JP2000017397A - Stainless steel material excellent in antibacterial characteristic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stainless steel material having superior workability and corrosion resistance and further having excellent antibacterial characteristic even if subjected to general purpose surface working including grinding, and its production. SOLUTION: Ag and Ti are incorporated into a stainless steel by 0.0001-1.0 wt.% and 0.001-3 wt.%, respectively. Moreover, >=0.0001% by volume ratio, in total, of one or >=2 kinds among silver grains, silver sulfides, and silver oxides are incorporated into a steel material, and further, titanium oxides are dispersed by >=0.0001% by volume ratio. It is preferable that, at the time of continuously casting a molten steel, the pouring rate at continuous casting is made to (0.7 to 1.7) m/min.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a stainless steel material, and more particularly to a stainless steel material which has excellent antibacterial properties and is suitable for use in kitchenware and other living related articles, medical equipment, electric equipment, chemical equipment, building materials and the like. The steel material in the present invention includes a steel plate, a steel strip, a steel pipe, and a steel wire.

[0002]

2. Description of the Related Art It has been known that silver and copper have an effect of suppressing the propagation of pathogenic bacteria represented by Escherichia coli and Salmonella and preventing food poisoning caused by pathogenic bacteria. Recently, materials using these metals to have an effect of inhibiting bacterial growth (hereinafter referred to as antibacterial properties) have been proposed. For example, Japanese Patent Application Laid-Open No. 8-49085 discloses that, by magnet sputtering, Cr containing Ag and / or Cu,
A stainless steel sheet having excellent antibacterial properties in which a metal layer or an alloy layer of Ti, Ni, Fe or the like is formed on the surface of a stainless steel base material is disclosed. In this steel plate, it is preferable to form a metal layer or an alloy layer containing 19 to 60% by weight of Ag.

Further, Japanese Patent Application Laid-Open No. 8-156175 proposes a coated steel sheet which can suppress the propagation of bacteria by applying a pigment containing silver. However, in the above-described method of forming a metal layer or an alloy layer containing an antibacterial metal on the surface of a steel sheet, or in a method of applying a pigment containing an antibacterial metal, the layer containing the antibacterial metal is formed by drawing or polishing the surface. There is a problem that the effect cannot be expected due to peeling or removal, and further, there is a problem that antibacterial properties cannot be maintained for a long period of time in applications where the surface is constantly rubbed for cleaning as in kitchenware. In addition, in the above-described method, the number of manufacturing steps for coating and forming a metal layer or an alloy layer increases, and the surface area per unit weight increases as the plate thickness decreases. There is also a problem that the number of layers and alloy layers increases, which is disadvantageous in cost.

Japanese Patent Application Laid-Open No. 8-239762 discloses that, by weight, Fe: 10 to 80%, Al: 1 to 10%, or
An antimicrobial and marine-resistant biological material containing 1 to 15% of any one or more of Ni, Mn, and Ag and the balance consisting of copper and unavoidable impurities is disclosed. However, this material has Al
% Of copper-based alloy or iron-based alloy, has low workability, and has a problem when used for thin plates such as tableware, kitchenware, electric equipment parts and the like.

In order to solve the above-mentioned problem, Japanese Patent Application Laid-Open No.
Japanese Patent No. 4953 discloses an austenitic stainless steel in which Cu is added in an amount of 1.1 to 3.5% by weight to enhance antibacterial properties.
Japanese Patent No. 104952 discloses a martensitic stainless steel having an enhanced antibacterial property by adding 0.3 to 5% by weight of Cu.
Japanese Patent Publication No. 8-170053 proposes a ferritic stainless steel in which Cu is added in an amount of 0.4 to 3.0% by weight to enhance antibacterial properties.

[0006] Separately, Japanese Patent Application Laid-Open No. 8-193219 proposes a stainless steel sheet having a titanium oxide layer formed on the surface to improve antibacterial properties and a method for producing the same.

