JPH09125284A - Antibacterial aluminum material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain an antibacterial property even when the Al surface is wiped by holding a colloidal particle as the combination of an antibacterial metal and an inorg. oxide in the pore. SOLUTION: A formed Al material is subjected to mechanical preprocessing, such as grinding, degreasing, working if necessary, and then introduced into an electrolyte such as sulfuric acid and oxalic acid after grinding. A current is applied with the pretreated Al material as an anode to oxidize its surface, and an oxide film is formed. There are innumerable pores in the oxide film, and the average diameter is 10-50μm. The antibacterial colloidal particle is inserted into the pore. The colloidal particle is a combination of an antibacterial metal or its oxide and an inorg. oxide other than the oxide. The antibacterial metal is silver, and the inorg. oxide is selected from silicon oxide and titanium oxide. Consequently, the colloidal particle is never wiped off.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an aluminum material having excellent antibacterial and antifungal properties.

[0002]

2. Description of the Related Art Aluminum has a high specific strength, a high thermal conductivity, is easy to process, and is lighter in weight than metals such as iron. It is used for various purposes such as machine parts, packaging of foods and medicines, beverage cans, medical equipment, household appliances and the like.

Recently, applications requiring antibacterial properties have been increasing from the viewpoints of usage and hygiene of aluminum products.

By the way, since aluminum metal itself has high activity, its surface is naturally oxidized in the atmosphere to form an oxide film, which exhibits an anticorrosion effect. However, since this oxide film is thin and weak, scratches, etc. Easy to get on. Therefore,
In order to form a thick and strong oxide film, anodic oxide film treatment, so-called alumite treatment, is performed.

[0005]

However, although the alumite treatment imparts the corrosion resistance of aluminum,
Does not impart antibacterial properties.

In order to obtain antibacterial properties, a method of applying an antibacterial agent on the surface of aluminum can be considered. When the alumite treatment is applied, numerous small holes are formed on the surface.
The average size is about 10 to 50 nm in diameter,
The number is about 60 to 800 per 1 μm ² .
However, generally known antibacterial agent particles are usually several tens of μm.
As above, the particles do not enter the small holes. Therefore, the applied antibacterial agent only adheres to the aluminum surface, and by wiping the aluminum surface, the antibacterial agent is easily wiped off.

Therefore, an object of the present invention is to provide an aluminum material which maintains its antibacterial effect even when the aluminum surface is wiped.

[0008]

In order to solve the above-mentioned problems, in the present invention, an antibacterial metal or its oxide and other oxides are contained in the small holes of the anodized film formed on the surface of aluminum. The colloidal particles formed by bonding with the inorganic oxide are retained.

Colloidal particles obtained by binding an antibacterial metal or its oxide and an inorganic oxide other than the above to the small pores formed when anodizing the aluminum surface, that is, the antibacterial colloidal particles I kept it, so
Even when the aluminum surface is wiped, the antibacterial colloid particles are not wiped off, and the antibacterial property can be maintained.

[0010]

Embodiments of the present invention will be described below.

First, the surface of aluminum is subjected to a so-called alumite treatment for preventing corrosion and increasing strength, that is, so-called alumite treatment. That is, the formed aluminum material is subjected to mechanical pretreatment such as polishing, degreasing, washing with water, polishing if necessary, and then placed in an electrolytic solution of sulfuric acid, oxalic acid, etc. As a result, a current is passed to oxidize the surface and form a film. The oxide film thus obtained has innumerable small holes, and the size thereof is about 10 to 50 nm in average in diameter.

Antibacterial colloidal particles are inserted into the small holes. The above-mentioned antibacterial colloidal particles to be inserted are those in which an antibacterial metal or its oxide (hereinafter referred to as an antibacterial metal component) and other inorganic oxides are bound.

