JPH0849085A - Antibacterial stainless steel sheet and its production - Google Patents

Abstract

PURPOSE:To impart antibacterial activity to a stainless steel sheet by forming a coating layer contg. an antibacterial element. CONSTITUTION:A metal or alloy layer of Cr, Ti, Ni, Fe, etc., contg. Ag and/or Cu as an antibacterial metal is formed on the surface of a stainless steel sheet by magnetron sputtering with a target obtd. by dispersedly arranging targets of Ag, Cu, an Ag-Cu alloy or compd. on a target of Cr, Ti, Ni or stainless steel to obtain the objective antibacterial stainless steel sheet sustaining antibacterial activity over a long period of time and excellent also in corrosion resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antibacterial stainless steel sheet suitable for use as a water supply article, medical equipment and the like, and a method for producing the same.

[0002]

2. Description of the Related Art The surface of a sink or the like is exposed to a humid atmosphere where bacteria can easily grow. The generation of bacteria can be prevented to some extent by always maintaining the surface of the sink in a dry atmosphere, but this puts a great burden on daily management. In the water supply pipes and the like, there is a possibility that fungi generated on the inner surface or the like where it is difficult to wipe off moisture will be entrained in the running water and mixed into drinking water. Although the fungi mixed in the running water can be removed to some extent by a filter such as activated carbon, bacteria are accumulated in the filter itself, which necessitates regular replacement of the filter.

Propagation of bacteria tends to be promoted by the spread of air conditioners. That is, since the indoor environment is kept constant by the air conditioner,
The sink and its peripherals provide a more suitable environment for bacterial growth. In addition, the surfaces of handrails and interior materials of hospitals and recreation facilities where hygiene is important are required to be in a clean state free of bacteria. Various antibacterial materials have been developed in various fields as materials requiring cleanliness. Of these, resins and ceramics generally carry ions of antibacterial elements. The carried ions are eluted in water and exert their effect against bacteria in a moist environment.

[0004]

In the ion-supporting antibacterial material, the supported ions are likely to be eluted in water. Although the antibacterial property is exhibited by the elution of ions, there is a possibility that the elution of ions may adversely affect the human body, fish, animals and the like. Further, it is difficult to suppress the elution of ions, and it is difficult to maintain a predetermined antibacterial property for a long period of time.
The appearance of metallic luster such as stainless steel tends to be preferred as a water supply article such as a sink. However, when the stainless steel is coated with a resin or ceramics carrying an antibacterial element, the original surface properties of the stainless steel are lost. In this respect, if antibacterial properties can be imparted without losing the original metallic luster, the demand for stainless steel expands in combination with excellent corrosion resistance. The present invention has been devised to solve such problems, and utilizes the fact that Ag, Cu, etc. exhibit antibacterial properties, and uses a metal layer or alloy layer containing Ag and / or Cu as a stainless steel surface. By forming into
The purpose is to impart antibacterial properties to stainless steel itself, which has excellent corrosion resistance and surface appearance.

[0005]

In order to achieve the object, the antibacterial stainless steel sheet of the present invention has a metal layer or alloy such as Cr, Ti, Ni, Fe containing antibacterial metal Ag and / or Cu. A layer is formed on the surface of the stainless steel substrate. 19 for metal or alloy layers
˜60 wt% Ag or 6-21 wt% Cu is preferred. This antibacterial stainless steel plate
A on a target of Cr, Ti, Ni or stainless steel
A target made of g, Cu, or an alloy or compound of these is dispersedly arranged and magnetized by magnetron sputtering.
It is manufactured by forming a metal layer or an alloy layer of Cr, Ti, Ni, Fe or the like containing g and / or Cu on the surface of a stainless steel substrate.

The stainless steel sheet of the present invention has a metal layer or alloy layer of Cr, Ti, Ni, Fe or the like containing Ag and / or Cu formed on the surface. Ag and Cu have a microbactericidal effect. That is, Ag or Cu in the film formed on the surface of stainless steel is ionized to be eluted into the liquid and attached to miscellaneous bacteria such as Escherichia coli to suppress the reproduction and finally disappear. This microbactericidal action can be sufficiently expected even with an elution amount on the order of ppb.
Further, Cr, Ti, Ni, Fe and the like which are coating layer forming elements are necessary elements for forming a surface layer excellent in corrosion resistance, hardness, metallic luster and the like. At this time, Cr, Ti, Ni, Fe
Ag or Cu with the content specified in the metal layer or alloy layer such as
Contains Ag, Cu and Ag while maintaining antibacterial properties
The surface of stainless steel is prevented from rusting or discoloring due to the elution of Further, since Ag and Cu are not supported in an ionic state, the elution amount is smaller than that of the conventional antibacterial material, the antibacterial property is maintained for a long period of time, and the harmful effect on the human body is suppressed. It

In the present invention, vapor deposition with vapor phase mixing is adopted in that the antibacterial metal is uniformly dispersed in the film. Vapor deposition methods include melt evaporation and sputtering. However, in melt evaporation, the melting point of Cr, Ni, Ti, etc. is high, so that the thermal efficiency is poor, and the material of the crucible is limited, which makes it expensive. On the other hand, in sputtering, the high melting point metal can be evaporated similarly to the low melting point metal. In particular, if a magnetron sputtering method in which plasma is confined by a magnetic field is adopted, the film forming rate can be increased.