[0007]

SUMMARY OF THE INVENTION
In the techniques described in JP-A-8-104953, JP-A-8-104952, and JP-A-8-170053, it is necessary to dissolve Cu as ions from the steel sheet surface in order to exhibit antibacterial properties. The elution of Cu as ions means that the passivation film is destroyed at that location, so that the antibacterial property is improved, but the corrosion resistance is significantly deteriorated. Therefore, there has been a problem that it is very difficult for Cu-added stainless steel to achieve both antibacterial properties and corrosion resistance.

In the technique described in JP-A-8-193219, since a titanium oxide layer is formed on the surface,
As the number of manufacturing processes increases and the sheet thickness decreases, the surface area per unit weight increases, so the amount of titanium oxide per unit weight increases, which is disadvantageous in terms of cost. There is a problem that the antibacterial property is not maintained in the used application.

The present invention advantageously solves the above-mentioned problems of the prior art, has excellent workability and corrosion resistance, and still has excellent antibacterial properties even when subjected to the currently widely used surface treatment including polishing. It is an object of the present invention to provide a stainless steel material having the following and a method for producing the same.

[0010]

Means for Solving the Problems The present inventors have developed a stainless steel sheet having both antibacterial properties, excellent workability and corrosion resistance, particularly with a field emission type Auger electron spectrometer and an electron beam microanalyzer. As a result of intensive research on the relationship between the chemical composition of the stainless steel sheet surface and the antibacterial activity, the appropriate amount of Ag was added to the stainless steel, and silver particles and silver were added to the surface of the stainless steel sheet and the steel sheet. It has been newly found that a stainless steel sheet having high antibacterial properties and excellent workability and corrosion resistance can be obtained by uniformly dispersing an appropriate amount of oxides and silver sulfides. With the conventional antibacterial material, the antibacterial property was expressed only on the surface and the cut end face did not have the antibacterial property.However, an appropriate amount of Ag was added to stainless steel, and silver particles and silver were added to the surface and the stainless steel sheet. It has been found that antimicrobial properties can be exhibited in any part of steel by uniformly dispersing an appropriate amount of oxide and silver sulfide. These stainless steel sheets have stable antibacterial properties even in applications that are subjected to forming and polishing processes and where the surface is rubbed or scraped off during use, eliminating the need for special post-treatment, and providing an advantage in terms of cost. Become.

Further, the present inventors have added Ti to stainless steel in addition to Ag, and in addition to silver particles, silver oxide and silver sulfide, added titanium oxide to the surface of the stainless steel sheet and in the steel sheet in an appropriate amount. By dispersing, it has been newly found that the antibacterial property can be maintained semipermanently and the antibacterial stainless steel material having excellent durability can be obtained. The present invention has been completed based on the above findings and further studies.

That is, the present invention provides a method for producing Ag: 0.0001 to 1.0 wt.
% And Ti: 0.001 to 3 wt%, wherein the steel material contains one or more of silver particles, silver sulfide and silver oxide in a total volume ratio of 0.0001% or more, and further contains titanium oxide. It is a stainless steel material excellent in antibacterial properties, characterized by containing a volume ratio of 0.0001% or more. Further, in the present invention, the stainless steel molten steel is continuously cast into a steel material, and the stainless steel molten steel is added in the form of pellets having a maximum diameter of 50 mm or less with Ag-containing material and Ti-containing material, and Ag: 0.0001 to 1.0 wt. % And Ti: 0.001 to 3wt%
And a casting speed of the continuous casting is set to 0.7 to 1.7 m / min.

