Cerium oxide nanoparticles and method for producing same

Abstract

Provided are cerium oxide nanoparticles having high oxidation performance, antiviral performance, and antibacterial performance, a dispersion liquid containing cerium oxide nanoparticles, a resin composition, and a fiber material. The invention relates to XPS (X-ray polystyrene) determination. Phosphorus compound adsorbed cerium oxide nanoparticles having a molar ratio of elemental phosphorus to elemental cerium (P / Ce ratio) of 0.72 or more, phosphorus compound adsorbed cerium oxide nanoparticles having a molar ratio of Ce4 + to the entirety of Ce4 + and Ce3 + of 0.070-0.89, and cerium (III) by containing condensed phosphoric acid or / and a salt thereof The cerium oxide nanoparticles are produced by adding an oxidizing agent to a solution of ions. In addition, the present invention is a dispersion liquid, a resin composition, and a fiber material containing the nanoparticles.

Description

Technical Field

[0001] The present invention relates to nanoparticles of cerium oxide, a dispersion containing the nanoparticles, an oxidizing agent, an antiviral agent, an antibacterial agent, a resin composition, a resin product, a fiber material, and a fiber product. Further, the present invention relates to a method for producing the nanoparticles of cerium oxide. Background Art

[0002] In recent years, with the increasing awareness of safety and hygiene management, antibacterial technologies for decomposing harmful substances and microorganisms have attracted attention. For example, titanium oxide has the property of oxidizing and decomposing organic substances through photocatalytic properties, and its performance is evaluated by decomposition reactions of organic pigments. Such oxidation and decomposition properties are expected to be used not only as antibacterial agents but also for decomposing various harmful substances such as low-molecular-weight substances like acetaldehyde and ammonia, allergens, and viruses.

[0003] On the other hand, nanoparticles of cerium oxide (nano cerium dioxide) have the same catalytic activity as oxidases such as oxidase and peroxidase, and are expected to be applied as oxidizing agents. Since these catalytic activities do not require a special light source such as ultraviolet light, it is expected to expand the use for decomposing harmful substances even in places where titanium oxide is difficult to use, such as indoors and in the dark.

[0004] When using metal nanoparticles that are easily aggregated as an oxidizing agent or the like, a method is used in which a stabilizer is added after synthesizing nanoparticles in a dispersion without adding a stabilizer to stably disperse the nanoparticles.

[0005] Here, Patent Document 1 discloses a whitening agent in which cerium oxide particles are dispersed. It is disclosed that the whitening agent becomes less susceptible to pH and its dispersion stability is improved by the addition of metaphosphoric acid.

[0006] Further, Patent Document 2 discloses that phosphoric acid, phosphonic acid, and their salts are used as stabilizers to treat metal nanoparticles such as cerium oxide in order to stably disperse the particles. In particular, in paragraph 0023 of this document, it is disclosed that phosphoric acid is preferably used.

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-045291

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2005-500436 Summary of the Invention

[0011] Problems to be Solved by the Invention

[0012] In Patent Document 1, nanoparticles obtained by a production method (hereinafter referred to as "post-addition") of adding metaphosphoric acid as a stabilizer after the formation of cerium oxide nanoparticles are disclosed. In addition, in Patent Document 2, nanoparticles obtained by a production method of adding phosphoric acid as a stabilizer after addition are disclosed. However, the oxidation performance of the nanoparticles disclosed in Patent Document 1 or 2 is low.

[0013] Thus, cerium oxide nanoparticles produced using condensed phosphoric acid containing metaphosphoric acid and phosphoric acid as stabilizers have problems such as low oxidation performance and antiviral performance.

[0014] Therefore, the present inventors further studied with the aim of finding cerium oxide nanoparticles with high oxidation performance using condensed phosphoric acid as a stabilizer. In addition, the present inventors also studied the antiviral and antibacterial properties of the nanoparticles.

[0015] Means for Solving the Problems

[0016] In order to solve the above problems, the present inventors focused on the production method of cerium oxide nanoparticles and found that cerium oxide nanoparticles produced by a production method (hereinafter referred to as "pre-addition") of adding an oxidizing agent to a solution containing condensed phosphoric acid or / and its salt and cerium(III) ions, and the dispersion liquid containing the particles have high oxidation performance, antiviral performance, and antibacterial performance. In addition, it was found that processed products such as resin compositions and fiber materials containing the particles also have high antiviral performance.

[0017] The present invention is as follows.

[0018] (1) Nanoparticles of cerium oxide with an inorganic acid adsorbed on the surface, having a Zeta potential of 0 mV or less at pH 7.

[0019] (2) Nanoparticles of cerium oxide adsorbed with a phosphorus compound, having a molar ratio of phosphorus element to cerium element (P / Ce ratio) of 0.72 or more in XPS measurement.

[0020] (3) The nanoparticles of cerium oxide according to (2), wherein the phosphorus compound is condensed phosphoric acid.

