JPH07330527A - Antimicrobial ceramic - Google Patents

Abstract

PURPOSE:To obtain an antimicrobial ceramic excellent in the safety, having a wide- ranging antimicrobial activity and a long-term durability and suitable for environmental use, e.g. sterilization of a sandbox or sterilization in water treatment by making an antimicrobial substance adhere through an expansible layered clay mineral to the surface of a ceramic base material. CONSTITUTION:This antimicrobial ceramic is obtained by making an antimicrobial substance adhere through an expansible layered clay mineral to the surface of a ceramic base material (preferably <=150 mesh particle diameter) and then calcining it at >= the temperature where the expansible layered clay mineral is converted to a semi-ceramic. As the antimicrobial substance, an antimicrobial metal such as silver, copper, zinc, tin or nickel or an inorganic antimicrobial agent composed of one of these anti-microbial metals supported on a ceramic is used. As the expansible layered clay mineral, a smectite-type mineral or a vermiculite-type mineral is preferably used. This antimicrobial ceramic is excellent in water resistance, chemical resistance and heat resistance and suitable for environmental use, e.g. sterilization of a sandbox, sterilization, fungusproofing and chemicalproofing in water treatment of exhausted water, city water, etc., fungus-proofing and algaproofing of a cooling tower and sterilization of toilet sand for pet.

Description

Detailed Description of the Invention

[0001]

[Field of industrial application] Highly safe, having a wide range of antibacterial ability, long-lasting, high water resistance, chemical resistance, and high heat resistance, for sterilizing sandboxes, for treating water such as drainage and water. The present invention relates to antibacterial ceramics suitable for environmental purposes such as disinfection / mold / algae prevention, mold / algae for cooling towers, and disinfection of pet toilet sand.

[0002]

In the industrial field such as resin processing, it is adsorbed or ion-exchanged with zeolite, zirconium phosphate, swelling layered clay minerals, etc. for use in kneading resins for antibacterial films, molded products and fibers. Inorganic antibacterial agents carrying antibacterial metal ions by these means are preferably used. These inorganic antibacterial agents are characterized by high safety, broad antibacterial ability, long-lasting efficacy, and high water resistance, chemical resistance, and heat resistance.
On the other hand, these are fine powders and are very expensive. Examples of these inorganic antibacterial agents include zirconium phosphate, silver zeolite, copper zeolite, silver montmorillonite, and silver glass. Some of these release the metal ions slowly and some do not.

In recent years, not only for industrial use but also in familiar living environments, such as sanitization of sand pits, water treatment of waste water and water, etc.
Antibacterial agents that are safe and inexpensive have come to be required for the prevention of mold and algae, the prevention of mold and algae in cooling towers, and the disinfection of pet toilet sand. However, in addition to being expensive, the above-mentioned conventional inorganic antibacterial agents are not suitable for such applications because they are difficult to handle because they are fine powders having an average particle size of 10 μm or less. It was For example, when applied to a sandbox, the difference in particle size from the sand was large, so the particles were not uniformly mixed in the sand and were unevenly distributed, and no antibacterial effect appeared in the entire sandbox. In addition, in water treatment applications, a considerable portion of the water was discharged along with the flow of water that was difficult to settle when added to water.

It is desired that the antibacterial ceramics which eliminates such inconvenience and is suitable for the above living environment has a particle size of 150 mesh or less. An antibacterial metal can be supported by ion exchange on carrier ceramics having a particle size of 150 mesh or less, for example, natural zeolite having an average particle size of 1 mm. However, most of the supported metal ions are present inside the zeolite, and only a part of the supported metal ions are present near the surface. Therefore, even if the same amount of metal ion is used, the antibacterial effect is significantly reduced as compared with the conventional inorganic antibacterial agents.

[0005]

[Problems to be Solved by the Invention] An inorganic carrier having a large particle size, which can be conveniently used for water treatment and sterilization of a living environment such as sand in a sandbox, is unevenly distributed and carries antibacterial metal ions at a high density. It is expected to provide antibacterial ceramics having a large antibacterial action.

[0006]

The present invention provides an objective antibacterial ceramic by adhering an antibacterial substance by a swelling layered clay mineral to the surface of a ceramic matrix.

