JPH1180617A - Antimicrobial treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antimicrobial treatment method which enables excellent antimicrobial activity to be developed for a long period of time without detriment to the appearance of the surface of the substrate by comprising the steps of: coating the surface of a substrate, to be antimicrobially treated, a soln. contg. an antimicrobial metal component with inorg. oxide colloid particles dispersed therein; and heat treating the coating. SOLUTION: The surface of a substrate to be antimicrobially treated is entirely or partially coated with a soln. contg. an antimicrobial metal component (e.g. Ag) pref. in an amt. of 0.05 to 25 wt.% (hereinafter referred to as '%'), still pref. 0.1 to 15%, in terms of oxide with inorg. oxide colloid particles (e.g. TiO2 .ZrO2 .SiO2 colloid particles) dispersed therein, the inorg. oxide colloid particles pref. having an average particle diameter of 3 to 500 nm, still pref. 5 to 250 nm, and having such a particle diameter distribution that the proportion of particles having a size of the average particle diameter ±30% being pref. not less than 50%, still pref. not less than 60%, particularly pref. 70 to 100%. The coated substrate is heat treated pref. at 50 to 1,000 deg.C, still pref. 100 to 800 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antibacterial treatment method for a surface of an inorganic or organic substrate, and more particularly, to an antibacterial activity obtained by dispersing inorganic oxide colloid particles containing an antibacterial metal component. The present invention relates to an antibacterial treatment method for a surface of a substrate to be treated for antibacterial treatment using an inorganic oxide colloid solution.

[0002]

2. Description of the Related Art In recent years, food poisoning due to bacteria has occurred frequently in Japan, which is hot and humid, and the living environment such as bacteria, fungi, and odors has deteriorated due to changes in the living environment due to the disturbance of apartment buildings. Since it is becoming a problem, there is a strong demand for purification of these environments. In order to purify such a living environment, there are various methods for imparting antibacterial properties to the surface of base materials such as household goods, building materials and tiles, ceramic products such as sanitary ware, which come into contact with human skin. Proposed.

Conventionally, as a method of imparting antibacterial properties to the surface of a substrate, a method of applying an antibacterial paint to the surface of the substrate is generally used. For example, JP-A-9-217027 discloses an antibacterial property. Baking paints are described. However, in the case of antibacterial organic paints, the resin deteriorates when used for a long period of time, and when used outdoors, dirt adheres to the surface,
The antibacterial property is liable to be reduced due to the peeling of the coating film due to the washing, or the deterioration due to ultraviolet rays, and there is a problem in durability.

[0004] Therefore, a method of baking using an antibacterial inorganic paint has been proposed. For example, JP-A-8-
No. 67835 discloses (a) a general formula: Si (OR ¹ )
₂₀ to 200 parts by weight of the silicon compound represented by Formula ₄ and / or colloidal silica, (b) a general formula: R ² S
i ^(OR ₁₎ 100 parts by weight of silicon compound represented by _3, and, (iii) the general ^formula: in a proportion of _R 2 2 Si ^(OR ₁₎ 0 to 60 parts by weight of a silicon compound represented by the ₂ And (d) an antibacterial inorganic paint characterized by containing an antibacterial agent in an inorganic paint having a weight average molecular weight of 900 or more in terms of polystyrene as an inorganic paint containing them. It is disclosed that the film is baked at a temperature of 200 ° C. or less by using the following method. [R above
¹ and R ² represent a monovalent hydrocarbon group. ]

[0005] JP-A-5-201747 discloses a glaze characterized by containing hydroxyapatite carrying an antibacterial metal,
It is disclosed that the enamel product and the ceramic product are baked and melted by applying the glaze.

However, in these methods, since the antibacterial component is buried in the inorganic paint component or glaze, the appearance of the substrate is impaired due to discoloration of the surface of the base material or the antibacterial performance is not sufficiently exhibited. There was such a problem.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an antibacterial treatment method capable of exhibiting excellent antibacterial performance over a long period of time on various substrate surfaces without impairing the appearance of the substrate surface. It is in.

[0008]

Means for Solving the Problems The present inventors have found a processing method for imparting antibacterial properties to the surface of various substrates without using a film forming component such as a paint component or a glaze, and completed the present invention. Reached.

The antibacterial treatment method according to the present invention comprises the steps of: applying an antibacterial inorganic oxide colloid solution, in which inorganic oxide colloid particles containing an antibacterial metal component are dispersed, to all or a part of the surface of the substrate to be subjected to antibacterial treatment. After the application, the antibacterial treatment substrate is heated.

