JPH107506A - Inorganic antibacterial agent and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inorganic antibacterial agent causing very little discoloration when compounded in resins, coatings, etc., and excellent in dispersibility and dispersion stability by coating the surface of particles of an inorganic mineral with an antibacterial agent through coalescing or binding. SOLUTION: This inorganic antibacterial agent is obtained by coating the surface of particles of (an) inorganic mineral(s) comprising one or more of mica-clay mineral, layer silicate mineral, silica mineral, carbonate mineral and sulfate mineral with an antibacterial material which is a metal (oxide) such as silver, copper, etc., (preferably used 1-30wt.% based on the inorganic mineral) through surfacecoalescing or binding. The inorganic antibacterial agent is produced by coating the antibacterial material on the surface of the inorganic mineral through surface-coalescing or binding by a mechanical mixing of a rotative motion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an inorganic antibacterial agent and a method for producing the same. More specifically, a resin composition,
The present invention relates to an inorganic antibacterial agent which can be used for films, packaging materials, fibers, filtration materials, paints and the like, and can impart excellent antibacterial activity, and a method for producing the same.

[0002]

2. Description of the Related Art It has been known that metals such as silver and copper and their ions have a bactericidal and antibacterial action. Inorganic antibacterial agents, such as metal ions and metal particles, metal compounds, etc. are carried on an inorganic substance, and exhibit an antibacterial activity by sustained release therefrom.As the inorganic carrier, apatite such as zeolite, Phosphates, clay minerals, glass and the like are also used. Because it is an inorganic substance, it is superior in safety, durability, heat resistance, etc. compared to conventional organic antibacterial agents, and it is also said that it does not generate resistant bacteria that have become a problem in recent hospital infections etc. ing. However, on the other hand, when an inorganic antibacterial agent is blended with a resin or the like, there is a problem that the metal ion or the like carried out elutes and the resin or the like discolors, which is not a problem with the organic antibacterial agent. For example, a so-called antibacterial zeolite in which metal ions are supported on zeolite, when exposed to sunlight, in particular, ultraviolet rays, not only discolors itself remarkably, but also a resin containing this discolors to brown over time. This property is the same for zeolites carrying metallic silver, and when blended in resins, paints, etc., the product value is significantly reduced, which has been a major problem. To improve this, an antibacterial agent based on titanium oxide has been proposed. This utilizes the catalytic action of photodecomposition of water by a semiconductor, and sterilization is caused by active oxygen generated by irradiating light.
Active oxygen did not have a strong antibacterial property like silver ions, and a sufficient antibacterial action was not obtained.

[0003]

Accordingly, the present invention provides
An object of the present invention is to provide an inorganic antibacterial agent which hardly causes discoloration of a blended resin or paint and exhibits a high antibacterial action.

[0004]

Means for Solving the Problems The present inventor has conducted intensive studies in view of the above-mentioned problems, and as a result, has formed a film by using inorganic mineral particles as a core material and fusing or binding a substance having an antibacterial action to the surface thereof. It has been found that the resulting composite is an antibacterial agent that hardly causes discoloration and has a high antibacterial action, and based on this finding, has accomplished the present invention. That is, the present invention provides (1) an inorganic antibacterial agent characterized in that the surface of an inorganic mineral particle is coated with an antibacterial substance by surface fusion or bonding, and (2) a metal in which the antibacterial substance has an antibacterial action. Or the inorganic antibacterial agent according to (1), which is a metal oxide;
(3) The inorganic antibacterial agent according to (1) or (2), wherein the inorganic mineral particles comprise at least one of a mica clay mineral, a layered silicate mineral, a silica mineral, a carbonate mineral, and a sulfate mineral. And (4) a method for producing an inorganic antibacterial agent, characterized in that an antibacterial substance is surface-fused or bonded to and coated on the surface of inorganic mineral particles by mechanical mixing by rotational movement.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The inorganic minerals serving as the core material of the inorganic antibacterial agent of the present invention include mica clay minerals such as muscovite, sericite and illite, montmorillonite, saponite, hectorite, stevensite, acid clay and the like. Silica minerals such as layered silicates, quartz and opal, carbonate minerals such as calcium carbonate and dolomite, and sulfate minerals such as gypsum and alunite can be used. These may be natural products or synthetic products, but it is preferable to use natural products from the viewpoint of economy. Any of these may be used alone, or two or more of them may be used in combination. The average particle size of the inorganic mineral can be appropriately set and is not particularly limited, but is preferably 100 μm or less, more preferably 0.05 to 30 μm. If the particle size of the inorganic mineral is too large, the dispersibility is poor, and when blended in a resin, a paint, or the like, discoloration may occur due to sedimentation or obstruction of light transmission. On the other hand, when the amount is too small, the effect cannot be obtained unless the added amount is increased, and the antibacterial effect may be reduced. The shape of the inorganic mineral particles may be any shape such as a layer shape, a plate shape, a fiber shape, etc., in addition to a spherical shape. The surface properties of the inorganic mineral particles used in the present invention are not particularly limited, but those having a microporous surface or a smooth surface are preferred.