The above-mentioned antibacterial metal component refers to a simple substance of metal having an antibacterial action or an oxide thereof, and a generally known one can be used. For example, as a simple metal,
Examples thereof include silver, copper, zinc, tin, lead and the like, and examples of the oxide thereof include oxides of the above simple metals. Among these, one or more kinds of antibacterial metal components selected from silver, copper, zinc or oxides thereof are preferable from the viewpoints of antibacterial action and safety to the human body. Further, when metallic silver is used as the antibacterial metal component, aggregation or oxidation of metallic silver occurs due to a photochemical reaction or an oxidizing action, and the color changes to brown or black. Among these discolorations, it is desirable to use titanium, zirconium, cerium, zinc or the like, which can act as an ultraviolet absorber, in combination with the silver component in order to prevent discoloration of the silver component due to photochemical reaction by ultraviolet rays.

On the other hand, as the inorganic oxide to be combined with the antibacterial metal component, if it is an inorganic oxide other than the oxide used as the antibacterial metal component, the generally known inorganic oxide constituting the colloidal particles. I can give you things. As the colloidal particles, it is possible to use single or composite inorganic oxide colloidal particles or a mixture thereof.

Colloidal particles of a single inorganic oxide include SiO ₂ , TiO ₂ , ZrO ₂ , Fe ₂ O ₃ and Sb.
₂ O ₅ , WO _{3 and the} like are exemplified, and examples of the composite oxide colloidal particles include composite oxide colloidal particles of each of the above-mentioned inorganic oxides and other inorganic oxides, for example, SiO ₂ · Al ₂ O ₃ ,
SiO ₂ · B ₂ O ₃ , SiO ₂ · P ₂ O ₅ , SiO ₂ ·
ZrO ₂ , SiO ₂ · Sb ₂ O ₅ , TiO ₂ · Ce
O ₂ , TiO ₂ · ZrO ₂ , SiO ₂ · TiO ₂ · Al
₂ O ₃ , SiO ₂ · TiO ₂ · CeO ₂ , SiO ₂ · T
iO ₂ · ZrO ₂ , SiO ₂ · TiO ₂ · Fe ₂ O ₃ ,
SiO ₂ · Al ₂ O ₃ · MgO, SiO ₂ · Al ₂ O ₃
・ CaO etc. can be given.

The above-mentioned antibacterial colloidal particles are in the form of a compound in which the above-mentioned antibacterial metal component is combined with the surface of the above-mentioned inorganic oxide, and they do not have such a strong bond as the above-mentioned combination, but Any of the forms of the complex with the above-mentioned inorganic oxide having a predetermined bond is preferable because the antibacterial effect is maintained for a long time. Also, the amount of binding does not need to be 100% bound, and it is sufficient if a predetermined proportion is bound.

The preferred binding ratio of the antibacterial metal component and the inorganic oxide in the antibacterial colloidal particles is
When the above-mentioned antibacterial colloidal particles were dispersed in a solvent such as water to form a colloidal solution, the weight A of the antibacterial metal component in this colloidal solution and the antibacterial properties released by ultracentrifugation treatment of this colloidal solution The ratio of the metal component to the weight B, that is, the value of the binding strength index I represented by B / A is 1.0 × 1.
This is the case where 0 ^-3 or less is shown.

The binding index I is determined by first quantifying the metal atom of the antibacterial metal component in the colloidal solution with a plasma emission spectrometer, and then subjecting a predetermined amount of the colloidal solution to ultracentrifugation at 45,000 rpm. It is treated with a separator for 1 hour to separate it into a solid content and a solution, and the amount of metal atoms of the antibacterial metal component contained in the separated solution is quantified by a plasma emission spectrometer to determine the liberated antibacterial metal component. Obtained by asking.

