Ce-Mo-based composite oxide ceramics, compacts, sintered bodies, and articles

Abstract

To provide a Ce-Mo based composite oxide ceramic or the like, excellent in antibacterial and antiviral property.SOLUTION: The Ce-Mo based composite oxide ceramic includes at least one species of trace elements selected from the group consisting of cerium, molybdenum, Al, Zr and Si.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to Ce-Mo-based composite oxide ceramics, compacted powders, sintered bodies, and articles. [Background technology]

[0002] Inorganic antibacterial and antiviral agents have advantages such as a wide operating temperature range and resistance to viruses, and have been the subject of active research in recent years. Examples of this type of antibacterial and antiviral agent that have been reported to date include metal-based agents such as Ag and Cu, photocatalytic agents such as TiO2, and metal oxide-based agents such as ZnO and CaO, and these are currently in use.

[0003] As shown in Patent Document 1, among inorganic antibacterial and antiviral agents, composite oxide ceramics containing cerium (Ce) and molybdenum (Mo), which have high antibacterial and antiviral activity, are attracting particular attention. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2022 / 014631 [Overview of the project] [Problems that the invention aims to solve]

[0005] Conventionally, when other elements besides cerium, molybdenum, and oxygen are mixed into composite oxide ceramics containing cerium and molybdenum, there has been no consideration whatsoever as to how those elements affect the antibacterial and antiviral properties of the composite oxide ceramics.

[0006] The object of the present invention is to provide Ce-Mo-based composite oxide ceramics and the like that have excellent antibacterial and antiviral properties. [Means for solving the problem]

[0007] As a result of diligent research to achieve the above objective, the inventors of the present invention discovered that when Ce-Mo composite oxide ceramics containing a composite oxide of cerium (Ce) and molybdenum (Mo) contain at least one trace element selected from the group consisting of Al, Zr, and Si, metal ions become more readily soluble, and excellent antibacterial and antiviral properties can be exhibited, leading to the completion of the present invention.

[0008] The means to solve the aforementioned problem are as follows: <1> A Ce-Mo composite oxide ceramic containing cerium, molybdenum, and at least one trace element selected from the group consisting of Al, Zr, and Si.

[0009] <2> The content of the aforementioned trace elements is 270 ppm or more. <1> Ce-Mo-based composite oxide ceramics as described above.

[0010] <3> The aforementioned trace elements are present in the crystalline phase. <1> or <2> Ce-Mo-based composite oxide ceramics as described above.

[0011] <4> Ce2Mo3O 13 The above including <1> or <2> Ce-Mo-based composite oxide ceramics as described above.

[0012] <5> The aforementioned <1> or <2> The Ce-Mo-based composite oxide ceramic described herein is in powder form, and the powdered Ce-Mo-based composite oxide ceramic is compressed and molded to form a compacted powder.

[0013] <6> The aforementioned <1> or <2> A sintered body obtained by sintering the Ce-Mo-based composite oxide ceramics described above.

[0014] <7> On at least a portion of the surface, <1> or <2> An article having the Ce-Mo composite oxide ceramics described above.

[0015] <8> An article wherein the Ce-Mo composite oxide ceramic according to <1> or <2> is dispersed in a base material.

Effects of the Invention

[0016] According to the present invention, a Ce-Mo composite oxide ceramic or the like excellent in antibacterial properties and antiviral properties can be provided. Brief Description of the Drawings

[0017] [Figure 1] Figure showing the production method (scheme) of the Ce-Mo composite oxide ceramic of Example 1 by a solid-phase synthesis method [Figure 2] Figure showing X-ray diffraction spectra of each calcined powder of Example 1 and Comparative Example 1 [Figure 3] Figure showing the temporal pH behavior of pure water in which each calcined powder of Example 1 and Comparative Example 1 is immersed Mode for Carrying Out the Invention

[0018] The Ce-Mo composite oxide ceramic of the present embodiment contains cerium (Ce), molybdenum (Mo), and at least one trace element selected from the group consisting of Al, Zr and Si.