[0013] The present invention also relates to a method for producing a cold-rolled stainless steel sheet in which a molten stainless steel is continuously cast into a steel material and then hot-rolled and cold-rolled. A Ti-containing material is added as a pellet having a maximum diameter of 50 mm or less to form a molten stainless steel containing 0.0001 to 1.0 wt% of Ag and 0.001 to 3 wt% of Ti.
Further, the present invention provides a method for producing a cold-rolled stainless steel sheet having excellent antibacterial properties, wherein the casting speed of the continuous casting is 0.7 to 1.7 m / min.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The reasons for limiting the chemical composition of the steel material of the present invention will be described. Austenitic stainless steel, ferritic stainless steel, and martensitic stainless steel are all suitable for the stainless steel material of the present invention. The chemical composition of austenitic stainless steel is C:
0.01 to 0.1 wt%, Si: 2.0 wt% or less, Mn: 2.0 wt% or less, P: 0.08 wt% or less, S: 0.02 wt% or less, Cr: 10 to 35
It is preferable to contain wt%, Ni: 6 to 15 wt%, and N: 0.01 to 0.1 wt%, with the balance being Fe and unavoidable impurities. In addition,
Mo: 3.0 wt% or less, Cu: 1.0 wt% or less, Co: 0.5 wt% or less, W: 0.30 wt% or less, Al: 0.3 wt% or less, Nb: 1.0 wt%
%, Zr: 1.0 wt% or less, B: 0.01 wt% or less
Species or two or more species may be contained.

The chemical composition of ferritic stainless steel is as follows:
C: 0.1 wt% or less, Si: 1.0 wt% or less, Mn: 2.0 wt% or less, P: 0.08 wt% or less, S: 0.02 wt% or less, Cr: 10 to 35
wt%, N: 0.10 wt% or less, with the balance being Fe and inevitable impurities. In addition, Al: 0.3 wt% or less,
Ni: 1.0 wt% or less, Mo: 3.0 wt% or less, Nb: 1.0 wt% or less, Zr: 1.0 wt% or less, V: 0.30 wt% or less, Cu: 1.0 wt%
%, Co: 0.5 wt% or less, W: 0.30 wt% or less, B: 0.01
One or more of wt% or less may be contained.

The chemical composition of martensitic stainless steel is as follows: C: 0.001 to 1.0 wt%, Si: 1.0 wt% or less, Mn: 2.
0 wt% or less, P: 0.08 wt% or less, S: 0.02 wt% or less, C
r: 12 to 17% by weight, N: 0.007 to 0.03% by weight, balance Fe
And it is preferable to use unavoidable impurities. In addition, Al:
1.5 wt% or less, Nb: 0.5 wt% or less, V: 0.30 wt% or less,
Co: 0.5 wt% or less, W: 0.30 wt% or less, Zr: 1.0 wt% or less, Ni: 3.0 wt% or less, Mo: 3.0 wt% or less, Cu: 1.0 wt%
% Or less, B: one or more of 0.01 wt% or less.

In the present invention, the stainless steel, preferably the stainless steel having the chemical composition in the above-mentioned range, further contains 0.0001 to 1.0 wt% of Ag and 0.001 to 3 wt% of Ti. Ag: 0.0001 to 1.0 wt% Ag is the most important element in the present invention, and has an effect of suppressing the growth of bacteria and is an element that enhances antibacterial properties. These effects are recognized at a content of 0.0001 wt% or more,
If the content exceeds t%, it has the effect of enhancing antibacterial properties, but the corrosion resistance deteriorates, the surface defects during hot rolling increase, and a large amount of expensive Ag is added, which is disadvantageous in cost. . For this reason, Ag was limited to the range of 0.0001 to 1.0 wt%.

Ti: 0.001 to 3 wt% Ti is an element that has the effect of suppressing the growth of bacteria as titanium oxide and enhances the antibacterial properties of steel. Titanium oxide (Ti
0 ₂ ) is a photocatalytic medium that converts oxygen on the material surface into active oxygen by irradiation with sunlight, fluorescent light, ultraviolet light, etc., decomposes enzymes contained in pathogenic bacteria, and kills bacteria. have. Note that this action is manifested when light is irradiated, but since the titanium oxide itself is manifested without being consumed, it lasts semipermanently. Such an effect is recognized when the content of Ti is 0.001 wt% or more, while
If the content exceeds wt%, surface defects increase during hot rolling,
This causes a reduction in hot workability. Because of this, Ti
Was limited to 0.001 to 3% by weight. In addition, preferably, 0.00
It is 5 to 2% by weight.