[0008]

Example A 60 mm × 60 mm test piece was cut out from a hairline finishing material of stainless steel SUS304 having a plate thickness of 1 mm, and an antibacterial film was vapor-deposited on the surface of the test piece by a high frequency magnetron sputtering device. At this time, a 5 mm × 20 mm and a 10 mm × 20 mm Ag plate and a Cu plate are arranged on a Cr target having a diameter of 100 mm, and the area ratio is changed so that Cr-Ag having an arbitrary composition is formed.
And Cr-Cu alloy vapor deposition film was formed. The film thickness of the film was set to 1 μm. ED for the obtained film
The composition was investigated by X. In the antibacterial property test, Escherichia coli and Staphylococcus aureus were dropped onto the vapor deposition surface at a specified concentration, and the number of bacteria after 24 hours was measured. Corrosion resistance test is SST (5% NaC
1, 35 ° C.) and BBT (50 ° C., relative humidity 98%), and the red rust occurrence rate and discoloration rate after 48 hours were measured.

[0009]

[Table 1]

As is clear from Table 1 showing the test results,
When Ag was added, the antibacterial activity against E. coli was found to be 2% by weight. The effect of Ag became remarkable at 19% by weight, and at 44% by weight or more, E. coli was not detected after 24 hours. For Staphylococcus aureus, Ag 44% by weight
The effect was confirmed from the above, and it was not detected at 90% by weight. From this, it can be seen that addition of Ag exhibits superior antibacterial activity against Escherichia coli than Staphylococcus aureus. On the other hand, when Cu was added, Escherichia coli and Staphylococcus aureus were not detected at 6% by weight or more, and the antibacterial activity was greater than that of Ag. Since Cu has a higher antibacterial property than Ag, Cu has a greater ionization tendency and C
It is presumed that the cause is that it is easily dissociated as u ions.

In the evaluation of corrosion resistance by BBT, 76% by weight or less when Ag was added, and 48% by weight or less when Cu was added, no rusting or discoloration was observed, and good corrosion resistance was obtained. In the corrosion resistance evaluation by SST, 60% by weight or less when Ag was added and 21% by weight or less when Cu was added, no rusting or discoloration was observed, showing good corrosion resistance.
From the above test results, Cr formed on the surface of stainless steel
It was confirmed that the antibacterial property and the corrosion resistance are compatible when the Ag content in the Ag-based coating layer is in the range of 19 to 60% by weight and the Cu content in the Cr-Cu-based coating layer is 6 to 21% by weight. . Further, even in the coating layer mainly composed of other metal components such as Ti, Ni, and Fe, when the Ag content of 19 to 60% by weight or the Cu content of 6 to 21% by weight is maintained, rust of A stainless steel plate with excellent antibacterial properties without rusting or discoloration was obtained.

[0012]

As described above, according to the present invention, by forming a hard coating containing antibacterial elements Ag and / or Cu on the surface of stainless steel,
A stainless steel plate having an action of suppressing the growth of bacteria such as Staphylococcus aureus can be obtained. This stainless steel sheet ionizes and elutes a regulated amount of antibacterial element,
It has excellent antibacterial properties as well as good corrosion resistance. Moreover, the antibacterial property is adjusted by changing the content of Ag and / or Cu. Therefore, the stainless steel according to the present invention is used as a water supply article and various equipment where hygiene is important.

Claims (4)

[Claims] 1. An antibacterial stainless steel sheet in which a metal layer or an alloy layer of Cr, Ti, Ni, Fe or the like containing antibacterial metal Ag and / or Cu is formed on the surface of a stainless steel substrate. 2. The metal layer or alloy layer according to claim 1,
An antibacterial stainless steel plate containing -60 wt% Ag. 3. The metal layer or alloy layer according to claim 1 is 6 to 6.
Antibacterial stainless steel plate containing 21% by weight of Cu. 4. A target made of Ag, Cu, an alloy or a compound thereof is dispersedly arranged on a Cr, Ti, Ni or stainless steel target, and Cr, Ti, N containing Ag and / or Cu is formed by magnetron sputtering.
A method for producing an antibacterial stainless steel sheet, which comprises forming a metal layer or alloy layer of i, Fe or the like on the surface of a stainless steel substrate.