Aqueous metal composition

Abstract

To provide an aqueous metal composition by which formation of precipitates is inhibited and aggregation hardly occurs even when the composition is stored for a prolonged period.SOLUTION: An aqueous metal composition comprises an aqueous medium, silver, and at least one metal M other than silver, in which the metal M exhibits antibacterial and / or antiviral properties, the content ratio of the metal M to the aqueous medium is 0.1 mass ppm or more and 100000 mass ppm or less, and the mass ratio of chlorine to silver (Cl / Ag) is 0.05 or less. In the aqueous metal composition, formation of precipitates is inhibited and aggregation hardly occurs even when the composition is stored for a prolonged period.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an aqueous metal composition comprising an aqueous medium and a metal. [Background technology]

[0002] Known examples of aqueous metal compositions containing an aqueous medium and a metal include a dispersion of nanometer-sized metal particles and a solution of metal ions. Because aqueous metal compositions have unique properties not found in bulk metals, they are widely used in a variety of fields, including electronic materials, magnetic materials, and catalyst materials. Depending on the type and form of the metal, these compositions can also exhibit antibacterial, antiviral, and deodorizing properties (see, for example, Patent Document 1).

[0003] Such aqueous metal compositions may suffer from aggregation, precipitation, and the like, and these problems tend to become more pronounced over time or depending on storage conditions. Therefore, there is a need for the production of aqueous metal compositions with improved metal dispersibility and solubility. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 082201 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, when the aqueous metal composition is a dispersion of metal nanoparticles, known means for improving the dispersibility of such a dispersion include adding a dispersion stabilizer and treating the surface of the metal particles to prevent aggregation.

[0006] However, even with the method of adding a dispersion stabilizer, it is difficult to stabilize the dispersibility of metal nanoparticles, and there is a problem that stability decreases over time. In addition, the addition of an excessive amount of dispersion stabilizer can inhibit the effects that the metal nanoparticles can exert. The method of surface-treating metal particles requires a separate step for surface treatment, which tends to complicate the manufacturing process. This problem of decreased stability of aqueous metal compositions can occur not only in dispersions of metal nanoparticles, but also in solutions of metal ions.

[0007] The present invention has been made in view of the above, and has as its object to provide an aqueous metal composition that suppresses the generation of precipitates and is less likely to cause aggregation even when stored for a long period of time. [Means for solving the problem]

[0008] As a result of extensive research into achieving the above object, the inventors have discovered that the above object can be achieved by adjusting the amount of chlorine contained in the composition within an appropriate range, and have thus completed the present invention.

[0009] That is, the present invention includes, for example, the subject matter described in the following sections. Item 1 An aqueous metal composition comprising an aqueous medium, silver, and at least one metal M other than silver, the metal M is a metal having antibacterial and / or antiviral properties, the content ratio of the metal M relative to the aqueous medium is 0.1 ppm by mass or more and 100,000 ppm by mass or less, An aqueous metal composition having a chlorine to silver mass ratio (Cl / Ag) of 0.05 or less. Section 2 Item 2. The water-based metal composition according to Item 1, wherein the silver and metal M are in particulate form. Section 3 Item 2. The aqueous metal composition according to Item 1, wherein the silver and metal M are ions. Section 4 4. The aqueous metal composition according to any one of items 1 to 3, wherein the metal M is at least one selected from the group consisting of platinum, gold, copper, zinc, nickel, and aluminum. Section 5 4. The aqueous metal composition according to any one of items 1 to 3, wherein the metal M is at least one selected from the group consisting of platinum, gold, copper, and zinc. [Effects of the Invention]

[0010] The aqueous metal composition of the present invention is inhibited from generating precipitates and is less likely to aggregate even when stored for a long period of time. DETAILED DESCRIPTION OF THE INVENTION

[0011]

[0023] In the present specification, the terms "contain" and "comprise" include the concepts of "contain," "comprise," "consist essentially of," and "consist only of."

[0012] The aqueous metal composition of the present invention comprises an aqueous medium, silver, and at least one metal other than silver, M. The metal M is a metal having antibacterial and / or antiviral properties, and the content of the metal M relative to the aqueous medium is 0.1 ppm by mass or more and 100,000 ppm by mass or less, and the mass ratio of chlorine to silver (Cl / Ag) is 0.05 or less. Here, the mass ratio of chlorine to silver (Cl / Ag) refers to the value obtained by dividing the mass of chlorine contained in the aqueous metal composition by the mass of silver (Ag) contained in the aqueous metal composition.

[0013] The aqueous metal composition of the present invention, which is configured as described above, is inhibited from generating precipitates and is less likely to aggregate even when stored for a long period of time.

[0014] In the aqueous metal composition of the present invention, the aqueous medium is not particularly limited, and examples thereof include water, lower alcohols having 1 to 3 carbon atoms, or mixed solvents thereof. Various types of water can be used, such as distilled water, tap water, industrial water, ion-exchanged water, deionized water, pure water, and electrolyzed water. Among these, ion-exchanged water, deionized water, pure water, and electrolyzed water are preferred, as they are less likely to be contaminated with chlorine.

[0015] From the viewpoint of improving the dispersion stability of the aqueous metal composition, the aqueous medium may contain water in an amount of 90% by mass or more, and particularly preferably 99% by mass or more. The aqueous medium may consist of water only.

[0016] The aqueous metal composition of the present invention contains silver and metal M as essential components. As described above, metal M is a metal having antibacterial and / or antiviral properties. That is, metal M is an antibacterial metal and / or antiviral metal. The type of metal M is not particularly limited as long as it has antibacterial and / or antiviral properties, and a wide range of known antibacterial metals and antiviral metals can be exemplified. In the present invention, antibacterial properties do not only apply to bacteria but also to a wide range of microorganisms in general.

[0017] Examples of the metal M include various noble metals, transition metal elements having antibacterial properties, and metals such as zinc. Examples of the metal M include platinum, gold, silver, copper, zinc, cobalt, aluminum, nickel, palladium, molybdenum, tungsten, silicon, titanium, chromium, manganese, tin, tantalum, lead, and zirconium.