[0021] (4) The nanoparticles of cerium oxide according to (2) or (3), having peaks in the range of 2θ = 30.5° or more and 32.0° or less and 41.5° or more and 43.0° or less in the XRD spectrum.

[0022] (5) Nanoparticles of cerium oxide adsorbed with a phosphorus compound, wherein the molar ratio of Ce 4+ relative to Ce 4+ and Ce 3+ is 0.070 or more and 0.89 or less with respect to the whole.

[0023] (6) The cerium oxide nanoparticles according to (5), wherein the phosphorus compound is condensed phosphoric acid.

[0024] (7) The cerium oxide nanoparticles according to (5) or (6), having peaks in the range of 2θ = 30.5° or more and 32.0° or less and 41.5° or more and 43.0° or less in the XRD spectrum.

[0025] (8) A method for manufacturing cerium oxide nanoparticles, which is manufactured by the following step (a),

[0026] Step (a) is a step of adding an oxidizing agent to a solution containing condensed phosphoric acid or / and its salt and cerium (III) ions.

[0027] (9) The cerium oxide nanoparticles according to (8), wherein the pH of the above solution when adding the above oxidizing agent is 5 or more.

[0028] (10) The cerium oxide nanoparticles according to (8) or (9), wherein the condensed phosphoric acid is polyphosphoric acid or metaphosphoric acid.

[0029] (11) The cerium oxide nanoparticles according to (10), wherein the polyphosphoric acid is pyrophosphoric acid, tripolyphosphoric acid, tetrapolyphosphoric acid, pentapolyphosphoric acid or hexapolyphosphoric acid.

[0030] (12) The cerium oxide nanoparticles according to (10), wherein the metaphosphoric acid is trimetaphosphoric acid, tetrametaphosphoric acid, pentametaphosphoric acid or hexametaphosphoric acid.

[0031] (13) The cerium oxide nanoparticles according to any one of (8) to (12) are manufactured by a process including the above step (a) and step (b),

[0032] Step (b) is a step of hydrothermally treating the solution obtained in step (a).

[0033] (14) The cerium oxide nanoparticles according to any one of (8) to (13), wherein the APHA of a dispersion containing 0.1% by mass of the above nanoparticles is 400 or less.

[0034] (15) The cerium oxide nanoparticles according to any one of (8) to (14), wherein the Zeta potential at pH 7 is -20 mV or less.

[0035] (16) A dispersion containing the cerium oxide nanoparticles according to any one of (1) to (15).

[0036] (17) An oxidizing agent containing the cerium oxide nanoparticles according to any one of (1) to (15).

[0037] (18) An antiviral agent comprising the cerium oxide nanoparticles described in any one of (1) to (15).

[0038] (19) An antibacterial agent comprising the cerium oxide nanoparticles described in any one of (1) to (15).

[0039] (20) A resin composition comprising the cerium oxide nanoparticles described in any one of (1) to (15).

[0040] (21) A resin product made using the resin composition described in (20).

[0041] (22) The resin product according to (21), wherein the resin product is a product selected from automotive interior materials, electrical product housings, grab handles, armrests, door handles, partitions, and coatings.

[0042] (23) A fiber material comprising the cerium oxide nanoparticles described in any one of (1) to (15).

[0043] (24) A fiber product made using the fiber material described in (23).

[0044] (25) The fiber product according to (24), wherein the fiber product is a product selected from masks, protective clothing, filters, mats, chairs, gowns, lab coats, curtains, sheets, automotive interior materials, and rags.

[0045] (26) A method for manufacturing cerium oxide nanoparticles, comprising the following step (a),

[0046] Step (a) is a step of adding an oxidizing agent to a solution containing a condensed phosphoric acid represented by the following general formula (I) and / or its salt and cerium(III) ions.

[0047] (27) The method for manufacturing cerium oxide nanoparticles according to (26), further comprising step (b),

[0048] Step (b) is a step of hydrothermally treating the solution obtained in step (a).

[0049] (28) The method for manufacturing cerium oxide nanoparticles according to (26) or (27), wherein the APHA of a 0.1 mass% dispersion of the above-mentioned cerium oxide nanoparticles is 400 or less.

[0050] Effects of the Invention

[0051] The nanoparticles of cerium oxide of the present invention or a dispersion liquid containing the nanoparticles exhibit high oxidation performance, antiviral performance, and antibacterial performance. In addition, the nanoparticles of cerium oxide of the present invention or processed products such as a dispersion liquid, a resin composition, and a fiber material containing the nanoparticles can be used as an oxidizing agent or a high-performance antiviral agent and antibacterial agent for inactivating various viruses. Detailed Description

[0052] The nanoparticles of cerium oxide of the present invention are sometimes simply referred to as the nanoparticles of the present invention in this specification. In addition, the dispersion liquid containing the nanoparticles of cerium oxide of the present invention is sometimes simply referred to as the dispersion liquid of the present invention in this specification.

