JPH03218765A - Antimicrobial ceramics material - Google Patents

Abstract

PURPOSE:To provide this material which exhibits a high antimicrobial power safely for a long period of time, has the good dispersibility in fibers, synthetic resins, and other base materials, is stable to heat, does not discolor in long-term preservation and is utilizable in wide fields by using a carrier which adsorbs and holds a specific amt. of an antimicrobial metal and/or metal ions. CONSTITUTION:The ceramics selected from calcium compds., such as hydroxy apatite, calcium phosphate, calcium hydrogenphosphate, calcium metaphosphate, calcium carbonate, and calcium silicate, and zeolite, are used as the carrier. These ceramics have a high rate of adsorption and cause shrinkage on calcination by heating to about 800 to 1300 deg.C. The metals and metal ions are, therefore, securely held and the elution of the metal ions does not arise. The color of the powder is white and the range of use is not limited even if silver is used as the metal. The ceramics are used by being ground to <=100mum in the production thereof. The content of the metal and/or metal ions is confined to 15 to 0.0001wt.% of the weight of the ceramics.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention allows highly safe ceramics to adsorb and retain at least one metal salt having antibacterial properties, that is, at least one metal salt selected from silver, zinc, and copper. After that, the ceramic is fired at a temperature at which the ceramic shrinks due to heating, preferably 800°C or higher, to prevent the adsorbed and retained metal and/or metal ions from desorbing from the ceramic into the water. It relates to ceramic materials.

(Prior art) It has been known for a long time that metals selected from silver, copper, and zinc, metal ions, and their salts have strong antibacterial properties, and they can be dispersed in base materials such as fibers and synthetic resins. Various methods have been proposed to utilize its antibacterial properties by adsorption or coating. However, since these metals have poor dispersibility in the base material, it is difficult to homogeneously disperse them in the base material, and the resulting products tend to have uneven antibacterial properties. In the presence of water, metal ions and metal salts are eluted, reducing the properties and antibacterial power of the product.
The eluted metal ions and metal salts may cause unexpected drug damage to others. Furthermore, since silver salts are easily discolored by sunlight, etc., it is difficult to store them for a long period of time, and discoloration of the products to which they are added also poses a problem. Although these metals and their salts are resistant to heat and have strong antibacterial activity, they have these drawbacks, so they are not often used as antibacterial agents and have been used only in extremely limited fields. In recent years, as a substance that safely utilizes the antibacterial properties of metals, metal ions, or metal salts, a substance that uses an ion exchanger as a base material and has the metal ions ion-exchanged thereon has been proposed. For example, JP-A-6
0-181002 discloses an antibacterial material in which these metal ions are ion-exchanged with zeolite. This method reduces desorption of antibacterial metal ions into water, improves dispersibility into base materials such as fibers and synthetic resins, and improves the drawbacks of conventional metals or metal salts when used as antibacterial materials. Antibacterial metals can now be used relatively safely.

However, the method of supporting antibacterial metal ions on an ion exchanger such as zeolite by ion exchange is difficult to achieve strong antibacterial activity because the amount of metal ions that can be ion exchanged is limited by the ion exchange capacity. It is necessary to specifically use an ion exchanger with ion exchange ability, which has the drawback of limiting the types of ion exchangers that can be used, and the antibacterial metal ions retained by ion exchange are limited by the medium used. The metal ions may be released into the medium due to the metal ions, and it is not guaranteed that they can be used safely in any medium.

Furthermore, although zeolite antibacterial agents made by ion-exchanging silver ions prevent discoloration compared to pure silver salts, they change color as they are ingested, making it difficult to store them for long periods of time, resulting in discoloration of products containing them. There is also a high possibility that deterioration will occur.

