Surface treatment liquid and surface treatment method

Abstract

To provide a surface treatment liquid that improves the antiviral and antibacterial properties of copper or copper alloys, and a surface treatment method using the same.SOLUTION: A surface treatment liquid for the antiviral and antibacterial properties of copper or copper alloys contains reduced glutathione, a C1-4 lower alcohol, and water. The proportion of the volume of the lower alcohol to the total volume of the lower alcohol and water is 80 vol.% or more and less than 100 vol.%. The concentration of the reduced glutathione is 2 mM or more and 20 mM or less.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a surface treatment solution for improving the antiviral and antibacterial properties of copper or a copper alloy, and a method for surface treatment of copper or a copper alloy. [Background technology]

[0002] In response to the recent spread of the novel coronavirus (COVID-19), hygiene awareness in society has increased, and infection control measures have become essential. As part of such infection control measures, there is a demand for antiviral and antibacterial agents that can inactivate viruses and bacteria.

[0003] Meanwhile, metallic copper and its alloys have been attracting attention as antibacterial and antiviral materials. Recently, a technology has been developed to improve the antibacterial properties of copper or copper alloys using a reducing substance in the body (see, for example, Patent Document 1). According to Patent Document 1, the immediate effect of the antibacterial action can be increased by treating the surface of copper or copper alloys with a reducing agent solution containing a reducing substance in the body.

[0004] However, in general, it takes several hours or more for copper and copper alloys to inactivate viruses, and therefore immediate antiviral action is required (see Non-Patent Documents 1 and 2). According to Non-Patent Document 1, the number of human influenza viruses seeded on pure copper is reduced to 1 / 2000 or less after 30 minutes, and to about 1 / 100000 or less after 1 hour. Also, according to Non-Patent Document 1, the number of feline calicivirus viruses seeded on pure copper is reduced to 1 / 200 or less after 30 minutes, and to about 1 / 1000 or less after 1 hour. However, neither method can reduce the infectivity to 0. Also, Non-Patent Document 2 reports that it takes about 8 hours for coronavirus to be completely inactivated on a copper surface.

[0005] Viruses are broadly classified into enveloped viruses that have an envelope (membrane lipid) and non-enveloped viruses that do not have an envelope. Enveloped viruses include coronaviruses, influenza viruses, herpes viruses, rubella viruses, etc. Non-enveloped viruses include noroviruses and rotaviruses. The feline calicivirus mentioned above is used as an alternative model for the non-enveloped virus norovirus.

[0006] It is known that the inactivation of viruses differs depending on whether the virus is an enveloped virus or a non-enveloped virus. For example, alcohol and surfactants destabilize the envelope and therefore inactivate enveloped viruses, but are less effective at inactivating non-enveloped viruses that do not have an envelope (see, for example, Non-Patent Document 3). Non-Patent Document 3 reports that disinfectant ethanol has a low inactivation effect on feline calicivirus, which is an alternative model for norovirus. Therefore, in order to inactivate non-enveloped viruses, a strong oxidizing agent such as hypochlorous acid is required. Such oxidizing agents have a limited range of application because they are highly reactive and damage materials and the human body. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2019 / 008950 [Non-patent literature]

[0008] [Non-Patent Document 1] The excellent bactericidal power of copper, Japan Copper Center document, March 5, 2016 [Non-Patent Document 2] The New England Journal of Medicine 382:1564-4567(2020) [Non-Patent Document 3] Kazuki Okamoto et al., Environmental Infection Journal, Vol. 25, no. 2, 2019 Summary of the Invention [Problem to be solved by the invention]

[0009] In view of the above, an object of the present invention is to provide a surface treatment liquid that improves the antiviral and antibacterial properties of copper or a copper alloy, and a surface treatment method using the same. A further object of the present invention is to provide a surface treatment liquid that improves the antiviral and antibacterial properties of copper or a copper alloy, not only against enveloped viruses but also against non-enveloped viruses, and a surface treatment method using the same. [Means for solving the problem]

[0010] The antiviral and antibacterial surface treatment liquid for copper or a copper alloy according to the present invention contains reduced glutathione, a lower alcohol having 1 to 4 carbon atoms, and water, in which the ratio (volume %) of the volume of the lower alcohol to the total volume of the lower alcohol and the water is 80% or more and less than 100%, and the concentration of the reduced glutathione is in the range of 2 mM or more and 20 mM or less, thereby solving the above-mentioned problems. The volume ratio of the lower alcohol may be 90% or more and less than 100%. The volume percentage of the lower alcohol may be 94% or more and less than 100%. The concentration of the reduced glutathione may be in the range of 3 mM to 20 mM. The concentration of the reduced glutathione may be in the range of 3 mM to 10 mM. The lower alcohol may be selected from the group consisting of methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, ethylene glycol, propylene glycol, and denatured alcohols thereof. The lower alcohol may be selected from the group consisting of methanol, ethanol, isopropyl alcohol and denatured alcohols thereof. The surface treatment solution may be for enveloped and non-enveloped viruses. The method for treating the surface of an article containing copper or a copper alloy according to the present invention comprises applying the above-mentioned surface treatment liquid to the surface of the article, thereby solving the above-mentioned problems. The application may be selected from the group consisting of dripping, dip coating, flow coating, curtain coating, spin coating, spray coating, airless spray coating, bar coating, roll coating, and brush coating. The amount of reduced glutathione applied to the surface of the article is 0.1 nmol / cm 2 More than 100nmol / cm 2 The following ranges may be used: The amount of reduced glutathione applied to the surface of the article is 0.25 nmol / cm 2 More than 50nmol / cm 2 The following ranges may be used: The copper alloy may be selected from the group consisting of a Cu-Zn alloy, a Cu-Ni alloy, a Cu-Ni-Zn alloy, a Cu-Sn alloy, a Cu-Sn-P alloy, a Cu-Sn-Ni-Zn alloy, and a Cu-Si-Pb-P-Zn alloy. The article may be selected from the group consisting of a handle, a button, a building material, an electronic component, and a musical instrument part. Effect of the Invention