[0053] The nanoparticles of cerium oxide of the present invention have a characteristic that the Zeta potential at pH 7 is 0 mV or less and inorganic acid is adsorbed on the surface.

[0054] The Zeta potential is one of the values representing the electro properties of the interface of a colloid in a solution. If a charged colloid is dispersed in a solution, a double electric layer is formed on the surface of the colloid by counter ions charged relative to the surface of the colloid. The potential of the colloid surface at this time is called the surface potential. Since the double electric layer is formed by the electrostatic interaction of the surface charge of the colloid, the ions are fixed more strongly on the colloid side. In the double electric layer, the layer in which the counter ions are strongly fixed to the colloid surface by electrostatic interaction is called the fixed layer, and the potential of the fixed layer is called the fixed potential. If the colloid is moved relative to the solution, the fixed layer moves together with the colloid. At this time, from the colloid, there is an interface that moves together with the colloid due to the viscosity of the solution outside the fixed layer. This interface is called the sliding surface or the shear surface. The potential of this sliding surface when the potential at a location sufficiently far from the colloid is set to zero is defined as the Zeta potential. Thus, since the Zeta potential changes depending on the surface charge of the colloid and the surface charge changes depending on the adsorption / desorption of protons depending on pH, in the present invention, the value in a solution at pH 7 is used as a reference. In addition, generally, since the distance to the sliding surface is small compared to the size of the colloid, the surface of the colloid can also be approximately expressed as the sliding surface.

[0055] The Zeta potential can be obtained by using electrokinetic phenomena such as electrophoresis, electroosmosis, streaming potential, and sedimentation potential, and can be measured by methods such as microscopic electrophoresis, electrophoresis using a rotating diffraction grating method, laser / Doppler electrophoresis, ultrasonic vibration potential method, and electroacoustic detection method. These measurements can be performed by using a Zeta potential measurement device. Zeta potential measurement devices are sold by Otsuka Electronics Co., Ltd., Malvern Instruments Ltd., RankuBrother Ltd., PenKem Inc., etc.

[0056] The Zeta potential can be measured using any of the above devices, but generally the laser / Doppler electrophoresis method is used. The laser / Doppler electrophoresis method is a measurement method that utilizes the Doppler effect in which the frequency changes when light or sound waves are scattered or reflected by an object moving through electrophoresis.

[0057] In the case of measuring the Zeta potential, the nanoparticles of the present invention are dispersed in a solution containing an electrolyte such as a sodium chloride solution, a HEPES buffer solution, etc., and the scattered light and reflected light of the dispersed nanoparticles are detected for measurement. The larger the size of the nanoparticles, the lower the concentration at which the scattered light and reflected light can be detected.

[0058] There are no particular limitations on the specific conditions for measuring the Zeta potential of the nanoparticles of the present invention by the laser / Doppler method. For example, it can be dissolved in a HEPES acid buffer solution (10 mM, pH 7) such that the concentration of the nanoparticles is 0.1 wt% or more and 1 wt% or less, or 0.001 wt% or more and 1 wt% or less. This solution is added to a measurement cell and placed in a Zeta potential measurement device based on the principle of laser / Doppler electrophoresis, and the measurement is carried out at room temperature. As the Zeta potential measurement device, for example, ELS-Z of Otsuka Electronics Co., Ltd. can be used.

[0059] The Zeta potential of the nanoparticles of the present invention having inorganic acid adsorbed on the surface at pH 7 is 0 mV or less, preferably -10 mV or less, and more preferably -20 mV or less.

[0060] In this specification, a term such as "nanoparticles of cerium oxide" also includes a concept of particles including inorganic acids or phosphorus compounds described later adsorbed on their surfaces. An inorganic acid is a general term for acids that do not contain carbon atoms. A phosphorus compound is a general term for compounds containing a phosphorus element. In this specification, the above inorganic acids include phosphoric acid and condensed phosphoric acid, and the above phosphorus compounds also include phosphoric acid and condensed phosphoric acid. The preferred inorganic acid is condensed phosphoric acid. The preferred phosphorus compound is condensed phosphoric acid.

[0061] The nanoparticles of the present invention have the characteristic of having inorganic acid adsorbed on the surface as described above.

[0062] In this specification, condensed phosphoric acid refers to a substance formed by dehydration condensation of two or more phosphoric acid molecules. Polyphosphoric acid refers to a linear substance among condensed phosphoric acids. Cyclic phosphoric acid refers to a cyclic substance among condensed phosphoric acids. Metaphosphoric acid refers to a mixture of polyphosphoric acid and cyclic phosphoric acid. Cyclic phosphoric acid includes ultraphosphoric acid having a network structure.