In the present invention, Ag contained in the steel material is contained in a total of 0.0001% or more by volume as one or more selected from silver particles, silver oxides and silver sulfides. , Ti is 0.0001% by volume as titanium oxide
It is contained above. When Ag is present as silver particles, silver oxide, silver sulfide, and Ti is present as a titanium oxide dispersed on the surface of the steel material at the time of use, the proliferation of bacteria is suppressed and the antibacterial property is significantly improved. The titanium oxide referred to in the present invention includes TiO ₂ alone or a composite oxide of titanium and other elements such as Ag ₂ TiO ₃ . Each of the silver particles, silver oxide, silver sulfide and titanium oxide may be present alone, or two or more of them may be combined to form a compound.

Silver particles, silver oxides, silver sulfides, titanium oxides, composite oxides of silver and titanium, or a mixture of these, which are constantly dispersed and present on the surface of steel at the time of use, exhibit antibacterial properties. It is important to maintain stability. Silver particles, silver oxides, silver sulfides, titanium oxides, not only on the surface at the time of product shipment, but also on the surface after grinding, cutting and grinding, or on the surface of the steel material in use where a new surface is formed due to wear etc. , A composite oxide of silver and titanium, or a mixture thereof.

The presence of Ag and Ti in the steel material is evaluated based on the information on the volume ratio in the cross-sectional direction obtained by elemental mapping measurement using an X-ray microanalyzer with respect to an arbitrary cross section of a test piece taken from the steel material. In addition, the measuring method of a volume ratio is as follows. The outermost surface of the test piece, thickness 1/2 from the surface, thickness 1/4 from the surface, thickness 1/10 from the surface,
For each surface with a thickness of 1/50 from the surface and a thickness of 1/100 from the surface, Ag (silver particles,
Perform elemental mapping of silver oxide, silver sulfide) and Ti (titanium oxide). At this time, the detection depth is adjusted to a constant thickness. Exist in a certain thickness range at each surface position
The amounts of Ag (silver particles, silver oxide, silver sulfide) and Ti (titanium oxide) are calculated as a volume from the size of the grains as determined by elemental mapping. Furthermore, the ratio of the volume of Ag (silver particles, silver oxide, silver sulfide) and Ti (titanium oxide) at each surface position is averaged, and the ratio to the entire material is defined as the volume ratio. .

The total amount of one or more selected from silver particles, silver oxides and silver sulfides is 0.00% by volume.
If it is less than 01%, no effect of suppressing the growth of bacteria is observed, and no antibacterial property is exhibited. On the other hand, if the total amount exceeds 5% by volume, the effect of improving the antibacterial properties is saturated, and the amount of Ag added increases, which is disadvantageous in terms of cost, and the corrosion resistance also deteriorates. For this reason, the total amount of one or more selected from silver particles, silver oxides and silver sulfides is desirably 0.0001% to 5% by volume. The size of silver particles, silver oxide and silver sulfide is 50 μm
If it exceeds, the corrosion resistance and workability may be reduced, so the size is preferably 50 μm or less.

If the volume ratio of titanium oxide is less than 0.0001%, no antibacterial property is exhibited. On the other hand, when the volume ratio of titanium oxide exceeds 5%, the antibacterial properties are saturated, and the corrosion resistance is slightly reduced. For this reason, the volume ratio of titanium oxide is set to 0.0001% or more, preferably 5% or less. If the size of the titanium oxide exceeds 50 μm, the corrosion resistance and the workability may be reduced. Therefore, the size is preferably 50 μm or less.

The stainless steel material of the present invention comprises the balance Fe and unavoidable impurities except for the chemical composition in the above-mentioned range. In addition, from the viewpoint of preventing deterioration of corrosion resistance, silver oxide,
It is desirable that the amount of soluble oxides and sulfides other than silver sulfide and titanium oxide be as small as possible. The steel material of the present invention,
In general, all known smelting methods can be applied and smelting can be performed. Therefore, the smelting method does not need to be particularly limited. For example, as a steelmaking method, smelting is performed in a converter, an electric furnace, etc., and SS-VOD (Strongly S
It is preferable to perform secondary refining by tirred vacuum oxygen decarburization).

