JPH0716613B2 - Photocatalytic function for biological activity suppression - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photocatalyst functional body for suppressing biological activity using a photocatalyst material.

(Background Art) It is conventionally known that when a semiconductor material is irradiated with light, it causes a photocatalytic action. For example, in a photoelectrochemical cell in which a titania electrode and a platinum electrode are combined, when the titania electrode is irradiated with light in an electrolyte aqueous solution, oxygen is generated from the titania electrode side and hydrogen is generated from the platinum electrode side. This is the decomposition of water by the photoelectrochemical effect.

As described above, titania exhibits a very strong photocatalytic action, but other than this, although the action effect is inferior to that of titania, semiconductor materials such as CdS, CdSe, WO ₃ , Fe ₂ O ₃ , and SrTiO ₃ are also photocatalytic. It has an action (hereinafter, these materials having a photocatalytic action are referred to as photocatalyst materials).

These photocatalyst materials have a wide range of applicability. Utilizing their reactivity, they exchanged light energy with chemical energy or electric energy, utilized for organic synthesis, and utilized bactericidal ability. Research on wastewater treatment, use for deodorizing, etc. has been conducted.

The present invention focuses on the above photocatalytic reactions of titania and the like, and an object thereof is to provide a photocatalytic functional body that can effectively exhibit these actions and is suitably used for the purpose of suppressing the activity of organisms. .

(Means for Solving the Problems) In order to achieve the above object, the present invention has the following configuration.

That is, the particle size of the sprayed material is 5
The photocatalyst material is characterized in that the photocatalyst material is deposited as a porous sprayed coating by spraying using a powder of the photocatalyst material of about 25 μm.

Further, titania can be particularly effectively used as the photocatalyst material.

(Summary of the Invention) A photocatalytic function body for suppressing biological activity according to the present invention is characterized in that a metal thin film is used as a base material, and a photocatalytic material is sprayed on the surface of the base material.

Here, the type of the metal thin film as the base material of the photocatalyst material is not particularly limited, and various metals such as stainless steel, copper, and iron can be used.

As the photocatalyst material, one having a photocatalytic action, for example, titania, CdS, GdSe or the like can be used. However, among the photocatalyst materials, titania exerts the photocatalytic action most strongly, and is most effective in actual use. It is considered that this is because the energy level of the valence band of titania is deeper than that of other photocatalyst materials, and the oxidation effect by holes generated by photoexcitation appears most strongly. Of course, in some cases, a photocatalytic material such as titania and another metal substance may be mixed and used. Titania has the advantage that it is completely harmless and can be obtained at a low price, as it has been approved for use as a composition material for cosmetics and as a food additive.

The photocatalyst functional body according to the present invention is characterized in that it is formed by spraying a photocatalyst material in a porous form on a base material of a metal thin film, and as a method for spraying on the base material, a powder of a photocatalyst material such as titania as a spray material. A method using (particle size of about 5 μm to 25 μm) can be used. This method is a method which is usually performed as a method for spraying a metal or the like using a ceramic powder. According to this method, titania or the like having a melting temperature of several thousand degrees can be sprayed onto a metal thin film having a small heat capacity, and a sprayed coating can be formed in a porous form on the surface of the base material.

As will be described later, the photocatalyst functional body thus obtained has an action of suppressing the activity of organisms such as suppressing the growth of algae and suppressing the germination of paddy by contacting with water. The action of the photocatalyst functional body according to the present invention to suppress the activity of organisms is considered to be due to the photocatalytic action by the photocatalyst material, but the photocatalyst functional body according to the present invention is that the photocatalyst material is applied to the base material by the thermal spraying method. The photocatalyst material is exposed as it is on the surface of the base material in a pure form and can directly contact with water to perform the photocatalytic action. By using the powder of the photocatalyst material as the thermal spray material, the photocatalyst material is deposited on the base material. There is an advantage that the contact area of the photocatalyst material becomes large. In addition, since the thermal spray coating is not completely covered in a non-porous state but is applied in a porous form in which the pores are clogged, when the photocatalyst functional body is immersed in water etc. Penetration occurs and the photocatalytic action is effectively exhibited between the conductor metal and the photocatalytic material. In addition, the photocatalyst material formed by adhesion is less likely to be peeled off from the base material, so that there is an advantage that the photocatalytic action continues and the effect is not attenuated.