[0063] Phosphoric acid undergoes dehydration condensation by heating. Through condensation, it becomes linear polyphosphoric acid, cyclic phosphoric acid, metaphosphoric acid or superphosphoric acid which is a mixture of linear and cyclic forms, and finally becomes phosphorus pentoxide (tetraphosphorus decoxide). In this specification, condensed phosphoric acid includes condensates of these phosphoric acids, that is, it includes polyphosphoric acid, cyclic phosphoric acid, superphosphoric acid, metaphosphoric acid and phosphorus pentoxide. As the counterion of the condensed phosphoric acid in the condensed phosphate, any ion such as lithium ion, sodium ion, potassium ion, ammonium ion can be used.

[0064] The condensed phosphoric acid preferably used in the present invention is polyphosphoric acid or metaphosphoric acid. As the polyphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, tetrapolyphosphoric acid, pentapolyphosphoric acid or hexapolyphosphoric acid can be more preferably used, and as the metaphosphoric acid, trimetaphosphoric acid, tetrametaphosphoric acid, pentametaphosphoric acid or hexametaphosphoric acid can be more preferably used.

[0065] In addition, polyphosphoric acid and metaphosphoric acid are sometimes sold as substances with higher degrees of polymerization or as mixtures of substances with different degrees of polymerization, and such substances can be used in the present invention.

[0066] The cerium oxide nanoparticles of the present invention are cerium oxide nanoparticles adsorbed with a phosphorus compound, which are characterized in that the ratio of phosphorus element to cerium element (P / Ce ratio) in XPS measurement is 0.72 or more.

[0067] XPS can obtain information related to elements and valence states, and the ratio of cerium element to phosphorus element can be quantified using the peak area ratio of the obtained spectra. When calculating the ratio of phosphorus element to cerium element (P / Ce ratio), the obtained spectrum is corrected for the horizontal axis so that the main peak of P2p becomes 133.0 eV, and then the peak area of phosphorus element is divided by the peak area of cerium element to calculate the P / Ce ratio. In the XPS measurement of the cerium oxide nanoparticles of the present invention, the ratio of phosphorus element to cerium element (P / Ce ratio) is in the range of 0.72 or more. The cerium oxide nanoparticles only need to have a ratio of phosphorus element to cerium element (P / Ce ratio) obtained by XPS measurement of 0.72 or more, which is the lower limit for the increase in oxidase activity, antiviral activity, antibacterial activity, etc., more preferably 0.75 or more, and further preferably 0.80 or more. The cerium oxide nanoparticles only need to have a molar ratio of phosphorus element to cerium element (P / Ce ratio) obtained by XPS measurement in the range of 0.72 or more and 1000 or less for the increase in oxidase activity, antiviral activity, antibacterial activity, etc., and it is better if it is 0.72 or more and 100 or less, more preferably 0.75 or more and 10 or less, and further preferably 0.80 or more and 8.0 or less. When measuring the molar ratio of phosphorus element to cerium element (P / Ce ratio) by XPS, the powder obtained by drying the nanoparticles is used. For example, a sample obtained by hot air drying or freeze drying a dispersion containing the cerium oxide nanoparticles of the present invention that has been membrane purified at 40°C or higher and 120°C or lower is used. In addition, if the nanoparticles are a composite with a membrane, resin, or fiber, the surface where the nanoparticles are processed is measured.

[0068] The cerium oxide nanoparticles of the present invention have Ce in XPS measurement 4+ relative to Ce 4+ and Ce 3+ and have the characteristic that the ratio to the whole is 0.070 or more and 0.89 or less.

[0069] In the cerium oxide nanoparticles of the present invention, the molar ratio of cerium(III) to cerium(IV) can be measured by X-ray photoelectron spectroscopy (XPS). After correcting the horizontal axis by the above method, the peak splitting of Ce3d is performed to calculate the molar ratio of each Ce ion. The Ce obtained by XPS measurement of the cerium oxide nanoparticles of the present invention 4+ relative to Ce 4+ and Ce 3 +The overall molar ratio is in the range of 0.070 or more and 0.89 or less. The cerium oxide nanoparticles only need to have the above molar ratio obtained by XPS measurement in the range of 0.070 or more and 0.89 or less, which is a range where the oxidase activity, antiviral activity, antibacterial activity, etc. are high. It is preferably 0.10 or more and 0.88 or less, and more preferably 0.20 or more and 0.86 or less.

[0070] When measuring the above molar ratio by XPS, the powder obtained by drying the nanoparticles is used. For example, a sample obtained by hot air drying or freeze drying a dispersion liquid containing the cerium oxide nanoparticles of the present invention that has undergone membrane purification at 40°C or more and 120°C or less is used. In addition, if the nanoparticles are a composite with a membrane, resin, or fiber, the surface of the nanoparticles that has been processed is measured.

[0071] The nanoparticles of the present invention are characterized in that a phosphorus compound is adsorbed on the surface as a stabilizer.