For the addition of Ag and Ti to molten steel, it is preferable to add the Ag-containing material and the Ti-containing material as additive raw materials in the form of pellets having a maximum diameter of 50 mm or less. When the maximum diameter of the pellet exceeds 50 mm, the total volume ratio of silver particles, silver sulfide and silver oxide is 0.0001% or more, and the volume ratio of Ti oxide is
It becomes difficult to set the content to 0.0001% or more, and furthermore, it is difficult to obtain a uniform dispersion of Ag and Ti, and it is difficult to obtain a stable expression of antibacterial properties.

Although the molten steel can be made into a steel material by a generally known casting method, it is preferable to apply a continuous casting method from the viewpoint of productivity and quality. In the continuous casting method,
In order to uniformly and finely disperse silver particles, silver oxide, silver sulfide, titanium oxide and their composite oxides in the steel more than the above-mentioned amount, the casting speed is set in the range of 0.7 to 1.7 m / min. It is desirable to do.

If the casting speed is less than 0.7 m / min, the silver particles, silver oxide, silver sulfide, titanium oxide and the composite oxide of silver and titanium become coarse, deteriorating the corrosion resistance and stabilizing antibacterial activity. It becomes difficult to express the property. On the other hand, when the casting speed exceeds 1.7 m / min, stable casting is difficult, and Ag is not uniformly dispersed in the steel, and silver oxide is present on the surface of the steel material in use in a dispersed state. Therefore, the antibacterial property is not stably exhibited. For these reasons, it is desirable that the casting speed in the continuous casting method be in the range of 0.7 to 1.7 m / min.

Incidentally, during the smelting process, Ti is made of metallic titanium,
Ti-containing material such as ferro-titanium, Ag may be added with Ag-containing material such as metallic silver, and part or all may be mixed during molten steel or continuous casting, or titanium oxide, Ag, silver oxide Alternatively, a fine powder of silver sulfide may be added to a continuous casting mold or a mold in the ingot forming method. It is needless to say that the present invention is not limited to these as long as titanium oxide, silver particles, silver oxide, and silver sulfide can be finely dispersed in the steel material.

In the present invention, molten stainless steel having the above-mentioned chemical composition is preferably cast continuously under the above-mentioned conditions to obtain a steel material, and if necessary, the steel material is heated to a predetermined temperature. Next, a hot-rolled sheet having a desired thickness is formed by hot rolling. The hot rolled sheet is preferably 700 if necessary.
After annealing at 11180 ° C., cold rolling is performed to obtain a cold-rolled sheet having a predetermined thickness.

The cold-rolled sheet is preferably subjected to annealing at 700 to 1180 ° C. and pickling to form a cold-rolled annealed sheet.
Further, in the present invention, the surface roughness of the steel material is 0.01 μm in Ra.
It is preferable to adjust the thickness to a range of from 10 μm. Ra is 0.01μ
If it is less than m, the time until the onset of antibacterial properties is long, and it is not effective as an antibacterial steel material. Also, when Ra exceeds 10 μm,
Bacteria easily accumulate and hardly exhibit antibacterial properties. The surface roughness of the steel material is preferably adjusted by pickling, polishing, dull rolling, skin pass rolling, shot blasting or the like.

[0031]

EXAMPLE A slab (steel material) having a thickness of 200 mm was produced by melting a stainless steel having the chemical composition shown in Table 1 and changing the casting speed by a continuous casting method, and then heating and hot rolling the slab. A hot-rolled sheet having a thickness of 4 mm was used. The addition of Ti was performed in the form of a pellet having the maximum diameter shown in Table 2 using titanium metal as a Ti-containing material. For Ti, metallic titanium was added to molten steel having different oxygen contents to change the amount of titanium oxide dispersed in the steel. Further, in some steel sheets, titanium oxide obtained by adding titanium oxide powder to a mold in a continuous casting method was dispersed in the steel sheet. Also, Ag
Was added to molten steel in the form of pellets having the maximum diameter shown in Table 2 using metallic silver as an Ag-containing material.

