JPH08215293A - Member having antibacterial function and production thereof - Google Patents

Abstract

PURPOSE: To eliminate the damage of the appearance of a member caused by discoloration and to enhance antibacterial power, in a member used in sanitary pottery or a washbowl, by forming a layer wherein a substance composed of N-type semiconductor oxide and silver are in contact with each other on the surface of a base material. CONSTITUTION: A silver compd. 4 is mixed with a suspension of a sol of a substance having photocatalytic function composed of N-type semiconductor oxide 1 and the resulting mixture is applied to the surface of a base material and baked to form a mixed layer of N-type semiconductor oxide 1 and silver 2 on the base material 3. Or, a precursor 5 of a substance composed of N-type semiconductor oxide 1 and the silver compd. 4 are applied to the surface of the base material 3 and backed to form the above mentioned mixed layer. N-type semiconductor oxide is oxide of a non-stoichiometric compsn. excessive in metal or having oxidized voids with respect to a stoichiometric compsn. Silver 2 is contained in an amt. of below 400% by.wt. of N-type semiconductor oxide. By this constitution, discoloration is prevented and antibacterial power is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member having an antibacterial function which can be suitably used as a member for tiles, sanitary ware, enamel, mirrors, wash basins, etc. used in toilets, bathrooms, kitchens and outdoors, and the production thereof. Regarding the method.

[0002]

2. Description of the Related Art In recent years, inorganic antibacterial agents mainly containing silver ions have been attracting attention because they are superior in safety, heat resistance and durability to organic antibacterial agents. As a form of utilization thereof, a structure in which silver ions are held in a porous ceramic is generally used because it can effectively exhibit the antibacterial performance of silver and is easy to use. At that time, as the porous ceramic that is the carrier,
Zeolite (JP-A-3-255010), layered silicate (JP-A-2-19308), calcium phosphate (JP-A-4-243908), zirconium phosphate (JP-A-3-83905), aluminum phosphate (special Kaihei 5
No. 229911), soluble glass (JP-A-3-720)
1), titanium oxide (JP-A-6-65012, JP-A-5-4816, JP-A-6-298532) and the like.

[0003]

When an antibacterial agent containing silver as a main component is used for antibacterial activity, the greater the amount of silver, the greater the antibacterial activity and the improved durability. However, if the amount of silver is simply increased, the member changes color from brown to black, impairing the external appearance of the member, and therefore the amount of addition is limited. The present invention has been made in view of the above circumstances, without impairing the appearance of the member due to discoloration, and a large antibacterial activity,
It is also an object of the present invention to provide a member having an antibacterial function having excellent durability and a method for manufacturing the member.

[0004]

In order to solve the above-mentioned problems, the present invention is characterized in that a layer in which a substance made of an n-type semiconductor oxide and silver are in contact with each other is formed on the surface of a base material. A member having an antibacterial function is provided.

Further, in the present invention, as a method of forming the above-mentioned member, it has an antibacterial function characterized by applying a precursor of a substance made of an n-type semiconductor oxide and a silver compound on the surface of a base material and then baking the same. A method for manufacturing a member is provided.

Further, there is provided a method for producing a member having an antibacterial function, which comprises coating a suspension of a sol of a substance consisting of an n-type semiconductor oxide on the surface of a base material, coating a silver compound, and then firing. To do.

Further, a silver compound is mixed with a suspension of a sol of a substance consisting of an n-type semiconductor oxide, and then the mixture is applied to the surface of a base material and baked to produce a member having an antibacterial function. Provide a way.

Further, there is provided a method for producing a member having an antibacterial function, which comprises applying a silver compound on the surface of a base material, applying a suspension of a sol of a substance consisting of an n-type semiconductor oxide, and baking the applied material. To do.

[0009]

When the substance composed of the n-type semiconductor oxide and silver are formed in contact with each other, oxygen molecules adhering around the silver particles precipitated during firing are converted into the n-type semiconductor oxide having excess metal components. Since it is deprived, it is understood that the disorder of the lattice due to the adsorption of oxygen on the surface of the silver crystal does not occur and coloring is less likely to occur. Therefore, even if the amount of silver added is increased up to 200% by weight with respect to the substance composed of the n-type semiconductor oxide, the appearance of the member is not spoiled, and therefore the amount of silver added can be increased, and therefore the discoloration Thus, it is possible to provide a member having a large antibacterial activity and an excellent antibacterial function without impairing the appearance of the member.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing an embodiment of the present invention, in which a silver compound is mixed with a suspension of a sol of a substance having a photocatalytic function composed of an n-type semiconductor oxide, and then the mixture is applied onto the surface of a substrate, A mixed layer of the n-type semiconductor oxide and silver is formed on the base material by the firing method.

