or granule is 10 μm or less. 5. The antibacterial powder or granule according to claim 1 or 2, wherein the powder or granule is 2 μm or less. 6. An antibacterial powder or granular material, characterized in that fine silver crystals are powder or granular material of 40 μm or less fixed to silica particles in a mixed state. 7. A fine particle of silver having a particle size of 40 μm or less fixed in a state of being mixed with silica particles, the composition of the granular material being 1 to 95 wt% of silver and 5 to 99 wt% of silica. An antibacterial powder granule characterized by being 8. The antibacterial powder according to claim 6, wherein the fine silver crystals are 1 μm or less. 9. The antibacterial powder or granule according to claim 6 or 7, wherein the powder or granule is 10 μm or less. 10. The antibacterial powder or granule according to claim 6 or 7, wherein the powder or granule is 2 μm or less. 11. An antibacterial granular material, wherein the granular material according to claim 1, 2, 6 or 7 is encapsulated in a capsule made of a water-insoluble porous inorganic compound. 12. The antibacterial powder particles according to claim 11, wherein the porous inorganic compound is one or two selected from silicic acid, magnesium silicate, calcium silicate, barium silicate, aluminum oxide, titanium oxide and zirconium oxide. body. 13. A first step of (a) mixing and stirring a silica sol and an aqueous solution of silver nitrate, and (b) a colloidal solution of silica sol and silver oxide, which is obtained by mixing and stirring an alkaline aqueous solution with the solution obtained in the first step. A second step of: (c) a third step of spray-drying the colloidal liquid obtained in the second step into a powder or granules, and a method for producing an antibacterial powder or granules. 14. A first step of (a) mixing and stirring a silica sol and a silver nitrate aqueous solution, and (b) a colloidal solution of silica sol and silver oxide, which is obtained by mixing and stirring an alkaline aqueous solution with the solution obtained in the first step. The second step, (c) the third step of spray-drying the colloidal liquid obtained in the second step to form a granular material, and (d) the antibacterial granular material is heat-treated to convert silver oxide into silver. A method for producing an antibacterial powder or granule, which comprises a fourth step of reducing. 15. The method for producing an antibacterial powder according to claim 14, wherein the heat treatment temperature is 120 ° C. or higher. 16. (a) A first step in which the antibacterial powder obtained by the method according to claim 13, 14 or 15 is slurried with an aqueous solution of an alkali metal hydroxide compound, and (b) the first step. The second step in which the slurry obtained in the step is added to an aqueous solution of an alkali metal silicate, (c) the dispersion obtained in the second step is mixed with an organic solvent having a solubility in water of 7% or less. Third step to make a W / O type emulsion,
(D) A fourth step of forming fine porous particles by adding an aqueous solution capable of insolubilizing the alkali metal silicate to the W / O type emulsion obtained in the third step and stirring the mixture. And a method for producing an antibacterial powder. 17. (a) A first step of making the antibacterial powder obtained by the method of claim 13 into a slurry using an aqueous solution of an alkali metal hydroxide compound, and (b) obtained in the first step. The second step of adding the slurry to an aqueous solution of an alkali metal silicate, (c) the dispersion obtained in the second step,
W / by blending with an organic solvent whose solubility in water is 7% or less
Third step of forming an O-type emulsion, (d) An aqueous solution capable of insolubilizing the alkali metal silicate is added to the W / O-type emulsion obtained in the third step and stirred to generate microporous particles. And (e) heat-treating the solid content obtained in the fourth step to reduce silver oxide to silver, and a fifth step. 18. (a) A first step of mixing and stirring a silica sol and a silver nitrate aqueous solution, and (b) an alkaline aqueous solution is mixed and stirred with the liquid obtained in the first step to obtain a slurry comprising silica sol and silver oxide. Second step, (c) third step of adding the slurry obtained in the second step to an aqueous solution of an alkali metal silicate, (d) solubility in water in the dispersion obtained in the third step Is mixed with an organic solvent of 7% or less to form a W / O type emulsion, and (e) the W / O type emulsion obtained in the fourth step is insolubilized with the alkali metal silicate. A method for producing an antibacterial powder comprising the step of adding an aqueous solution to be obtained and stirring the mixture to form microporous particles. 19. (a) A first step of mixing and stirring a silica sol and a silver nitrate aqueous solution; and (b) a slurry solution comprising silica sol and silver oxide, which is mixed and stirred with the liquid obtained in the first step. Second step, (c) the third step of adding the slurry obtained in the second step to an aqueous solution of an alkali metal silicate, (d) the dispersion obtained in the third step, with respect to water. Fourth step of blending an organic solvent having a solubility of 7% or less into a W / O type emulsion, (e)
An aqueous solution capable of insolubilizing the alkali metal silicate is added to the W / O type emulsion obtained in the fourth step, and the mixture is stirred to form fine porous particles. (F) In the fifth step A method for producing an antibacterial powder or granule, which comprises heat-treating the obtained solid content. 20. The method for producing an antibacterial powder according to claim 19, wherein the heat treatment temperature is 120 ° C. or higher.