Next, the hot-rolled sheet was annealed at 700 to 1180 ° C., pickled, and then cold-rolled into a cold-rolled sheet having a thickness of 1.0 mm. Next, the cold-rolled sheet was annealed and, if necessary, pickled and polished to obtain a cold-rolled annealed sheet having various surface finishes (surface roughness). The annealing temperature of the cold rolled sheet was 1100 ° C for austenitic (γ) stainless steel, 850 ° C for ferritic (α) stainless steel, and 800 ° C for martensitic (α ') stainless steel.

With respect to these cold rolled annealed sheets, the surface roughness,
A workability test, a corrosion resistance test, and an antibacterial test were performed. In order to confirm the durability and durability of the antibacterial property, a repeated antibacterial test was performed. Also, to confirm safety,
Microbial mutagenicity tests were performed. The test method of each test described above is shown below. (1) Antibacterial property test The antibacterial property was evaluated based on the following procedure.

A 25 cm ² specimen is washed and degreased with absorbent cotton containing 99.5% ethanol. E. coli is dispersed in a 1/500 NB solution. (The number of bacteria is 2.
It was adjusted to 0 × 10 ^{5 to} 1.0 × 10 ⁶ cfu / ml. The 1/500 NB solution is a solution obtained by diluting a normal Bion medium (NB) 500 times with sterilized purified water. Normal Bion medium (NB) is meat extract 5.0g, sodium chloride 5.0g, peptone 10.0
g, purified water 1.000 ml, pH: 7.0 ± 0.2. ) Inoculate the test sample (3 each) with the bacterial solution at a rate of 0.5 ml / 25 cm ² .

The specimen is stored for 24 hours under a fluorescent lamp irradiation condition at a temperature (25 ± 1.0 ° C.) and RH (relative humidity) of 90% or more. The number of viable cells is measured by an agar culture method (35 ± 1.0 ° C, 40 to 48 hours). The antibacterial property is calculated using the sterilization rate defined by the following formula, ◎,
△, △, × were evaluated on a four-point scale. ◎ indicates that the sterilization rate of all three specimens is 99.5% or more, ○ indicates that the sterilization rate of all three specimens is 99.0% or more (except when all three specimens are 99.5% or more)
In the case of, △ indicates that one or two of the three specimens had a sterilization rate of less than 99.0% and the remainder was 99.0% or more, and X indicates that the sterilization rate of all three specimens was less than 99.0%.

Bacteria reduction rate (%) = ((number of bacteria in the control−number of bacteria after the test) / (number of bacteria in the control)) × 100 The number of bacteria in the control was determined by conducting an antibacterial test using a sterilized petri dish. The viable cell count after the test was 9.30 × 10 ⁷ cfu / ml. The number of bacteria after the test is the number of viable bacteria measured. In addition, the same antibacterial test was repeatedly performed 10 times using the test body after the antibacterial test, and the persistence of the antibacterial property was similarly evaluated. (2) Corrosion resistance test The corrosion resistance was evaluated by a salt-dry / wet combined cycle test.