The photocatalyst functional body according to the present invention can be used for sterilization of drinking water for general use, sterilization of humidifiers, sterilization of miscellaneous treatment tanks, etc. by utilizing its action of suppressing the activity of organisms, and for medical use. It can also be used for things that cannot be sterilized at high temperature.

In addition, in this specification, suppressing the activity of the organism means suppressing the growth of algae in water, suppressing the germination of paddy, and suppressing the growth of bacteria.

(Experimental example) The following experiment was conducted in order to investigate the effect of the photocatalyst functional body according to the present invention.

[Experimental Example 1] Water and algae were placed in a container, and the appearance of algae growth was observed over a predetermined period. The samples were as follows with the same amounts of water and algae.

Nothing except water and algae.

A ceramic ball soaked.

A polyester film sprayed with titania.

A photocatalyst functional body obtained by spraying titania on one surface of a stainless steel thin plate.

Regarding each of the above-mentioned samples, when the state of algae growth was observed for about 3 months while shining light, the algae in the container grew more than in the initial stage of charging, but the algae in the container did not grow. It was not seen, and it was seen that the amount of algae decreased. Also, the water in the container of, was turbid after 3 months, but the water in the container was clear even after 3 months. The amount of algae in the container of ,,, was the smallest. This may be due to the far infrared rays emitted from the ceramic film, but the degree of inhibition of algae growth in the container was extremely remarkable compared to the effect.

The results of this experiment show that the photocatalyst functional body formed by spraying titania onto a stainless steel thin plate is effective in suppressing the activity of organisms.

[Experimental Example 2] Water and tofu were put in a container, kept at 30 ° C and left to observe the progress. The following were used as samples.

Only water and tofu.

Tofu placed on stainless steel foil and immersed in water.

Titanium is sprayed on one side of stainless steel foil, tofu is placed on it, and it is immersed in water.

In this state, after 9 days, and in the container, the tofu was completely decomposed and lost its shape, mold was generated in the tofu, and the water was completely turbid. On the other hand, in the container, the tofu had not yet rotted and retained its original shape, and the water showed transparency. Furthermore, after 14 days, the tofu did not lose its shape in the container and the rot did not progress so much.

It is considered that this result indicates that the suppression of the activity of the organism (bactericidal action) by the photocatalytic action effectively functioned in the prevention of putrefaction in the container.

[Experimental Example 3] Saline solution and Chinese cabbage were placed in the container, the temperature was kept at 30 ° C, and the progress was observed. The following were used as samples.

Only saline and Chinese cabbage.

A stainless steel foil soaked.

One in which titania is sprayed on one side of stainless steel foil and immersed.

After 9 days, and Chinese cabbage was putrefaction and a thin film of mold was formed on the water surface. On the other hand, no decay of Chinese cabbage was observed in the container, and no thin film of mold spread on the water surface. After 14 days, some cloudiness of the saline solution was also seen in the container. It is considered that this experimental result also shows the suppression of the activity of the organism (bactericidal action) by the photocatalyst functional body.

[Experimental Example 4] A germination test was conducted using paddy. The following were used as samples.

It is made by immersing paddy on stainless steel foil and immersing it in water.

Far-infrared radiation ceramics sprayed on a stainless steel foil and then immersed in water.

It is made by spraying titania on a stainless steel net and immersing it in water.

A piece of stainless steel foil sprayed with titania and paddy on it and immersed in water.