On the other hand, in JP-A No. 60-181002, in order to reduce the conversion of metals into oxides and to quickly remove gases generated during use, metal-substituted zeolite is heated at a temperature of 340°C to 580°C below the start of thermal decomposition of zeolite. It is disclosed that the metal-substituted zeolite is calcined at a temperature of There are no major differences in terms of metal ion release, discoloration over time, etc. Furthermore, if zeolite carrying silver is fired at a temperature of 600°C or higher, which is higher than the 340°C to 580″C described in JP-A-60-181002, it will turn gray to black due to the action of silver.
It becomes impossible to use it widely.

(Problems to be Solved by the Invention) The present invention eliminates the need to consider drug damage caused by metals and metal ions because the antibacterial metals and metal ions do not elute into any medium, and the antibacterial metals and metal ions can be used in relatively large amounts. and/or because metal ions are adsorbed and retained, it exhibits strong antibacterial activity safely for a long time, has good dispersibility in fibers, synthetic resins, and other base materials, is stable against heat, and has antibacterial properties. as well as/
Another object is to provide an antibacterial ceramic material that adsorbs and retains metal ions and does not change color even during long-term storage.

(Means and effects for solving the problem) As mentioned above, antibacterial zeolite obtained by ion-exchanging antibacterial metal ions with zeolite is an antibacterial material that is relatively safe and easy to use. The amount of metal ions used depends on the ion exchange capacity of the zeolite used.
Depending on the type of zeolite used and ion exchange conditions,
The antibacterial activity obtained is markedly different, and since the ion-exchanged metal ions are gradually eluted into the medium, the antibacterial activity gradually decreases with long-term use. Therefore, antibacterial metals and/or
Or, it is safe because it carries a large amount of metal ions and the metal or metal ions hardly elute into any medium.
As a result of investigating a method for manufacturing an antibacterial ceramic material that exhibits strong antibacterial properties and does not show any decline in antibacterial activity even after long-term use, we were able to manufacture the desired antibacterial ceramic material. That is, all ceramics are porous and have a strong adsorption ability, and after adsorbing and supporting antibacterial metal salts on these ceramics, the ceramics are heated and fired to absorb metal and/or metal salts. We also learned that metal ions bind strongly to ceramics, and that antibacterial metals and metal ions do not elute from ceramics no matter what kind of medium it is treated with. According to this method, a significantly larger amount of metal and/or metal ions is adsorbed and retained than the amount of metal ions supported by ion exchange, so the antibacterial activity of the obtained antibacterial ceramic material is greater than that of the ceramic obtained by ion exchange. Significantly stronger than antibacterial materials,
Therefore, only a small amount is required, and the bond between the ceramic and antibacterial metals and metal ions is strengthened by firing.
Since elution of the metal ions is extremely small in any medium, it can be used safely for a long period of time.

The carrier used in the present invention can also be a carrier that is generally used as an adsorbent, such as alumina, silica gel, bentonite, acid clay, diatomaceous earth, etc.; It becomes vitrified and cannot be used as a powder. Also, materials with high melting points such as alumina, wrinkle strength, titanium dioxide, zirconium oxide, etc.
Ceramics that are stable even when heated to 0°C do not strongly support metals even when fired, so many metal ions are eluted, and when silver is used as the metal, the color of the powder is gray to black. Silica has a brownish color and is difficult to use, so its range of use is very limited.

However, hydroxyapatite, calcium phosphate,
Ceramics selected from calcium compounds such as calcium hydrogen phosphate, calcium metaphosphate, calcium carbonate, and calcium silicate and zeolites have a large adsorption amount and shrink when fired when heated at approximately 800°C to 1,300°C, so they cannot be used with metals, metals, etc. Ions can be firmly held and metal ions do not elute.

Further, even when silver is used as the metal, the color of the powder is white, and the range of use is not limited. For the manufacture of these, ceramic sox is used with an IIL of 100 μm or less.