The antibacterial substance covering the surface of the inorganic mineral is not particularly limited. In addition to the inorganic antibacterial substance, other antibacterial agents such as preservatives, fungicides, disinfectants and the like are used. Among them, inorganic antibacterial substances are preferable, and among them, metals, metal oxides, metal salts and the like having antibacterial properties are more preferably used. Among these, metals such as silver, copper, zinc, zinc oxide, titanium oxide, aluminum, manganese, nickel and cadmium,
Salts such as chlorides, nitrates and sulfates, or metal oxides can be used, and silver or copper is most preferably used. This antibacterial substance is a dry type, which is formed into a thin film under the application of shear stress, and is fused or bonded to the surface of the inorganic mineral particles to form a film and coat the surface of the inorganic mineral particles. The average particle size of the antibacterial substance is 1/1 to 1 of the particle size of the inorganic mineral particles.
/ 60, preferably 1/6 to 1/30. The finer the antimicrobial particles, the better. If the particle size of the antibacterial particles is too large, the specific surface area will be small, and it will not be possible to cover the particles of the inorganic mineral densely, resulting in a decrease in antibacterial performance. In the present invention, the surface of the inorganic mineral particles is coated with antibacterial particles. The coating of the antimicrobial particles may partially cover the surface of the inorganic mineral particles, but most preferably covers the entire surface. In the case of partial coating, it is more preferable to cover at least 60% or more of the surface. The amount of the antibacterial particles used varies depending on the type of the inorganic mineral and the antibacterial particles.
It is 40% by weight, preferably 1 to 30% by weight. The thickness of the film as a coating layer of the inorganic antibacterial agent is 0.01 to 5.0.
μm, preferably 0.05 to 1.0 μm.

In the inorganic antibacterial agent of the present invention, the coating layer of the antibacterial particles does not peel off even when dispersed in an aqueous system by surface fusion or bonding. Therefore, for example, when a swellable layered silicate is used for the core material, the antibacterial particle layer does not peel off even if the core material swells in an aqueous system. Thus, an excellent inorganic antibacterial agent imparted with antibacterial properties can be obtained without impairing the properties of the core material. Further, by adding a coloring agent such as a pigment and a dye to the inorganic mineral, an inorganic antibacterial agent having a desired color and physical properties can be obtained.

[0008] The surface fusion or bonding of the inorganic mineral and the antibacterial particles is formed by a mechanical complexing treatment. The mechanical compounding treatment of the method of the present invention is a treatment for applying a physical force due to the rotational movement of the device to the powder, for example, the inorganic mineral and the conductive particles are centrifugally applied to the inner wall of the rotating casing. There is a stationary arm with an arc-shaped head in this casing, and the powder layer caught between the head and the inner wall of the casing due to the difference in curvature between the head and the inner wall of the casing is rapidly compressed and strong. This is a method for producing an inorganic antibacterial agent by undergoing shearing. A device generally used as a fine pulverizer can be used. For example, a high-speed rotary impact pulverizer (pin mill, disk mill), a grinding mill, a medium stirring type pulverizer, Cosmos (trade name, Kawasaki Heavy Industries, Ltd.) ), Mechano Fusion System (trade name, manufactured by Hosokawa Micron), Mechano Mill (trade name, manufactured by Okada Seiko Co., Ltd.), Theta Composer (trade name, manufactured by Tokuju Kogyo Co., Ltd.), etc. Can be

[0009] The process of producing the inorganic antibacterial agent by mechanical compounding is considered as follows. First, antibacterial particles adhere and grow on the surface of the inorganic mineral particles serving as the core material,
The specific surface area of the inorganic mineral particles decreases while the adhesion rate increases with the treatment time. Then, after the increase in the adhesion rate stops, the antibacterial particles on the surface of the core material become denser, and the specific surface area further decreases with the treatment time. In this way, the inorganic mineral particles and the antibacterial particles are fixed to the inner wall of the rotating casing and receive a very strong shearing action under a strong compressive force in the gap between the inner piece with the head having a curvature,
Thereafter, the process of peeling and mixing with a scraper is repeated. Since the compression and shearing effects act simultaneously, the individual particles tend to rotate in the powder layer, and the fusion of the particles is promoted by the relative friction between the particles, resulting in a dense coating layer of antibacterial particles. Is formed on the surface of the inorganic mineral particles. Therefore, it is possible to change the microstructure of the coating layer of the inorganic antibacterial agent by changing the stress condition and the processing time of the rotational motion of the device, and it is possible to adjust the antibacterial performance. The temperature is increased by this mechanical treatment, and the temperature is 20 to 250 ° C, preferably 80 to 1 ° C.
50 ° C. As for the stress condition, it is necessary to adjust the rotation speed, the geometrical factor of the device, the flow of air in the device, and the like so as to be at least equal to or less than the fracture limit of the inorganic mineral.
00-3000 rpm, more preferably 1000-2
Processing is performed at 500 rpm. The processing time is usually 1 minute or more, preferably 10 to 60 minutes. Since the method of the present invention is a dry method using no solvent, no solvent remains in the antibacterial agent. In addition, it can be easily manufactured without requiring a process for removing the solvent.