The ceramic matrix is required to be large in size, does not necessarily require characteristics such as adsorption capacity and ion exchange capacity, and is an inorganic substance that does not melt at the firing temperature of the swellable layered clay mineral. I wish I had it. Natural zeolite as a preferred ceramic matrix for the present invention,
Mention may be made of sand, ceramic compacts, glass, pearlite, alumina, titania, silica and other silicates. As the ceramic matrix used in the present invention, it is preferable to use a ceramic having a particle size of 150 mesh or less, preferably 100 mesh or less. By using the ceramics having such a particle size as the matrix of the antibacterial ceramics, the ceramics can be conveniently used for sanitization in a sandbox or water treatment.

The antibacterial substance used in the present invention is an antibacterial metal such as silver, copper, zinc, tin, nickel or the like used in conventional inorganic antibacterial agents, or an inorganic antibacterial metal supported on ceramics. Use antibacterial agents. When the antibacterial metal is directly used, it can be directly adsorbed from the aqueous solution to the ceramic matrix as a carrier in the form of water-soluble ions such as chloride or nitrate, but generally,
After the antibacterial metal ions are supported on the swellable layered clay mineral in water, the dispersion can be directly attached to the ceramic matrix. An inorganic antibacterial agent in which antibacterial metal ions are supported on ceramics can be similarly prepared by adsorbing metal ions from water. For this ceramic, for example, zelite, zirconium phosphate, montmorillonite, vermiculite, etc. can be used. The average particle size of these inorganic antibacterial agents is about 0.1 to 10 μm.

By adhering these antibacterial substances to the surface of the ceramic matrix by using a swelling layered clay mineral as an adhesive, the antibacterial substances are made to exist on the surface of the ceramic matrix at a high density. The swellable layered clay mineral generally has a property of being swollen by water, whereby the interlayer voids are changed and particles of various sizes can be taken in between the layers. Further, it has a characteristic of exhibiting a film-forming property by swelling and then drying, and since it has an affinity with various ceramics, it can act as an adhesive between a ceramic base and an antibacterial substance. This adhesion can be further increased by firing. On the other hand, since the swelling layered clay mineral has a large number of fine pores, it has a large effective surface area and can effectively exhibit the antibacterial action of the metal taken into the swelling layered clay mineral. As the swelling layered clay mineral, not only montmorillonite, hectorite, beidellite, nontronite, saponite, chlorite and other smectite type minerals, vermiculite,
Includes swellable fluoromica and its homomorphic substitutes. Further, viscosity such as a smectite type mineral as a main component, for example, acid clay or bentonite can also be used.

Thus, effective antibacterial activity can be imparted to particles having a large particle size and a relatively small surface area and having a particle size of 150 mesh or less. The size of the obtained antibacterial ceramic is substantially the same as that of the ceramic matrix, and the particle size is 150 mesh or less. The use ratio of the bacterial antibacterial substance and the ceramic matrix can be selected so that the antibacterial metal is contained in the obtained antibacterial ceramic in an amount of 0.01 to 10% by weight, preferably 0.1 to 3% by weight.

The antibacterial ceramics can be produced by any of the following methods. (A) After immersing the ceramic matrix in the dispersed water of the antibacterial substance and the swellable layered clay mineral, pulling it up and drying it. (B) Applying the dispersed water of the antibacterial substance and the swellable layered clay mineral to the surface of the ceramic matrix and then drying it. . (C) After dry-mixing the antibacterial substance, the swelling layered clay mineral and the ceramic matrix, water is added, and the mixture is wet-mixed and dried. Since the swellable layered clay mineral generally has a film-forming property after being dried if it swells in water, at this stage, a film in which an inorganic antibacterial agent is dispersed is formed on the surface of the ceramic matrix. When the antibacterial substance is made of a swelling layered clay mineral, the antibacterial substance can be swelled in water as it is and adhered to the ceramic matrix to form the antibacterial ceramic of the present invention.