[0019] The Ce-Mo composite oxide ceramic is a composite oxide ceramic containing cerium (Ce) and molybdenum (Mo), and contains the aforementioned trace element as an essential component. The composition ratio (molar ratio) of cerium (Ce) to molybdenum (Mo) contained in the Ce-Mo composite oxide ceramic is not particularly limited as long as the object of the present invention is not impaired. For example, the molar ratio may be Ce:Mo = 2:3, or may be Ce:Mo = 1:2.

[0020] The amount of oxygen atoms (O) contained in the Ce-Mo composite oxide ceramic may be a stoichiometric composition, or may deviate from the stoichiometric composition. In other words, the Ce-Mo composite oxide ceramic may be a non-stoichiometric compound.

[0021] Examples of Ce-Mo composite oxide ceramics include Ce(MoO4)2, Ce2MoO6, Ce2(MoO4)3, and Ce2Mo3O 13 Ce2Mo4O 15 Ce6(MoO4)8(Mo2O7), Ce8Mo 12 O 49 Examples include Ce2Mo3O. 13 It is preferable.

[0022] The aforementioned trace elements contained in the Ce-Mo composite oxide ceramic may be present at any location in the Ce-Mo composite oxide ceramic as long as the objectives of the present invention are not impaired. However, from the viewpoint of making it easier to maintain the Ce-Mo composite oxide ceramic in a preferred crystal structure (for example, a γ-type crystal structure), it is preferable that they be present in the crystalline phase of the Ce-Mo composite oxide ceramic.

[0023] As described above, the aforementioned trace element consists of at least one selected from the group consisting of Al, Zr, and Si. For example, aluminum is preferred as the trace element.

[0024] The content (percentage) of trace elements in the Ce-Mo composite oxide ceramic is preferably 270 ppm or more, more preferably 500 ppm or more, and even more preferably 700 ppm or more. There is no particular upper limit to the content (percentage) of trace elements in the Ce-Mo composite oxide ceramic, as long as it does not impair the objective of the present invention, but for example, it is preferably 100,000 ppm or less, more preferably 75,000 ppm or less, and even more preferably 50,000 ppm or less.

[0025] When the content (percentage) of the aforementioned trace elements in the Ce-Mo composite oxide ceramics is within this range, it is presumed that the trace elements penetrate the crystal structure of the Ce-Mo composite oxide, altering its structure and making it easier for metal ions constituting that crystal structure to dissolve. As a result, the pH is presumed to decrease when the Ce-Mo composite oxide ceramics are added to water. Consequently, the antibacterial and antiviral properties of the Ce-Mo composite oxide ceramics are presumed to be higher than those of Ce-Mo composite oxide ceramics that do not contain trace elements.

[0026] Trace elements in Ce-Mo composite oxide ceramics are detected, for example, using an X-ray fluorescence spectrometer (XRF). Based on the detection results, the content (percentage) of trace elements in the Ce-Mo composite oxide ceramics is determined.

[0027] The Ce-Mo composite oxide ceramics may contain other elements (e.g., H, F, Ba, Zn, Mg, Fe, Y, etc.) in addition to the aforementioned trace elements, as long as the objectives of the present invention are not impaired. These other elements may be present in the Ce-Mo composite oxide ceramics at a concentration of 0.01% by mass or less (100 ppm or less), or at a concentration of 0.008% by mass or less (80 ppm or less). These other elements in the Ce-Mo composite oxide ceramics can be detected using an X-ray fluorescence spectrometer (XRF) or an ICP emission spectrometer (ICP).

[0028] Ce-Mo composite oxide ceramics may be crystalline in the form of a single crystal or polycrystalline material, or amorphous such as glassy material, or a combination of crystalline and amorphous parts. Furthermore, the crystalline phase may be a single phase or a combination of two or more different phases.

[0029] The method for producing Ce-Mo composite oxide ceramics is not particularly limited as long as it does not impair the objectives of the present invention, but for example, a solid-phase reaction method can be used. As a method for producing Ce-Mo composite oxide ceramics, a solid-phase reaction method is preferred from the viewpoint of being easy to adjust the amount of trace elements to be included to a predetermined level.

[0030] Here, we illustrate a method for producing Ce-Mo-based composite oxide ceramics by a solid-phase reaction method. This method includes, for example, a compounding step, a drying step, and a calcination step.

[0031] The compounding process involves mixing a predetermined amount of cerium compound, a predetermined amount of molybdenum compound, and a predetermined amount of trace elements or trace element compounds to obtain a mixture thereof.