[0018] Among these, the metal M is preferably at least one selected from the group consisting of platinum, gold, silver, copper, zinc, cobalt, aluminum, nickel, palladium, molybdenum, tungsten, lead, and zirconium, more preferably at least one selected from the group consisting of platinum, gold, silver, zinc, copper, nickel, and aluminum, and even more preferably at least one selected from the group consisting of platinum, gold, copper, and zinc. In these cases, the aqueous metal composition is more likely to suppress the generation of precipitates and is less likely to cause aggregation even when stored for a long period of time. An even more preferred metal M is at least one selected from the group consisting of platinum, gold, and copper, and an especially preferred metal M is at least one selected from the group consisting of platinum and gold, with platinum being particularly preferred.

[0019] In the aqueous metal composition of the present invention, the silver and metal M are preferably in the form of particles or ions. That is, one embodiment of the aqueous metal composition of the present invention is an aqueous metal composition in which the silver and metal M are in the form of particles, and another embodiment of the aqueous metal composition of the present invention is an aqueous metal composition in which the silver and metal M are ions.

[0020] When the silver and metal M are in particulate form, the aqueous metal composition of the present invention contains silver particles and metal M particles.

[0021] Silver particles are particles whose constituent component is silver (Ag) and are usually formed of elemental silver alone, but may also contain silver compounds such as silver oxides. Silver particles may also contain alloys of silver and other metal elements. Silver particles are preferably formed of elemental silver (Ag) alone.

[0022] Metal M particles are particles containing metal M as a constituent component, and are usually formed of metal M alone, but may also contain a compound of metal M such as an oxide of metal M. Metal M particles may also contain an alloy of metal M and another metal element. Metal M particles are preferably formed of metal M alone.

[0023] An example of an embodiment of silver particles and metal M particles is a dispersion in which silver particles and platinum particles are dispersed in an aqueous medium. This dispersion not only exhibits particularly excellent antibacterial and / or antiviral activity, but also is particularly suppressed in the formation of precipitates and is particularly resistant to aggregation even when stored for a long period of time.

[0024] The average primary particle diameters of the silver particles and metal M particles are not particularly limited and are, for example, both 0.1 to 1000 nm. The average primary particle diameter here refers to a value measured using a zeta potential measuring device (Zetasizer Nano ZS90, manufactured by Malvern). The average primary particle diameters of the silver particles and metal M particles are both preferably 1 to 800 nm, more preferably 5 to 500 nm, and even more preferably 15 to 350 nm. The average primary particle diameters of the silver particles and metal M particles may be different from each other, and the preferred ranges of the average primary particle diameters may also be different.

[0025] When silver and metal M are ions, the aqueous metal composition of the present invention contains silver ions and ions of metal M. In this case, when the ions of each metal have multiple valencies, the valencies are not particularly limited.

[0026] The counter ion (anion) of the silver ion is not particularly limited and may include, for example, organic carboxylates such as nitrate, nitrite, halogen ions, sulfate, sulfite, phosphate, hydrogen phosphate, acetate, citrate, and hydrogen citrate, and sulfonate ions such as alkyl sulfonate, benzene sulfonate, and alkyl benzene sulfonate. The counter ion (anion) of the metal M ion is not particularly limited and may include, for example, organic carboxylates such as nitrate, nitrite, halogen ions, sulfate, sulfite, phosphate, hydrogen phosphate, acetate, citrate, and hydrogen citrate, and sulfonate ions such as alkyl sulfonate, benzene sulfonate, and alkyl benzene sulfonate. The aqueous metal composition of the present invention may also contain chloride ions, provided that the chlorine-to-silver mass ratio (Cl / Ag) does not exceed 0.05.

[0027] An example of an embodiment of silver ions and metal M ions is a solution in which silver ions and platinum ions are dissolved in an aqueous medium. Such a solution can exhibit particularly excellent antibacterial and / or antiviral activity, and is particularly resistant to the formation of precipitates and aggregation even when stored for a long period of time.

[0028] In the aqueous metal composition of the present invention, the content of the metal M relative to the aqueous medium is 0.1 ppm by mass or more and 100,000 ppm by mass or less, whether the metal is in the form of particles or ions. If the content of the metal M relative to the aqueous medium is less than 0.1 ppm by mass, the effect of the metal M may not be fully exerted, while if the content of the metal M exceeds 100,000 ppm by mass, the aqueous metal composition of the present invention may be prone to precipitate formation and may be prone to aggregation when stored for a long period of time.

[0029] Conventionally, when the content of the metal M relative to the aqueous medium is high (for example, when it is several tens of ppm by mass or more), there has been a problem that precipitation is likely to occur and aggregation is also likely to occur when the composition is stored for a long period of time. In this regard, in the aqueous metal composition of the present invention, the mass ratio of chlorine to silver (Cl / Ag) is adjusted to an appropriate range, so that such problems do not occur.

[0030] In the aqueous metal composition of the present invention, when each metal is in the form of particles, the content of the metal M relative to the aqueous medium is preferably 0.1 ppm by mass or more, more preferably 1 ppm by mass or more, even more preferably 10 ppm by mass or more, and particularly preferably 20 ppm by mass or more, and is preferably 10,000 ppm by mass or less, more preferably 1,000 ppm by mass or less, even more preferably 500 ppm by mass or less, particularly preferably 300 ppm by mass or less, and may be 100 ppm by mass or less.

[0031] In the aqueous metal composition of the present invention, when each metal is an ion, the content of the metal M relative to the aqueous medium is preferably 0.1 ppm by mass or more, more preferably 1 ppm by mass or more, even more preferably 10 ppm by mass or more, and particularly preferably 20 ppm by mass or more, and is preferably 10,000 ppm by mass or less, more preferably 1,000 ppm by mass or less, even more preferably 500 ppm by mass or less, particularly preferably 300 ppm by mass or less, and may be 100 ppm by mass or less.

[0032] In the aqueous metal composition of the present invention, when each metal is in the form of particles, the silver content relative to the aqueous medium is, for example, 0.1 ppm by mass or more, preferably 1 ppm by mass or more, more preferably 2 ppm by mass or more, even more preferably 5 ppm by mass or more, and particularly preferably 10 ppm by mass or more, and may also be, for example, 100,000 ppm by mass or less, preferably 50,000 ppm by mass or less, more preferably 10,000 ppm by mass or less, even more preferably 1,000 ppm by mass or less, particularly preferably 300 ppm by mass or less, and may be 100 ppm by mass or less.