FIG. 2 is a view showing another embodiment of the present invention, in which a sol suspension of a substance having a photocatalytic function consisting of an n-type semiconductor oxide is applied on the surface of a substrate, and then a silver compound is applied. The mixed layer of the n-type semiconductor oxide and silver is formed on the base material by the firing method.

FIG. 3 is a view showing another embodiment of the present invention. After coating a silver compound on the surface of a substrate, a suspension of a sol of a substance having a photocatalytic function composed of an n-type semiconductor oxide is coated. The mixed layer of the n-type semiconductor oxide and silver is formed on the base material by the firing method.

Here, the n-type semiconductor oxide is an oxide having a non-stoichiometric composition in which a metal is excessive or oxygen vacancies are present with respect to the stoichiometric composition. It is more preferable that the n-type semiconductor oxide has a substance having a photocatalytic function. In addition to silver, antibacterial action due to photocatalytic function can be expected,
This is because the deodorizing and antifouling effects due to the photocatalytic function can be expected. Here, the substance having a photocatalytic function is an n-type semiconductor oxide particle having a band gap sufficient to exert an antibacterial function and a deodorizing function. The theory that photocatalyst particles have antibacterial properties is that they are electrocuted when a voltage higher than a predetermined level is applied (Japanese Patent Publication No. 4-29393).
However, it is generally considered to be due to active oxygen generated during light irradiation, as in the deodorizing function. According to this theory,
In order to have antibacterial properties, that is, to generate active oxygen, the position of the conduction band of the semiconductor must be above the hydrogen generation potential and the upper end of the valence band must be below the oxygen generation potential when expressed in a band model. Requires. N-type semiconductor oxides that satisfy this condition include titanium oxide, zinc oxide, strontium titanate, and the like. When atomized, the position of the conduction band moves upward, so if the layer can be made up of particles of about 1 to 10 nm, tungsten trioxide, ferric oxide, dibismuth trioxide, tin oxide, etc. can also have antibacterial properties. There is a nature. Of these, titanium oxide, zinc oxide, strontium titanate, tungsten trioxide, ferric oxide, and tin oxide are preferable because they are oxides that are stable and have no toxicity to the atmosphere. The substance having a photocatalytic function may be used alone or in combination of two or more.

The precursor of the substance made of the n-type semiconductor oxide includes a sol of the substance made of the n-type semiconductor oxide, an alkoxide containing the constituent metal element of the substance made of the n-type semiconductor oxide, a lactate salt, and an acetate salt. And the like, and inorganic metal salts such as sulfates and nitrates. Among these, it is preferable to use a sol of a substance composed of an n-type semiconductor oxide because the particle size can be easily controlled.

The silver compound may be basically any kind, but it is preferable that it is a salt soluble in a solution because it can be uniformly applied. Water is most often used for the solution because of its low processing cost and highest safety. Therefore, the silver compound is more preferably a salt soluble in water. Examples of such silver compounds include silver lactate, silver acetate, silver nitrate, silver sulfate, silver fluoride and the like. Among these, silver nitrate and silver lactate are preferable because of their high solubility in water, and silver lactate is more preferable among the above two because of its excellent safety.

As a method for applying the composition to the surface of the substrate, a spray coating method, a dip coating method, a roll coating method, a sputtering method, a CVD method or the like can be used.
Among them, the spray coating method is preferable because no special equipment is required, the amount of the solution used is small, and the film thickness is easily controlled.

The firing temperature for decolorization is 700 ° C. or higher. This means that after heat treatment of the silver nitrate aqueous solution, the powder X
When observed by line diffraction, it corresponds to the fact that at 400 ° C., silver nitrate crystals are observed, whereas at 700 ° C., almost only silver crystals are observed. In this case, the reason why silver is not colored is that it is fired together with a substance composed of an n-type semiconductor oxide with an excess of metal components, so that oxygen molecules around the silver crystal are deprived by the n-type semiconductor oxide and the silver crystal surface is It is understood that the disorder of the lattice due to oxygen adsorption does not occur.