[0072] The Bragg angle (2θ) of the cerium oxide nanoparticles of the present invention can be measured by X-ray diffraction (XRD). Information related to crystallinity can be obtained from the positions and intensities of the peaks in the obtained XRD spectrum.

[0073] The cerium oxide nanoparticles of the present invention preferably have peaks in the XRD spectrum in the ranges of 2θ of 30.5° or more and 32.0° or less and 41.5° or more and 43.0° or less. These characteristics are detected in the cerium oxide nanoparticles that have undergone hydrothermal treatment among the manufacturing methods described below. As peaks derived from cerium oxide, the cerium oxide nanoparticles of the present invention can further have peaks in the XRD spectrum at Bragg angles 2θ of 28.5° or more and 29.1° or less, 33.0° or more and 33.2° or less, 47.2° or more and 48.6° or less, 56.1° or more and 56.3° or less, and 59.1° or more and 59.4° or less. A diffraction peak refers to a maximum value of intensity in the XRD spectrum. When calculating the Bragg angle showing the diffraction peak, when the intensity of the obtained spectrum is low, processing such as smoothing can be performed.

[0074] In the above XRD spectrum, the cerium oxide nanoparticles having peaks in the ranges of 2θ of more than 30.5° and less than 32.0° and more than 41.5° and less than 43.0° preferably have the above two peaks in the ranges of 2θ of more than 30.8° and less than 31.8° and more than 41.7° and less than 42.7°, more preferably in the ranges of 2θ of more than 31.1° and less than 31.6° and more than 41.8° and less than 42.3°. When measuring the XRD spectrum, a powder obtained by drying the nanoparticles is used. For example, a sample obtained by subjecting a dispersion liquid containing the cerium oxide nanoparticles of the present invention that has undergone membrane purification to hot air drying or freeze drying at 40°C or higher and 120°C or lower is used. In addition, if the nanoparticles are a composite with a membrane, resin, or fiber, the surface on which the nanoparticles are processed is measured.

[0075] The cerium oxide nanoparticles of the present invention are produced by adding an oxidizing agent to a solution containing condensed phosphoric acid or / and its salt and cerium(III) ions. That is, the cerium oxide nanoparticles of the present invention are produced by a production method of "pre-adding" a stabilizer. In the synthesis of the cerium oxide nanoparticles of the present invention, a water-soluble cerium salt is used as one of the raw materials, and the synthesis is carried out in water or a solvent compatible with water. From the viewpoint of having moderate hydrophilicity and having the property of stabilizing the dispersion of nanoparticles by forming a complex with the hydroxyl groups of metal oxides, as an embodiment, condensed phosphoric acid or / and its salt is used as a stabilizer. Uncondensed phosphoric acid is not preferred because it strongly binds to cerium ions to form a precipitate.

[0076] Production method of nanoparticles

[0077] A dispersion liquid containing the cerium oxide nanoparticles of the present invention is produced by a production method of adding an oxidizing agent to a solution containing condensed phosphoric acid or / and its salt and cerium(III) ions, that is, "pre-adding". Hereinafter, the production method of the dispersion liquid of the cerium oxide nanoparticles of the present invention will be described.

[0078] [Step (a): Step of forming nanoparticles]

[0079] The step of forming the nanoparticles of the present invention includes the first step and the second step described below.

[0080] [Step (a-1): First step]

[0081] The first step is a step of obtaining a solution containing condensed phosphoric acid or / and its salt and cerium(III) ions. The solution of condensed phosphoric acid or / and its salt used in this step can be prepared by dissolving condensed phosphoric acid or / and its salt in an arbitrary solvent. The solvent is preferably water or a solvent compatible with water. Specific examples of the solvent compatible with water include methanol, ethanol, propanol, isopropanol, butanol, tert-butanol, tetrahydrofuran, acetone, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), glycerol, ethylene glycol, propylene glycol, oligoethylene glycol, 2-pyrrolidone, N-methyl-2-pyrrolidone, etc. In the case where condensed phosphoric acid or / and its salt is not easily soluble in the solvent, heating or ultrasonic treatment can be carried out for dissolution.

[0082] The amount of condensed phosphoric acid or / and its salt only needs to be in the range of 0.01 to 1000 molar equivalents relative to cerium(III) ions, preferably 0.1 to 100 molar equivalents, more preferably 0.5 to 50 molar equivalents, and most preferably 1 to 30 molar equivalents.

[0083] In order to obtain a solution containing condensed phosphoric acid or / and its salt and cerium(III) ions, a solution of condensed phosphoric acid or / and its salt and a solution containing cerium(III) ions can be separately prepared and mixed. In the case where the solvent of the solution of condensed phosphoric acid or / and its salt is water or a solvent compatible with water, a cerium(III) salt can be added to the solution of condensed phosphoric acid or / and its salt for mixing, or condensed phosphoric acid or / and its salt can be added to the solution containing cerium(III) ions for mixing.

