Ag-cu-zn alloy excellent in antibacterial and antimold property

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to an Ag-Cu-Zn alloy that exhibits stable antibacterial and antifungal effects over a long period of time.

【0002】

[Conventional technology]

There are two types of antibacterial agents and fungicides currently in use: inorganic and organic. Organic antibacterial and antifungal agents include surfactants, biguanides, alcohols, phenols, anilides, iodines, imidazoles, thiazoles, isothiazolones, triazines, nitriles, fluorines, sugars. An extremely wide variety of compounds such as phenolic compounds, tropolone compounds, and organic metal salt compounds have been developed and are commercially available. All organic antibacterial and antifungal agents exhibit excellent antifungal activity, but are inferior in antibacterial activity. In addition, although it is excellent in quick-acting, it has a problem in sustainability. Therefore, there is a demand for the development of a new antibacterial and antifungal agent having excellent antibacterial and antifungal properties and good durability.

【0003】

On the other hand, as inorganic antibacterial and antifungal agents, inorganic simple substances such as zeolite, titania, apatite, silica, calcium phosphate, silica gel, zirconium phosphate, porous ceramics, montmorillonite, low molecular weight glass, carbon fiber and activated carbon can be used. Ag, Cu, which was supported metal ions such as Zn have been developed, the city is sales. Recently, an inorganic simple substance carrying two metal ions of Ag and Cu or Ag and Zn has been developed. Due to the synergistic effect of metal ions, those carrying metal ions of two components show superior antibacterial activity as compared with those carrying metal ions by themselves, and also against peculiar bacteria and molds. It has been reported that it exhibits a wide range of antibacterial activity.

【0004】

[Problems to be Solved by the Invention]

Inorganic antibacterial and antifungal agents are all evaluated to have excellent heat resistance compared to organic ones, good durability because the amount of metal eluted is small, and high safety to the human body. There is. However, although it exhibits excellent antibacterial properties as compared with organic substances, it is inferior in antifungal properties. Moreover, when kneaded into plastics or dispersed in paints, various problems arise. For example, zeolites carrying Ag and Cu using ion exchange reactions, chelate reactions, inclusion reactions, etc. can be used as antibacterial and antifungal processing agents for synthetic fibers, antibacterial plastic processed products dispersed in plastics, etc. Although it is beginning to be used, it has the following problems. In the future, it is necessary to solve these problems in order to use it in a wide range of application fields.

【0005】

During spinning or heat molding, Ag ions liberated from the carrier react with the resin to discolor the product. Since the carrier contains adsorbed water, evaporation of the adsorbed water causes bubbles and turbidity in the product, which causes thread breakage and the like. It is also being considered to use an inorganic antibacterial / antifungal agent mixed with an organic antibacterial / antifungal agent, but this does not basically solve the problems of the inorganic antibacterial / antifungal agent mentioned above. .. The present invention has been devised to solve such a problem, and by specifying the composition of the Ag-Cu-Zn system, it is excellent in antibacterial property, antifungal property, and durability, and Ag ion during heating. It is an object of the present invention to provide a high-performance metal-based antibacterial / antifungal agent that is difficult to release and does not contain any adsorbed water.

【0006】

[Means for solving problems]

The Ag-Cu-Zn alloy of the present invention is characterized by having a composition of Ag: 20 to 60 atomic%, Cu: 20 to 60 atomic%, Zn: 20 to 60 atomic% in order to achieve the object. .. This Ag-Cu-Zn alloy has a composition of Ag: 20 to 60 atomic%, Cu: 20 to 60 atomic%, Zn: 20 to 60 atomic%, and is even more excellent in antibacterial and antifungal properties when exhibiting an amorphous phase. It exerts its action. In the periodic table, metals such as Ag, Cu, IIB Group Zn, Cd, Hg, IVB group Ge, Sn, Pb, metal salts, organic metal compounds, etc. show antibacterial activity against microorganisms. It has been known. However, Ge is an expensive metal, and Cd, Hg, Pb, etc. have problems in terms of toxicity, so they are not used in actual applications except in special cases. Currently, the most commonly used are Ag and Cu-based metal salts and organometallic compounds. In particular, the Ag type has excellent antibacterial properties, and the Cu type has excellent antifungal and algae-proof properties.