The material of the base material may be a material having heat resistance of 700 ° C. or higher. For example, ceramics, ceramic materials, metals or composites thereof can be used. The shape of the base material may be basically any, for example, a tile, a wall material, a plate-like material such as a flooring material, a spherical object, a cylindrical object, a cylindrical object, a sacrificial object, a prismatic object, It may have a simple shape such as a hollow prismatic shape, or may have a complicated shape such as sanitary ware, a washbasin, a bathtub, a sink and the like, and its accessories.

In the method of implementation shown in FIG. 1, when a silver compound is mixed in a suspension of a sol of a substance consisting of an n-type semiconductor oxide, the pH of the silver compound solution consists of an n-type semiconductor oxide. It is better to make it approximately equal to the suspension of the sol of substances. This is to maintain the dispersibility of the substance composed of the n-type semiconductor oxide in the suspension of the sol. At this time, when the n-type semiconductor oxide has a photocatalytic function, the mixed solution may be irradiated with light. By doing so, silver ions can be preferentially fixed to the active sites of the n-type semiconductor oxide having a photocatalytic function.

In the method of implementation shown in FIG. 2, it is preferable that after the suspension of the sol of the n-type semiconductor oxide is applied to the surface of the substrate, it is dried before applying the silver compound. This allows a larger amount of silver compound to be easily fixed on the surface of the base material.

In the method shown in FIG. 2, when the n-type semiconductor oxide has a photocatalytic function, it is preferable to apply a silver compound and then irradiate with light. By light irradiation,
Since the silver ions in the position close to the n-type semiconductor oxide having a photocatalytic function in the silver compound are preferentially fixed to the active points of the n-type semiconductor oxide having a photocatalytic function, they are more firmly fixed. By covering the active site of the substance having the photocatalytic function in advance, it is possible to prevent deterioration of the photocatalytic function due to adhesion of polymer, dust, etc. to the active site of the substance having the photocatalytic function during use. That is the reason.

A more specific embodiment will be described below. (Example 1) A tile base material of 10 cm square has an average particle size of 0.0
Spray a 5 wt% suspension of 1 μm titanium oxide sol.
After applying by a coating method and drying, a 5 wt% silver lactate aqueous solution was applied by a spray coating method and dried again. At this time, the coating amount of silver lactate was variously changed. Then, in a small muffle furnace at 850 ° C for 10
Sample A was obtained by firing for minutes and cooling.

For comparison, 5% by weight of titanium oxide sol having an average particle diameter of 0.01 μm is applied to a 10 cm square tile substrate.
The suspension was applied by the spray coating method, dried and then baked in a small muffle furnace at 850 ° C. for 10 minutes and cooled. Thereafter, a 1 wt% silver nitrate aqueous solution was applied by a spray coating method, dried, and then irradiated with light from a BLB lamp to fix silver on the titanium oxide sol to obtain a comparative sample B. At this time, the coating amount of silver nitrate was variously changed.

An acid resistance test is conducted as one of the durability tests,
The appearance was also observed. The acid resistance test is "JIS-A
5209, 7.12, Chemical resistance test ". That is, first, the entire tile sample was immersed in 3% hydrochloric acid for 8 hours, then taken out, washed with running water for 1 hour, and evaluated by examining the antibacterial property of the dried sample.

The antibacterial property was evaluated by Escherichia coli ( Escheric)
Hia coli W3110 strain) was used and evaluated by the method shown below. That is, the surface of the sample that had been sterilized with 70% ethanol in advance and coated with titanium oxide, etc.
After adhering a glass plate (100 × 100) onto which 5 ml (10,000 to 50,000 CFU) had been dropped, 30 spectral irradiation (white light, 3500 lux) was applied (L), and 3.
The survival rate of the bacterium when left in a dark room for 0 minute (D) was obtained by wiping the bacterium solution of each treated sample with sterile gauze, collecting in 10 ml of physiological saline and counting, and used as an index for evaluation. The evaluation index is shown below. ++: E. coli survival rate less than 10% ++: E. coli survival rate 10% or more and less than 30% +: Escherichia coli survival rate 30% or more and less than 70% −: E. coli survival rate 70% or more

The appearance was evaluated by measuring the color difference ΔE with respect to the ivory-colored tile substrate with a spectroscopic color difference meter (Tokyo Denshoku Co., Ltd.). The evaluation index is shown below. ⊚: ΔE <1 ○: 1 ≦ ΔE <2 Δ: 2 ≦ ΔE <10 ×: 10 ≦ ΔE