The test piece is sprayed with a 5.0% aqueous NaCl solution (temperature: 35 ° C.) for 0.5 hours, and then kept in a dry atmosphere at a humidity of 40% or less and a temperature of 60 ° C. for 1.0 hour. Hold for 1.0hr in a humid atmosphere with a humidity of 95% or more and a temperature of 40 ° C. Is combined into one cycle, and after repeating 10 cycles, the rusting area ratio (%) of the test piece surface is measured. If the rusting area rate is less than 5%, it is evaluated as ○, and the rusting area rate is 10% or more. If so, it was evaluated as ×. In addition, when the rusting area ratio was 5% or more and less than 10%, it was evaluated as Δ. (3) Workability test Workability was evaluated by a close contact bending test. The adhesion bending test was performed at an inner radius of 0 and a bending angle of 180 ° in accordance with the JIS Z 2248 metal material bending test method. When no crack was generated in the bent portion, it was evaluated as ○, and when crack was generated, it was evaluated as ×. (4) Mutagenicity test The mutagenicity test was performed using Escherichia coli WP2 u as a microorganism.
Using a vrA strain and a Salmonella Typhimurium TA strain, a reversion test including metabolic activation was performed. did. (5) Surface roughness test The surface roughness was measured using a stylus type surface roughness meter on a test piece having a size of 50 × 50 mm, which was sampled from each steel plate, using a stylus type surface roughness meter. ).

Table 2 shows the results.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

[Table 4]

From Table 2, it can be seen that a steel sheet containing Ag and Ti and having a total amount of one or more of silver particles, silver oxides and silver sulfides, and a titanium oxide amount within the scope of the present invention. (Example of the present invention) is excellent in processability and corrosion resistance, and is excellent in antibacterial property by reducing the number of Escherichia coli by 99% or more in an antibacterial test, and also reduces Escherichia coli in a repeated antibacterial test. It can be confirmed that the antibacterial activity is excellent. In addition, the above results can be confirmed for any of austenitic, ferritic, and martensitic stainless steels regardless of the type of stainless steel. In addition, the steel sheets of the present invention were all negative in the mutagenicity test using microorganisms, and had no safety problems.

On the other hand, in a comparative example outside the scope of the present invention,
Regardless of the type of stainless steel, the amount of Escherichia coli is small and the antibacterial property is deteriorated, or the antibacterial property by repeated antibacterial tests is reduced, and the sustainability of the antibacterial property is deteriorated.

[0045]

According to the present invention, the antibacterial properties are excellent without deteriorating the workability and corrosion resistance, the durability of the antibacterial properties is excellent, and the excellent antibacterial properties are obtained even after surface treatment including polishing. It is possible to provide a stainless steel material having a property, and it is possible to provide industrially remarkable effects. Furthermore, there is also an effect that the use of stainless steel can be expanded to uses where high workability is strongly required and antibacterial properties which have not been applied so far are required. Further, the stainless steel material of the present invention is formed,
It is polished and is suitable for members used in applications where importance is placed on hygiene in humid environments such as kitchens and bathtubs.

Continued on the front page (72) Inventor Susumu Sato 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba F-term in the Technical Research Institute, Kawasaki Steel Co., Ltd. 4E004 MC05 NC02 4H011 AA02 BA01 BB18 BC18

Claims (3)

[Claims] 1. Ag: 0.0001 to 1.0 wt% and Ti: 0.001
A stainless steel material containing at least 0.0001% by volume of at least one of silver particles, silver sulfides and silver oxides, and 0.0001% by volume of titanium oxide. % Stainless steel with excellent antibacterial properties. 2. A continuous casting of molten stainless steel to form a steel material, wherein the molten stainless steel is added to a material containing Ag and Ti in the form of pellets having a maximum diameter of 50 mm or less, and Ag: 0.0001 to 1.0 wt. % And Ti: 0.001 to 3wt%
A method for producing a stainless steel material, characterized in that a molten steel containing stainless steel is contained and the casting speed of the continuous casting is 0.7 to 1.7 m / min. 3. A method for manufacturing a cold-rolled stainless steel sheet, comprising subjecting a stainless steel molten steel to continuous casting to form a steel material, followed by hot rolling and cold rolling, wherein the stainless steel molten steel is made of a material containing Ag and a material containing Ti: In the form of pellets having a maximum diameter of 50 mm or less, Ag: 0.0001 to 1.0 wt% and Ti: 0.001 to
A method for producing a cold-rolled stainless steel sheet having excellent antibacterial properties, wherein molten stainless steel containing 3 wt% is used and the casting speed of the continuous casting is 0.7 to 1.7 m / min.