[0032] Cerium compounds are compounds containing cerium (Ce) necessary for producing Ce-Mo composite oxide ceramics, and examples include CeO2, cerium nitrate, cerium chloride, cerium sulfate, cerium hydroxide, cerium carbonate, and cerium acetate. As the cerium compound, at least one selected from the group consisting of CeO2, cerium nitrate, cerium chloride, cerium sulfate, cerium hydroxide, cerium carbonate, and cerium acetate may be used. CeO2 is preferred as the cerium compound.

[0033] Molybdenum compounds are compounds containing molybdenum (Mo) necessary for producing Ce-Mo composite oxide ceramics, and examples include MoO3, MoO2, MoO, Mo(OH)3, and Mo(OH)5. At least one molybdenum compound selected from the group consisting of MoO3, MoO2, MoO, Mo(OH)3, and Mo(OH)5 may be used. MoO3 is preferred as the molybdenum compound.

[0034] The mixing ratio of the cerium compound and the molybdenum compound may be adjusted so that the molar ratio Ce:Mo = 2:3, Ce:Mo = 1:2, Ce:Mo = 1:1, Ce:Mo = 2:1, Ce:Mo = 3:4, or Ce:Mo = 3:5. A molar ratio of Ce:Mo = 2:3 is preferred.

[0035] In the compounding process, trace elements may be used individually, or trace element compounds containing trace elements may be used.

[0036] When the trace element is aluminum (Al), examples of trace element compounds (aluminum compounds) include Al(NO3)3, Al2O3, aluminum sulfate, and aluminum chloride. Al(NO3)3 is preferred as the aluminum compound.

[0037] When the trace element is zirconium (Zr), examples of trace element compounds (zirconium compounds) include zirconium chloride, zirconium hydroxide, zirconium carbonate, zirconium sulfate, and zirconium acetate. Zirconium chloride is preferred as the zirconium compound.

[0038] When the trace element is silicon (Si), examples of trace element compounds (silicon compounds) include silicon dioxide, silicon monoxide, silicon carbide, and silicon nitride. Silicon dioxide is preferred as the silicon compound.

[0039] The mixing ratio of trace element compounds to cerium compounds and molybdenum compounds is set appropriately so that the content (percentage) of trace elements in the Ce-Mo composite oxide ceramic falls within the numerical range described above.

[0040] The compounding process involves, for example, placing a predetermined amount of cerium compound and a predetermined amount of molybdenum compound into a resin container (resin pot), and then adding a predetermined amount of a solvent such as a lower alcohol (ethanol) and a predetermined amount of trace element compound to the same container. These are then mixed for a predetermined time (for example, 5 to 30 hours) using pebbles (zirconia pebbles, alumina pebbles, etc.). This compounding process yields a slurry-like wet mixture.

[0041] The drying process involves drying the slurry-like wet mixture obtained after the blending process. There are no particular limitations on the drying method of the wet mixture as long as it does not impair the objective of the present invention. Examples include water bath drying, drying using a vibrating dryer, and drying using a spray dryer.

[0042] After the drying process, the wet mixture dries into a powder. The resulting powdered mixture (mixed powder) consists of solid-phase cerium compounds, solid-phase molybdenum compounds, and trace element compounds (or trace elements) mixed together.

[0043] The calcination process is a process in which the mixed powder obtained after the drying process is calcined in a solid state. For example, in the calcination process, the mixed powder is calcined at a temperature of 400°C to 650°C for 1 to 24 hours. The calcination process does not need to be carried out in a special synthetic air atmosphere and can be carried out in a normal atmospheric atmosphere. Note that the calcination process is not intended for sintering cerium compounds, molybdenum compounds, etc., in the mixed powder.

[0044] The calcination process yields a calcined powder (an example of a Ce-Mo composite oxide ceramic) consisting of a reaction product of a cerium compound, a molybdenum compound, and a trace element compound (or trace element).

[0045] The calcined powder may be granulated by spray drying or other methods as needed to prepare it into granules. Such granules may be used as Ce-Mo-based composite oxide ceramics.

