JPH09299724A - Sterilizing filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sterilizing filter having air permeability and water permeability being safe and sustaining sterilizing effect by depositing zinc oxide particles smaller than a specific size in an average particle size to a filter base body surface without a binder material. SOLUTION: This filter uses a filter base body made from a raw material consisting of fiber products (cloth, nonwoven cloth, etc.) such as synthetic fiber, natural fiber and paper products, etc. A zinc ion-containing solution dissolved zinc sulfate and zinc chloride, etc., is brought into contact with an alkali aqueous solution such as NaOH under presence of this filter base body. Then, zinc oxide is deposited on the filter base body surface and zinc oxide having <=0.1μm average particle size can be deposited to the filter base body surface without any binder material. Like this, zinc oxide fine particles are used as the sterilizing agent and they stick to the filter base surface strongly, thus the sterilizing filter with high performance can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antibacterial filter, and more particularly to an antibacterial filter in which fine particles of zinc oxide are adhered to the surface of a filter substrate without a binder and have air permeability and water permeability. .

[0002]

2. Description of the Related Art As an antibacterial measure for a filter having air permeability and water permeability, there is a method of supporting an organic antibacterial agent on the surface of a filter substrate. It is difficult to support the surface for a long time (that is, to keep the antibacterial effect for a long time), and there is a tendency that a safety problem occurs due to dissolution or scattering of the organic antibacterial agent. There is also an inorganic antibacterial agent such as silver zeolite, but in order to fix it to the filter substrate, it is necessary to use a method using a binder (coating) or a method of kneading into the filter raw material resin. In this case, the antibacterial agent is buried in the resin and does not work effectively.

It is known that zinc oxide has an antibacterial action and an antifouling / purifying action. Antibacterial activity of zinc oxide,
It is often practiced to fix zinc oxide on a substrate to utilize its antifouling activity and purification activity. Conventionally, zinc oxide is fixed to a substrate by kneading it into a resin such as a molding material and then including it in a molded article such as fiber, or by dispersing zinc oxide in a paint to obtain a zinc oxide dispersion. A coating material was applied, or a dispersion liquid containing zinc oxide fine particles and a binder was applied, and heat treatment was performed for deposition. When kneading into the resin or dispersing it in the paint in this way, most of zinc oxide remains trapped in the resin and paint and is hard to appear on the surface, so the effect of adding zinc oxide is small, and However, when the paint is applied to a textile product, there is a drawback that uneven coating may occur.

When the dispersion liquid is applied, heat treatment is required to achieve evaporation of the dispersion medium and deposition with a binder, and further the binder is attached to the surface of the zinc oxide fine particles to add zinc oxide. It has the drawback of reducing effectiveness. There is also known a method in which a substrate is coated with zinc hydroxide and then thermally decomposed to coat zinc oxide.
It must be heated to 50 ° C. or higher, and may be deformed, deteriorated or melted depending on the material of the substrate. Further, the coating film is easily peeled off during heating, and it is difficult to obtain a strong zinc oxide adherend.

As a method of depositing zinc oxide on the surface of the substrate, a thermal spraying method can be considered. In this case, however, the particle diameter of zinc oxide becomes several μm or more, and zinc oxides are fused to each other. For example, when it is applied to a textile product, the flexibility and tactile sensation of the substrate are lost and it becomes impractical. It is also possible to deposit zinc oxide by sputtering or vapor deposition, but in this case, it is possible to deposit only on the outermost surface of the substrate. Zinc cannot be applied.

[0006]

The object of the present invention is to use zinc oxide fine particles as an antibacterial agent, and zinc oxide fine particles can be adhered firmly to the surface of a filter substrate without causing the above-mentioned drawbacks. The present invention aims to provide a breathable, water-permeable antibacterial filter which is safe and has a sustained antibacterial effect. Another object of the present invention is that the zinc oxide fine particles are firmly adhered to the filter substrate surface without a binder,
An object of the present invention is to provide a breathable, water-permeable antibacterial filter which is safe and has a sustained antibacterial effect.

[0007]

Means for Solving the Problems As a result of various studies to achieve the above object, the present inventors have found that zinc oxide fine particles can be firmly adhered to the surface of a filter substrate without using a binder. Found and completed the present invention. That is, the antibacterial filter having air permeability and water permeability of the present invention is characterized in that zinc oxide fine particles having an average particle size of 0.1 μm or less are adhered to the surface of the filter substrate without a binder.