The antibacterial ceramics having a swelling layered clay mineral containing an antibacterial substance as a surface layer increases the adhesive force by firing, but the swelling layered clay mineral loses its fine pores when sufficiently fired. The densification results in a reduction of the parenchymal surface area and impaired antimicrobial activity. Hold the fine holes,
In order to exert better adhesive strength, it is necessary to fire in a semi-ceramic state (state of unglazed), and the firing temperature is 300 to 800 ° C, preferably 400 to 700 ° C. Water resistance can be obtained by firing, but if water resistance is not so required, firing is not always necessary.

[0013]

EXAMPLES The effects of the present invention will be described below with reference to examples. Example 1 100 parts by weight of natural zeolite (average particle size 1 mm), 1 part by weight of inorganic antibacterial agent (zirconium phosphate carrying silver ions, average particle size 0.5 μm), and 1 part by weight of synthetic hectorite were dry-mixed. After uniform mixing, 30 parts by weight of water was added and wet-mixed. The particles were then screened using a 150 mesh screen. 150 thus obtained
The particles below the mesh were dried and fired at 500 ° C. for 1 hour to obtain antibacterial ceramics I.

In order to confirm the effect of the antibacterial ceramics thus obtained, the antibacterial effect was tested on sewer water and sand in the sandbox. (1) 1% by weight of the antibacterial ceramics I of the present invention was added to one of the two containers containing sewer water, and 0.01% by weight of the above-mentioned inorganic antibacterial agent used as a raw material was added to the other container, and 1 hour later Both sewers were sterile. A large number of bacteria were confirmed in the sewer water before adding the antibacterial agent. However, in the case of the antibacterial ceramics I, the supernatant was easily taken out, but in the case of the inorganic antibacterial agent, a filtering device, labor and time were required to separate the antibacterial agent and water. (2) Similarly, 10% by weight of the antibacterial ceramics I of the present invention was added to one of two containers containing sand in a sandbox, and 0.1% by weight of the above-mentioned inorganic antibacterial agent used as a raw material was added to the other. , Each was mixed as described below. The sand and the antibacterial agent were uniformly mixed in the case of the antibacterial ceramics I, but the inorganic antibacterial agent was localized in the lower part of the sand. When the presence or absence of bacteria was checked separately for the upper and lower parts of the sand, the upper and lower parts were aseptic for antibacterial ceramics I, but the lower part was aseptic for inorganic antibacterial agents. However, a few bacteria were present in the upper part.

Example 2 Example 1 was repeated except that synthetic calcium silicate (average particle size 1 to 2 mm) was used as the ceramic matrix and copper ion-supported zeolite (average particle size 3 to 5 μm) was used as the inorganic antibacterial agent. Antibacterial ceramics II was obtained in the same manner as. The antibacterial effect was similar to that of Example 1.

Antibacterial Test Method (1) Sewer Water Test Sewer water and an antibacterial agent were placed in a closed container and left to stand. After 1 hour, 1 ml of water was taken out, sucked into a general bacterial test paper, and cultured at 35 to 37 ° C. for 24 hours. (2) Sandbox sand test The sandbox sand and the antibacterial agent were placed in a closed container, shaken lightly 10 times and then left. After 1 day, add sterilized water, immediately take out 1 ml of the supernatant and inhale it with general bacteria test paper for 35-35
The cells were cultured at 37 ° C for 24 hours.

[0017]

INDUSTRIAL APPLICABILITY The antibacterial agent of the present invention enables more convenient and effective disinfection of water and sand in a sandbox than conventional inorganic antibacterial agents.

Claims (5)

[Claims] 1. An antibacterial ceramic in which an antibacterial substance is adhered to the surface of a ceramic matrix by a swelling layered clay mineral. 2. The antibacterial ceramic according to claim 1, wherein the antibacterial substance is an inorganic antibacterial agent carrying an antibacterial metal or an antibacterial metal ion. 3. The antibacterial ceramic according to claim 1, wherein the particle size of the ceramic matrix is 150 mesh or less. 4. The antibacterial ceramic according to claim 1, wherein the swellable layered clay mineral is a smectite type mineral or vermiculite. 5. The method for producing an antibacterial ceramic according to claim 1, wherein the antibacterial substance is adhered to the surface of the ceramic matrix by the swelling layered clay mineral, and then fired at a temperature at which the swelling layered clay mineral becomes semiceramic or higher. .