[0011] The antiviral and antibacterial surface treatment liquid for copper or copper alloy according to the present invention contains reduced glutathione, a lower alcohol having 1 to 4 carbon atoms, and water, and therefore improves antiviral properties in addition to antibacterial properties. In particular, the volume ratio (volume %) of the lower alcohol is 80% or more and less than 100%, which improves antiviral properties and can inactivate not only enveloped viruses but also non-enveloped viruses. In addition, the concentration of reduced glutathione is in the range of 2 mM or more and 20 mM or less, which can also improve antibacterial properties. [Brief description of the drawings]

[0012] [Figure 1] A flow chart showing the steps of treating the surface of an article containing copper or a copper alloy using the surface treatment solution of the present invention. [Diagram 2] FIG. 1 shows the GSH concentration dependence of nucleic acid recovery rate on the surface of a copper substrate treated with a surface treatment solution containing ethanol. [Diagram 3] FIG. 1 shows the nucleic acid recovery rate on a copper substrate surface treated with a surface treatment solution containing methanol and isopropyl alcohol. [Figure 4] FIG. 13 shows the change in viability of Escherichia coli on the surface of a copper substrate treated with the surface treatment solution of Example 14. [Diagram 5] FIG. 13 shows the change in viable cell rate of Staphylococcus aureus on the surface of a copper substrate treated with the surface treatment solution of Example 14. [Figure 6] FIG. 1 shows the change in the infectivity rate of bacteriophage on the copper substrate surface and the glass substrate surface after surface treatment with the surface treatment solutions of Examples 14 and 25 (1 hour after application) versus phage contact time. [Figure 7] FIG. 13 shows the change in the infectivity of bacteriophage on the copper substrate surface and the glass substrate surface after surface treatment with the surface treatment solutions of Examples 14 and 25 (24 hours after application) versus phage contact time. [Figure 8] FIG. 1 shows the time course of the infectivity rate (5 minutes after contact) of bacteriophage on the copper substrate surface treated with the surface treatment solution of Example 14. [Figure 9] FIG. 1 shows the time course of the infectivity rate (10 minutes after contact) of bacteriophage on the copper substrate surface treated with the surface treatment solution of Example 14. [Figure 10] FIG. 13 shows the change in the infectivity rate of bacteriophage over time on the copper substrate surface treated with the surface treatment solutions of Examples 14 to 16. [Figure 11] FIG. 13 shows the change in the infectivity rate of bacteriophage over time on the copper substrate surfaces treated with the surface treatment solutions of Examples 7, 14, and 23. [Figure 12]FIG. 13 is a graph showing the change in the infectivity rate of bacteriophage over time on the copper alloy substrate surface treated with the surface treatment solution of Example 14. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that like elements are given like reference numerals and their description will be omitted. (Embodiment 1) In the first embodiment, a surface treatment liquid for improving the antiviral and antibacterial properties of copper or a copper alloy according to the present invention will be described.

[0014] Prior to describing the surface treatment solution of the present invention, the copper and copper alloys used in the present invention will be described.

[0015] Copper and copper alloys are not particularly limited as long as they can elute copper (I) ions in the presence of a reducing agent (reduced glutathione in this specification). For example, copper includes oxygen-free copper (JIS H3100 alloy number C1020), tough pitch copper (JIS H3100 alloy number C1100), phosphorus-deoxidized copper (JIS H3100 alloy number C1201, C1220), and electrolytic copper foil, which are specified in JIS H0500 and JIS H3100, and have a purity of 95% by mass or more, more preferably 99.90% by mass or more. These coppers elute copper (I) ions by a reducing agent, particularly reduced glutathione, which will be described later.

[0016] The copper alloy used in the present invention is an alloy containing 50% or more by mass of the above-mentioned copper, and examples thereof include, but are not limited to, an alloy of copper and zinc (brass: Cu-Zn alloy), an alloy of copper and nickel (cupronickel: Cu-Ni alloy), an alloy of copper, nickel and zinc (nickel silver: Cu-Ni-Zn alloy), an alloy of copper and tin (bronze: Cu-Sn alloy), an alloy of copper, tin and phosphorus (phosphor bronze: Cu-Sn-P alloy), an alloy of copper, tin, nickel and zinc (Cu-Sn-Ni-Zn alloy), and an alloy of copper, silicon, lead, phosphorus and zinc (Cu-Si-Pb-P-Zn alloy).

[0017] In addition, as the copper alloy, for example, a binary alloy having two major component elements including copper, a ternary alloy having three major component elements including copper, and an alloy having four or more major component elements including copper can be used. As the binary alloy, for example, a Cu-Zn alloy can be mentioned, specifically, for example, brass (JIS H3100 alloy number C2600, C2680) can be mentioned. As the ternary alloy, for example, a Cu-Ni-Zn alloy can be mentioned, preferably having a composition containing 50.0 mass% or more and 60.0 mass% or less of Cu, 5.0 mass% or more and 15.0 mass% or less of Ni, and the balance being zinc and unavoidable impurities. In addition, as the copper alloy having four or more major component elements, for example, a Cu-Sn-Ni-Zn alloy and a Cu-Si-Pb-P-Zn alloy can be mentioned. Preferably, the Cu-Sn-Ni-Zn alloy contains 60.0% by mass or more and 80.0% by mass or less of Cu, 0.1% by mass or more and 1.0% by mass or less of Sn, 0.5% by mass or more and 5.0% by mass or less of Ni, and the remainder is composed of zinc and inevitable impurities. Also, preferably, the Cu-Si-Pb-P-Zn alloy contains 65.0% by mass or more and 85.0% by mass or less of Cu, 1.0% by mass or more and 5.0% by mass or less of Si, 0.01% by mass or more and 1.0% by mass or less of Pb, and 0.01% by mass or more and 0.5% by mass or less of P, and the remainder is composed of zinc and inevitable impurities. These copper alloys dissolve copper (I) ions by a reducing agent, particularly reduced glutathione, which will be described later.