[0010]

Since the inorganic antibacterial agent of the present invention is coated with an antibacterial substance, the bactericidal substance is concentrated only on the surface of the particles at a high concentration, and exhibits an extremely excellent antibacterial action.
The inorganic antibacterial agent of the present invention, since the coating layer of the antibacterial particles firmly coated on the surface of the inorganic mineral particles does not peel off even when dispersed, it is unlikely to cause discoloration even when blended into a resin or paint, and the product value is reduced. It does not lower. In addition, antibacterial properties can be imparted without impairing the properties such as viscosity increase of the inorganic mineral, and excellent in dispersibility and dispersion stability. Therefore, according to the present invention, an antibacterial agent or the like having reversible water swelling properties can be obtained by selecting a core material. In addition, the method for producing an inorganic antibacterial agent of the present invention is simple because it is a dry-type mechanical treatment, and is coated with an antibacterial substance that is hardly soluble in a solvent such as water or alcohol, thereby providing an inexpensive inorganic antibacterial agent. Agent can be obtained.

[0011]

Next, the present invention will be described in more detail with reference to examples. Example 1 99.5% by weight of montmorillonite (Kunipia, manufactured by Kunimine Industries, average particle size: 15 μm) and silver (manufactured by Soekawa Chemical Co., Ltd.)
0.5 ground by a jet mill to an average particle size of 0.8 μm)
The weight% was treated at 2000 rpm for 60 minutes with a mechanofusion system (manufactured by Hosokawa Micron, Inc., AM-15F) to obtain an inorganic antibacterial agent (average particle size: 14 μm, thickness of silver film: 0.05 μm).

Example 2 A mica having a plate-like particle shape (manufactured by Yamaguchi Mica Industrial Co., Ltd., average particle size 8 μm)
m) 99.5% by weight of the same silver as used in Example 1
5% by weight was treated exactly as in Example 1 to obtain an inorganic antibacterial agent (average particle size: 8 μm, thickness of silver film: 0.06 μm).

Example 3 Calcium carbonate (Nitto Powder Chemical Co., Ltd., average particle size 2 μm)
99.5% by weight and 0.5% by weight of zinc (pulverized to a mean particle size of 0.9 μm by a jet mill manufactured by Soegawa Chemical Co., Ltd.) were treated in the same manner as in Example 1 to obtain an inorganic antibacterial agent (average particle size). 2μ
m, zinc film thickness 0.05 μm).

Comparative Example Montmorillonite (Kunipia, Kunimine Industries) 9
A mixture of 9.5% by weight and 0.5% by weight of benzalkonium chloride reagent (manufactured by Kanto Chemical Co.) was treated in the same manner as in Example 1 to obtain an inorganic antibacterial agent.

Test Examples The antibacterial activities of the antibacterial agents obtained in Examples 1 to 3 and Comparative Example were tested by the following two methods. The results are shown in Table 1. (1) Bacterial count measurement method 1 g of each of the antibacterial agents obtained in Examples and Comparative Examples was added to 50 ml of sterile physiological saline, and test bacteria (Escherichia) were added thereto.
coli (IFO 3806) Escherichia coli), the cells were shake-cultured at the initial stage and for 1 hour, the viable cell count was measured, and the bactericidal rate was determined by the following equation. Sterilization rate (%) = [initial viable cell count− (viable cell count after 1 hour) /
Initial viable cell count] × 100 (2) Halo method Each of the antibacterial agents obtained in Examples and Comparative Examples was ground in a mortar, and then a tablet was molded by applying a pressure of about 8 t. Plate medium (peptone 1) inoculated with
After dissolving 0 g, 5 g of salt, 10 g of meat extract, and 15 g of agar in 1 liter of distilled water, the autoclave (121
(At 25 ° C., 1.1 atm) for 20 minutes, then buried in the center of a petri dish and solidified in a petri dish, placed in a thermostat adjusted to 28 ± 2 ° C., and cultured for 2 days. After the culture, the halo (inhibition zone) was observed, and the antibacterial activity was evaluated according to the following criteria. Antibacterial activity: with formation of inhibition zone No antibacterial activity: without formation of inhibition zone

[0016]

[Table 1]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication location C09C 1/42 PAY C09C 1/42 PAY 3/06 PBS 3/06 PBS

Claims (4)

[Claims] 1. An inorganic antibacterial agent, wherein an antibacterial substance is surface-fused or bonded to the surface of an inorganic mineral particle and coated. 2. The inorganic antibacterial agent according to claim 1, wherein the antibacterial substance is a metal or a metal oxide having an antibacterial action. 3. The inorganic antibacterial agent according to claim 1, wherein the inorganic mineral particles comprise at least one of a mica clay mineral, a layered silicate mineral, a silica mineral, a carbonate mineral, and a sulfate mineral. 4. A method for producing an inorganic antibacterial agent, characterized in that a surface of inorganic mineral particles is fused or bonded with an antibacterial substance and coated by mechanical mixing by rotational movement.