【0007】

By the way, when Ag, Cu, Zn or the like is used as a single metal, the metal itself is not directly ionized and eluted in water. Once a film of oxides, hydroxides, chlorides, etc. is formed on the surface, it becomes an ionic state and elutes into water. However, since inorganic compounds such as Ag, Cu, and Zn are generally sparingly soluble, sufficient antibacterial and antifungal properties cannot be obtained. Even when used as a binary alloy such as Ag-Cu, Ag-Zn, Cu-Zn, there are various problems. For example, in the Ag-Cu system which does not have a reducing action by Zn, Cu is eluted not as a monovalent ion but as a divalent ion having poor antibacterial and antifungal properties. In the Ag-Zn system, only Zn is eluted due to the sacrificial anticorrosion action, and Ag is hardly eluted. The Cu-Zn system, which does not contain Ag, has poor antibacterial properties.

【0008】

Therefore, as a result of examining the antibacterial property and antifungal property of the ternary alloy of Ag-Cu-Zn, the present inventors, Ag: 20 to 60 atomic%, Cu: 20 to 60 atomic%, Zn: 20 to When the composition was specified at 60 atomic%, it was found that excellent antibacterial and antifungal effects were exhibited. When Ag, Cu, and Zn are alloyed at this blending ratio, the actions of each element are synergistically expressed, and excellent antibacterial and antifungal properties can be obtained. Among them, a ternary alloy having a composition of 20 to 60 atomic%, Cu: 20 to 60 atomic%, Zn: 20 to 60 atomic% and exhibiting an amorphous phase exhibits even more excellent characteristics. In the Ag-Cu-Zn alloy of the present invention, in addition to Ag, Cu, Zn, if the content is 10 atomic% or less, Ni, Cr, Sb, Co, Mn, Ti, Al, Mo, Ta, Zr, Nb , Hf, W, N, B, P selected from one or more. Ni, Cr, Sb, etc. exhibit antibacterial properties against specific bacteria. Cr, Co, Mn, Ti, etc. are effective in improving corrosion resistance. Al, Mo, Ta, Zr, Nb, Hf, W, etc. improve heat resistance. N, B, P, etc. facilitate the formation of an amorphous phase.

【0009】

When the Ag-Cu-Zn alloy exhibits an amorphous phase, corrosion resistance and oxidation resistance are significantly improved as compared with an alloy having a structure composed of ordinary metal crystals. In addition, no preferential elution of Zn was observed, and each component was eluted almost evenly. Therefore, even if the usage environment is high temperature, high humidity, acidic or alkaline, the elution amount of Ag, Cu, Zn is almost constant, and extremely stable performance is maintained for a long period of time. In order to obtain an amorphous phase Ag-Cu-Zn alloy, it is necessary that the atomic weight ratio of Ag, Cu and Zn is 1: 1: 1 in principle. In this respect, if each component is less than 20 atomic% or more than 60 atomic%, it will not be amorphized. However, in a binary system such as Ag-Cu, Cu-Zn, Ag-Zn, an amorphous phase cannot be obtained regardless of the atomic weight ratio.

【0010】

In the amorphous alloy according to the present invention, it is important to solidify the molten alloy molten metal in an extremely short time, as in the case of producing an ordinary amorphous alloy. It is also possible to apply an amorphous alloy coating to the surface of various powders and steel sheets by a sputtering method or the like. The sputtering method requires that the temperature of the powder during sputtering be maintained at least 300 ° C. In the sputtering method, a target having an average composition equal to that of the amorphous alloy to be produced, composed of a plurality of crystal phases, and produced by a sintering method, a melting method, or the like is used. Alternatively, a combination target in which the metal to be alloyed is embedded in a metal plate composed of the main component of the amorphous alloy to be produced can also be used.

【0011】

[Action]

It is generally said that the critical concentration of Ag required to exhibit antibacterial activity against microorganisms is 20 ppb or more, which is extremely small. However, if the amount of Ag-based metal salts and organometallic compounds used is small, there is a problem with sustainability. On the contrary, if the amount used is too large, Ag ions liberated from the simple substance during spinning or heat molding react with the resin to make the product. The drawback of discoloring appears. Therefore, in order to exert effective antibacterial and antifungal effects, it is necessary to increase the Ag content as much as possible, but to devise a method that does not release as Ag ions during heat molding. In this respect, in the Ag-Cu-Zn alloy of the present invention, although it contains a large amount of Ag, excessive liberation of Ag ions is caused by the sacrificial anticorrosion action due to the coexistence of the divalent ion species Zn and Cu. It is suppressed. Due to this property, for the first time, it was possible to develop an antibacterial and antifungal material having excellent antibacterial and antifungal properties and having good durability.