[0018] The surface treatment liquid of the present invention contains reduced glutathione, a lower alcohol having 1 to 4 carbon atoms, and water. The inventors of the present application have discovered that reduced glutathione can be dissolved in lower alcohol by using it together with water. Furthermore, they have discovered that by combining these, antibacterial and antiviral properties can be imparted. Here, the ratio (volume %) of the volume of the lower alcohol to the total volume of the lower alcohol and water is 80 volume % or more and less than 100 volume %, and therefore it has been found that it is effective against not only enveloped viruses but also non-enveloped viruses. In addition, by setting the concentration of reduced glutathione in the range of 2 mM (mmol / L) to 20 mM, antibacterial properties can also be improved.

[0019] The mechanism by which the surface treatment solution of the present invention improves the antiviral and antibacterial properties of copper and copper alloys is believed to be as follows. 2Cu 2+ +2GSH→2Cu + +GSSG+2H + (1) 2Cu + +2H + +O 2 →2Cu 2+ +H 2 O 2 (2) Cu + +H 2 O 2 →Cu 2+ +OH - +·OH···(3) Here, GSH is reduced glutathione, and GSSG is oxidized glutathione, which is the oxidized form of reduced glutathione. When exposed to air and no moisture, the copper surface is covered with cuprous oxide (Cu 2 O) and copper oxide (CuO) films are formed. In aqueous solution, copper and copper alloys corrode and release thermodynamically stable copper (II) ions. However, when reduced glutathione is present, copper (I) ions are generated (Equation (1)). Copper (I) ions are converted to hydrogen peroxide (H 2 O 2) is generated (equation (2)). The generated hydrogen peroxide reacts with copper(I) ions to generate active oxygen, typically the hydroxyl radical (·OH) (equation (3)).

[0020] Here, not only bacteria but also viruses are damaged by copper (I) ions generated by the action of the reducing agent in addition to copper (II) ions, and further by active oxygen (hydroxyl radicals) generated by the action of the copper (I) ions, so that the antibacterial and antiviral properties of the copper surface can be improved. Furthermore, according to the surface treatment liquid of the present invention, since it contains 80% by volume or more of lower alcohol, reduced glutathione is retained on the surface for a long period of time (for example, one week or more depending on the composition preparation) without corroding copper and copper alloys. As a result, the start of the reaction of the above formula (1) can be delayed. In addition, since the water contained in the surface treatment liquid of the present invention is limited to less than 20% by volume, the reaction of the above formula (2) is controlled. Accordingly, the generation of active oxygen by the above formula (3) is also controlled, so that the reactions of the above formulas (1) to (3) act directly on the bacteria and viruses by contacting the treated surface not immediately after application of the surface treatment liquid but after a certain period of time has passed, and the antibacterial and antiviral properties can be effectively expressed. In particular, since it contains a high concentration of reduced glutathione, at a concentration of 2 mM or more and 20 mM or less, it can quickly generate a sufficient amount of active oxygen and damage bacteria and viruses, even after a certain period of time has passed.

[0021] Each of the components of the surface treatment solution of the present invention will now be described in detail. [Reduced glutathione (GSH)] Reduced glutathione (GSH) can function as a reducing agent that reduces the copper (II) ions dissolved from the above-mentioned copper and copper alloys, or the copper (II) in the copper oxide film formed on the surface of copper and copper alloys, and dissolves the copper (I) ions. Reduced glutathione includes reduced glutathione represented by the following formula and its derivatives.

[0022] [ka]

[0023] Derivatives of reduced glutathione include solvates, salts, and those in which part of the above chemical formula is substituted with a lower alkyl group having 1 to 3 carbon atoms or other substituents, provided that the function of reduced glutathione as a reducing agent is not impaired.

[0024] The concentration of reduced glutathione satisfies the range of 2 mM or more and 20 mM or less. By setting it in this range, it is possible to make copper and copper alloys exhibit excellent antibacterial and antiviral properties. From the viewpoint of preparation of the surface treatment liquid and antibacterial and antiviral properties, the concentration of reduced glutathione is preferably in the range of 3 mM or more and 20 mM or less, more preferably in the range of 3 mM or more and 10 mM or less, and even more preferably in the range of 3 mM or more and 5 mM or less.

[0025] [water] The water is not particularly limited, and may be, for example, tap water, soft water, ion-exchanged water, distilled water, RO water, Milli-Q water, or purified water. The water is preferably soft water, ion-exchanged water, RO water, or distilled water. These may be used alone or in combination of two or more. Since the water is contained, a surface treatment liquid in which reduced glutathione is dissolved can be provided.

[0026] [Lower alcohol] The lower alcohol having 1 to 4 carbon atoms is, for example, selected from the group consisting of methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, ethylene glycol, propylene glycol, and denatured alcohols thereof. These may be used alone or in combination.

[0027] Among the lower alcohols, from the viewpoint of compatibility with water, an alcohol selected from the group consisting of ethanol, methanol, isopropyl alcohol, and denatured alcohols thereof is preferred. Considering the antibacterial and antiviral properties and the effect on the human body, ethanol and its denatured alcohols are more preferred.

[0028] The ratio of the volume of the lower alcohol to the total volume of the lower alcohol and water (volume %) satisfies 80% or more and less than 100%. Within this range, antiviral properties can be increased. From the viewpoint of antibacterial and antiviral properties, the volume ratio of the lower alcohol is preferably 90% or more and less than 100%, more preferably 94% or more and less than 100%, and from the viewpoint of the solubility of reduced glutathione and antibacterial and antiviral properties, it is even more preferably in the range of 94% or more and 99% or less.

[0029] The surface treatment liquid of the present invention can improve the antibacterial and antiviral properties of copper and copper alloy surfaces, but what is noteworthy is that it can inactivate non-enveloped viruses. Until now, a strong oxidizing agent was required to inactivate non-enveloped viruses, but the surface treatment liquid of the present invention is extremely advantageous because it can inactivate non-enveloped viruses using copper (I) ions and active oxygen (hydroxyl radicals) from reduced glutathione without using an oxidizing agent. In addition, since the surface treatment liquid of the present invention contains a lower alcohol, it can naturally inactivate enveloped viruses as well, as has been reported. Therefore, the surface treatment liquid of the present invention is effective against both enveloped and non-enveloped viruses, and does not cause damage to the human body or materials.