In the antibacterial filter having air permeability and water permeability of the present invention, preferably, a zinc ion-containing solution is contacted with an alkaline aqueous solution in the presence of a filter substrate to deposit zinc oxide on the surface of the filter substrate, It is an antibacterial filter obtained by applying it. More preferably, the antibacterial filter having air permeability and water permeability of the present invention is such that the filter substrate having the zinc ion-containing solution adhered to the surface of the filter substrate is contacted with an alkaline aqueous solution under a temperature condition of 50 ° C. or higher. Is an antibacterial filter obtained by reacting to deposit and deposit zinc oxide on the surface of the filter substrate.

In the present invention, the filter substrate to which the zinc oxide fine particles are adhered may be any material in any shape such as synthetic fiber, natural fiber, inorganic fiber fiber products (woven fabric, nonwoven fabric, etc.), paper products, ceramics and the like. Well, it is preferably a textile product such as a woven fabric or a non-woven fabric. In the air-permeable, water-permeable antibacterial filter of the present invention, the deposition of the zinc oxide fine particles on the surface of the filter substrate is carried out on a woven or non-woven fabric before being processed into a filter substrate shape,
Alternatively, it may be performed after pleating. The zinc ion-containing solution used in the present invention is, for example, zinc sulfate, zinc chloride, zinc nitrate or the like dissolved in water, and the alkaline aqueous solution is, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide or the like in water. It was dissolved in.

When the antibacterial filter having air permeability and water permeability of the present invention is obtained by contacting and reacting the filter substrate having the zinc ion-containing solution adhered on the surface of the filter substrate with an alkaline aqueous solution, zinc ion is used. It is preferable to contact and react with an alkaline aqueous solution in the state of being in contact with the surface of the filter substrate. Further, when the zinc ion-containing solution is brought into contact with and reacted with the alkaline aqueous solution, it is preferably carried out under a temperature condition of 50 ° C. or higher. If the temperature is lower than 50 ° C., zinc oxide containing few impurities tends to be difficult to obtain, the reaction rate is slow, and zinc oxide fine particles having an average particle size of 0.1 μm or less are sufficiently deposited and deposited on the surface of the filter substrate. Tends to be difficult to do.

When the surface of the filter substrate used in the present invention is hydrophobic, the surface of the filter substrate is treated with, for example, a surfactant to make it hydrophilic, and then zinc oxide fine particles are deposited on the surface of the filter substrate. By applying the zinc oxide particles, the zinc oxide fine particles can be more firmly applied to the surface of the filter substrate.

In the present invention, the filter substrate having the zinc ion-containing solution deposited on the surface of the filter substrate as described above is contacted with an aqueous alkali solution under a temperature condition of 50 ° C. or higher and reacted immediately, and then immediately oxidized. It is preferable to put it in a solution in which zinc is hardly soluble and to age it for 5 minutes or more under a temperature condition of 50 ° C. or more. When the pH value of the zinc oxide hardly soluble solution is 9 or more, zinc oxide containing very few impurities is deposited, so that the pH value is preferably 9 or more. The temperature and time during the aging are the temperature and time at which zinc oxide fine particles having an average particle size of 0.1 μm or less can be sufficiently deposited and deposited on the surface of the filter substrate.
Under the temperature condition of less than ℃, it tends to be difficult to obtain zinc oxide with less impurities, and the required time becomes too long,
If it is less than 5 minutes, it tends to be difficult to sufficiently deposit and deposit zinc oxide fine particles having an average particle diameter of 0.1 μm or less on the surface of the filter substrate.

By producing under the above-mentioned conditions, a breathable and water-permeable antibacterial filter having zinc oxide fine particles having an average particle size of 0.1 μm or less adhered on the surface of the filter substrate without a binder is obtained. To be In the present invention,
"Antibacterial" means to kill fungi such as Escherichia coli and mold, and "antifouling" means to reduce the degree of surface contamination by decomposing contaminants adhering to the surface. "Purification" means decomposing pollutants in a gas or a liquid to maintain the gas or the liquid in a clean state.

[0014]

【Example】

Example 1 Dust collection filter for room air conditioner (Toshiba RB-A40
2D, synthetic fiber non-woven fabric) was treated with a surfactant to make its surface hydrophilic. Immediately after taking out this treated filter in a zinc sulfate aqueous solution (2N) at 90 ° C. and taking it out,
A 90 ° C aqueous solution of sodium hydroxide (2
N), and immediately after that, an aqueous solution of sodium sulfate (0.5
It was immersed in N) and boiled at 100 ° C. for 20 minutes, after which the filter was washed with water and dried.

As a result of X-ray diffraction of the filter thus obtained, a diffraction peak of zinc oxide was confirmed. As a result of observing the surface of the filter with an electron microscope, zinc oxide fine particles of 100 nm or less were deposited almost uniformly on the fiber surface of the filter. This zinc oxide coated filter has the same feel as the filter before treatment,
No dropout or scattering of zinc oxide was observed.