【0012】

Further, in the Ag-Cu-Zn alloy of the present invention, the ratios when Ag, Cu, and Zn are ionized and eluted are constant. This is due to the ionization tendency of each metal, and the amount of Zn eluted is the largest and the amount of Ag eluted is the smallest. Moreover, Cu ions elute as monovalent ions rather than as divalent ions. With ordinary metal Cu, patina and the like are generated on the surface due to corrosion and oxidation. When such a film is formed, the amount of Cu ions eluted changes considerably and is usually eluted as divalent ions, so that the antibacterial and antifungal properties are inferior. However, in the Ag-Cu-Zn ternary system, since there is a reducing action by Zn, Cu is eluted as a monovalent ion having excellent antibacterial and antifungal properties. Furthermore, extremely strong antibacterial and antifungal properties are exhibited by the synergistic effect of three types of metal ions, Ag, Cu and Zn. Therefore, it exhibits a wide range of antibacterial activity against many types of bacteria and molds as compared with conventional products.

【0013】

[Example]

A stainless steel plate SUS304 having a plate thickness of 0.3 mm, a width of 50 mm, and a length of 50 mm was set in a sputtering apparatus, and a ternary alloy of Ag-Cu-Zn having various compositions shown in Table 1 was sputter-coated. 2 × 10 maintained in Ar gas atmosphere in advance for coating^-3The surface of the stainless steel sheet was activated by reverse sputtering for 10 minutes at an output of 100 W under reduced pressure of Thor. Continue to use the ternary alloy target 2x10^-3Sputtering was performed at an output of 300 W for 1 hour under a reduced pressure of Thor. At this time, the temperature of the coating film was kept cool at 250 ° C. or lower to make it amorphous, and the temperature was raised to 350 ° C. or higher to make it crystalline. As a result, the surface of the stainless steel sheet was coated with a ternary alloy having a thickness of about 1 μm. After the sputtering was completed, the coated stainless steel sheet was cooled and taken out of the apparatus.

【0014】

Test pieces were cut out from stainless steel sheets coated with various coatings and subjected to antibacterial and antifungal tests. In the antibacterial test, 500 ml of Escherichia coli culture solution was inoculated into a sterilized petri dish with a diameter of 90 mm, 10 ml of bouillon agar medium was poured, and a sample with a diameter of 30 mm was fixed in the center of the medium just before solidification, and 48 at 37 ± 1 ° C. Inoculate for hours. Then, the viable cell count before and after the test was investigated, and the antibacterial property was evaluated by the degree of decrease in the viable cell count. In the antifungal test, 0.5 ml of mixed spore suspension was inoculated into a sterilized petri dish with a diameter of 90 mm, 10 ml of inorganic salt agar medium was poured, and a sample with a diameter of 30 mm was fixed in the center of the nuclear plate medium just before solidification. The cells were cultured at ± 1 ° C for 7 days. Then, the viable cell count before and after the test was investigated, and the antifungal property was evaluated by the degree of decrease in the number of spores. The test results are shown in Table 1. The evaluation criteria in Table 1 are that ++ has very strong antibacterial or mold resistance, + has antibacterial or mold resistance, and plus has weak antibacterial or mold resistance. Indicates that there is,-indicates that there is no antibacterial or mold resistance.

【0015】

<img file="JPH09111380A_D0001.tif" />【0016】

[Effect of the invention]

As described above, in the Ag-Cu-Zn ternary alloy of the present invention, Ag, Cu, and Zn are alloyed at a predetermined blending ratio, so that Ag's bactericidal action, Cu's antifungal action, and Zn The reducing action of zinc works synergistically to obtain a material exhibiting excellent antibacterial and antifungal properties that has never been seen before. Among them, the amorphized Ag-Cu-Zn ternary alloy homogenizes the elution of each alloy element over a long period of time and exhibits more excellent antibacterial and antifungal properties. Therefore, for example, various powders coated with Ag-Cu-Zn ternary alloy are mixed and dispersed in plastics, paints, etc., and house interior materials, exterior materials, wallpaper, carpets, unit baths, air conditioning filters, sanitary goods, etc. It can be used in a wide range of fields such as daily bath products, kitchen products, medical products, clothing fibers, socks, stationery, water treatment products, food containers, and packaging films.