[0030] In addition to the above-mentioned components, the surface treatment liquid of the present invention may contain, as necessary, any known optional components such as deodorants, preservatives, fragrances, oily components, thickeners, moisturizers, pigments, emulsifiers, pH adjusters, ceramides, sterols, antioxidants, singlet oxygen quenchers, ultraviolet absorbers, whitening agents, anti-inflammatory agents, surfactants, etc., as long as they are capable of improving the antibacterial and antiviral properties of copper and copper alloys. These may be used alone or in combination of two or more kinds.

[0031] The surface treatment solution of the present invention is prepared as follows. First, reduced glutathione is dissolved in water. Then, it is sufficient to mix with a lower alcohol. At this time, the volume ratio of the lower alcohol to water is adjusted to satisfy the above range, and the final concentration of reduced glutathione is adjusted to satisfy the above range. In this way, a surface treatment solution in which reduced glutathione is dissolved can be provided.

[0032] Although reduced glutathione has been described as a reducing agent, the antibacterial and antiviral properties of copper and copper alloys can also be improved by using N-acetylcysteine, sodium ascorbate, sodium sulfite, and cysteine ​​as reducing agents. Those skilled in the art can adjust the concentration, volume percentage of lower alcohol, etc., depending on the reducing agent selected.

[0033] As described above, by using the surface treatment solution of the present invention, the antibacterial and antiviral properties of copper and copper alloys can be improved, and in particular, not only enveloped viruses but also non-enveloped viruses can be inactivated without the use of a strong oxidizing agent.

[0034] (Embodiment 2) In the second embodiment, a surface treatment method using the surface treatment liquid described in the first embodiment will be described.

[0035] FIG. 1 is a flow chart showing the steps of treating the surface of an article containing copper or a copper alloy with the surface treatment liquid of the present invention.

[0036] The processing method of the present invention includes the following steps. Step S110: The surface treatment liquid of the present invention described in the first embodiment is applied to the surface of an article containing copper or a copper alloy. When the surface treatment liquid of the present invention is applied to the surface of an article, the reduced glutathione remains on the surface of the article for a long period of time even after the solvent has evaporated, without corroding the copper or copper alloy. This is the effect of the large amount of lower alcohol in the surface treatment liquid, and is different from Patent Document 1. As a result, when bacteria or viruses adhere to or scatter on the surface of the article, the reduced glutathione can timely elute copper(I) ions and generate active oxygen via the copper(I) ions, so that the improved antibacterial and antiviral properties of copper or copper alloys can be maintained for a long period of time after surface treatment.

[0037] Explain in detail. In step S110, the surface treatment liquid is the same as that described in the first embodiment, and therefore a description thereof will be omitted.

[0038] Here again, the copper or copper alloy is the copper or copper alloy described in the first embodiment, but is preferably a copper rolled product. In this specification, the copper rolled product is a general term for products such as copper and copper alloy plates, strips, tubes, rods, and wires made by hot or cold plastic processing such as rolling, extrusion, drawing, and forging, according to the definition specified in JIS H0500. By treating the surface of such a copper rolled product with the surface treatment liquid of this embodiment, the bacteria and bacteria attached to the surface and the viruses scattered thereon are more efficiently inactivated, and the surface of the article is subjected to a sterilization and antiviral treatment. The copper rolled product to which the surface treatment method of this embodiment can be applied is not limited to one used alone, and may be used in combination with other products.

[0039] The article containing copper or a copper alloy is not particularly limited as long as it contains the copper or copper alloy described in the first embodiment, but may be, for example, selected from the group consisting of handles, buttons, building materials, electronic parts, and musical instrument parts. Handles include, for example, handrails, doorknobs, door handles, levers, poles, nurse carts, bedside rails, grips, writing implements, desk and chair pipes, and the like, and are used by being held by human hands. Buttons include, for example, elevator buttons and various switches, and are used by being pressed by human hands. Building materials include, for example, wall materials and floor materials in houses, bathrooms, medical institutions, nursing homes, pharmaceutical and medical device manufacturing facilities, and kitchen parts such as sinks. Electronic parts include, for example, smartphones, tablet terminals, cameras, displays, navigation systems, non-contact IC cards, electronic keys, and the like, and are directly operated by human hands. Musical instrument parts include wind instruments such as trumpets, horns, and saxophones, electronic instruments such as pianos and synthesizers, and musical instrument accessories such as guitar strings, and are directly operated by human hands.

[0040] In step S110, the method of applying the surface treatment liquid to the article is not particularly limited, but may be selected from the group consisting of a dripping method, a dip coating method, a flow coating method, a curtain coating method, a spin coating method, a spray coating method, an airless spray coating method, a bar coating method, a roll coating method, and a brush coating method. A person skilled in the art can appropriately select the application method depending on the size and shape of the article to which the surface treatment liquid is to be applied.

[0041] In step S110, the amount of reduced glutathione applied to the article in the surface treatment solution is not particularly limited. However, from the viewpoint of antiviral and antibacterial properties, it is preferable to use a concentration of 0.1 nmol / cm 2 More than 100nmol / cm 2 The amount of reduced glutathione provided may be in the range of 0.25 nmol / cm 2 More than 50nmol / cm 2 and more preferably 0.25 nmol / cm 2 More than 50nmol / cm 2The range is as follows: The amount of reduced glutathione to be provided is calculated as follows. (Coating density of reduced glutathione on the copper or copper alloy substrate surface after coating) = (Concentration of reduced glutathione in the surface treatment solution) x (Amount of coating solution) / (Coating area)

[0042] In step S110, when the surface treatment liquid is applied to the article, most of the solvents are lower alcohols having 1 to 4 carbon atoms, so that the liquid can be dried naturally, but when the application area is large, drying may be performed as necessary. For such drying, air flow, heat drying using a hot plate, or other well-known drying methods can be used.