After 18 days, the germination of the paddy in the container was most prominent, the germination was slightly in and, and the germination was hardly in. After the lapse of 23 days, the buds greatly expanded outside the container, and even the buds expanded outside the container. On the other hand, no elongation of buds was observed in the container, and no germination from the paddy was observed even if the plate obtained by spraying the titania on the stainless steel foil was removed from the container. In the container of No. 2, the result showed that the germination of paddy was completely suppressed.

In each of the above experimental examples, it is considered that the photocatalyst functional body formed by spraying titania onto the stainless steel foil has high reactivity, and the activity suppressing effect on the living body is effectively exerted.

The following tests were performed on a plurality of types of bacteria as an antibacterial property test of a photocatalyst functional body formed by spraying a photocatalyst material on a metal thin film.

[Antibacterial test]

a: Sample Polyester cloth electrolessly nickel-plated as a conductor metal (hereinafter referred to as conductor cloth) One side of the above-mentioned conductor cloth sprayed with titania in an oxidizing atmosphere.

The conductor cloth is sprayed with titania in a reducing atmosphere on one side.

b: Test sample strain IAM-1011: Staphylococcus aureus IAM-1253: Escherichia coli IAM-1069: Bacillus subtilis IAM-4125: Sake yeast IFO-6352: Blue mold IFO-6341: Black knot mold c: Measurement method: Inhibition zone ( Halo) According to JIS Z-2911 by the measuring method, the above sample of (, 2.0 cm x 2.5 cm square) was embedded in an agar medium inoculated with the above-mentioned test bacteria, and after culturing, a growth inhibition zone (halo) around the sample Check for the formation of seeds, measurement of width, and presence of growth above the sample.

d: Evaluation judgment +: Inhibition zone is observed 3 mm << 5 mm ±: Inhibition zone is observed 3 mm <-(0): No inhibition zone is observed, but there is no growth and growth on the upper part of the sample.

-(5): No inhibition zone is observed. 100% growth and growth on top of the sample.

Test results 1. The results of antibacterial test against bacteria are shown. This is the result of observing antibacterial properties by placing the sample in a dark room.

For Staphylococcus aureus, no inhibition zone (halo) nor growth inhibition of the upper surface of the sample was observed. A zone of inhibition was observed for Escherichia coli and Bacillus subtilis. However, an inhibition zone was observed in the sample for E. coli.

Test results 2. The results of antibacterial test against fungi are shown below. This is also a test result in a dark room.

Regarding the sample, a remarkable inhibition zone (halo) was observed for all of the test strains of sake yeast (IAM-4125), blue mold (IFO-6352), and black koji mold (IFO-6341). An inhibition zone was also observed in the sample for blue mold.

Test results 3. In order to investigate the antibacterial effect with and without light irradiation, the above test was performed under normal room light and in a dark room. The test results for bacteria are shown below.

It was found that the antibacterial property was improved by the presence of the sample and light. The sample also showed antibacterial properties by light irradiation.

Test results 4. The results of examining the antibacterial properties of fungi with and without light irradiation are shown below.

The results of this test indicate that the fungi have antibacterial properties regardless of the presence or absence of light.

It is considered that the above antibacterial property is due to the activity suppressing effect on the organism by the photocatalyst material sprayed on the conductor.

(Effects of the Invention) As described above, the photocatalytic function body for suppressing biological activity according to the present invention is suitable for suppressing the biological activity because the photocatalytic action of the photocatalytic material and the base material of the metal thin film is suitably exerted. It is possible to exert an action. Further, since the photocatalyst material is sprayed on the base material, the biological activity suppressing ability can be suitably maintained, which is very effective.

Claims (2)

[Claims] 1. A photocatalyst material is deposited as a porous sprayed coating on the surface of a base material of a metal thin film by spraying a powder of a photocatalyst material having a particle size of about 5 to 25 μm as a spraying material. A photocatalyst functional body for suppressing biological activity. 2. A photocatalyst functional body for suppressing biological activity according to claim 1, wherein titania is used as the photocatalyst material.