In the conventional technology, as disclosed in Japanese Patent Application Laid-Open No. 60-181002, firing at temperatures of 340"C to 580°C does not make much of a difference from unfired compositions, and there are problems such as elution of metal ions and discoloration over time. It cannot be completely prevented.Also 60
Firing at a temperature of 0° C. or higher causes the color to turn gray to black due to the decomposition of the zeolite and the action of silver, so this has not been considered until now.

However, the present inventors found that 80% of zeolite supporting metal
It was discovered that by firing the zeolite to a temperature higher than 0"C, the color becomes white again, and metals no longer elute from the zeolite. This increases safety and maintains antibacterial properties for a long period of time, increasing the scope of use. After adsorbing an aqueous solution containing antibacterial metal salts, i.e., salts of silver, copper, and zinc, onto ceramics using a conventional method, the treated ceramics are washed.
Fire after drying. The firing temperature can be arbitrarily selected depending on the type of ceramics used, but it is desired to be as high as possible, preferably at 800°C or higher, and it is possible to fire to the boiling point of silver. Since metal evaporates during firing, firing at a temperature of 1300° C. or lower is desired. This firing prevents the adsorbed metal and/or metal ions from eluting into the solvent even if the ceramic is treated with a solvent. The amount of metal and metal ions to be adsorbed is selected depending on the ceramic used, the type of metal salt to be treated, the concentration, and the adsorption temperature, but since metal oxides may precipitate, the amount of metal and metal ions to be adsorbed is The amount is less than the saturation amount for ceramics, preferably 15 to 0.
．． It is about 0 0 0 1% by weight.

The antibacterial ceramic material obtained in this way has a metal elution amount in water that is below the detection limit, is safe to use, maintains antibacterial properties for a long period of time, does not discolor, and is preferably 50% by weight or less compared to other materials. is about 0. Sufficient antibacterial activity is exhibited by adding 1 to 10% by weight. In addition, it does not lose its antibacterial properties even when heated, and is well dispersed in organic substances, so even if it is dispersed in a synthetic resin and molded, a molded product with homogeneous antibacterial properties can be easily obtained. Generally, when powder is fired, bonding between solid particles progresses. Total surface area of powder, porosity,
It has been observed that the water absorption rate decreases. It is presumed that in this method as well, firing strengthens the bonds between the adsorbed metals and metal ions and the ceramic, reduces the reactivity with water, and no longer detects elution of the adsorbed metals into water.

EXAMPLES The present invention will be specifically explained below with reference to Examples.

Example l) 10! Add 1.0 hydroxyapatite, 32 g of silver nitrate, and 69 g of zinc nitrate to distilled water and stir. Wash the product well with distilled water, dry it, and crush a portion to remove about 2.
%, antibacterial hydroxyapatite containing about 1.5% zinc was obtained (1-1).

The remainder was calcined at 1.200°C and pulverized to obtain antibacterial hydroxyapatite carrying about 2% silver and about 1.5% zinc (1-2).

Example 2) Add 1.0 liters of tricalcium phosphate to 10 liters of distilled water. 0 kg,
Add 30 g of silver nitrate and 45 g of zinc nitrate and stir.

The product was thoroughly washed with distilled water, dried, and a portion was ground to remove approximately 0.0% silver. Antibacterial tricalcium phosphate containing about 8% zinc and about 1% zinc was obtained (2-1). The remainder was calcined at 1,100''C and pulverized to obtain antibacterial tricalcium phosphate carrying approximately 0.5% silver and approximately 1% zinc (2-2).

Example 3) Calcium carbonate 1.0kg, silver nitrate 0 in 10f distilled water
．． Add Olg and stir. The product was thoroughly washed with distilled water, dried, and a portion was pulverized to obtain antibacterial calcium carbonate containing 0.0001% silver (3-1).

The remainder was fired at 800"C and crushed to give 0.0001 silver.
% antibacterial calcium carbonate was obtained (3-2).