When the value of the binding force index I is larger than 1.0 × 10 ^-3 , the binding force of the antibacterial metal component to the inorganic oxide is weak, so that the antibacterial metal is added to the solvent of the colloid solution. The components are easily eluted and the antibacterial effect is inferior in sustainability. Further, when metallic silver is used as the antibacterial metal component, it causes aggregation and the like and causes discoloration, which is not preferable.
The more preferable value of the binding index I is 5.0 × 10 ⁻⁴
Hereafter, 1.0 × 10 ⁻⁴ or less is particularly preferable. When two or more antibacterial metal components are used, it is preferable that the cohesive index of each antibacterial metal component is 1.0 × 10 ⁻³ . Further, the lower limit of the binding index I is preferably 0 or more since it is most preferable that the antibacterial metal component is not eluted into the solvent of the colloid solution.

The amount of the antibacterial metal component is preferably in the range of 0.1 to 25% by weight, and in the range of 0.1 to 15% by weight, calculated as oxide in the antibacterial colloid particles. Is more preferable. When the content of the antibacterial metal component is less than 0.1% by weight, a large amount of the above antibacterial colloid particles is required to exert the antibacterial effect. When the amount of the antibacterial metal component is more than 25% by weight, the antibacterial action does not differ from that when the amount is 25% by weight, and when metallic silver is used as the antibacterial metal component, aggregation It is easy to cause discoloration.

The size of the above-mentioned antibacterial colloid particles is required to enter the small holes on the surface of the aluminum material, so that the diameter thereof is required to be 50 nm or less, and 1 to 30 nm.
Is preferred.

An antibacterial colloidal solution containing such antibacterial colloidal particles is manufactured by Catalyst Kasei Co., Ltd .: A
TOMYBALL (s) etc. can be mentioned.

Next, a method for producing the antibacterial colloidal particles will be described.

First, a metal or an oxide thereof, such as zinc oxide, silver oxide, copper oxide, etc., used as the antibacterial metal component is dissolved in a solvent capable of dissolving the metal component such as aqueous ammonia to prepare an antibacterial metal component solution. To manufacture.

Then, the solution in which the inorganic oxide is dissolved and the antibacterial metal component solution are simultaneously added to the alkaline solution, or both are mixed and heated to thereby disperse the antibacterial colloid particles. A sex colloidal solution is produced.

For example, the production of the above-mentioned antibacterial colloidal solution using a composite inorganic oxide produced from a silicate and an alkali-soluble inorganic compound as the above-mentioned inorganic oxide is disclosed in Japanese Patent Laid-Open Publication No. Hei 5-
It can be prepared according to the production method described in 132309. That is, an antibacterial colloid solution is produced by simultaneously adding an alkali metal, ammonium or organic base silicate, an alkali-soluble inorganic compound, and the antibacterial metal component solution to an alkaline aqueous solution having a pH of 10 or more. .

The production of the above-mentioned antibacterial colloidal solution using a composite oxide produced from titanic acid and a silicon compound or a zirconium compound as the above-mentioned inorganic compound is described in JP-A-63-270620. It can be prepared according to the method. That is, the titanic acid aqueous solution obtained by adding hydrogen peroxide to a gel or sol of hydrous titanic acid and the antibacterial metal component solution, if necessary, by heat treatment in the presence of a silicon compound or a zirconium compound, An antibacterial colloidal solution is produced.

In order to improve the suspension stability of the above-mentioned antibacterial colloidal particles, various surfactants such as nonionic, cationic and anionic surfactants are added, and various protective colloids and dispersion aids are used as dispersion stabilizers. It is also possible to add.

Water, which is the dispersion medium of the antibacterial colloid solution obtained by the above method, can be replaced with an organic solvent by a known method to obtain an antibacterial colloid solution using the organic solvent as the dispersion medium. In addition, these antibacterial colloid solutions are
The desired concentration can be adjusted by a known method using an ultrafiltration membrane or the like.

The concentration of the above-mentioned antibacterial colloidal solution during storage can be adjusted to a concentration of the colloidal solution suitable for use, but in terms of stability of the colloidal solution, the range of 0.5 to 20% by weight is preferable. The range of 1 to 10% by weight is more preferable.