[0084] The solution containing cerium(III) ions can be prepared by dissolving a cerium(III) salt in an arbitrary solvent. As the cerium(III) salt, inorganic salts such as nitrates, chlorides, sulfates, phosphates, organic acid salts such as acetates, oxalates, cerium coordination compounds having ligands such as NH3 (ammine) and NO3 (nitrato), hydrates, etc. can be used. The preferred cerium(III) salt is nitrate, and for example, cerium(III) nitrate·hexahydrate can be used.

[0085] Regarding the amount of the cerium(III) salt, it can be mixed with the solution of condensed phosphoric acid or / and its salt so that the final concentration of the reaction solution becomes in the range of 0.01 mass% to 10 mass%. The mixed solution is preferably mixed for 5 minutes or more until the solution becomes uniform.

[0086] In the first step, the solution containing condensed phosphoric acid or / and its salts and cerium(III) ions preferably does not contain carboxylic acids having three or more carboxyl groups, such as the compounds shown below. Even when contained, the amount is preferably 0.1 equivalent or less, more preferably 0.01 equivalent or less, relative to the cerium(III) ions. Examples of carboxylic acids having three or more carboxyl groups specifically include nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), ethylenediaminedisuccinic acid (EDDS), ethylene glycol ether diamine tetraacetic acid (EGTA), diethylenetriaminepentaacetic acid (DTPA), citric acid, hydroxyethyl ethylenediaminetetraacetic acid (HEDTA), polyacrylic acid, and / or their salts.

[0087] When doping a metal into the cerium oxide nanoparticles of the present invention, a transition metal can be further added in the first step. The transition metal can be directly added in a solid state as a metal salt to the solution containing condensed phosphoric acid or / and its salts and cerium(III) ions or cerium(III) salts, or a solution prepared by dissolving the metal salt in an arbitrary solvent can be added to the solution containing condensed phosphoric acid or / and its salts and cerium(III) ions or cerium(III) salts.

[0088] The amount of the transition metal is preferably in the range of 0.0001 mol to 0.3 mol, more preferably in the range of 0.001 mol to 0.2 mol, relative to 1 mol of the cerium(III) ions. In addition, in the amount of the transition metal, the amount of elements other than the transition metal contained in the salt of the transition metal is not included.

[0089] [Step (a-2): Second step]

[0090] The second step is a step of adding an oxidizing agent to the mixed solution obtained in the first step. Examples of the oxidizing agent used in the second step include nitric acid, potassium nitrate, hypochlorous acid, chlorous acid, chloric acid, perchloric acid, halogens, permanganates, chromic acid, dichromic acid, oxalic acid, sulfur dioxide, sodium thiosulfate, sulfuric acid, hydrogen peroxide, oxygen, ozone, etc. Oxygen in the air is sometimes used as the oxidizing agent. The oxidizing agent used in the second step is preferably hypochlorous acid, permanganates, chromic acid, dichromic acid, hydrogen peroxide, oxygen, or / and ozone. Among them, hydrogen peroxide is particularly preferred. The addition amount of the oxidizing agent can be 0.1 equivalent or more and 10 equivalents or less, more preferably 0.5 equivalent or more and 5 equivalents or less, and preferably 0.5 equivalent or more and 2 equivalents or less, as a molar equivalent relative to the cerium(III) ions.

[0091] If an oxidizing agent is added to a solution containing condensed phosphoric acid or / and its salt and cerium(III) ions, the cerium(III) ions are oxidized to cerium(IV), and the formation reaction of cerium oxide particles composed of a mixture of Ce2O3 and CeO2 starts. In addition, during this reaction, the solution is colored yellow, orange, red, brown, etc. This is the color development caused by the change of cerium(III) ions to cerium(IV), and the degree of coloring is determined by the ratio of cerium(III) to cerium(IV) present on the surface of the cerium oxide nanoparticles. The end of the reaction can be judged by the point at which the color no longer changes.

[0092] The formation reaction of cerium oxide nanoparticles can be carried out at any pH. However, from the viewpoint that the reaction is easy to proceed under weakly acidic to alkaline conditions, the pH of the solution when adding the oxidizing agent is preferably adjusted to 5 or more in advance, more preferably adjusted to pH 6 or more in advance, and further preferably adjusted to pH 7 or more in advance. When adjusting the pH, an aqueous sodium hydroxide solution, an aqueous ammonia solution, etc. can be used. In addition, since the pH of the solution tends to be on the acidic side as this reaction proceeds, the pH of the reaction solution can be maintained at 5 or more during the period from the addition of the oxidizing agent to the end of the reaction. Usually, the reaction ends in about 5 minutes to 1 hour, and a dispersion containing the cerium oxide nanoparticles of the present invention is obtained. For example, if 10 ml of a 10 mass% aqueous solution of cerium(III) nitrate hexahydrate is added to 2.72 g / 250 ml of an aqueous sodium polyphosphate solution (pH 9.3), and then 20 ml of a 1.2 mass% aqueous hydrogen peroxide solution is added and stirred at room temperature, the solution changes to yellow in about 5 minutes. The particle formation reaction ends in about 2 hours, and the dispersion of the present invention is obtained.