The antibacterial inorganic oxide colloid solution used in the present invention is a colloid solution (sol) in which inorganic oxide colloid particles containing an antibacterial metal component are dispersed.
As the antibacterial metal component contained in the colloid particles, generally known ones can be used, and examples thereof include silver, copper, zinc, tin, lead, bismuth, cadmium, and chromium. In particular, one or more antibacterial metal components selected from silver, copper, and zinc are preferable from the viewpoints of antibacterial action, discoloration, and safety to the human body.

Examples of the inorganic oxide of the inorganic oxide colloid particles containing an antibacterial metal component include inorganic oxides constituting a generally known colloid solution. It is possible to use single or composite oxide colloid particles, or mixtures thereof.

As a single inorganic oxide, SiO ₂ , A
l ₂ O ₃ , TiO ₂ , ZrO ₂ , Fe ₂ O ₃ , Sb ₂ O
₃ , WO ₃ , CeO _{3 and the} like, and examples of the composite oxide include SiO ₂ .Al ₂ O ₃ , SiO ₂ .TiO ₂ , and Si
O ₂ .ZrO ₂ , Al ₂ O ₃ .TiO ₂ , Al ₂ O _3.
CeO ₃ , TiO ₂ · CeO ₃ , TiO ₂ · ZrO
_{2, SiO 2} TiO ₂ ZrO ₂ , SiO ₂ TiO
_2. CeO _{3 and the} like.

It is desirable that the content of the antibacterial metal component in the inorganic oxide colloid particles containing the antibacterial metal component is in the range of 0.05 to 25% by weight in terms of oxide. If the content is less than 0.05% by weight, the antibacterial action may not be sufficiently exhibited, and even if the content is more than 25% by weight, there is not much difference in the antibacterial action as compared with the case of 25% by weight. . A more preferable content of the antibacterial metal component is 0.1.
1 to 15% by weight.

The antibacterial inorganic oxide colloid solution according to the present invention has an average particle diameter of the inorganic oxide colloid particles of 3 to 3.
It is preferably in the range of 500 nm. If the average particle diameter of the inorganic oxide colloid particles is larger than 500 nm, the appearance of the substrate surface and the adhesiveness of the colloid particles tend to deteriorate when an antibacterial treatment is applied to the substrate surface. If the average particle size is smaller than 3 nm, the stability of the colloid solution may be deteriorated. The preferred range of the average particle size of the colloid particles is from 5 to 250 nm.

In the particle size distribution of the above-mentioned inorganic oxide colloid particles, it is preferable that the ratio of the average particle size to the range of the particle size of ± 30% is 50% or more. The ratio is 5
If the colloidal solution is smaller than 0%, the particle size distribution becomes broad.
In some cases, the surface of the base material lacks uniformity, resulting in poor appearance.
In the particle size distribution, the ratio of the average particle size to the range of the particle size of ± 30% is preferably 60% or more, and more preferably 70 to 100%.

The antibacterial inorganic oxide colloid solution of the present invention preferably has a solid content of 0.1% by weight and a light transmittance at a wavelength of 500 nm of 50% or more. Here, the light transmittance is a thickness 1c.
100% light transmittance at 500nm wavelength in 100m water
When the solid concentration of 1 cm thick is 0.1
It refers to the relative value of the transmittance of the same wavelength light in the antibacterial inorganic oxide colloid solution of weight%.

If the light transmittance of the antibacterial inorganic oxide colloid solution is less than 50%, the pattern or color of the substrate may be impaired when the colloid solution is applied to the surface of the substrate. is there. The light transmittance of the antibacterial inorganic oxide colloid solution used in the present invention is preferably 60% or more,
More preferably, it is desirable to be 70 to 100%.

The antibacterial inorganic oxide colloid solution described above comprises:
For example, it can be prepared according to the method for producing a composite oxide colloid solution described in JP-A-5-132309, or according to the production method described in JP-A-63-270620. It can also be prepared.

The method of the present invention is characterized in that after applying the above-mentioned antibacterial inorganic oxide colloid solution to all or a part of the surface of the substrate to be treated, the substrate to be treated is heated. I do.

For the application of the colloid solution to the surface of the substrate to be treated for antimicrobial treatment, a usual coating method is employed. For example, a method of dipping the substrate to be treated with antimicrobial treatment in the colloid solution, a method of spraying the colloid solution onto the surface of the substrate to be treated with antimicrobial treatment, or applying a brush is used. Upon application, the solid concentration of the antibacterial inorganic oxide colloid solution can be arbitrarily adjusted and used, but is preferably 0.01 to
A range of 20% by weight is desirable. In the present invention, it is preferable to use the colloid solution alone, but it is also possible to use it in combination with a paint component.