Next, a method of inserting and holding the above-mentioned antibacterial colloid particles in the small holes formed on the surface of the alumite-treated aluminum will be described.

First, the molded aluminum material is subjected to mechanical pretreatment such as polishing, degreasing, washing with water, polishing if necessary, and then placed in an electrolytic solution such as sulfuric acid or oxalic acid. Using this as an anode, an electric current is applied to oxidize the surface to form a film. After that, usually, after washing with water, a sealing treatment such as hot water treatment for closing the small pores is performed, but in this case, after washing with water, dipping in the antibacterial colloid solution without performing the sealing treatment Let By this immersion, the antibacterial colloid particles in the antibacterial colloid solution are inserted into the small holes. For this insertion, ultrasonic vibration or the like is also an effective means, but it is sufficient to just immerse it.

The concentration of the antibacterial colloid solution used for the dipping may be the same as the concentration at the time of storage, but may be diluted if necessary. The dilution degree is preferably 1 to 1000 times, more preferably 1 to 500 times. If the dilution degree exceeds 1000 times, the amount of the above-mentioned antibacterial colloid particles inserted into the small pores decreases, and it becomes difficult to exhibit the antibacterial property.

Since this dipping operation is performed immediately after the aluminum material is anodized and washed with water, air will not enter the small holes. Therefore, the above-mentioned antibacterial colloidal particles can be easily inserted into the small holes only by dipping. Therefore, the immersion time and temperature are not particularly limited, and any time and temperature can be selected.

[0035]

EXAMPLES The present invention will be described in more detail below with reference to examples.

Production Example [Alumite Treatment] After polishing aluminum pieces, 60
Degreasing treatment was performed for 5 minutes at ˜70 ° C. using a fine cleaner (FC-315 manufactured by Nippon Parkerizing Co., Ltd.). Then, rinse with water at room temperature for 2.5 minutes, and
Etching treatment was performed at 0 to 55 ° C. for 5 minutes using a 5% sodium hydroxide aqueous solution. After the etching treatment, the product was washed with clean water at room temperature, immersed in a 7.5% nitric acid aqueous solution for 4 minutes for neutralization, and again rinsed with clean water.

Using the aluminum piece thus pretreated as an anode, an electric current was applied in a 15% sulfuric acid aqueous solution at 20 ° C. for 40 minutes to carry out anodization.

After completion of the anodic oxidation, at room temperature, it was immersed in three tanks containing clean water in order and washed with water.

Example 1 [Dip in antibacterial colloid solution] As an antibacterial colloid solution, ATOMYBALL (s) (manufactured by Catalysts & Chemicals Co., Ltd.) was used. Table 1 shows the physical property values of ATOMYBALL (s).

The above ATOMYBALL (s) was diluted 20 times, and the aluminum piece obtained in the production example was immersed for 3 minutes. The liquid temperature of the colloidal solution at this time was 20 ° C. After that, pull out from the colloidal solution, 180 ℃
After air-drying for 5 minutes, the surface of the aluminum piece was wiped clean and subjected to the antibacterial property test without performing the sealing treatment.

[0041]

[Table 1]

[Antibacterial Test] Escherichia coli (IFO-3301) was inoculated into Neutritoendobroth and cultured at 37 ° C. for 20 to 24 hours. The cultivated bacteria were inoculated into the same medium again and cultured under the same conditions. The obtained broth of the bacteria was diluted 100 times with a diluent containing 3.13 × 10 ⁻⁴ M potassium dihydrogen phosphate-sodium hydroxide buffer solution (pH 7.2) to prepare a test bacterial solution.

Two aluminum pieces dipped in the antibacterial colloidal solution were placed in a sterile petri dish, and 100 μl of the test bacterial solution was dropped on each aluminum piece.