[0043] The surface treatment of copper or copper alloy with the surface treatment liquid is preferably performed in a state where the surface of the copper or copper alloy to be treated is dry. For example, the surface treatment of copper or copper alloy with the surface treatment liquid can be performed in an air atmosphere controlled at a temperature of 15°C to 30°C and a relative humidity of 70%RH or less, which is a normal environment. Under such conditions, the corrosion of copper or copper alloy by glutathione applied to the substrate surface does not progress rapidly, so that when bacteria or viruses come into contact in the form of droplets, the moisture in the droplets is utilized to rapidly promote the reaction of the above formula (2), thereby facilitating the elution of copper (I) ions and the generation of active oxygen. However, the effect of the present invention can be obtained even under conditions where the temperature is higher than 30°C or the relative humidity is higher than 70%RH.

[0044] In another embodiment, the copper or copper alloy may be fibers, fine particles, foils, etc. (hereinafter simply represented by copper fibers) of copper or copper alloy contained in woven fabric, nonwoven fabric, sponge-like material, or other generally soft porous material (hereinafter represented by cloth). In this case, the surface of the copper fibers is treated with the surface treatment liquid of this embodiment by applying the surface treatment liquid to such cloth, and the antibacterial / antiviral cloth moistened with the surface treatment liquid is brought into contact with the surface of the object (for example, wiped or wiped), whereby the germs, bacteria, etc., and viruses adhering to the surface of the object are transferred to the surface of the antibacterial / antiviral cloth and removed, and are rapidly and efficiently inactivated by the eluted copper ions and active oxygen generated in the vicinity of the copper fibers, and depending on the concentration adjustment, the surface of the object is subjected to a sterilization / viral treatment.

[0045] The present invention will now be described in detail with reference to specific examples, but it should be noted that the present invention is not limited to these examples. EXAMPLES

[0046] [Items subject to surface treatment liquid] Substrates made of the following materials were used as objects to which the surface treatment solution was applied. Oxygen-free copper substrate (Alloy number C1020. Also written as "C1020" or "Cu". Size: For nucleic acid degradation test: 100mm x 100mm x 0.5mm, For antibacterial and antiviral test: 15mm x 15mm x 0.05mm) Brass substrate (alloy number C2680. Also written as "C2680". Size: for antibacterial and antiviral testing: 15mm x 15mm x 0.05mm) Glass substrate (the bottom surface of a regular glass petri dish is used. Size: 60mmφ)

[0047] In order to prevent contamination by residual organic matter, the surfaces of all the substrates were cleaned with a surfactant solution, rinsed with tap water and ultrapure water, and then air-dried.

[0048] [Examples 1 to 27: Preparation of surface treatment solution and antibacterial / antiviral test] As shown in Table 1, surface treatment solutions containing reduced glutathione at various concentrations were prepared. Reduced glutathione (GSH, Fujifilm Wako Pure Chemical Industries, for molecular biology) represented by the above structural formula was dissolved in distilled water and prepared at various concentrations. It was then mixed with lower alcohols, such as absolute ethanol (Fujifilm Wako Pure Chemical Industries, special grade), methanol (Fujifilm Wako Pure Chemical Industries, special grade), and isopropyl alcohol (Fujifilm Wako Pure Chemical Industries, special grade), and stirred thoroughly. Considering the solubility of reduced glutathione and ease of preparation, the lower limit of the lower alcohol was set to 80%.

[0049] [Table 1]

[0050] (1) Nucleic acid degradation test Since it is known that there is a correlation between the ability to decompose nucleic acids and antibacterial and antiviral properties, nucleic acid decomposition tests were carried out using the surface treatment solutions of Examples 1 to 14 and Examples 26 to 27 to determine the conditions for the GSH concentration. The tests were carried out as follows.

[0051] 10 μL of the surface treatment solutions of Examples 1 to 14 and Examples 26 to 27 were dropped and applied to an area of ​​about 20 mm × 20 mm on the surface of an oxygen-free copper (C1020) substrate (Step S110 in FIG. 1). The thickness of the liquid film of the applied surface treatment solution was about 2.5 μm. The amount of reduced glutathione (GSH) on the substrate surface after application was 0.25 to 50 nmol / cm 2 It was.

[0052] Next, after coating, the substrate surface was air-dried in the air at room temperature (25°C) for about 1 minute when the water concentration (volume %) in the surface treatment solution was 5% or less, for 1 to 2 minutes when the water concentration (volume %) was 20%, and for 15 minutes when the water concentration (volume %) was 100%.

[0053] After air drying, 1 μL of a 0.5% solution of salmon testis-derived deoxyribonucleic acid in a surfactant (2-[4-(2,4,4-trimethylpentan-2-yl)phenoxy]ethanol) prepared to a specified concentration as a nucleic acid source was spread over an area of ​​10 mm x 10 mm on the GSH-coated area (20 mm x 20 mm) of the substrate surface, and left to stand at room temperature (25°C) for 5 minutes.

[0054] The nucleic acid-coated area was wiped with a polyester swab soaked in 0.03% sodium dodecyl sulfate (SDS) solution, and the relationship between the nucleic acid recovery rate and the surface treatment solution was examined from the amount of nucleic acid adsorbed to the swab. Specifically, the swab was wiped 20 times in the X direction on the XY plane of the sample, then 20 times in the Y direction, and this process was repeated two and a half times (i.e., a total of 100 times in the XYXYX directions) while changing the side of the swab. The tip of the swab was then cut off with scissors and vigorously stirred in a 0.03% SDS solution to extract the nucleic acid sample adsorbed to the swab. The amount of extracted nucleic acid was quantified using the fluorescent molecule acridine orange (AO), which adsorbs to nucleic acids.

[0055] As a control, the nucleic acid solution was applied to the surface of an untreated (GSH solution not applied) copper substrate (C1020) in the same manner, and the amount of nucleic acid recovered by the swab after 5 minutes was set as 100%, and the recovery rate of nucleic acid recovered from the copper substrate surface coated with GSH solution was calculated. The results are shown in Figures 2 and 3.

[0056] FIG. 2 is a graph showing the GSH concentration dependence of nucleic acid recovery rate on the surface of a copper substrate treated with a surface treatment solution containing ethanol. FIG. 3 is a graph showing the recovery rate of nucleic acid on the surface of a copper substrate treated with a surface treatment liquid containing methanol and isopropyl alcohol.