The heat treatment in the present invention can be performed by using a known method. Heat treatment temperature is 50-1000
It is preferable to select in the temperature range of ° C. according to the material of the substrate. If the heat treatment temperature is as low as 50 ° C., the adhesion of the inorganic oxide colloid particles containing the antibacterial metal component to the substrate is poor, and the durability of the antibacterial property may be poor. If the treatment temperature is higher than 1000 ° C., the antibacterial performance may be reduced. When the substrate to be treated is an organic substance, it is treated at a relatively low temperature, and when it is an inorganic substance, it is treated at a relatively high temperature. The heat treatment temperature is preferably in the range of 100 to 800C, more preferably 200 to 600C for 0.1 to 100 hours.

Examples of the substrate to be subjected to antibacterial treatment in the present invention include organic substrates such as plastic products, ceramic products such as tiles, porcelain, enamel or glass, cement products such as building materials, sewer pipes, playground equipment for parks and the like. And inorganic base materials such as metal products such as aluminum, aluminum-plated steel sheet and hot-dip galvanized steel sheet.

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples.

[0024] Production Example 1 [antimicrobial preparation of inorganic oxide colloidal solution] titanium sulphate was dissolved in pure water to obtain an aqueous solution containing 1.0 wt% as TiO _2. While stirring the aqueous solution, 28% by weight aqueous ammonia was gradually added to obtain a white slurry. The slurry was filtered and washed to obtain a wet titanic acid cake. An aqueous solution concentration of 1.0% by weight was added to 31.4 g of the cake.
Pure water was diluted by adding so that, after addition of further 33% by weight hydrogen peroxide 219.8G, and heated at 80 ° C. 14 h, the hydrogen peroxide was heated decompose, as TiO ₂ 1.0
3136 g of a% by weight solution were obtained. This titanic acid solution was yellow-brown and transparent, and had a pH of 8.2.

Next, 0.64 g of silver oxide was dissolved in 20 g of 28% by weight aqueous ammonia and 350 g of pure water to obtain an aqueous solution of an ammine complex salt of silver, and 38.7 g of a 20% by weight silica sol was added to this aqueous solution. A solution obtained by dissolving 15.4 g of ammonium zirconium carbonate in 170 g of pure water was added. This mixed aqueous solution was added to the titanic acid solution, and 1
After heating at 50 ° C. for 24 hours to generate colloidal particles, the particles were washed with an ultrafiltration membrane to convert the silver component to an oxide of 1.3.
An antibacterial inorganic oxide colloid solution (A) containing about 10% by weight was obtained.

The pH of this colloid solution was 7.5 and the solid content concentration was 1.0% by weight. The average particle diameter of the colloid particles in this colloid solution was 24.3 nm, and the ratio of the average particle diameter to the range of ± 30% of the particle diameter was 72%. Further, the light transmittance at a wavelength of 500 nm at a solid content concentration of 0.1% by weight of the colloid solution was measured using a spectrophotometer (U-2000, manufactured by Hitachi, Ltd.). As a result, the light transmittance was 79.9%. Met.

Production Example 2 [Zeolite antibacterial agent] Na-Y type zeolite was suspended in water to prepare 400 g of a suspension slurry having a concentration of 5% by weight. Then, the suspension slurry was heated to 70 ° C., and 9.2 g of a 5% by weight aqueous solution of AgNO ₃ was added.
, And left for 1 hour to carry out silver ion exchange. This slurry was filtered, sufficiently washed with warm water at 60 ° C., dried at 120 ° C., and calcined at 550 ° C. for 1 hour to prepare a powdery antibacterial agent (B). This antibacterial agent (B) contains 1.5% by weight of a silver component in terms of oxide,
The average particle size was 1.0 μm.

Example 1 Pure water was added to the colloidal solution of antibacterial inorganic oxide (A) obtained in Production Example 1 and diluted 50-fold to prepare a colloidal solution having a solid content of 0.02% by weight. This solution was applied to the surface of the tile with a bar coat at a thickness of 50 μm, and then dried at room temperature for 24 hours. Next, this tile was fired at 400 ° C. for 1 hour to obtain an antibacterial tile sample (S-1). Further, in order to check the durability of the antibacterial property, the tile (S-1) was rubbed 10 times with a bundle using a 30% by weight aqueous solution of a detergent (Homing Cleanser, manufactured by Kao Corporation), and then washed with water. A washed sample (S-2) was prepared.