[0033] In the aqueous metal composition of the present invention, when each metal is an ion, the silver content relative to the aqueous medium is, for example, 0.1 ppm by mass or more, preferably 1 ppm by mass or more, more preferably 2 ppm by mass or more, even more preferably 5 ppm by mass or more, and particularly preferably 10 ppm by mass or more, and may be, for example, 100,000 ppm by mass or less, preferably 50,000 ppm by mass or less, more preferably 10,000 ppm by mass or less, even more preferably 1,000 ppm by mass or less, particularly preferably 300 ppm by mass or less, and may be 100 ppm by mass or less.

[0034] In the aqueous metal composition of the present invention, when each metal is in the form of particles, the content ratio of silver to metal M is not particularly limited, and for example, the content of metal M can be 0.01 part by mass or more, preferably 0.1 part by mass or more, more preferably 1 part by mass or more, even more preferably 10 parts by mass or more, particularly preferably 30 parts by mass or more, or may be 100 parts by mass or more, or can be 10,000 parts by mass or less, preferably 5,000 parts by mass or less, more preferably 4,000 parts by mass or less, even more preferably 3,500 parts by mass or less, and particularly preferably 1,000 parts by mass or less, per 100 parts by mass of silver.

[0035] In the aqueous metal composition of the present invention, when each metal is an ion, the content ratio of silver to metal M is not particularly limited, and for example, the content of metal M can be 0.01 part by mass or more, preferably 0.1 part by mass or more, more preferably 1 part by mass or more, even more preferably 10 parts by mass or more, and particularly preferably 40 parts by mass or more, relative to 100 parts by mass of silver. Alternatively, the content can be 4000 parts by mass or less, preferably 400 parts by mass or less, more preferably 200 parts by mass or less, even more preferably 100 parts by mass or less, and particularly preferably 80 parts by mass or less.

[0036] As described above, the aqueous metal composition of the present invention has a chlorine to silver mass ratio (hereinafter referred to as "Cl / Ag") of 0.05 or less. If the Cl / Ag value exceeds 0.05, the aqueous metal composition of the present invention is prone to precipitate formation and aggregation occurs when stored for a long period of time. Therefore, by ensuring that the Cl / Ag value of the aqueous metal composition of the present invention is 0.05 or less, the formation of precipitates is suppressed and the composition can be stored for a long period of time.

[0037] In order to prevent aggregation and precipitation even after long-term storage, the Cl / Ag value is preferably 0.04 or less, more preferably 0.03 or less, even more preferably 0.02 or less, and particularly preferably 0.015 or less. The Cl / Ag value may be 0.01 or less. The aqueous metal composition of the present invention may also have a Cl / Ag value of 0. That is, the aqueous metal composition of the present invention may be free of Cl (chlorine). The phrase "free of Cl" in an aqueous metal composition not only means that the Cl content is 0 ppm by mass, but also means that chlorine cannot be detected by elemental analysis (i.e., is below the detection limit). The lower limit of the Cl / Ag value is, for example, about 0.001.

[0038] The method for adjusting the Cl / Ag value to 0.05 or less is not particularly limited, and various methods can be applied. For example, the amount of chlorine and silver contained in the aqueous metal composition after production can be adjusted by changing the type and amount of raw materials and aqueous medium used in the production of the aqueous metal composition of the present invention. That is, the Cl / Ag value can be adjusted to 0.05 or less by changing the production conditions used in producing the aqueous metal composition of the present invention. Such production methods will be described later. Other examples include a method for adjusting the Cl / Ag value to 0.05 or less by adding chlorine to the aqueous metal composition, a method for adjusting the Cl / Ag value to 0.05 or less by removing chlorine from the aqueous metal composition, and a method for adjusting the Cl / Ag value to 0.05 or less by adding silver to the aqueous metal composition.

[0039] The method for quantifying the Cl / Ag value of the aqueous metal composition of the present invention is not particularly limited, and for example, a wide variety of known methods can be used. In particular, in the present invention, the Cl / Ag value of the aqueous metal composition is quantified by quantifying metal components (e.g., platinum and silver) by ICP-MS analysis and quantifying chloride ions by ion chromatography.

[0040] The sample solution used for quantifying metal components using ICP-MS analysis is prepared as follows: First, approximately 0.4 g of sample is weighed and heated to remove the solvent. Before drying, 0.1 mL of sulfuric acid and 1 mL of nitric acid are added and heated to decompose the solution. Then, heat and concentrate until white sulfuric acid smoke is generated. 2 mL of aqua regia is added and further heated and decomposed. Next, heat and concentrate again until white sulfuric acid smoke is generated. 10 mL of aqua regia is added and heated to dissolve. After cooling, the solution is adjusted to exactly 20 mL with aqua regia, and this is the sample solution. The measurement conditions for ICP-MS analysis are as follows: The sample solution is diluted by a specified ratio to prepare a diluted solution. The diluted solution is then injected into the ICP-MS instrument to measure the concentration of each metal. For quantifying chloride ions using ion chromatography, the sample solution obtained as described above is diluted by a specified ratio to prepare a diluted solution. The diluted solution is then injected into the ion chromatography instrument to measure the concentration of each metal.

[0041] When the method for producing the aqueous metal composition of the present invention is known, the Cl / Ag value of the aqueous metal composition is determined based on the amount of chlorine and the amount of metal contained in the raw materials.

[0042] The aqueous metal composition of the present invention may contain metal particles or metal ions other than silver and metal M. When other metal particles or metal ions are contained, their content is not particularly limited, and is 10% by mass or less, preferably 5% by mass or less, and more preferably 1% by mass or less, based on the total amount of silver and metal M. The metal contained in the aqueous metal composition of the present invention may consist only of silver and metal M. In this case, metals inevitably contained in the aqueous metal composition are acceptable.

[0043] The pH of the aqueous metal composition of the present invention is not particularly limited, and for example, the pH is preferably 7 or less, more preferably 6 or less, and particularly preferably 5 or less.