Regarding the comparative sample B, the acid resistance was good even when it was carried by about 0.1%, but it was found that the appearance was already impaired when the carried amount was about 1%. Regarding the sample A and the comparative sample B obtained by the above method, the relationship between the weight of silver with respect to the weight of titanium oxide and the appearance was examined. The results are shown in Table 1. From these results, it can be seen that the sample A baked after applying the silver compound was compared with the comparative sample B applied with the silver compound after baking.
It was found that even if a larger amount of silver (1000 times or more) is carried, the appearance is not impaired, and it is advantageous in exerting antibacterial properties.

[0028]

[Table 1]

(Example 2) A 5% by weight suspension of titanium oxide sol having an average particle size of 0.01 μm was applied to a 10 cm square tile base material by a spray coating method, dried and then 5% by weight silver lactate. The aqueous solution was applied by spray coating and dried again. At this time, the surface of the base material was colored dark brown. After that, 850 in a small muffle furnace
The sample was baked at 10 ° C. for 10 minutes and cooled to obtain a sample C.

A 10% silver nitrate aqueous solution was applied on a 15 cm square tile by a spray coating method, dried, and a 15% titanium oxide sol suspension having an average particle diameter of 0.01 μm was applied thereon by a spray coating method. And dried. The surface of the substrate was colored blackish black. Then, it was baked at 880 ° C. for 60 minutes with a roller hearth kiln and cooled to obtain a sample D.

A suspension of 15% titanium oxide sol having an average particle diameter of 0.01 μm and an aqueous solution containing 0.2% by weight of silver oxide fine particles are mixed and irradiated with light from a BLB lamp to fix silver oxide on the titanium oxide sol. After that, the mixed solution is applied on a 10 cm square tile by a spray coating method,
Dried. The surface of the base material was colored brown. Then, it was baked at 850 ° C. for 10 minutes in a small muffle furnace and cooled to obtain a sample E. The results are shown in Table 2. All the samples showed good results in terms of appearance, ⊚. Also regarding acid resistance,
In both cases of L / D, good results of ++ to +++ were shown.

[0032]

[Table 2]

[0033]

EFFECTS OF THE INVENTION By coating a precursor of a substance consisting of an n-type semiconductor oxide and a silver compound on the surface of a base material and baking it, silver is decolorized during baking, so that the appearance of the member due to discoloration is not damaged. Thus, it becomes possible to manufacture a member having good acid resistance and an excellent antibacterial function.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a method for carrying out the present invention.

FIG. 2 is a schematic view showing another method of carrying out the present invention.

FIG. 3 is a schematic view showing another method of carrying out the present invention.

[Explanation of symbols]

1 ... n-type semiconductor oxide, 2 ... silver, 3 ... substrate, 4 ... silver compound, 5 ... n-type semiconductor precursor.

Claims (9)

[Claims] 1. A member having an antibacterial function, wherein a layer in which a substance made of an n-type semiconductor oxide and silver are in contact with each other is formed on the surface of a base material. 2. The silver content is 4 with respect to the n-type semiconductor oxide.
The content is less than 00% by weight.
A member having the antibacterial function described in 1. 3. A method for producing a member having an antibacterial function, which comprises applying a precursor of a substance composed of an n-type semiconductor oxide and a silver compound on the surface of a base material, and then baking the applied material. 4. A method for producing a member having an antibacterial function, which comprises applying a suspension of a sol of a substance made of an n-type semiconductor oxide on a surface of a base material, applying a silver compound, and then firing the silver compound. 5. A method for producing a member having an antibacterial function, which comprises mixing a silver compound with a suspension of a sol of a substance consisting of an n-type semiconductor oxide, coating the mixture on the surface of a base material, and baking the mixture. Method. 6. A method for producing a member having an antibacterial function, which comprises applying a silver compound on a surface of a base material, applying a suspension of a sol of a substance composed of an n-type semiconductor oxide, and firing the applied material. 7. The method for producing a member having an antibacterial function according to claim 2, wherein the silver compound is silver lactate. 8. The method for producing a member having an antibacterial function according to claim 2, wherein the firing temperature is 700 ° C. or higher. 9. The member having an antibacterial function and the method for manufacturing the same according to claim 1, wherein the n-type semiconductor oxide has a photocatalytic function.