JPH07187933A - Antimicrobial agent for soil - Google Patents

Abstract

PURPOSE:To obtain a soil antimicrobial agent avoiding the elution of antimicrobial metal ions, not causing troubles such as water pollutions and chemical damages accompanied by the elution of the metal ions, and used for being added to soil to prevent the generation of mold, pathogenic microbes, etc. CONSTITUTION:This soil antimicrobial agent comprises antimicrobial particles comprising amorphous calcium phosphate(ACP) containing antimicrobial metal ions, preferably silver ions, adsorbed thereon. A mixture slurry 3 containing the ACP particles 1 and the antimicrobial metal ions 2 is prepared. The slurry is fed into a spray drier 5 through a fixed displacement pump 4, and the mixture slurry is sprayed, granulated and dried with an atomizer 6 in the flow of hot air in the spray drier 5. Antimicrobial particles 7 comprising antimicrobial metal ion-containing ACP powder having a particle diameter of 1-100mum is collected with a cyclone 8. Since the elusion of the antimicrobial metal ions is avoided, the antimicrobial property of the antimicrobial metal ions can be exhibited over a long period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soil antibacterial agent which is added to soil to suppress the generation of mold and pathogenic bacteria.

[0002]

2. Description of the Related Art Conventionally, soil pathogenic fungi that cause diseases in plants cultivated in soil, such as vegetables, fruits and plants, have been known. Examples of diseases caused by such soil pathogens include, for example, tomatoes and cucumbers caused by bacterium of the genus Viseum
Seedling rot and root rot in radish, burdock, etc. in greenhouses or hydroponics, due to Aphanomyces spp. Examples include root-knot disease, white silkworm disease caused by Cortisium, tulip disease caused by Phytophthora, tulip root rot caused by Pythium, and spring baldness of turf caused by Pythium.

For the prevention and treatment of these diseases, copper, inorganic organic copper salts, thiuram, benomyl agents, thiophanate methyl agents, dithianon / copper, TPN, iprodione, captan, mepronil, flutolanil, validamycin, pencyclone, PCNB, eclomezole, metalaxyl,
Fungicides and antibacterial agents such as chloropicrin, methyl isothiocyanate, methyl bromide, difortan and trichlamide are used.

[0004]

However, when pesticides are used to avoid the above-mentioned diseases, there is concern about the effects of residual pesticides on the human body, and in recent years, especially in rivers due to the large use of pesticides on golf courses. Agrochemical contamination of drinking water is a problem. On the other hand, plants are also damaged by pesticides, which causes a problem of chemical damage such as growth failure of plants due to copper.

[0005]

Means for Solving the Problems The soil antibacterial agent of the present invention comprises:
In order to solve the above problems, the present invention is characterized by being antibacterial granulated particles composed of amorphous calcium phosphate particles having adsorbed antibacterial metal ions.

As the antibacterial metal ion, at least one metal selected from gold, silver, zinc, copper, tin, lead, arsenic, platinum, iron, antimony, nickel, aluminum, barium, cadmium and manganese, or a mixture thereof, Alternatively, those metal compounds and their aqueous solutions can be used.

The above-mentioned antibacterial granulated particles are composed of antibacterial metal ions and amorphous calcium phosphate particles (Amorphous Calcium).
Phosphate: hereinafter, a slurry containing ACP) is mixed and granulated. By thus mixing the slurry and the antibacterial metal ions, the ion-exchangeable metal ions in the ACP particles of the slurry are replaced with the antibacterial metal ions by ion exchange, and the antibacterial metal ions are converted into ACP particles. Adsorbed.

The slurry containing the above ACP particles is mixed with a calcium hydroxide suspension with stirring by adding a neutral or weakly alkaline water-soluble polymer dispersant, for example, a weakly alkaline ammonium triacrylate salt. After the solution is obtained, the pH of the mixed solution under stirring is adjusted to 10 to 5 by dropping an aqueous solution of phosphoric acid, thereby containing ACP particles having a particle size of about 0.1 μm or less.

The above water-soluble polymer dispersant is added in order to avoid agglomeration of ACP particles having a particle size of about 0.1 μm or less in the slurry, and the addition amount thereof is 0.1 to 10 relative to the calcium hydroxide suspension. The weight ratio is set to preferably 0.1 to 3% by weight.

In this slurry, an antibacterial metal powder, an antibacterial metal compound, or a mixture obtained by mixing an aqueous solution of them is mixed in an amount of 50% by weight or less, and the mixture is granulated by a spray drying granulation method or the like. The particles were obtained.