[0044] The aqueous metal composition of the present invention may contain various additives as long as the effects of the present invention are not impaired.

[0045] The aqueous metal composition of the present invention contains an aqueous medium, silver, and at least one metal other than silver (M) in predetermined amounts, and has a Cl / Ag ratio of 0.05 or less, thereby suppressing the generation of precipitates and making the composition less susceptible to aggregation even when stored for long periods of time.

[0046] The presence or absence of a precipitate in the aqueous metal composition of the present invention immediately after production can be determined by visually observing the aqueous metal composition and determining whether or not a precipitate is visible.

[0047] The presence or absence of a precipitate in the waterborne metal composition of the present invention can be determined by visually observing the waterborne metal composition after storing it under the storage conditions described below and determining whether or not a precipitate is visible.

[0048] [Storage conditions] 100 mL of the aqueous metal composition is sealed in a 110 mL container in an air atmosphere, and the container is left standing in a thermostatic chamber maintained at a constant temperature of 40° C. for storage for 3 weeks and 6 weeks.

[0049] Furthermore, if no visible precipitate is observed after storage for 3 weeks or more under the above storage conditions, then from the standpoint of storage stability of the aqueous metal composition, the composition can generally be used in practice without any particular problems.

[0050] The aqueous metal composition of the present invention is suitable for various applications requiring storage, for example, because it is resistant to precipitation and aggregation even when stored for a long period of time. The aqueous metal composition of the present invention can be used in industrial applications (e.g., many industrial products or raw materials such as water-containing pulp, coated paper, paper coating solutions, paints, binders, adhesives, latex, inks, etching solutions, soaking solutions, wood, fibers, wood flour, plastics, cement admixtures, sealants, resin emulsions, and building materials), as well as in various applications where safety is particularly important, such as in the agricultural field (e.g., plant cultivation), the food field (e.g., antibacterial bottles), and physicochemical materials (e.g., cell culture substrates). It is particularly useful as an antibacterial agent, antialgic agent, biofilm formation inhibitor, and antiviral agent.

[0051] The method for producing the aqueous metal composition of the present invention is not particularly limited, and for example, a wide variety of known methods can be employed. As an example of the method for producing the aqueous metal composition of the present invention, the aqueous metal composition of the present invention can be produced by mixing a silver precursor and a metal M precursor (hereinafter referred to as "production method A"). The silver precursor is, more specifically, a silver particle precursor or a silver ion precursor, and the metal M precursor is, more specifically, a metal M particle precursor or a metal M ion precursor (which can also be simply referred to as a metal M precursor).

[0052] In production method A, the silver precursor refers to, for example, a compound containing silver, which can be chemically treated to form silver particles or silver ions. Similarly, the metal M precursor refers to, for example, a compound containing metal M, which can be chemically treated to form metal M particles or metal M ions.

[0053] Examples of silver precursors include silver complexes. Silver complexes can be obtained, for example, by complexing a silver source. Examples of silver sources include silver oxide, hydroxide, chloride, carbonate, acetate, nitrate, oxalate, and phosphate.

[0054] In the present invention, since it is necessary to adjust the amount of chlorine contained in the aqueous metal composition to a certain amount or less, the silver source preferably contains a chlorine-free compound such as a chloride, for example, the silver source preferably contains at least silver nitrate.

[0055] When a chlorine-containing compound such as a chloride is used as the silver source, it is necessary to adjust the amount used so that the Cl / Ag ratio of the resulting aqueous metal composition satisfies 0.05 or less. For example, when a chloride is used as the silver source, the amount of chlorine contained in the resulting aqueous metal composition can be adjusted to a predetermined range by using a chloride in combination with a separate chlorine-free silver source.

[0056] The method for complexing the silver source is not particularly limited, and can be carried out, for example, by reacting the silver source with an organic salt. As the organic salt, trisodium citrate or sodium acetate is preferably used. Trisodium citrate or sodium acetate may be a hydrate. The complexing of the silver source can be carried out, for example, in water.

[0057] When complexing the silver source, the ratio of the silver source to the organic salt is not particularly limited. For example, the silver source can be complexed using 2 moles or more of the organic salt per mole of silver contained in the silver source.

[0058] An example of a precursor of metal M is a complex of metal M. The complex of metal M can be obtained, for example, by complexing a source of metal M. Examples of the M source include oxides, hydroxides, chlorides, carbonates, acetates, nitrates, diaminedinitro compounds, oxalates, phosphates, ammonium salts, sulfates, and sulfites of metal M.

[0059] In the present invention, since it is necessary to adjust the amount of chlorine contained in the aqueous metal composition to a certain amount or less, the M source preferably contains a chlorine-free compound such as a chloride. For example, the M source preferably contains at least a diaminedinitro compound of metal M. An example of a diaminedinitro compound of metal M is dinitrodiammineplatinum(II) (Pt(NO2)2(NH3)2).

[0060] When a chlorine-containing compound such as a chloride is used as the M source, it is necessary to adjust the amount used so that the Cl / Ag of the resulting aqueous metal composition satisfies 0.05 or less. For example, when a chloride is used as the M source, the amount of chlorine contained in the resulting aqueous metal composition can be adjusted to a predetermined range by using it in combination with a separate chlorine-free M source.

[0061] The method for complexing the M source is not particularly limited, and can be carried out, for example, by reacting the M source with an organic salt. Trisodium citrate is preferably used as the organic salt. Trisodium citrate may be a hydrate. Complexation of the M source can be carried out, for example, in water.

[0062] When complexing the M source, the ratio of the M source to the organic salt is not particularly limited. For example, the M source can be complexed using 2 moles or more of the organic salt per mole of metal M contained in the M source.

[0063] In production method A, there is no particular limitation on the method for mixing the silver precursor and the precursor of metal M. For example, there can be mentioned a method of mixing a solution of the silver precursor in the aqueous solvent (e.g., an aqueous solution) with a solution of the precursor of metal M in the aqueous solvent (e.g., an aqueous solution). The temperature during this mixing is also not particularly limited, and can be, for example, room temperature, specifically 15 to 35°C.