[0057] Figure 2 shows the results after 1 hour of application of a surface treatment solution containing ethanol. There was a tendency for the nucleic acid recovery rate to decrease with increasing GSH concentration (i.e., for nucleic acids to decompose more). For example, focusing on the results for the surface treatment solution with a water concentration of 1% by volume, indicated by "x" in Figure 2, the nucleic acid recovery rate decreased significantly at GSH concentrations of 2 mM or higher. Other surface treatment solutions with water concentrations of 5% and 20% by volume also showed a tendency for the nucleic acid recovery rate to decrease when the GSH concentration exceeded 2 mM. In detail, the nucleic acid recovery rate when surface treatment solutions with water concentrations of 1% and 5% by volume were used decreased significantly compared to that when the surface treatment solution with water concentration of 20% by volume was used.

[0058] As shown in Figure 3, when the surface treatment solutions of Example 26 using methanol and Example 27 using isopropyl alcohol were used, a decrease in the nucleic acid recovery rate was confirmed, similar to that of ethanol. This suggests that, in addition to ethanol, lower alcohols with carbon numbers of 1 to 4, including methanol and isopropyl alcohol, are also effective.

[0059] From the above, it was suggested that a surface treatment solution containing reduced glutathione, a lower alcohol having 1 to 4 carbon atoms, and water, in which the volume ratio (volume %) of the lower alcohol is 80% or more and less than 100%, and the concentration of reduced glutathione is in the range of 2 mM to 20 mM, improves the antibacterial and antiviral properties of copper and copper alloys. For this reason, the following experiments were mainly performed with a GSH concentration of 2 mM or more.

[0060] (2) Antibacterial test using the film method Antibacterial tests were carried out on copper substrates after surface treatment with the surface treatment solution of the present invention using Escherichia coli and Staphylococcus aureus in accordance with the JIS Z2801 antibacterial test method.

[0061] Using the same procedure as in the above (1) nucleic acid degradation test, the surface treatment solution of Example 14 (GSH concentration: 4 mM, ethanol: 99% by volume, water: 1% by volume, GSH 4 mM, water 1% - EtOH 99%) was dropped and applied to an area of ​​approximately 14 mm x 14 mm on the surface of an oxygen-free copper substrate (C1020) as a substrate, and then dried (step S110 in FIG. 1). At this time, the back surface of the substrate was covered with a thin silicone sheet. Again, the thickness of the applied liquid film was approximately 2.5 μm, and the amount of reduced glutathione (GSH) on the substrate surface was 10 nmol / cm 2 It was.

[0062] After 24 hours had passed since application, the substrate was placed on the bottom of a glass container. Then, approximately 1.0×10 6 50μL of each of E. coli and Staphylococcus aureus suspensions with bacteria / mL were placed on the plate, and a polyethylene film cut into 12mm squares was placed on top to spread the bacterial solution evenly and bring it into contact with the substrate surface. After the bacterial solution was seeded, the glass container was left in an incubator at 35±1℃, and after 5, 10, and 30 minutes, the glass container was removed from the incubator, the polyethylene film was removed, 1mL of NB medium (normal bouillon medium) was added, and the bacteria were collected by pipetting three times.

[0063] The number of bacteria in the collected bacterial solution was measured by the WST-1 method. Specifically, 180 μL of the collected bacterial solution was placed in a well of a 96-well microplate, and 20 μL of detection reagent was added to it. The detection reagent was a mixture of 5 mM WST-1 [2-(4-Iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt] and 0.2 mM 1-methoxy-PMS (1-Methoxy-5-methylphenazinium methylsulfate).

[0064] After adding the detection reagent, the samples were cultured at 35°C and the absorbance at 450 nm was measured at regular intervals (20 min for E. coli, 30 min for Staphylococcus aureus) for about 16 to 24 hours. From the results, the time until the absorbance exceeded 0.5 was calculated, and the initial number of bacteria was estimated using a calibration curve that was created by measuring the number of bacteria inoculated in advance. The results are shown in Figures 4 and 5.

[0065] FIG. 4 is a graph showing the change in viable cell rate of Escherichia coli on the copper substrate surface treated with the surface treatment solution of Example 14. FIG. 5 is a graph showing the change in viable cell rate of Staphylococcus aureus on the copper substrate surface treated with the surface treatment solution of Example 14.

[0066] As a control, Fig. 4 and Fig. 5 also show the change in the viable cell rate on the surface of an oxygen-free copper (C1020) substrate when no surface treatment liquid was applied. In Fig. 4 and Fig. 5, the vertical axis shows the ratio of the number of viable cells in the recovered cell solution to the number of seeded cells as the viable cell rate. According to Fig. 4 and Fig. 5, it was found that for all bacteria, the viable cell rate on the substrate surface coated with the surface treatment liquid of Example 14 (GSH 4mM-water 1%-EtOH 99%) was significantly reduced with only 10 minutes of contact with the bacteria, compared to that of the substrate surface that had not been surface-treated. Although not shown, a similar tendency was confirmed with the surface treatment liquid of Example 10 (GSH 2mM-water 1%-EtOH 99%).

[0067] From the above, it was shown that the antibacterial properties of copper and copper alloys can be improved by treating the surface of copper or a copper alloy with a surface treatment solution containing reduced glutathione, a lower alcohol having 1 to 4 carbon atoms, and water, in which the volume percentage of the lower alcohol (volume %) is 80% or more but less than 100%, and the concentration of reduced glutathione is in the range of 2 mM or more and 20 mM or less.

[0068] (3) Antiviral test using Qβ bacteriophage Using Qβ bacteriophage as a non-enveloped virus, an antiviral test was carried out on a copper substrate that had been surface-treated with the surface treatment solution of the present invention. The test was carried out with reference to JIS R1706:2020.

[0069] Using the same procedure as in the above (1) nucleic acid decomposition test, various surface treatment solutions were dropped and applied to an area of ​​approximately 14 mm x 14 mm on the surfaces of oxygen-free copper (C1020), brass (C2680), and glass substrates, and then dried (step S110 in Figure 1). At this time, the backside of the substrate was covered with a thin silicone sheet.