Example 4) 10! Calcium silicate in distilled water 1. Add 0 kg, 180 g of silver nitrate, and 200 g of copper nitrate, and stir while boiling. The product was thoroughly washed with distilled water, dried, and a portion was pulverized to obtain antibacterial calcium silicate containing about 10% silver and about 5% copper (4-1). The remainder was calcined at 1,200°C and pulverized to obtain antibacterial calcium silicate carrying about 10% silver and about 5% copper (4-2).

Example 5) A commercially available antibacterial zeolite loaded with about 2% silver and about 1.5% zinc was used as a comparative sample in the following experiment (
5).

Example 6) 1.0 kg of zeolite in 1042 g of distilled water, 32 g of silver nitrate
g, and 46 g of zinc nitrate were added and stirred. The product was thoroughly washed with distilled water, dried, and a portion was pulverized to obtain an antibacterial zeolite containing about 2% silver and about 1% zinc (6-1).

The remainder was calcined at 800°C and pulverized to obtain antibacterial zeolite carrying about 2% silver and about 1% zinc (6-2).

Example 7) 1 g of each sample of metal ion elution tests 1-1 to 6-2 was added to 10 J of distilled water.
After stirring for 30 minutes, metal ions in the solution were measured using an atomic absorption spectrophotometer to determine the elution amount.

As described above, elution of metals could be prevented by firing ceramics containing metals.

Example 8) Antibacterial activity test 0.1% by weight of samples 1-1 to 2-2 and 4-1 to 5,
E. coli bacterial solution was added to phosphate buffered saline containing 50% by weight of samples 3-1 and 3-2, and the antibacterial activity against E. coli was measured.

*In the table, the number 1 is due to the limit of bacterial count measurement and means that no bacteria were detected.

Example 9) Discoloration test White antibacterial hydroxyapatite (1-2) and white commercially available antibacterial zeolite (5) were placed in a plastic bag and left indoors. As a result, the commercially available antibacterial zeolite showed slight yellowing after half a year, and pale yellow after one year (it was clearly seen that the powder on the surface was darker yellow than the powder inside the bag, and The powder was also yellowed.) However, the antibacterial hydroxyapatite remained white even after one year and did not change color. In addition, the antibacterial zeolite (6-2) prepared by the method of the present invention also remained white and did not change color. It is clear that the antibacterial ceramic material obtained by the method of the present invention has antibacterial activity equivalent to that of conventional antibacterial zeolite, has very little elution of metal ions, and does not discolor for a long period of time.

(Effects of the Invention) The antibacterial ceramic according to the present invention is resistant to heat and has good dispersibility, so it can be added to fibers, plastics, paper, ceramics, etc. and used in a wide range of fields. In addition, since there is no elution of metals or metal ions, it can be used in fields that particularly require safety, such as cosmetics, quasi-drugs, food packaging, medical devices, and biomaterials. In particular, since there is no elution of metals or metal ions or deterioration of antibacterial properties even in boiling water, it can be used in packaging materials that require boiling, water purifiers that use hot water, and the like.

Claims (6)

[Claims] (1) At least one water-soluble metal salt selected from silver, copper, and zinc is adsorbed onto at least one ceramic selected from hydroxyapatite, calcium phosphate, calcium hydrogen phosphate, calcium carbonate, calcium silicate, and zeolite. An antibacterial ceramic material characterized by being held and then fired. (2) The antibacterial ceramic material according to claim (1), wherein the ceramic is hydroxyapatite. (3) Claim (1) wherein the water-soluble metal salt is a salt of silver and zinc.
) antibacterial ceramic materials. (4) Claim (1) wherein the content of metal and/or metal ions is 15 to 0.0001% by weight based on the ceramic.
Or (2) antibacterial ceramic material. (5) Claims (1) and (1) wherein the firing temperature is 800°C or higher.
The antibacterial ceramic material according to any one of 2) or (3). (6) An antibacterial ceramic material in which fired ceramics support at least one metal and/or metal ion.