[0064] In production method A, after mixing the silver precursor and the precursor of metal M to obtain a mixed solution, an acid can be further added to the mixed solution. The addition of this acid appropriately adjusts the pH of the mixed solution, thereby promoting particle generation, making it possible to easily and quickly obtain a dispersion containing the aforementioned silver particles and metal M particles. Examples of acids include inorganic acids such as hydrochloric acid, nitric acid, and sulfuric acid; and organic acids such as acetic acid, citric acid, and succinic acid. Among these, the use of organic acids is preferred, and the use of citric acid is particularly preferred, from the viewpoint of good dispersion stability of the generated particles.

[0065] Alternatively, after mixing the silver precursor and the precursor of metal M to obtain a mixed solution, the mixed solution can be further heated. This heating allows the heating temperature to be appropriately adjusted, thereby accelerating particle generation, allowing for easy and rapid production of a dispersion containing the aforementioned silver particles and metal M particles. Therefore, when producing an aqueous metal composition that is a dispersion of metal particles, it is more preferable to further heat the mixed solution after mixing the silver precursor and the precursor of metal M to obtain a mixed solution. The heating temperature is preferably 40°C or higher, more preferably 45°C or higher, and particularly preferably 50°C or higher, in order to facilitate reaction progression. Furthermore, the heating temperature is preferably 100°C or lower, more preferably 98°C or lower, and particularly preferably 95°C or lower, in order to facilitate particle size control.

[0066] When producing an aqueous metal composition that is a solution of metal ions, the heating step may not be performed.

[0067] After the aqueous metal composition is obtained by the above-described production method A, an aqueous medium can be mixed as needed to adjust the concentrations of silver and metal M within the desired range.

[0068] In Production Method A, for example, the Cl / Ag value can be adjusted to 0.05 or less based on the amounts of chlorine and silver contained in the raw materials used. Specifically, the chlorine and silver amounts of each raw material used in the production of the aqueous metal composition of the present invention are calculated, and the raw materials are used in amounts such that the Cl / Ag value is 0.05 or less, thereby producing the desired aqueous metal composition. As mentioned above, the desired aqueous metal composition can also be produced by methods such as removing chlorine from the aqueous metal composition, adding chlorine, or adding silver.

[0069] The method for producing the waterborne metal composition is not limited to the above-mentioned Production Method A, and other production methods may also be used. For example, the waterborne metal composition can be produced by a method in which silver particles and metal M particles are separately produced and then mixed, or by a method in which commercially available silver particles and metal M particles are separately prepared and then mixed.

[0070] In specifying the inventions included in the present disclosure, the components (properties, structures, functions, etc.) described in the embodiments of the present disclosure may be combined in any manner. In other words, the present disclosure includes all subject matter consisting of all combinations of the components that can be combined as described in this specification. [Example]

[0071] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0072] (Production example 1-1; silver precursor) 0.104 g of silver nitrate and 0.15 g of trisodium citrate dihydrate were dissolved in 100 mL of ion-exchanged water (25 °C) and stirred for 30 minutes to prepare an aqueous solution containing a silver complex. The aqueous solution containing the silver complex thus obtained was designated as an aqueous solution containing a silver precursor. The chlorine concentration in the aqueous solution was measured by ion chromatography and found to be below the detection limit. The silver concentration in the aqueous solution was measured by ICP-MS and found to be 660 ppm by mass.

[0073] (Production example 1-2; silver precursor) 0.788 g of silver nitrate and 0.3 g of trisodium citrate dihydrate were dissolved in 100 mL of ion-exchanged water (25 °C) and stirred for 30 minutes to prepare an aqueous solution containing a silver complex. The aqueous solution containing the silver complex thus obtained was designated as an aqueous solution containing a silver precursor. The chlorine concentration in the aqueous solution was measured by ion chromatography and found to be below the detection limit. The silver concentration in the aqueous solution was measured by ICP-MS and found to be 5000 ppm by mass.

[0074] (Production Example 2-1; Platinum precursor) 0.3 g of trisodium citrate dihydrate was dissolved in 100 g of an aqueous solution containing 0.027 g of dinitrodiammineplatinum(II) and 0.178 g of potassium chloroplatinate(II) (K2PtCl4), and the solution was stirred for 30 minutes to prepare an aqueous solution containing a platinum complex. The resulting aqueous solution containing the platinum complex was designated as an aqueous solution containing a platinum precursor. The chlorine concentration in the aqueous solution was measured by ion chromatography and found to be 594 ppm by mass.

[0075] (Production Example 2-2; Platinum precursor) 0.3 g of trisodium citrate dihydrate was dissolved in 100 g of an aqueous solution containing 0.119 g of dinitrodiammineplatinum(II) and 0.059 g of potassium chloroplatinate(II), and the solution was stirred for 30 minutes to prepare an aqueous solution containing a platinum complex. The aqueous solution containing the platinum complex thus obtained was designated as an aqueous solution containing a platinum precursor. The chlorine concentration in the aqueous solution was measured by ion chromatography and found to be 198 ppm by mass.

[0076] (Production Example 2-3; Platinum precursor) 0.3 g of trisodium citrate dihydrate was dissolved in 100 g of an aqueous solution containing 0.149 g of dinitrodiammineplatinum(II) and 0.020 g of potassium chloroplatinate(II), and the solution was stirred for 30 minutes to prepare an aqueous solution containing a platinum complex. The aqueous solution containing the platinum complex thus obtained was designated as an aqueous solution containing a platinum precursor. The chlorine concentration in the aqueous solution was measured by ion chromatography and found to be 66 ppm by mass.

[0077] (Production example 2-4; platinum precursor) 0.15 g of trisodium citrate dihydrate was dissolved in 100 g of an aqueous solution containing 0.157 g of dinitrodiammineplatinum(II) and 0.010 g of potassium chloroplatinate(II), and the solution was stirred for 30 minutes to prepare an aqueous solution containing a platinum complex. The aqueous solution containing the platinum complex thus obtained was designated as an aqueous solution containing a platinum precursor. The chlorine concentration in the aqueous solution was measured by ion chromatography and found to be 33 ppm by mass.

[0078] (Production Example 2-5; Platinum precursor) 0.15 g of trisodium citrate dihydrate was dissolved in 100 g of an aqueous solution containing 0.160 g of dinitrodiammineplatinum(II) and 0.006 g of potassium chloroplatinate(II), and the solution was stirred for 30 minutes to prepare an aqueous solution containing a platinum complex. The aqueous solution containing the platinum complex thus obtained was designated as an aqueous solution containing a platinum precursor. The chlorine concentration in the aqueous solution was measured by ion chromatography and found to be 19.8 ppm by mass.

[0079] (Production Example 2-6; Platinum precursor) 0.15 g of trisodium citrate dihydrate was dissolved in 100 g of an aqueous solution containing 0.163 g of dinitrodiammineplatinum(II) and 0.002 g of potassium chloroplatinate(II), and the solution was stirred for 30 minutes to prepare an aqueous solution containing a platinum complex. The aqueous solution containing the platinum complex thus obtained was designated as an aqueous solution containing a platinum precursor. The chlorine concentration in the aqueous solution was measured by ion chromatography and found to be 6.6 ppm by mass.

[0080] (Production Example 2-7; Platinum precursor) 0.15 g of trisodium citrate dihydrate was dissolved in 100 g of an aqueous solution containing 0.165 g of dinitrodiammineplatinum(II) and stirred for 30 minutes to prepare an aqueous solution containing a platinum complex. The aqueous solution containing the platinum complex thus obtained was designated as an aqueous solution containing a platinum precursor. The chlorine concentration in this aqueous solution was measured by ion chromatography and found to be 0 ppm by mass.

[0081] (Production Example 2-8; Platinum precursor) 2.0 g of trisodium citrate dihydrate was dissolved in 100 g of an aqueous solution containing 0.318 g of dinitrodiammineplatinum(II) and 0.015 g of potassium chloroplatinate(II), and the solution was stirred for 30 minutes to prepare an aqueous solution containing a platinum complex. The aqueous solution containing the platinum complex thus obtained was designated as an aqueous solution containing a platinum precursor. The chlorine concentration in the aqueous solution was measured by ion chromatography and found to be 50 ppm by mass.

[0082] (Production example 3-1; gold precursor) An aqueous solution containing a gold complex was prepared by dissolving 0.15 g of trisodium citrate dihydrate in 100 g of an aqueous solution containing 0.214 g of sodium gold sulfite and 0.002 g of tetrachloroaurate(III) tetrahydrate (HAuCl4·4H2O) and stirring for 30 minutes. The resulting aqueous solution containing the gold complex was designated as an aqueous solution containing a gold precursor. The chlorine concentration in the solution was measured by ion chromatography and found to be 6.6 ppm by mass. The gold concentration in the solution was measured by ICP-MS and found to be 1000 ppm by mass.

[0083] (Production Example 4-1; Zinc Precursor) An aqueous solution containing a zinc complex was prepared by dissolving 0.15 g of trisodium citrate dihydrate in 100 g of an aqueous solution containing 0.413 g of zinc sulfate heptahydrate (ZnSO2·7H2O) and 0.013 g of zinc chloride (ZnCl2) and stirring for 30 minutes. The resulting aqueous solution containing the zinc complex was designated as an aqueous solution containing a zinc precursor. The chlorine concentration in the aqueous solution was measured by ion chromatography and found to be 66 ppm by mass. The zinc concentration in the aqueous solution was measured by ICP-MS and found to be 1000 ppm by mass.

[0084] (Production Example 4-2; Zinc Precursor) An aqueous solution containing a zinc complex was prepared by dissolving 0.15 g of trisodium citrate dihydrate in 100 g of an aqueous solution containing 0.437 g of zinc sulfate heptahydrate (ZnSO2·7H2O) and 0.001 g of zinc chloride (ZnCl2) and stirring for 30 minutes. The resulting aqueous solution containing the zinc complex was designated as an aqueous solution containing a zinc precursor. The chlorine concentration in the aqueous solution was measured by ion chromatography and found to be 6.6 ppm by mass. The zinc concentration in the aqueous solution was measured by ICP-MS and found to be 1000 ppm by mass.

[0085] [Metal particles] Example 1a To a preparation solution consisting of 100 mL of the aqueous solution of the silver precursor obtained in Production Example 1-1 and 790 mL of ion-exchanged water, 100 mL of the aqueous solution of the platinum precursor obtained in Production Example 2-4 was added dropwise over 60 minutes while stirring to obtain a mixed solution. The pH of the resulting mixed solution was adjusted to 2-4 by adding 0.36 g of citric acid, and 10 mL of washing water was added. The mixture was stirred for an additional 60 minutes and then heated at 90°C for 24 hours. This resulted in an aqueous dispersion containing silver particles and platinum particles as an aqueous metal composition. The particle content of the resulting aqueous metal composition was confirmed by ICP-MS (PerkinElmer Elan DRC II), which revealed a platinum particle content of 100 ppm by mass and a silver particle content of 66 ppm by mass. Based on the charged amounts, the chlorine concentration was calculated to be 3.3 ppm by mass. Therefore, the Cl / Ag value was 0.05.

[0086] Example 2a An aqueous metal composition was obtained in the same manner as in Example 1a, except that the aqueous platinum precursor solution obtained in Preparation Example 2-5 was used instead of the aqueous platinum precursor solution obtained in Preparation Example 2-4. The particle content in the resulting aqueous metal composition was confirmed by ICP-MS (PerkinElmer Elan DRC II), and found to be 100 ppm by mass of platinum particles and 66 ppm by mass of silver particles. From the amounts charged, the chlorine concentration was calculated to be 1.98 ppm by mass. Therefore, the Cl / Ag value was 0.03.

[0087] Example 3a An aqueous metal composition was obtained in the same manner as in Example 1a, except that the aqueous platinum precursor solution obtained in Preparation Example 2-6 was used instead of the aqueous platinum precursor solution obtained in Preparation Example 2-4. The particle content in the resulting aqueous metal composition was confirmed by ICP-MS (PerkinElmer Elan DRC II), and found to be 100 ppm by mass of platinum particles and 66 ppm by mass of silver particles. From the amounts charged, the chlorine concentration was calculated to be 0.66 ppm by mass. Therefore, the Cl / Ag value was 0.01.

[0088] Example 4a An aqueous metal composition was obtained in the same manner as in Example 1a, except that the aqueous platinum precursor solution obtained in Preparation Example 2-7 was used instead of the aqueous platinum precursor solution obtained in Preparation Example 2-4. The particle content in the resulting aqueous metal composition was confirmed by ICP-MS (PerkinElmer Elan DRC II), and found to be 100 ppm by mass of platinum particles and 66 ppm by mass of silver particles. From the amounts charged, the chlorine concentration was calculated to be 0 ppm by mass. Therefore, the Cl / Ag value was 0.

[0089] Example 5a To a preparation solution consisting of 100 mL of the aqueous solution of the silver precursor obtained in Production Example 1-2 and 790 mL of ion-exchanged water, 100 mL of the aqueous solution of the platinum precursor obtained in Production Example 2-8 was added dropwise over 60 minutes with stirring to obtain a mixed solution. To the resulting mixed solution, 2.73 g of citric acid was added to adjust the pH of the mixed solution to 2-4, 10 mL of washing water was added, and the mixture was stirred for an additional 60 minutes and then heated at 90°C for 24 hours. This resulted in an aqueous dispersion containing silver particles and platinum particles as an aqueous metal composition. The ion content of the resulting aqueous metal composition was confirmed by ICP-MS (PerkinElmer Elan DRC II), which revealed 200 ppm by mass of platinum particles and 500 ppm by mass of silver particles. Based on the amounts charged, the chlorine concentration was calculated to be 5 ppm by mass. Therefore, the Cl / Ag value was 0.01.

[0090] Example 6a To a preparation solution consisting of 100 mL of the aqueous solution of the silver precursor obtained in Production Example 1-1 and 790 mL of ion-exchanged water, 100 mL of the aqueous solution of the gold precursor obtained in Production Example 3-1 was added dropwise over 60 minutes while stirring to obtain a mixed solution. The pH of the resulting mixed solution was adjusted to 2-4 by adding 0.36 g of citric acid, and 10 mL of washing water was added. The mixture was stirred for an additional 60 minutes and then heated at 90°C for 24 hours. This resulted in an aqueous dispersion containing silver particles and gold particles as an aqueous metal composition. The particle content of the resulting aqueous metal composition was confirmed by ICP-MS (PerkinElmer Elan DRC II), which revealed 100 ppm by mass of gold particles and 66 ppm by mass of silver particles. Based on the charged amounts, the chlorine concentration was calculated to be 0.66 ppm by mass. Therefore, the Cl / Ag value was 0.01.

[0091] (Comparative Example 1a) An aqueous metal composition was obtained in the same manner as in Example 1a, except that the aqueous platinum precursor solution obtained in Preparation Example 2-1 was used instead of the aqueous platinum precursor solution obtained in Preparation Example 2-4. The particle content in the resulting aqueous metal composition was confirmed by ICP-MS (PerkinElmer Elan DRC II), and found to be 100 ppm by mass of platinum particles and 66 ppm by mass of silver particles. From the amounts charged, the chlorine concentration was calculated to be 59.4 ppm by mass. Therefore, the Cl / Ag value was 0.9.

[0092] (Comparative example 2a) An aqueous metal composition was obtained in the same manner as in Example 1a, except that the aqueous solution of platinum precursor obtained in Preparation Example 2-2 was used instead of the aqueous solution of platinum precursor obtained in Preparation Example 2-4. The particle content relative to the aqueous medium in the obtained aqueous metal composition was confirmed using ICP-MS (PerkinElmer Elan DRC II), and the platinum particles were 100 ppm by mass and the silver particles were 66 ppm by mass. From the amounts charged, the chlorine concentration was calculated to be 19.8 ppm by mass. Therefore, the Cl / Ag value was 0.3.

[0093] (Comparative example 3a) An aqueous metal composition was obtained in the same manner as in Example 1a, except that the aqueous platinum precursor solution obtained in Preparation Example 2-3 was used instead of the aqueous platinum precursor solution obtained in Preparation Example 2-4. The particle content in the resulting aqueous metal composition was confirmed by ICP-MS (PerkinElmer Elan DRC II), and found to be 100 ppm by mass of platinum particles and 66 ppm by mass of silver particles. From the amounts charged, the chlorine concentration was calculated to be 6.6 ppm by mass. Therefore, the Cl / Ag value was 0.1.

[0094] [Metal ions] Example 1b To a preparation solution consisting of 100 mL of the aqueous solution of the silver precursor obtained in Production Example 1-1 and 790 mL of ion-exchanged water, 100 mL of the aqueous solution of the platinum precursor obtained in Production Example 2-6 was added dropwise over 60 minutes with stirring to obtain a mixed solution. The pH of the resulting mixed solution was adjusted to 2-4 by adding 0.36 g of citric acid, and 10 mL of washing water was added. The mixture was stirred for an additional 60 minutes to obtain an aqueous solution containing silver ions and platinum ions as an aqueous metal composition. The ion content of the resulting aqueous metal composition was confirmed by ICP-MS (PerkinElmer Elan DRC II), which revealed 100 ppm by mass of platinum ions and 66 ppm by mass of silver ions. From the amounts charged, the chlorine concentration was calculated to be 0.66 ppm by mass. Therefore, the Cl / Ag value was 0.01.

[0095] Example 2b To a preparation solution consisting of 100 mL of the aqueous solution of the silver precursor obtained in Production Example 1-2 and 790 mL of ion-exchanged water, 100 mL of the aqueous solution of the platinum precursor obtained in Production Example 2-8 was added dropwise over 60 minutes with stirring to obtain a mixed solution. To the resulting mixed solution, 2.73 g of citric acid was added to adjust the pH of the mixed solution to 2-4, 10 mL of washing water was added, and the mixture was stirred for an additional 60 minutes to obtain an aqueous solution containing silver ions and platinum ions as an aqueous metal composition. The ion content of the resulting aqueous metal composition was confirmed by ICP-MS (PerkinElmer Elan DRC II), which revealed 200 ppm by mass of platinum ions and 500 ppm by mass of silver ions. From the charged amounts, the chlorine concentration was calculated to be 5 ppm by mass. Therefore, the Cl / Ag value was 0.01.