The above ACP particles were subjected to powder X-ray diffractometry to determine the pattern of calcium phosphate [Ca ₃ (PO ₄ ) ₂
nH ₂ O] and its pattern is broad, confirming that it is amorphous calcium phosphate. In addition, the ACP particles are considered to be an electrostatically active substance because they contain water of crystallization, and it is presumed that various ACF particles are easily adsorbed. Also,
It is considered that the ACP particles are easily adsorbed to soil components having an electrostatic bias such as hydrophilic groups and polarized molecules.

Further, since the obtained antibacterial granulated particles have a large specific surface area, the particle size of the ACP particles in the slurry is 0.1 μm or less, and the antibacterial metal powder and the antibacterial metal to be added are added. The particle size of the compound powder is preferably 20 μm or less. Moreover, it is desirable to mix the slurry with the antibacterial metal powder, the antibacterial metal compound powder or the antibacterial metal aqueous solution added at room temperature.

However, 90 ACP particles in the slurry
If it exceeds 5% by weight, the viscosity of the slurry becomes high, which makes it unsuitable for granulation. By changing the content of ACP particles in the slurry within the range of 1 to 90% by weight, antibacterial granulated particles having a desired average particle size can be obtained.

As the granulation method, if the obtained antibacterial granulated particles are porous and have a substantially spherical shape with a particle size of 200 μm or less and a specific surface area of 10 m ² / g or more. Although not particularly limited, in addition to the above-mentioned spray drying granulation method, a granulation method obtained by freeze-drying and pulverization, or a high-speed stirring granulation method may be used. Further, as the granulation method, a granulator such as a pelletizer, Marumerizer (manufactured by Fuji Paudal Co., Ltd.), CF Granurex (manufactured by Freund Sangyo Co., Ltd.) may be used.

[0015]

EXAMPLE An example of the present invention will be described below with reference to FIG. In the soil antibacterial agent, antibacterial granulated particles 7 are used as shown in FIG. Such antibacterial granulated particles 7 are composed of silver ions 2 as antibacterial metal ions and amorphous calcium phosphate (Amorphous Ca).
lcium Phosphate: hereinafter abbreviated as ACP) A slurry containing particles 1 was mixed and granulated.

Next, a method for producing a slurry containing ACP particles 1 will be described. First, although not shown,
0.5% by weight of ammonium triacrylate as a water-soluble polymer dispersant in a calcium hydroxide suspension with stirring.
Added to obtain a mixed solution.

Thereafter, the above mixed solution under stirring was adjusted to pH 10 by dropping an aqueous phosphoric acid solution to obtain a slurry containing ACP particles having a particle size of about 0.1 μm or less. In order to obtain such ACP particles having a particle size of about 0.1 μm or less, it is necessary to add the water-soluble polymer dispersant for avoiding the aggregation of the ACP particles.

AC prepared by diluting the above slurry with ion-exchanged water so that the concentration of ACP is 20% by weight.
A P slurry was obtained. Anhydrous silver nitrate dissolved in ion-exchanged water was mixed with the ACP slurry to a concentration of 0.5 mol%, and the mixture was stirred with a stirring motor for 1 hour to obtain a mixture slurry 3. The amount of silver ions added can be adjusted within the range of 0.1 to 10 mol%, and the content of silver ions can be adjusted to mol.
To convert from% to% by weight, 1.07 should be applied as the conversion coefficient.

The above mixture slurry 3 containing ACP particles 1 and silver ions 2 was supplied to a spray dryer (L-8, manufactured by Okawara Kakoki Co., Ltd.) 5 by a metering pump. At this time, the atomizer 6 of the spray dryer 5 was rotated at high speed, and the mixture slurry 3 was granulated and dried by being sprayed by the atomizer 6 into the hot air flow for drying in the spray dryer 5.

AC containing silver ions obtained by granulation drying
The substantially spherical antibacterial granulated particles 7, which are P fine powder, were collected by a cyclone 8 having a particle size of 1 to 100 μm. At this time, ultrafine powder that could not be collected by the cyclone 8 was separately collected by a bag filter (not shown).

The operating conditions in the above spray drying granulation were as follows. The supply rate of the mixture slurry 3 as a raw material by the metering pump 4 is 1 to 3 kg / hr, and the temperature of the hot air heated by the electric heater 10 via the air filter 9 is equal to the inlet temperature of the hot gas chamber 11. 200 ~
The outlet temperature at the discharge hole 12 connected to the cyclone 8 was controlled to 250 ° C. so as to always exceed 100 ° C., and the rotation speed of the atomizer 6 was set within the range of 10,000 to 37,000 rpm.