One of the above aluminum pieces is 2 g /
10 ml rinse and sterile glass beads consisting of 3.13 × 10 ⁻⁴ M potassium dihydrogen phosphate-sodium hydroxide buffer solution (pH 7.2) containing 1 lecithin and 14 g / l Tween-80. Immediately added 40 to 50 pieces, and shaken well to rinse off the bacterial solution.

This rinsed-off bacterial solution was diluted with the above-mentioned diluent, and the diluted solution was inoculated on a Mueller Hinton agar medium and cultured at 37 ° C. for 48 hours to measure the viable cell count.

The remaining one piece of aluminum is
The sterilized petri dish was capped and allowed to stand at 25 ° C. for 6 hours. Then, the bacterial solution on the aluminum piece was rinsed off and the viable cell count was measured in the same manner as above.

Further, another aluminum piece dipped in the antibacterial colloidal solution was dipped, air-dried, wiped off and left in the open air for one month, and then the above antibacterial test was conducted. Table 2 shows the results.

[Examples 2 to 12] Dilution ratio of the above-mentioned antibacterial colloid solution, temperature of the antibacterial colloid solution at the time of dipping aluminum pieces, dipping time, and presence or absence of air drying Table 2
The aluminum piece obtained in the Production Example was immersed in the antibacterial colloid solution in the same manner as in Example 1 except that the conditions described in 1) were performed. Then, the antibacterial test described in Example 1 was performed to measure the viable cell count. Table 2 shows the results.

Comparative Example 1 The antibacterial test described in Example 1 was carried out without immersing the aluminum piece obtained in Example 1 in the above antibacterial colloid solution, and the viable cell count was measured. Table 2 shows the results.

[Comparative Examples 2 and 3] According to the conditions shown in Table 2, the aluminum pieces obtained in Production Examples were immersed in the above antibacterial colloid solution, air-dried, and the surface thereof was wiped off. Then, it was immersed in hot water at 90 ° C. for 20 minutes to perform a sealing treatment. Then, the antibacterial test described in Example 1 was performed to measure the viable cell count. Table 2 shows the results.

[0051]

[Table 2]

By immersing the alumite-treated aluminum pieces in the antibacterial colloid solution, the viable cell count is greatly reduced and the antibacterial properties are exhibited. In addition, since the viable cell count was increased by performing the sealing treatment, it became clear that the antibacterial colloid particles were present in the small pores. Further, even when the antibacterial test was carried out one month later, it was clarified that the antibacterial property of the antibacterial colloid particles is maintained because it has an antibacterial effect.

[0053]

EFFECTS OF THE INVENTION According to the present invention, colloidal particles in which an antibacterial metal or its oxide and an inorganic oxide other than that are bound to the small pores formed when the aluminum surface is anodized. Since the colloidal particles are retained, the colloidal particles are not wiped off even when the aluminum surface is wiped, and the antibacterial property can be maintained.

Front page continuation (72) Inventor Katsuhiro Shirono 13-2 Kitaminato-cho, Wakamatsu-ku, Kitakyushu-shi, Fukuoka Inside Wakamatsu Factory, Catalysis Chemicals Co., Ltd. (72) Atsushi Tanaka 13-2 Kitaminato-cho, Wakamatsu-ku, Kitakyushu, Fukuoka No. Catalytic Chemicals Co., Ltd. Wakamatsu Plant (72) Inventor Kenichi Akiyama 2-8-11 Nishishimbashi, Minato-ku, Tokyo MK Nets Co., Ltd.

Claims (2)

[Claims] 1. An antibacterial property in which colloidal particles comprising an antibacterial metal or its oxide and an inorganic oxide other than that are held in the small pores of an anodized film formed on the surface of aluminum. Aluminum material. 2. The antibacterial metal or oxide thereof is a metal or oxide selected from silver or silver oxide, and the inorganic oxide is an inorganic oxide selected from silicon oxide or titanium oxide. The antibacterial aluminum material described.