[0046] Alternatively, the calcined powder may be subjected to a final calcination to obtain a sintered body, which may then be used as a Ce-Mo composite oxide ceramic. For example, the calcined powder can be compressed into a predetermined shape (e.g., cylindrical, disc-shaped, etc.) using a predetermined press, and the resulting molded body (compacted powder) can be fired at a predetermined temperature (e.g., 400°C to 650°C) for 1 to 24 hours to obtain a sintered body that can be used as a Ce-Mo composite oxide ceramic.

[0047] This firing process is a firing process for sintering the Ce-Mo-based composite oxide ceramics in the calcined powder, and can be carried out in an atmospheric environment.

[0048] Furthermore, the Ce-Mo composite oxide ceramics of this embodiment may be manufactured as appropriate by applying, for example, the citric acid polymerization method or hydrothermal synthesis method described in International Publication No. 2022 / 014631.

[0049] The Ce-Mo composite oxide ceramics of this embodiment exhibit antibacterial properties (antibacterial activity) and antiviral properties (antiviral activity) even before sintering. Furthermore, the Ce-Mo composite oxide ceramics of this embodiment exhibit antibacterial and antiviral properties after sintering, similar to those before sintering. Such Ce-Mo composite oxide ceramics can be used as an antibacterial agent with antibacterial properties, an antiviral agent with antiviral properties, or an antibacterial / antiviral agent possessing both antibacterial and antiviral properties.

[0050] The antibacterial and antiviral properties of Ce-Mo composite oxide ceramics can be evaluated, for example, by a film adhesion method in accordance with JIS R 1756. For example, for Ce-Mo composite oxide ceramics, the virus reduction rate after 24 hours using the aforementioned film adhesion method is 99% or more.

[0051] The shape of the Ce-Mo composite oxide ceramic in this embodiment is not particularly limited as long as it does not impair the objective of the present invention, and can be any shape desired depending on the application. For example, the Ce-Mo composite oxide ceramic may be in powder form, or it may be in granular form obtained by granulating the powder by spray drying or the like. The Ce-Mo composite oxide ceramic may also be used in the form of a compacted powder obtained by compression molding of powdered ceramic material. Furthermore, the Ce-Mo composite oxide ceramic may also be used in the form of a sintered body.

[0052] Furthermore, Ce-Mo composite oxide ceramics may be used in a form that is applied to at least a portion of the surface of an article. The materials constituting the article to which the Ce-Mo composite oxide ceramics are applied are not particularly limited as long as they do not impair the purpose of the present invention, and examples include glass, ceramics, synthetic resins such as thermoplastic resins and thermosetting resins, rubber (natural rubber, synthetic rubber), genuine leather (natural leather), synthetic leather, metallic materials consisting of metals or alloys, wood, paper, fibers, nonwoven fabrics, silicon (silicon wafers, etc.), carbon materials, minerals, gypsum, and the like.

[0053] Furthermore, Ce-Mo composite oxide ceramics may be used in a form dispersed in a predetermined substrate. The substrate in which the Ce-Mo composite oxide ceramics are dispersed is not particularly limited as long as it does not impair the objective of the present invention, and examples include glass, ceramics, synthetic resins such as thermoplastic resins and thermosetting resins, rubber (natural rubber, synthetic rubber), synthetic leather, metallic materials consisting of metals or alloys, paper, fibers, nonwoven fabrics, carbon materials, minerals, gypsum, and the like.

[0054] The present invention will be further described below based on the following examples. However, the present invention is not limited in any way by these examples.

[0055] [Example 1] CeO2 was prepared as the cerium compound, MoO3 as the molybdenum compound, and Al(NO3)3 as the trace element compound (aluminum compound). The raw material powders of the cerium compound and the molybdenum compound were weighed in a molar ratio of 2:3 (Ce:Mo = 2:3). After weighing, each raw material powder was placed in a resin container (resin pot), and then a predetermined amount of ethanol and a predetermined amount of the trace element compound (Al(NO3)3) were added to the container, and these were mixed for 24 hours using zirconia pebbles (mixing step). The resulting slurry-like wet mixture was dried in a water bath to obtain a mixed powder (drying step). In the mixed powder, the solid-phase cerium compound, the solid-phase molybdenum compound, and the trace element compound are mixed together.