Example 2 Purified water was added to the antibacterial inorganic oxide colloid solution (A) obtained in Production Example 1 and diluted 50-fold to prepare a colloid solution having a solid content of 0.02% by weight. This liquid was sprayed onto the tile surface and applied, and then dried at room temperature for 24 hours. Next, it was baked at 600 ° C. for 1 hour to obtain an antibacterial tile sample (T-1). Further, in order to examine the durability of the antibacterial property, a sample (T-
2) was obtained.

Comparative Example 1 Pure water was added to the antibacterial inorganic oxide colloid solution (A) obtained in Production Example 1 to dilute it 50-fold to prepare a colloid solution having a solid content of 0.02% by weight. This solution was applied to the surface of the tile with a bar coat at a thickness of 50 μm, and then dried at room temperature for 24 hours to obtain an unheated antibacterial tile sample (U-1). Further, in order to examine the durability of the antibacterial property, a sample (U-
2) was obtained.

Comparative Example 2 Pure water was added to the zeolite-based antibacterial agent (B) obtained in Production Example 2 to prepare a 0.02% by weight aqueous suspension. This aqueous suspension solution was applied to the tile surface with a bar coat to a thickness of 50 μm, and then dried at room temperature for 24 hours. Next, the tile was fired at 400 ° C. for 1 hour to obtain an antibacterial tile sample (V-
1) was obtained. Further, a sample (V-2) was obtained by performing the same washing operation as in Example 1 in order to check the durability of the antibacterial property.

Comparative Example 3 A coating obtained by adding 1% by weight of a zeolite-based antibacterial agent (B) obtained in Production Example 2 to a coating mainly composed of a thermosetting resin varnish was applied to the tile surface by a bar coat to a thickness of 50 μm. After baking, a baking treatment was performed at a baking temperature of 180 ° C. for 20 minutes to obtain an antibacterial tile (W-1). Further, a sample (W-2) was obtained by performing the same washing operation as in Example 1 in order to check the durability of the antibacterial property.

Example 3 [Antibacterial activity test] The following antibacterial activity tests were carried out on the antibacterial tile materials (unwashed and washed) obtained in Examples 1 and 2 and Comparative Examples 1, 2 and 3. Test sample: 5 × 5 cm Medium: meat extract, 10 mg / L + peptone, 20 mg /
L + sodium chloride, 10 mg / L Test bacteria: Escherichia coli, Staphylococcus aureus Measurement method: Inoculate 0.5 mL of the bacterial suspension on the test sample, cover with a cover film, cover, and then cover at 35 ° C
For 24 hours, and the number of viable bacteria was measured. The sterilization rate was determined by the following equation (1). Table 1 shows the measurement results.

[0034]

[Equation 1] Bacteria reduction rate (%) = 100 × (initial viable cell count−viable cell count after 24 hours) / initial viable cell count

[0035]

[Table 1]

The tile treated by the method of the present invention does not decrease its antibacterial action even when subjected to a washing treatment and has excellent durability.
The appearance was good without discoloration.

[0037]

The antibacterial treatment method of the present invention is a simple method in which antibacterial inorganic oxide fine particles (colloidal particles) are applied to a substrate to be treated by antibacterial treatment by spraying or dipping and then heat-treated. The antibacterial inorganic oxide fine particles are fixed to the surface of the substrate without impairing the appearance of the substrate, and the durability of the antibacterial action can be improved.

Claims (4)

[Claims] 1. An antimicrobial inorganic oxide colloid solution containing an antimicrobial metal component-containing inorganic oxide colloid particle dispersed therein is applied to the whole or a part of the surface of the substrate to be subjected to antimicrobial treatment. An antibacterial treatment method, which comprises subjecting a treated substrate to heat treatment. 2. The inorganic oxide colloid particles have an average particle diameter in the range of 3 to 500 nm, and the particle diameter distribution occupies 50% of the average particle diameter ± 30% in the particle diameter range. The antibacterial treatment method according to claim 1, which is as described above. 3. The antibacterial inorganic oxide colloid solution,
Wavelength 50 of the colloid solution having a solid content of 0.1% by weight.
The antibacterial treatment method according to claim 1 or 2, wherein the light transmittance at 0 nm is 50% or more. 4. The heat treatment is performed at a temperature of 50 to 1000 ° C.
4. The antibacterial treatment method according to claim 1, wherein the method is performed in the range of: