JP2000017356A - Copper alloy having photocatalystic function and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a material simultaneously having bactericidal action and antibacterial properties based on photocatalystic function and furthermore having excellent workability. SOLUTION: This copper alloy is the one having a compsn. contg., by weight, 0.1 to 7.3% titanium and contg. if need be, one or more kinds among 0.001 to 10% zinc, 0.001 to 3% silicon and 0.001 to 1% silver and whose surface layer contains titanium-contg. oxides. The copper alloy exhibits bactericidal action owing to copper as a base and exhibits antibacterial action based on photocatalystic function owing to the titanium-contg. oxides dispersed into the surface layer. The titanium-contg. oxides can be formed by heating the copper alloy having the above compsn. produced by an ordinary method at 200 to 800 deg.C and preferentially oxidizing titanium. In the case zinc and silicon are incorporated, these elements are preferentially oxidized as well by the above heating to form oxides, zinc exhibits antibacterial action and bactericidal action, and silicon exhibitis hydrophilic action. Silver exhibits bactericidal action.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal material having excellent bactericidal properties and antibacterial properties based on a photocatalytic function, and a method for producing the same.

[0002]

2. Description of the Related Art Copper and silver are known as metal elements exhibiting bactericidal properties, and alloys containing these elements have been used for money, decorative articles, tableware and the like since ancient times. These metals exhibit their bactericidal properties when they are directly contacted by the target bacteria or become ions in an aqueous solution. Examples of the germicidal metal material containing copper include Cu-containing stainless steel (JP-A-8-229107), stainless steel having an increased Cu concentration in the surface layer, and a method for producing the same (JP-A-8-60301, JP-A-8-60301). 8-60302, JP-A-8-603
No. 03), and a material which does not need to prevent infection such as periodic disinfection by adding Cu to stainless steel (JP-A-9-170053) has been proposed. All of them directly touch and sterilize and purify attached substances.

On the other hand, it is known that antimicrobial properties are exerted by photocatalysis when ultraviolet light is irradiated on titanium oxide. As an antibacterial material applying this principle, a TiO ₂ thin film formed on a tile is used. (Japanese Patent Laid-Open No. 8-66)
As an example of a metal material containing TiO _{2 and} having a photocatalytic function, an antibacterial material in which a titanium oxide is dispersed in a titanium alloy and a nickel alloy has been developed. JP-A-8-252461 describes a method for producing a photocatalytic functional material in which a titanium alloy containing 0 to 20% of a transition metal as an auxiliary component is subjected to an acid treatment using an inorganic acid and then heat-treated. Japanese Patent Application Laid-Open No. 10-18095 proposes a high corrosion-resistant antibacterial metal film comprising a composite metal film obtained by plating nickel or a nickel-chromium alloy as a matrix and dispersing titanium oxide in the matrix. It is described that it is effective in places where various germs are easy to propagate, such as water products such as kitchen equipment of facilities and various facilities. JP-A-8-261495 describes that by providing a zinc oxide film on the outer surface of the heat exchange member, the growth of bacteria and mold can be prevented. As a patent describing the advantages of hydrophilicity, Japanese Patent Application Laid-Open No. 10-8266 is cited, and it is stated that inorganic silica-coated metal plates are hardly dewed, and that applying such materials to a living environment is effective in ensuring comfort. .

[0004]

In the prior art, there is no metal material having both a bactericidal action and an antibacterial property based on a photocatalytic function. The bactericidal action alone has no effect in the non-contact state, and the antibacterial action based on the photocatalytic action alone has no effect in the absence of light irradiation. In addition, it is hard to say that any material having a photocatalytic function has good workability, and titanium and materials containing titanium as a main component also belong to difficult-to-process materials among metals. The present invention has been made in view of such problems of the related art, and it is an object of the present invention to obtain a material having both a bactericidal action and an antibacterial property based on a photocatalytic function and having excellent workability. It is another object of the present invention to obtain a material which has hydrophilic properties and has excellent bactericidal action and antibacterial property not only in the atmosphere but also in a humid atmosphere or liquid exposed to water vapor.

[0005]

According to the present invention, titanium is used in an amount of 0.1 to 1.0.
A copper alloy containing 1 to 7.3% and containing an oxide containing titanium in a surface layer thereof, which is a copper alloy having both a bactericidal action and an antibacterial property based on a photocatalytic function. As the copper alloy of the present invention containing 0.1 to 7.3% of titanium, for example, a copper alloy containing 0.1 to 7.3% of titanium and the balance consisting of copper and unavoidable impurities, or Further zinc according to: 0.001-10%,
Copper alloys containing appropriately one or more of silicon: 0.001 to 3% and silver: 0.001 to 1% are exemplified.

In the copper alloy of the present invention, antibacterial properties are imparted by imparting bactericidal properties by copper and dispersing an oxide containing titanium having a photocatalytic action in the copper alloy. By dispersing the oxide containing zinc, the bactericidal property can be further enhanced. In addition, by dispersing an oxide containing hydrophilic silicon, the bactericidal and antibacterial properties can be effectively utilized even in a wet atmosphere or liquid exposed to water vapor or the like. Silver has the effect of enhancing bactericidal properties. The copper alloy of the present invention can be produced in the form of a plate / strip, foil, wire, expanded metal or tube.
In the copper alloy of the present invention, in order to form an oxide containing the above element on the surface layer thereof, in the atmosphere, atmosphere or vacuum, a heating furnace, corona discharge, glow discharge, laser light, plasma or infrared light, etc. An oxide may be formed by performing a heat treatment so that the actual temperature becomes 200 to 800 ° C. Titanium, zinc and silicon are preferentially oxidized to form oxides. Further, an anodic oxidation treatment may be performed prior to the oxide formation treatment.

When the copper alloy of the present invention is placed in a gas or liquid, the contacting organic substance is decomposed and reduced by the bactericidal and antibacterial actions on the surface. So, for example,
It has the effect of killing or reducing, or decomposing and purifying many organic substances such as cigarette smoke, formalin, ammonia, mold spores, legionella bacteria, pollen allergens (antigens), house dust such as mites, and Escherichia coli. In addition, the copper alloy of the present invention is excellent in workability, so that it can be formed into various shapes and incorporated into necessary parts as an antibacterial member, making use of the high electrical conductivity, thermal conductivity, corrosion resistance, etc. of the copper alloy. It can be used for various applications. Further, by performing cladding, bonding, coating, mixing, and the like with other metal materials, ceramics, glass, resin, and the like, it is possible to provide features such as weight reduction, higher strength, and heat resistance.

[0008] Therefore, the copper alloy of the present invention can be used in fields requiring a sterilizing and antibacterial atmosphere, such as pharmaceutical manufacturing, medical institutions, food manufacturing and sales, and eating and drinking, in halls where a large number of people gather and pass, and in conference rooms. It can be used as a building material for interior parts such as places and spaces that want to maintain a natural environment. Moreover,
Many applications are possible, including applications to air purifiers, components used in air conditioners, and vehicles such as automobiles, ships, and aircraft.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The reasons for limiting the components in the present invention and the production method will be described below. (Reason for selecting copper alloy as base material) Copper is a metal having a strong bactericidal action next to silver. In addition, it has excellent spreadability, solderability, weldability, etc., is easily formed and assembled into various shapes, and has excellent properties such as strength, thermal conductivity, electrical conductivity, and corrosion resistance. In the present invention, as shown below, an oxide having an antibacterial action by a photocatalytic reaction (an oxide containing titanium and an oxide containing zinc) and an oxide having a bactericidal action (an oxide containing zinc) Is dispersed in a copper alloy, silver having a bactericidal action is further added, and an oxide having a hydrophilic property (an oxide containing silicon) is dispersed, so that a bactericidal effect is more effectively exerted.

[0010] oxidizing the copper alloy containing (titanium) titanium, titanium is preferentially oxidized, becomes oxide based on TiO _2, copper alloy titanium oxide is dispersed in the surface layer is obtained. When such a copper alloy is irradiated with ultraviolet rays having a wavelength of 388 nm or less, titanium oxide exerts a photocatalytic action to generate active oxygen and hydroxyl radicals, thereby decomposing organic substances (compounds) and the like in the air, and Change to carbon and water. Also, put this copper alloy in water,
Even in the case of irradiating with ultraviolet rays, organic substances and the like mixed in the water can be decomposed into carbon dioxide and water and purified. Further, it has been known that when ultraviolet light is irradiated in the state where water is present on the surface of the titanium oxide, the contact angle of water on the surface decreases and finally approaches 0 ° (superhydrophilicity). Irradiation of ultraviolet rays also greatly improves water wettability of a copper alloy containing a titanium oxide on its surface, so that it is effective in decomposing organic substances dissolved in water. 0.1% titanium content in copper alloy
If the amount is less than the above, the amount of the formed titanium oxide is small, and the antibacterial effect and the hydrophilicity due to the photocatalytic action are not sufficiently exhibited. On the other hand, if the content of titanium exceeds 7.3%, hot workability and cold workability decrease, and the target plate / strip, foil,
Processing into wire, expanded metal and tube shapes becomes difficult. Therefore, the content of titanium is set to 0.1 to 7.3%.

When a copper alloy containing (zinc) zinc is oxidized, zinc is preferentially oxidized together with titanium, and an oxide mainly composed of ZnO is formed on the surface layer. Irradiation of ultraviolet rays to zinc oxide exerts a photocatalytic function similar to that of TiO ₂ and has an antibacterial effect. Furthermore, since zinc oxide also has bactericidal properties, bacteria such as Escherichia coli can be killed even when, for example, ultraviolet rays are not irradiated. If the zinc content is less than 0.001%, the effect is not sufficient.
If it exceeds 0%, the effect is saturated. Therefore, the content is made 0.001 to 10%. (Silicon) When a copper alloy containing silicon is oxidized, silicon is preferentially oxidized together with titanium to form an oxide mainly composed of SiO ₂ . Since this oxide has hydrophilicity, it is likely that the entire surface will be wetted by water condensed on the copper alloy in the air. Therefore, the hydrophilicity of the titanium oxide can be further enhanced. Similarly, even in a wet atmosphere, the entire surface is likely to be wet. Therefore, organic substances and bacteria existing in the air are likely to adhere to the surface of the copper alloy material, and have an effect of enhancing the sterilizing action of the alloy. Silicon content is 0.
If it is less than 001%, the above effect is small, and if it exceeds 3%, the workability is reduced. Therefore, the content is 0.001 to
3%.

(Silver) Silver has the strongest bactericidal action among the metal elements, and further enhances the bactericidal action of the present alloy. However, if the content is less than 0.001%, the effect is not sufficient, so 0.001% or more is necessary. The higher the silver content, the better the bactericidal action, but the higher the price. Therefore, its content is made 0.001 to 1%. (Other elements) Zr, Nb and Sr can be contained in the copper alloy. These elements form oxides (ZrO ₂ , Nb ₃ O ₃ , SrTiO _3, etc.) by surface oxidation treatment, and exhibit a photocatalytic function. The preferable content of these elements is 0.5% or less in total of one or more kinds. Furthermore, as long as the formation of the oxide of the copper alloy of the present invention is not hindered,
To further improve mechanical properties or corrosion resistance,
Mg, Al, P, Ca, Cr, Mn, Fe, Co, N
i, at least one element selected from Sn, in a total amount of 0.5
% Or less may be contained.

(Production Method) In the copper alloy of the present invention, titanium, silicon, and zinc are oxidized in a heating furnace such as an electric furnace or a gas furnace, corona discharge, glow discharge, laser light in the atmosphere, atmosphere or vacuum. Heat treatment may be performed using plasma or infrared rays so that the actual temperature of the copper alloy rises to 200 to 800 ° C. These elements have much higher affinity with oxygen (oxide standard free energy of formation) than copper, and can be preferentially oxidized.
Since oxygen diffuses in the copper alloy, the amount, dimensions, depth of the oxide layer, etc., of the formed oxide are controlled by combining the heating atmosphere (oxygen partial pressure), temperature, and time, and industrially. It is possible to produce. If the temperature is lower than 200 ° C., the preferential oxidation speed of Ti, Zn, and Si is slow, and the oxidation time is long. On the other hand, when the temperature exceeds 800 ° C., oxidation of copper itself becomes severe, loss is large, and it is difficult to control oxidation of Ti, Zn, and Si. Therefore, the heating temperature is set to 200 to 800 ° C. as the actual temperature of the copper alloy. In addition, when the above oxide formation treatment is performed after the anodic oxidation treatment, the heating time can be shortened and the oxides can be uniformly dispersed.

In order to produce the copper alloy of the present invention, an ingot of a copper alloy containing a predetermined component is produced by a usual melting casting method. The ingot is prepared by appropriately combining hot working, cold working, and annealing to produce a predetermined plate / strip, foil, wire or pipe, or expanded metal, and oxidizing by the above-described method. Oxygen is further diffused to form an oxide to a certain thickness. In these shapes, an oxide may be formed on only one side or both sides or the entire surface. In the oxidation treatment step of the copper alloy of the present invention, TiO ₂ , ZnO and SiO ₂ are mainly formed. These composite oxides, and composite oxides containing copper and impurity elements and the like in some cases, may be formed, but even in such a case, the bactericidal and antibacterial properties of the copper alloy of the present invention can maintain their effects. . The oxide is first formed on the surface, but if the thickness of the surface layer where the oxide particles are present is 0.1 μm or more,
It can maintain sterilization, antibacterial and hydrophilic effects.
In addition, in order to maintain good workability of the copper alloy containing the oxide of the present invention, it is desirable that the size of the formed oxide particle is such that the radius of a circle circumscribing the particle is 5 μm or less.

In any case, the oxidation treatment
The oxide film formed on the surface contains mineral acids such as sulfuric acid.
It may be washed with a pickling solution. By this pickling, CuO,
Cu ₂Removal of oxide film composed of copper oxide such as O
Acid containing titanium, zinc, silicon, etc.
The surface of the copper alloy in which the oxide particles are dispersed appears. CuO, Cu
₂Oxide film such as O is oxidized plate / strip, foil, wire, government, etc.
Not only impairs the appearance of expanded metal, etc.
Pickling is desirable because it is easy to peel off. Oxidation treatment
After that, further plastic working or annealing afterwards
The shape, mechanical properties and physical properties to predetermined values.
Can also be. After oxidation, plastic working, punching, and soldering
・ Members of predetermined shape by combining brazing, welding, etc.
Maintains bactericidal, antibacterial and hydrophilic effects even when processed
be able to. In addition, other metals and alloys, resins, glass,
Clad with ceramics, soldering, spot melting
A composite material is obtained by a method such as bonding, bonding (adhesion),
Adds properties such as weight reduction, high strength, heat resistance, etc.
It is possible. Making the copper alloy of the present invention exhibit photocatalysis
Is desirably irradiated with ultraviolet rays having a wavelength of 388 nm or less.
However, ultraviolet light sources include sunlight, light bulbs, fluorescent lights, and 3
Electroluminescence of 88 nm or less as a light source
You may use it.

[0016]

EXAMPLE 10 kg of a copper alloy having the composition shown in Table 1 was melted in a vacuum melting furnace to obtain a sheet material after hot rolling at 880 ° C. At the time of melting, in order to remove S mixed from the raw material, Mg
Was added at 0.01%, and the residual Mg was 0.001% or less. The same effect is obtained by adding 0.01% of Ca.
The same is true even when Mg and Ca are simultaneously supplied. Furthermore, after cold rolling and heating at 880 ° C. × 2 hours, rapid cooling in water was repeated to finally obtain a cold-rolled material having a thickness of 0.5 mm. The oxide film on the way was washed with a solution containing sulfuric acid and hydrogen peroxide. A cold-rolled material having a thickness of 0.5 mm was heated at 880 ° C. for 2 hours and then quenched in water. However, the comparative alloy No. 11 Cu
Since -7.5% Ti cracked during hot rolling and could not be processed into a sheet material, it was suspended halfway and the following test was not performed.

[0017]

[Table 1]

Alloy No. 20% H ₂ S
O ₄ + 5% H ₂ O ₂ + 0.2% ethylene glycol liquid 5
After washing at 0 ° C. for 30 seconds, 20% H ₂ SO ₄ + 5% NH ₄
Immersed in an F.HF solution for 30 seconds, washed with water, then immersed in ethyl alcohol, dried, and immediately placed on a hot plate and heated at 300 ° C. for 30 minutes or 350 ° C. for 5 minutes. In addition, alloy Nos. 1 without heat treatment of the plate material, Ti, manufactured by Ishihara Sangyo Co., Ltd.
An O ₂ film and a glass plate (the same as the cover glass on which the bacterial solution is placed) were used. 2.5cm ×
The test material was cut into 2.5 cm. Using this test material, a bacterial test (both with and without UV irradiation) and a test for the generation of radicals due to UV irradiation were performed in the following procedure.

The bacterial test was performed using E. coli IFO1350
0) was stored in an L medium (yeast e
xtract: 5 g, peptone: 10 g, sodium chloride
Culture: 5 g, pH: 7.0) with shaking at 37 ° C overnight.
(Approximately 2.0 × 10 ⁸CFU / ml)
About 1.0 × 10 in 0.85% saline⁷CFU / m
The sample diluted to 1 was used as a test bacterium. This test bacterial solution was added to 24
Spread evenly on the cover glass of mm square,
The placed surface was placed on the test material and left at 20 ° C. × 1 hour.
At this time, in the test without UV irradiation,
Direct contact between the cover glass and the test material, with UV irradiation
In the test, as shown in the image diagram in Fig. 1,
Cover glass 2 on which the bacteria were applied
Cloth) and test material 3 are 1 mm apart to prevent direct contact
Ultraviolet light of 1 to 365 nm with a light intensity of 300 μW / cm²so
Irradiated. Then, to determine the antibacterial activity,
Washes with 10 ml of 0.85% saline solution
Issued. Furthermore, the viable cell count was measured using a standard agar medium (meat
Kiss: 5 g, peptone: 10 g, sodium chloride: 5
g, agar: 15 g) and spread with diluted solution.
After culturing at 7 ° C for 20 hours, the number of growing colonies was calculated.
Survival rates were determined.

In the test for the presence or absence of the generation of Hiroki radicals by ultraviolet irradiation, the reaction solution was 50 ml Tris (2-ml).
Amino, 2-hydroxystil, 1-3-propanediol buffer pH 8.0 + 1 ml DTA + 10 μl NM
A). 5 ml of the reaction solution was placed in a small Petri dish having a diameter of 50 mm, and a test material of 2.5 cm × 2.5 cm was placed therein.
Irradiation with 365 nm ultraviolet light was performed at 20 ° C. for 1 hour. When a hydroxyl radical is generated when titanium dioxide is irradiated with ultraviolet rays (388 nm or less), it reacts with NMA (p-nitrosodimethylaniline), and the yellow color of NMA becomes colorless (1 mol of hydroxyl radical and 1 mol of NMA react). The presence or absence of radical generation can be detected. At this time, the amount of change of NMA from yellow to colorless is 440 nm.
The reduction in absorption at different wavelengths was compared with a spectrophotometer. Table 2 shows the above results.

[0021]

[Table 2]

As is clear from Table 2, it is clear that the copper alloys (samples Nos. 1 to 9) within the scope of the present invention have not only a bactericidal action by copper but also an antibacterial action based on a photocatalytic action. On the other hand, even when the content of titanium was within the range of the present invention, sample No. In No. 10, an antibacterial effect was not exhibited since no oxide containing titanium was formed on the surface layer, and only a bactericidal effect by copper was observed. Sample N having a titanium content lower than the range of the present invention
o. In No. 11, the antibacterial effect due to the photocatalytic action was small even when the oxidation treatment was performed, and only the bactericidal effect due to copper was observed. T
Sample No. using the iO ₂ film In No. 12, since it does not contain copper, there is no bactericidal action, but only an antibacterial action by ultraviolet irradiation. In addition, the sample No. 13 glass plates are made of copper, TiO
_2, both of which do not have a bactericidal action and an antibacterial action by ultraviolet irradiation.

[0023]

The titanium-containing copper alloy of the present invention contains a predetermined amount of titanium and, if necessary, a predetermined amount of zinc, silicon, silver or the like singly or with a plurality of elements. Since the substance is formed, when irradiated with light including ultraviolet rays having a wavelength of 388 nm or less, it has antibacterial properties based on a photocatalytic function. Further, since the titanium-containing copper alloy of the present invention is mainly composed of Cu, it also has a bactericidal action regardless of light irradiation. The living environment is improved by using the titanium-containing copper alloy of the present invention in spaces, places, parts, etc. where antibacterial properties are required in architecture, building materials, medical-related, restaurant industry, automobiles, ships, aircraft, and the like. be able to.

[Brief description of the drawings]

FIG. 1 is an image diagram of a test of an antibacterial action (ultraviolet irradiation).

[Explanation of symbols]

 1 UV light source 2 Cover glass 3 Test material

Continued on the front page (72) Inventor Sadako Yamada 1-5-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture Inside Kobe Steel Research Institute Kobe Research Institute (72) Inventor Takenori Nakayama 1-chome Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture No.5-5 Kobe Steel, Ltd. Kobe Research Institute (72) Inventor Wataru Urushihara 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Prefecture Kobe Steel Co., Ltd. Kobe Research Institute F-term (reference) 4C080 AA07 BB05 BB06 BB08 HH05 JJ03 KK08 LL10 MM01 MM02 MM07 NN01 NN22

Claims (10)

[Claims] 1. A copper alloy having a photocatalytic function, characterized in that a copper alloy containing titanium in an amount of 0.1 to 7.3% (% by weight, hereinafter the same) contains an oxide containing titanium in a surface layer thereof. alloy. 2. A photocatalytic function comprising a copper alloy containing 0.1 to 7.3% of titanium and the balance being copper and unavoidable impurities, wherein the surface layer contains an oxide containing titanium. Copper alloy having 3. Titanium content of 0.1 to 7.3% and zinc content of 0.1 to 0.3%.
A copper alloy having a photocatalytic function, wherein the copper alloy contains 001 to 10%, the balance being copper and unavoidable impurities, wherein the surface layer contains an oxide containing titanium and an oxide containing zinc. 4. Titanium content of 0.1 to 7.3% and silicon content of 0.1 to 7.3%.
A copper alloy having a photocatalytic function, characterized in that a copper alloy containing 001 to 3% and the balance being copper and unavoidable impurities, the surface layer of which contains an oxide containing titanium and an oxide containing silicon. 5. Titanium 0.1 to 7.3% and zinc 0. 1%.
001 to 10%, containing 0.001 to 3% of silicon, the balance being a copper alloy consisting of copper and unavoidable impurities, the surface layer containing an oxide containing titanium and an oxide containing zinc or / and silicon A copper alloy having a photocatalytic function. 6. The copper alloy having a photocatalytic function according to claim 2, further comprising 0.001 to 1% of silver. 7. The method according to claim 1, wherein the shape is a plate / strip, foil, wire, expanded metal or pipe.
A copper alloy having a photocatalytic function according to any one of the above. 8. The copper alloy having a photocatalytic function according to claim 7, wherein the copper alloy is combined with another metal / alloy material, ceramic material, glass or resin. 9. A heat treatment is performed on the copper alloy according to any one of claims 1 to 7 so that its actual temperature becomes 200 to 800 ° C., and an oxide is formed on a surface layer thereof. A method for producing a copper alloy having a photocatalytic function. 10. The method for producing a copper alloy having a photocatalytic function according to claim 9, wherein an anodic oxidation treatment is performed prior to the oxide formation treatment.