[0056] Next, the mixed powder was calcined in an air atmosphere at a temperature of 475°C for 1 hour to obtain a calcined powder (Ce-Mo composite oxide ceramic) consisting of a reaction product of a cerium compound, a molybdenum compound, and a trace element compound. Figure 1 shows the method (scheme) for producing the Ce-Mo composite oxide ceramic of Example 1 by solid-phase synthesis.

[0057] [Comparative Example 1] Except for not mixing trace element compounds (aluminum compounds) with the raw material powders of the cerium compound and the molybdenum compound, a calcined powder consisting of a reaction product of a cerium compound and a molybdenum compound was obtained in the same manner as in Example 1.

[0058] [Identification of crystalline phases using XRD] The crystalline phase of each calcined powder from Example 1 and Comparative Example 1 was identified using powder X-ray diffraction (XRD). The measurement conditions were as follows.

[0059] <Measurement conditions> Measurement device: Powder X-ray diffractometer (device name "Smart lab", manufactured by Rigaku Corporation) Detector: D / teX Ultra250. Optical system: Concentrated optical system Bragg-Brentano type X-ray output: 40kV-30mA Step width: 0.0100° Scanning axis: 2θ / θ Scanning range: 10.00°~80.00°

[0060] <Measurement Result> The XRD measurement result (X-ray diffraction spectrum) is shown in Figure 2. Figure 2 is a diagram showing the X-ray diffraction spectra of each calcined powder of Example 1 and Comparative Example 1. Note that the measurement result of Example 1 is shown on the upper side of Figure 2, and the measurement result of Comparative Example 1 is shown on the lower side of Figure 2. From the X-ray diffraction peak of the measurement result shown on the lower side of Figure 2, the calcined powder of Comparative Example 1 has Ce₂Mo₃O 13 and it was confirmed that the powder has this crystal structure.

[0061] Furthermore, from the X-ray diffraction peak of the measurement result shown on the upper side of Figure 2, it was confirmed that the calcined powder of Example 1 also has the same Ce₂Mo₃O 13 crystal structure as Comparative Example 1. Note that it is presumed that the crystal phase of the calcined powder of Example 1 contains not only Ce₂Mo₃O 13 but also aluminum (Al), which is a trace element. In other words, it is presumed that a part of the elements of Ce₂Mo₃O 13 (Ce-Mo based composite oxide ceramics) constituting the crystal phase of Example 1 is substituted with aluminum (a trace element).

[0062] [pH Behavior during Immersion in Pure Water] 100 mg of the calcined powder of Example 1 was immersed in 100 ml of pure water in a glass container, and the pure water containing the calcined powder was stirred and mixed. The time point when the calcined powder was immersed was defined as 0 hour, and the time-dependent pH behavior of the pure water containing the calcined powder was measured using a pH meter. The time-dependent pH behavior of pure water containing the calcined powder of Comparative Example 1 was also measured in the same manner. The results are shown in Figure 3.

[0063] Figure 3 is a graph showing the pH behavior over time of pure water into which the calcined powders of Example 1 and Comparative Example 1 were immersed. In Figure 3, the solid line corresponds to Example 1, and the dashed line corresponds to Comparative Example 1. As shown in Figure 3, it was confirmed that at all times, Example 1 had a lower pH value and higher acidity than Comparative Example 1. This is due to the influence of aluminum (trace element) contained in the calcined powder of Example 1, which affects Ce-Mo composite oxide ceramics (Ce2Mo3O 13 It is presumed that the change in the crystal structure of the calcined powder makes it easier for metal ions to leach out, thus causing a decrease in the pH of the pure water in which the calcined powder was immersed.

Claims

1. comprising Ce₂Mo₃O₁₃ and Al as a trace element, A Ce-Mo composite oxide ceramic having a trace element content of 270 ppm or more and 75,000 ppm or less.

2. The Ce-Mo composite oxide ceramic described in Claim 1 is in powder form, and the powdered Ce-Mo composite oxide ceramic is compressed and molded to form a compact.

3. A sintered body obtained by sintering the Ce-Mo-based composite oxide ceramic described in Claim 1.

4. An article having the Ce-Mo composite oxide ceramic described in claim 1 on at least a portion of its surface.

5. An article comprising the Ce-Mo composite oxide ceramic described in Claim 1 dispersed in a substrate.

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