[0070] The substrate was placed on the bottom of the glass container 1 hour, 3 hours, 24 hours, and 168 hours after coating. 7 50μL of pfu / mL phage suspension was placed on the plate, and a polyethylene film cut into 12mm squares was placed on top to spread the phage liquid evenly and bring it into contact with the plate surface. After inoculation with the phage liquid, the glass container was left at room temperature for 5, 10, and 30 minutes, after which the polyethylene film was removed, 1mL of SCDLP medium was added, and the phage was collected by pipetting three times.

[0071] The infectious titer of the recovered phage solution was confirmed by plaque assay. Specifically, a 10-fold dilution series of the recovered phage solution was prepared using peptone-added saline, and a small amount of each solution was added to 2 mL of soft agar medium containing the host Escherichia coli, and layered on a soft agar medium dish prepared in advance. After the medium solidified, the medium was cultured at 37°C for about 18 hours, and the number of plaques in the dish of the appropriate dilution series was counted to determine the infectious titer of the recovered phage solution. The results are shown in Table 2 and Figures 6 to 12.

[0072] [Table 2]

[0073] FIG. 6 is a graph showing the change in infectivity of bacteriophage over phage contact time on the copper substrate surface and the glass substrate surface after surface treatment with the surface treatment solutions of Examples 14 and 25 (1 hour after application). FIG. 7 is a graph showing the change in infectivity of bacteriophage on a copper substrate surface and a glass substrate surface after surface treatment with the surface treatment solutions of Examples 14 and 25 (24 hours after application) versus phage contact time.

[0074] 6 and 7 also show, as controls, the change in infectivity titer versus phage contact time on an oxygen-free copper (C1020) substrate surface and a glass substrate surface when no surface treatment solution was applied.

[0075] Focus on the infectivity titer on the copper substrate surface in Figures 6 and 7. According to the results of the control where no surface treatment solution was used, the infectivity titer showed a tendency to decrease with the passage of contact time, but did not reach 0 even after 20 minutes of phage contact. This shows that although copper itself has antiviral properties, they are not sufficient.

[0076] Furthermore, according to the results for the copper substrate surface treated with the surface treatment solution of Example 25 (0 mM GSH-1% water-99% EtOH), the change in infectivity was equivalent to the result for the control in which no surface treatment solution was used, and no significant effect on the antiviral activity was observed.

[0077] However, when the copper substrate surface was treated with the surface treatment solution of Example 14 (GSH 4 mM - water 1% - EtOH 99%), all phages were surprisingly inactivated (infectivity titer 0) 5 minutes after contact with the phages, even 24 hours after application of the surface treatment solution. It is noteworthy that the surface treatment solution of the present invention can increase the antiviral activity of copper metal against non-enveloped viruses.

[0078] On the other hand, when focusing on the infectivity titers on the glass substrate surfaces in Figures 6 and 7, the results for the control in which no surface treatment solution was used and the results for the surface treatment solution of Example 25 (GSH 0 mM, water 1%, EtOH 99%) showed no decrease in the infectivity titer, and no antiviral activity was observed. The infectivity titer on the glass substrate surface treated with the surface treatment solution of Example 14 (GSH 4 mM, water 1%, EtOH 99%) was only slightly lower than the results for the control and the surface treatment solution of Example 25, but even after 20 minutes of phage contact, the infectivity titer was approximately 3 x 10 5 pfu / mL, which was much higher than that of the control, a copper substrate surface that had not been treated with the surface treatment solution.

[0079] From the above, it was shown that both copper and reduced glutathione (GSH) are necessary to improve antiviral properties, and that the antiviral properties of copper can be improved by treating the surface of copper with the surface treatment solution of the present invention, which contains reduced glutathione, a lower alcohol having 1 to 4 carbon atoms, and water, in which the volume ratio (volume %) of the lower alcohol is 80% or more and less than 100%, and the concentration of reduced glutathione is in the range of 2 mM or more and 20 mM or less. It was also shown that the surface treatment solution of the present invention is effective not only against enveloped viruses, but also against non-enveloped viruses.

[0080] FIG. 8 is a graph showing the change in infectivity of bacteriophage (contact time: 5 minutes) on the surface of a copper substrate treated with the surface treatment solution of Example 14 over time after application. FIG. 9 is a graph showing the change in infectivity of bacteriophage (contact time: 10 minutes) on the copper substrate surface treated with the surface treatment solution of Example 14 over time after application.

[0081] As a control, Fig. 8 and Fig. 9 also show the change in infectivity titer over time after application on the surface of an oxygen-free copper (C1020) substrate when the surface treatment solution was not applied. According to Fig. 8 and Fig. 9, the infectivity titer on the copper substrate surface treated with the surface treatment solution of Example 14 (GSH 4 mM - water 1% - EtOH 99%) was 0 1 hour, 3 hours, and 24 hours after application, regardless of the phage contact time, and all phages were inactivated. In particular, according to Fig. 9, the infectivity titer on the copper substrate surface 168 hours after application of the surface treatment solution of Example 14 was also 0, indicating excellent antiviral properties.

[0082] From the above, it was demonstrated that the surface treatment solution of the present invention can improve the antiviral properties of copper even more than 24 hours after application (treatment), and is effective for a long period of time.

[0083] FIG. 10 is a graph showing the change in infectivity of bacteriophage on the copper substrate surfaces treated with the surface treatment solutions of Examples 14 to 16 over time with contact with the phage.

[0084] FIG. 10 also shows the change in infectivity titer on the surface of an oxygen-free copper (C1020) substrate with phage contact time when no surface treatment liquid was applied as a control. According to FIG. 10, the infectivity titer of the copper substrate surface treated with the surface treatment liquid of Example 14 (GSH 4 mM, water 1%-EtOH 99%) was 0 after 5 minutes of phage contact. The infectivity titer of the copper substrate surface treated with the surface treatment liquid of Example 15 (GSH 4 mM, water 5%-EtOH 95%) was 0 after 10 minutes of phage contact. The infectivity titer of the copper substrate surface treated with the surface treatment liquid of Example 16 (GSH 4 mM, water 20%-EtOH 80%) was 0 after 20 minutes of phage contact. In other words, it was found that the lower the water content (the higher the ethanol content), the more improved the antiviral properties.