Room air conditioner (Toshiba RAS-251L
The above-mentioned zinc oxide-coated filter and untreated filter were attached to T), respectively, and by using the usual method,
It was used for 6 months in a general household. After 6 months, in order to examine the presence or absence of general bacteria in the filter, the front surface and the back surface of the filter were transferred with a food stamp (standard agar manufactured by Nissui Pharmaceutical Co., Ltd.) and cultured in an incubator. As a result, bacterial colonies were observed at all 6 sites on the front and back of the untreated filter, but only 1 out of 6 sites on the front and back of the zinc oxide-coated filter were colonized with bacteria. Was only observed. Thus, it was confirmed that the zinc oxide-coated filter has an antibacterial effect.

Example 2 A cotton woven cloth was treated with an aqueous zinc chloride solution at 70 ° C. (2N, 200 m).
l). Next, all of the zinc chloride aqueous solution containing the cotton woven cloth is treated with a 100 ° C. sodium hydroxide aqueous solution (2N,
200 ml) and continued boiling for another 30 minutes.
A large amount of zinc oxide was deposited on the cotton woven fabric, and excess zinc oxide was suspended in the solution. Take out the cotton woven cloth after 30 minutes,
It was washed with water and dried. As a result of observing the surface of the cotton woven fabric with an electron microscope, zinc oxide fine particles of 100 nm or less were almost uniformly adhered to the fiber surface of the cotton woven fabric.

150 μl of a bacterial solution containing E. coli (containing about 20,000 E. coli) was dropped onto the zinc oxide-coated cotton woven fabric.
Immediately after the dropping and after 1, 2 and 3 hours, the bacterial solution on the surface of the cotton woven fabric was collected and cultured on standard agar for 24 hours. Also,
As a comparison, the same test was carried out on a cotton woven fabric having no zinc oxide film. The test results are shown in Table 1. The data in Table 1 are converted values.

[0019]

This cotton woven fabric is made into Japanese Industrial Standard L02.
17 (1995). Washing (40 ° C.) was performed according to the washing method based on No. 103. When the cotton woven fabric after washing was observed with an electron microscope, it was confirmed that zinc oxide was adhered even after washing. When this cotton woven fabric was used as a filter, it became an antibacterial cotton woven fabric filter showing the same effect as the above data, and it was possible to kill the adhered E. coli.

Example 3 A nonwoven fabric filter made of glass fibers was dipped in a zinc chloride aqueous solution (2N) at 90 ° C., and immediately after being taken out, a 90 ° C. sodium hydroxide aqueous solution (2
N), then aqueous sodium chloride solution (0.5N)
And boiled at 100 ° C. for 20 minutes, and then the nonwoven fabric filter was washed with water and dried.

As a result of X-ray diffraction of the filter thus obtained, a diffraction peak of zinc oxide was confirmed. Also, as a result of observing the surface of the filter with an electron microscope, it was found that 100 n was found on the glass fiber surface of the filter.
Zinc oxide fine particles of m or less were deposited almost uniformly. The zinc oxide-coated filter was used as an air cleaning filter in combination with a ventilation fan, and continuously operated for 1 month. 1
After a month, the filter was washed with sterilized distilled water, the wash water was applied to a standard agar medium and cultured at 37 ° C. for 1 day, but no colonies were detected. That is, it was confirmed that bacteria did not propagate on this zinc oxide-coated filter.

[0023]

INDUSTRIAL APPLICABILITY In the air-permeable and water-permeable antibacterial filter of the present invention, zinc oxide fine particles having an average particle size of 0.1 μm or less are firmly adhered to the surface of the filter substrate without using a binder, and are safe. It has antibacterial, deodorant and antifouling effects.

Claims (4)

[Claims] 1. An antibacterial filter having air permeability and water permeability, wherein zinc oxide fine particles having an average particle diameter of 0.1 μm or less are adhered to the surface of a filter substrate without a binder. 2. The antibacterial filter according to claim 1, which is obtained by bringing a zinc ion-containing solution into contact with an alkaline aqueous solution in the presence of a filter substrate to deposit and deposit zinc oxide on the surface of the filter substrate. 3. A zinc oxide-containing solution is deposited on the surface of the filter substrate by contacting and reacting the filter substrate having the zinc ion-containing solution on the surface of the filter substrate with an aqueous alkaline solution at a temperature of 50 ° C. or higher. The antibacterial filter according to claim 1, which is obtained by depositing. 4. The antibacterial filter according to claim 1, 2 or 3, wherein the filter substrate is a woven or non-woven fabric.