[0093] The formation reaction of cerium oxide nanoparticles can be carried out at any temperature from 4°C to 230°C. In the case of cooling, a cold bath such as BBL101 of Yamato Scientific Co., Ltd. can be used, and in the case of heating, a hot bath such as OHB-1100S manufactured by Tokyo Rika Kikai Co., Ltd. can be used. In either case, the reaction solution is placed in a container and cooled, heated, heated under reflux, or hydrothermally treated while stirring. The material of the above container is glass, plastic, stainless steel, etc., and there is no particular limitation. When the above temperature exceeds 100°C, a container that can withstand a pressure exceeding 1 atmosphere is sufficient.

[0094] The dispersion of the present invention can adjust the pH after the reaction ends. The pH of the dispersion of the present invention only needs to be in the range of pH 1 to 12, preferably pH 2 to 10. The pH can be adjusted by adding a buffer solution, and can be adjusted by adding acids such as nitric acid, sulfuric acid, hydrochloric acid, ammonia, sodium hydroxide, potassium hydroxide and other bases. In addition, in the case of performing the following step (b): the hydrothermal treatment step, the pH adjustment of the dispersion can be performed after step (b), or can be performed after the purification of the dispersion such as filtration with an ultrafiltration membrane and dialysis with a semipermeable membrane described below.

[0095] The dispersion of the present invention can be purified by filtering the dispersion after the reaction ends with an ultrafiltration membrane or performing dialysis with a semipermeable membrane to remove the unreacted oxidant, cerium(III) ions, and excess condensed phosphoric acid or / and its salts remaining in the dispersion after the reaction ends. At this time, it only needs to be removed so that the cerium(III) concentration becomes 10 mM or less, and preferably becomes 5 mM or less. In addition, the nanoparticle concentration can also be increased by filtration with an ultrafiltration membrane and dialysis with a semipermeable membrane. Then, the cerium oxide nanoparticles can be separated from the dispersion of the present invention by the method described below. The above purification can be performed after the following step (b): the hydrothermal treatment step. Condensed phosphoric acid still remains adsorbed on the surface of the cerium oxide nanoparticles obtained after the above purification.

[0096] [Step (b): Hydrothermal treatment step]

[0097] In the present invention, the reaction solution after adding the oxidant obtained in step (a-2), the dispersion after the above purification, drying and redispersion can be heat-treated at any temperature from 30°C to 230°C. If the heating is below 100°C, the dispersion can be heated in a glass container, and the heating above 100°C is performed by hydrothermal treatment by the method described below. In the present invention, hydrothermal treatment is preferably performed.

[0098] In the present invention, hydrothermal treatment is a process of treating with water at a temperature higher than 100 °C and a pressure higher than 101 kPa (1 atmosphere). The hydrothermal treatment achieves the effect of improving the colorability of cerium oxide nanoparticles. When the dispersion liquid containing cerium oxide nanoparticles is colored deep orange, red, etc., it changes to light yellow or light brown by hydrothermal treatment. The effect of hydrothermal treatment depends on the temperature and time of hydrothermal treatment. Regarding the treatment temperature, the higher the hydrothermal treatment temperature and the longer the reaction time, the more significantly the colorability is improved. The pressure in hydrothermal treatment can be obtained from the saturated water vapor pressure table and temperature. The hydrothermal treatment can be carried out at a temperature higher than 100 °C (101 kPa) and below 230 °C (2.80 MPa), preferably 105 °C (121 kPa) to 200 °C (1.55 MPa), more preferably 110 °C (143 kPa) to 180 °C (1.00 MPa). In addition, the time can be arbitrarily set between 1 and 180 minutes. Even for heat treatment, if the heating is not at a temperature higher than 100 °C and a pressure higher than 101 kPa, the colorability is not improved.

[0099] The hydrothermal treatment of the present invention can be carried out by heating the reaction liquid added with an oxidant obtained in step (a-2) in a pressure-resistant container. For example, the reaction liquid can be added to a pressure-resistant container composed of a PTFE inner cylinder and a pressure-resistant stainless steel outer cylinder and heated by an oil bath. In addition, the purified dispersion liquid can be added to a culture medium bottle and treated using a sterilization device such as LSX-500 of Tommy Industries Co., Ltd.