Antibacterial granulated particles 7 thus obtained
Became a porous sphere by using the spray granulation method. Next, the specific surface area of the antibacterial granulated particles 7 was measured using a specific surface area meter (manufactured by Shimadzu Corporation, trade name: Flowsorb 2300). As a result, the specific surface area of the antibacterial granulated particles 7 was 100 m ² / g or more. As a comparison, antibacterial apatite composite particles supporting silver ions (commercial product, specific surface area 2.31 m ² / g) were used. As is clear from the above results, the antibacterial granulated particles 7 of the above examples showed an extremely large specific surface area.

The antibacterial granulated particles 7 are added in an oxidizing atmosphere within the range of 450 to 800 ° C., more preferably 500.
The water-soluble polymer dispersant may be extinguished by heating within the range of 550 ° C. Thereby, the antibacterial granulated particles 7
Is completely suppressed from decomposing into each ACP particle 1 even when submerged.

Next, the antibacterial properties of the above antibacterial granulated particles 7 were examined. First, the antibacterial granulated particles 7 were added to the soil in a predetermined amount to obtain (A). Next, what did not add the antibacterial granulated particles 7 was set to (B). Finally, the above-mentioned antibacterial apatite composite particles (commercial product, silver ion supported amount 2% by weight)
The same amount as in (A) was added to the soil (C)
And A plant was planted in each of the soils (A) to (C), water was regularly sprayed and fertilizer was applied, and the growth of each plant and the state of each soil were visually observed.

As a result of observation, the growth of the above plants was (A).
Was the best, followed by (C), and the worst was (B). Regarding the condition of each soil, (A) had the least mold, followed by (C), and the most mold had (B).

As described above, from the above observation results, the antibacterial granulated particles 7 are antibacterial in spite of having a smaller silver ion content than the antibacterial apatite particles which are commercially available as conventional antibacterial particles. It was shown that the action was high.

This was considered to be due to the following reason. That is, since the antibacterial granulated particles 7 are porous, they have a large specific surface area, which is the area in contact with bacteria, and the ACP particles 1 used as a carrier for silver ions 2 have a high bacteria adsorption capacity (Asahi Shimbun, It is considered that the antibacterial action of the silver ion 2 can be more effectively exerted since it has an evening edition of January 16, 1993).

Next, the elution of silver ions 2 in the antibacterial granulated particles 7 was examined. First, the antibacterial granulated particles 7 and water were placed in a container and the container was shaken at room temperature for 24 hours. After that, the supernatant in the above-mentioned container is taken, and the filtrate obtained by filtering the supernatant is used as a sample for high-frequency plasma spectroscopic analysis (manufactured by SEIKO, ICP SPS-4000, detection limit 0.005).
The presence or absence of silver ions in the above sample was analyzed by (ppm).

However, as a result of the analysis, silver ions were not detected in the above sample. As a result, the silver ions 2 in the antibacterial granulated particles 7 are adsorbed by the ACP particles 1 to prevent elution, and the silver ions 2 in water due to the dissolution of the antibacterial granulated particles 7 in water. It can be seen that the release to the is also avoided.

As described above, the antibacterial granulated particles 7 are AC
The bacteria adsorption capacity of P particles 1 and the increase in specific surface area due to granulation can improve the antibacterial property due to silver ions 2.
Elution of silver ions 2 can be avoided by the particles 1, and the antibacterial properties of the silver ions 2 can be exhibited for a longer period of time. Also, since the elution of silver ion 2 can be avoided,
There is no need to consider the obstacles caused by the silver ion 2,
It is possible to prevent water pollution to drinking water and phytotoxicity to plants.

As a result, the antibacterial granulated particles 7 are obtained.
Is an indoor garden, home garden such as potted plants and flower beds, and horticultural farming,
It is suitable for use in vast areas such as orchards and vegetable fields, such as golf course lawns and forests.

In the structure of the above embodiment, silver ion 2
Although the addition amount of 0.5 mol% was given as an example, it is not particularly limited to the above. For example, it is possible to add up to 10 mol% of silver ion 2 or other antibacterial metal ion to the ACP slurry. Is possible.

Further, in the constitution of the above-mentioned embodiment, the antibacterial granulated particles 7 having a particle diameter of 1 to 100 μm are used, but it is easier to handle and to collect them after mixing with soil, Further, the particle size may be increased. The particle size of such antibacterial granulated particles is preferably 0.1 to 20 mm. The shape of the particles here is formed into a spherical shape, a granular shape, a cylindrical shape, or the like, but the shape is not particularly limited.