[0085] From the above, it was shown that the surface treatment solution of the present invention can improve the antiviral properties of copper even after 24 hours from application (treatment), and has long-term effectiveness. It was also shown that the surface treatment solution of the present invention can exhibit excellent antiviral properties when the volume ratio of the lower alcohol is preferably 90% or more and less than 100%, more preferably 94% or more and less than 100%.

[0086] FIG. 11 is a graph showing the change in infectivity of bacteriophage on the copper substrate surfaces treated with the surface treatment solutions of Examples 7, 14 and 23 as a function of phage contact time.

[0087] FIG. 11 also shows the change in infectivity titer with phage contact time on the surface of an oxygen-free copper (C1020) substrate when no surface treatment solution was applied as a control. The results of the copper substrate surface treated with the surface treatment solution of Example 14 (GSH 4 mM, water 1%-EtOH 99%) in FIG. 11 are the same as those in FIG. 10, and the infectivity titer was 0 after 5 minutes of phage contact. The infectivity titer of the copper substrate surface treated with the surface treatment solution of Example 23 (GSH 20 mM, water 5%-EtOH 95%) was 0 after 10 minutes of phage contact. The infectivity titer of the copper substrate surface treated with the surface treatment solution of Example 7 (GSH 1 mM, water 1%-EtOH 99%) was reduced compared to that of the control without the surface treatment solution, but no significant effect was observed.

[0088] From the above, it has been demonstrated that in the surface treatment solution of the present invention, when the concentration of reduced glutathione is 2 mM or more and 20 mM or less, more preferably 3 mM or more and 20 mM or less, and most preferably 3 mM or more and 5 mM or less, excellent antiviral activity can be exhibited.

[0089] FIG. 12 is a graph showing the change in the infectivity of bacteriophage on the copper alloy substrate surface treated with the surface treatment solution of Example 14 versus phage contact time.

[0090] Figure 12 also shows the change in infectivity titer on the brass (C2680) substrate surface as a control when no surface treatment solution was applied, depending on the phage contact time. According to Figure 12, the infectivity titer on the copper alloy substrate surface treated with the surface treatment solution of Example 14 (GSH 4 mM - water 1% - EtOH 99%) was reduced to at least 1 / 10 compared to the control result when no surface treatment solution was applied. Moreover, the infectivity titer became 1 / 1000,000 of the infectivity titer of the seeded phage after 20 minutes of phage contact.

[0091] From the above, it has been demonstrated that the surface treatment liquid of the present invention can improve the antiviral properties of copper alloys in addition to copper metal, and is effective not only against enveloped viruses but also against non-enveloped viruses. [Industrial Applicability]

[0092] By simply applying the surface treatment solution of the present invention to an article containing copper metal or copper alloy, the antibacterial and antiviral properties of the copper metal or copper alloy can be improved, and the surface treatment solution of the present invention can be used in environments where antibacterial and antiviral properties of articles containing copper metal or copper alloy are desired. In particular, the surface treatment solution of the present invention is advantageous in that it can inactivate non-enveloped viruses without using a strong oxidizing agent, without damaging the human body or materials. In addition, since the improved antiviral activity is maintained for a certain period after application of the surface treatment solution, it can also be applied to products or components that cannot be disinfected or wiped frequently. Furthermore, since the antibacterial and antiviral activity is expressed in a short time of 5 minutes, it can also be used for the purpose of disinfecting or sterilizing the surface of copper or copper alloy substrates.

Claims

1. Reduced glutathione and a lower alcohol having 1 to 4 carbon atoms; Water and Contains a ratio (vol %) of the volume of the lower alcohol to the total volume of the lower alcohol and the water is 80% or more and less than 100%; The antiviral and antibacterial surface treatment solution for copper or a copper alloy, wherein the concentration of the reduced glutathione is in the range of 2 mM or more and 20 mM or less.

2. The surface treatment solution according to claim 1 , wherein the volume ratio of the lower alcohol is 90% or more and less than 100%.

3. The surface treatment solution according to claim 2 , wherein the volume ratio of the lower alcohol is 94% or more and less than 100%.

4. 2. The surface treatment solution according to claim 1, wherein the concentration of the reduced glutathione is in the range of 3 mM to 20 mM.

5. 5. The surface treatment solution according to claim 4, wherein the concentration of the reduced glutathione is in the range of 3 mM to 10 mM.

6. 2. The surface treatment solution according to claim 1, wherein the lower alcohol is selected from the group consisting of methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, ethylene glycol, propylene glycol, and denatured alcohols thereof.

7. 7. The surface treatment solution according to claim 6, wherein the lower alcohol is selected from the group consisting of methanol, ethanol, isopropyl alcohol, and denatured alcohols thereof.

8. The surface treatment solution according to claim 1 , wherein the surface treatment solution is for enveloped viruses and non-enveloped viruses.

9. 1. A method for treating the surface of an article containing copper or a copper alloy, comprising: Applying the surface treatment liquid according to any one of claims 1 to 8 to the surface of the article. The method includes:

10. 10. The method of claim 9, wherein the application is selected from the group consisting of dripping, dip coating, flow coating, curtain coating, spin coating, spray coating, airless spray coating, bar coating, roll coating, and brush coating.

11. The amount of reduced glutathione applied to the surface of the article is 0.1 nmol / cm ２ 100nmol / cm or more ２ 10. The method of claim 9, wherein the range is:

12. The amount of reduced glutathione applied to the surface of the article is 0.25 nmol / cm ２ 50nmol / cm or more ２ 12. The method of claim 11, wherein the range is:

13. 10. The method of claim 9, wherein the copper alloy is selected from the group consisting of Cu—Zn alloy, Cu—Ni alloy, Cu—Ni—Zn alloy, Cu—Sn alloy, Cu—Sn—P alloy, Cu—Sn—Ni—Zn alloy, and Cu—Si—Pb—P—Zn alloy.

14. 10. The method of claim 9, wherein the article is selected from the group consisting of a handle, a button, a building material, an electronic component, and a musical instrument component.

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