[0096] (Comparative example 1b) To a preparation solution consisting of 100 mL of the aqueous solution of the silver precursor obtained in Production Example 1-1 and 790 mL of ion-exchanged water, 100 mL of the aqueous solution of the platinum precursor obtained in Production Example 2-2 was added dropwise over 60 minutes with stirring to obtain a mixed solution. The pH of the resulting mixed solution was adjusted to 2-4 by adding 0.36 g of citric acid, and 10 mL of washing water was added. The mixture was stirred for an additional 60 minutes to obtain an aqueous solution containing silver ions and platinum ions as an aqueous metal composition. The ion content of the resulting aqueous metal composition was confirmed by ICP-MS (PerkinElmer Elan DRC II), which revealed 100 ppm by mass of platinum ions and 66 ppm by mass of silver ions. From the amounts charged, the chlorine concentration was calculated to be 19.8 ppm by mass. Therefore, the Cl / Ag value was 0.3.

[0097] Example 3b To a preparation solution consisting of 100 mL of the aqueous solution of the silver precursor obtained in Production Example 1-1 and 790 mL of ion-exchanged water, 100 mL of the aqueous solution of the gold precursor obtained in Production Example 3-1 was added dropwise over 60 minutes with stirring to obtain a mixed solution. The pH of the resulting mixed solution was adjusted to 2-4 by adding 0.36 g of citric acid, and 10 mL of washing water was added. The mixture was stirred for an additional 60 minutes to obtain an aqueous solution containing silver ions and gold ions as an aqueous metal composition. The ion content of the resulting aqueous metal composition was confirmed by ICP-MS (PerkinElmer Elan DRC II), which revealed 100 ppm by mass of gold ions and 66 ppm by mass of silver ions. From the amounts charged, the chlorine concentration was calculated to be 0.66 ppm by mass. Therefore, the Cl / Ag value was 0.01.

[0098] Example 4b To a preparation solution consisting of 100 mL of the aqueous solution of the silver precursor obtained in Production Example 1-1 and 790 mL of ion-exchanged water, 100 mL of the aqueous solution of the zinc precursor obtained in Production Example 4-2 was added dropwise over 60 minutes with stirring to obtain a mixed solution. The pH of the resulting mixed solution was adjusted to 2-4 by adding 0.36 g of citric acid, and 10 mL of washing water was added. The mixture was stirred for an additional 60 minutes to obtain an aqueous solution containing silver ions and zinc ions as an aqueous metal composition. The ion content of the resulting aqueous metal composition was confirmed by ICP-MS (PerkinElmer Elan DRC II), which revealed 100 ppm by mass of zinc ions and 66 ppm by mass of silver ions. From the amounts charged, the chlorine concentration was calculated to be 0.66 ppm by mass. Therefore, the Cl / Ag value was 0.01.

[0099] (Comparative Example 2b) An aqueous metal composition was obtained in the same manner as in Example 1a, except that the aqueous zinc precursor solution obtained in Preparation Example 4-1 was used instead of the aqueous zinc precursor solution obtained in Preparation Example 4-2. The particle content in the resulting aqueous metal composition was confirmed by ICP-MS (PerkinElmer Elan DRC II), and found to be 100 mass ppm of zinc ions and 66 mass ppm of silver ions. From the amounts charged, the chlorine concentration was calculated to be 6.6 mass ppm. Therefore, the Cl / Ag value was 0.1.

[0100] [Evaluation method] The aqueous metal compositions obtained in each of the Examples and Comparative Examples were stored under the storage conditions described below, and then the aqueous metal compositions were visually observed to determine whether or not a precipitate was visible. If a precipitate was visible, the result was rated as "present," and if no precipitate was visible, the result was rated as "absent."

[0101] Storage conditions 100 mL of the aqueous metal composition was sealed in a 110 mL container in an air atmosphere, and the container was left standing in a thermostatic chamber maintained at a constant temperature of 40° C. for storage for 3 weeks and 6 weeks.

[0102] (Evaluation results) Tables 1, 2, 3, 4, and 5 show the formulation conditions, Cl / Ag values, and evaluation results before and after the storage conditions for the aqueous metal compositions produced in each Example and Comparative Example. The "particle size Dn50" in Tables 1 and 3 is a value measured using a zeta potential analyzer (Zetasizer Nano ZS90, manufactured by Malvern) and refers to the average primary particle size of the aqueous metal composition. Note that the aqueous metal compositions of Comparative Examples 1a, 2a, and 3a exhibited significant aggregation, making it difficult to measure their particle sizes accurately; therefore, they are indicated as "not measured."

[0103] Tables 1 and 2 show that the aqueous metal compositions obtained in the examples did not produce precipitates and were particularly resistant to aggregation even after long-term storage. Therefore, it was demonstrated that aqueous metal compositions in which the content of metal M (platinum, gold, or zinc) relative to the aqueous medium was 0.1 mass ppm or more and 100,000 mass ppm or less and the mass ratio of chlorine to silver (Cl / Ag) was 0.05 or less suppressed the production of precipitates and were resistant to aggregation even after long-term storage. In particular, aqueous metal compositions with a Cl / Ag ratio of less than 0.05 (specifically, 0.03 or less) showed no visible precipitates even after storage for not only 3 weeks but also 6 weeks, demonstrating significantly superior stability.

[0104] [Table 1]

[0105] [Table 2]

[0106] [Table 3]

[0107] [Table 4]

[0108] [Table 5]

Claims

1. An aqueous metal composition comprising an aqueous medium, silver, and at least one metal M other than silver, the metal M is a metal having antibacterial and / or antiviral properties, the content of the metal M relative to the aqueous medium is 0.1 ppm by mass or more and 100,000 ppm by mass or less; An aqueous metal composition having a chlorine to silver mass ratio (Cl / Ag) of 0.05 or less.

2. 10. The water-based metal composition of claim 1, wherein the silver and metal M are in particulate form.

3. 10. The water-based metallic composition of claim 1, wherein the silver and metal M are ions.

4. 4. The aqueous metal composition according to claim 1, wherein the metal M is at least one selected from the group consisting of platinum, gold, copper, zinc, nickel, and aluminum.

5. 4. The aqueous metal composition according to claim 1, wherein the metal M is at least one selected from the group consisting of platinum, gold, copper, and zinc.

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