Therefore, in order to obtain, for example, antibacterial granulated particles having a columnar shape and a large specific surface area, the antibacterial granulated particles 7 obtained in the above-mentioned embodiment and an organic binder aqueous solution (0.1 to 20%) and mixed, and further granulated into a columnar shape with a pelletizer. This cylindrical granule has a diameter of 0.5 to 40 mmφ and a height of 0.5 to 10 mm, for example.

After drying this at 80 to 150 ° C. in a dryer, it is heated in the range of 450 to 800 ° C. in an oxidizing atmosphere,
The binder is gasified and eliminated to obtain antibacterial granulated particles which become a porous body composed of amorphous calcium phosphate particles having adsorbed antibacterial metal ions.

When the heating temperature is less than 450 ° C., the disappearance of the binder becomes incomplete, and when it exceeds 800 ° C., the amorphous calcium phosphate particles are crystallized to reduce the adsorption capacity of the bacteria in the antibacterial granulated particles. Therefore, the antibacterial property is deteriorated. The heating temperature is more preferably in the range of 500 to 550 ° C. This is preferably 500 ° C or higher to complete the disappearance of the binder, and it is economically advantageous.
This is because it is preferably 50 ° C or lower.

Further, for example, in order to obtain antibacterial granulated particles having a large spherical specific surface area, the above antibacterial granulated particles 7 are mixed with an organic binder aqueous solution (0.1 to 20%) and mixed in a pelletizer. And further granulated into a cylindrical shape. Such columnar granules have a diameter of 0.5 to 40 depending on the application.
The height is set to 0.5-10 mm in mmφ.

This was further granulated into a substantially spherical shape with a marumerizer (the number of revolutions of the top plate was 300 to 650 rpm), dried in a dryer at 80 to 150 ° C., and in an oxidizing atmosphere at 450 to 800 ° C.
, More preferably in the range of 500 ~ 550 ℃, to eliminate the binder, to form a substantially spherical porous body consisting of amorphous calcium phosphate particles adsorbed antibacterial metal ions antibacterial Granulated particles are obtained.

Here, two kinds of methods can be considered for producing spherical antibacterial granulated particles having a target particle diameter. 1
One is a method of making larger than the target particle size with a pelleter and making it spherical by grinding, and the other is spraying the antibacterial granulated particles 7 while spraying a binder on a granulated product smaller than the target, and the above granulation. This is a method of depositing on the surface of an object and making it spherical.

Since the antibacterial granulated particles having such a large particle size are large, they are easy to handle, and when mixed with soil, their shape is large, so that they are prevented from moving in the soil when they are submerged. It Therefore, even when the antibacterial granulated particles mixed in the soil are recovered later, they can be easily recovered by a sieve or the like.

In the constitution of the above-mentioned embodiment, the example in which the granulated antibacterial granulated particles 7 are used is given. However, instead of the antibacterial granulated particles 7, a slurry in which silver ions 2 are mixed is used. It is also possible to use ACP particles 1 that adsorb silver ions 2 obtained by drying.

[0042]

As described above, the soil antibacterial agent of the present invention is
The composition is an antibacterial granulated particle composed of amorphous calcium phosphate particles having adsorbed antibacterial metal ions.

Therefore, the above-mentioned constitution can improve the antibacterial property of the antibacterial metal ion by adsorbing the amorphous calcium phosphate particles on the bacteria and increasing the specific surface area by granulation.
Further, in the above structure, the elution of antibacterial metal ions can be avoided by the amorphous calcium phosphate particles, and the antibacterial properties of the antibacterial metal ions can be exhibited for a longer period of time.

Further, in the above-mentioned constitution, since the elution of the antibacterial metal ions can be avoided by using the amorphous calcium phosphate, it is not necessary to consider the damage to humans and plants due to the elution of the antibacterial metal ions, and the beverage Water pollution such as water and chemical damage can be avoided.

As a result, the above structure is
It has the effect of being suitable for use in vast areas such as lawns and mountain forests of golf courses from home vegetable gardens such as potted plants and flower beds, horticultural agriculture, orchards and vegetable fields.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a spray dryer for producing antibacterial granulated particles which is a soil antibacterial agent of the present invention.

[Explanation of symbols]

 1 ACP particles (amorphous calcium phosphate particles) 2 Silver ions (antibacterial metal ions) 7 Antibacterial granulated particles

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location A01N 59/06 Z 59/08 Z 59/22 59/26

Claims (1)

[Claims] 1. A soil antibacterial agent, which is an antibacterial granulated particle composed of amorphous calcium phosphate particles having adsorbed antibacterial metal ions.