[0100] [Post-treatment of dispersion liquid]

[0101] The nanoparticles of cerium oxide of the present invention can be separated by drying the dispersion of the present invention using an evaporator, a freeze dryer, or the like. In addition, the nanoparticles of cerium oxide can also be separated by dropping the dispersion of the present invention onto substrates such as glass, plastic, and ceramic, followed by air drying, or drying in a dryer, or drying with a desiccant or a dryer. In addition, separation can also be achieved by dropping the dispersion of the present invention onto a heating block and heating it to volatilize the solvent. In addition, separation can also be achieved by drying the dispersion of the present invention through a spray dryer or the like to volatilize the solvent. In addition, separation can also be achieved by subjecting the dispersion of the present invention to a centrifuge to precipitate the nanoparticles of cerium oxide and removing the supernatant. In addition, by filtering the dispersion of the present invention through ultrafiltration or suction filtration to completely remove the water, the nanoparticles of cerium oxide can also be separated on the filter membrane. In order to improve the efficiency of the drying process in the above operations, an azeotropic solvent can be added to the dispersion of the present invention, or the solvent of the dispersion can be replaced with a solvent having a lower boiling point. In addition, in order to improve the efficiency of the centrifugation operation, a coprecipitant can be added to the dispersion of the present invention, the ionic strength can be increased, or a solvent that reduces the dispersibility of the nanoparticles can be added. In addition, before the above operations, the dispersion of the present invention can be size-fractionated for the nanoparticles using an ultrafiltration membrane, centrifugation, or the like.

[0102] The dispersion of the present invention may contain ionic components. As the ionic components and components imparting buffering properties, acetic acid, phthalic acid, succinic acid, carbonic acid, tris(hydroxymethyl)aminomethane (Tris), 2-morpholinoethanesulfonic acid, monohydrate (MES), bis(2-hydroxyethyl)iminotris(hydroxymethyl)methane (Bis-Tris), N-(2-acetamido)iminodiacetic acid (ADA), piperazine-1,4-bis(2-ethanesulfonic acid) (PIPES), N-(2-acetamido)-2-aminoethanesulfonic acid (ACES), 2-hydroxy-3-morpholinopropanesulfonic acid (MOPSO), N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES), 3-morpholinopropanesulfonic acid (MOPS), N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid (TES), 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid (HEPES), 2-hydroxy-N-tris(hydroxymethyl)methyl-3-aminopropanesulfonic acid (TAPSO), piperazine-1,4-bis(2-hydroxy-3-propane sulfonic acid), piperazine-1,4-bis(2-hydroxy-3-propanesulfonic acid))(POPSO), 2-hydroxy-3-[4-(2-hydroxyethyl)-1-piperazinyl]propanesulfonic acid (HEPSO), 3-[4-(2-hydroxyethyl)-1-piperazinyl]propanesulfonic acid (HEPPS), (Tricine), N,N-bis(2-hydroxyethyl)glycine (Bicine), N-tris(hydroxymethyl)methyl-3-aminopropanesulfonic acid (TAPS). As components that do not impart buffering properties, sodium chloride and potassium chloride can be cited. These ionic components can be added so that the final concentration ranges from 0.1 mM to 1 M. These ionic components can be added to the dispersion after the reaction in step (a-2). In the case of performing the hydrothermal treatment in step (b), they can also be added to the dispersion after step (b). They can be added after filtration with an ultrafiltration membrane, can be used as a dialysis solution, or can be added to the dispersion after dialysis. They can be added to the dried cerium oxide nanoparticles to prepare a dispersion.,

[0103] The dispersion of the present invention can be stored as the dispersion after the reaction, can also be stored as a purified product obtained by filtering the dispersion after the reaction with an ultrafiltration membrane or a purified product obtained by dialysis with a semipermeable membrane, and can also be stored as cerium oxide nanoparticles separated by drying using an evaporator, a spray dryer, a freeze dryer, etc.

[0104] In the case of forming a dry powder, in order to inhibit the aggregation of the cerium oxide nanoparticles of the present invention, a dispersant can be added before or after drying. As the dispersant, hydrophilic polymers such as starch, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyethylene oxide, and polyacrylamide, cationic surfactants such as quaternary ammonium salts, anionic surfactants such as higher fatty acid salts and alkyl sulfates, amphoteric surfactants such as alkyl betaines, and nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters and polyoxyethylene alkyl ethers are preferred, and polyvinyl alcohol, polyvinylpyrrolidone, cationic surfactants or nonionic surfactants are more preferred.

[0105] In addition, the dispersion of the present invention can be stored as a dispersion containing an additional solvent component such as the above-mentioned azeotropic solvent and ionic components, or can be stored as a pH-adjusted dispersant. When storing, it is preferably stored refrigerated.

[0106] Characteristics of Cerium Oxide Nanoparticles

[0107] In the present invention, the cerium oxide nanoparticles are composed of a mixture of Ce2O3 and CeO2. In addition to the above oxide form, cerium oxide can also include forms as hydroxides and hydroxyoxides. The above oxides can have a crystal structure or can be in an amorphous state. The ratio of Ce2O3 to CeO2 can be calculated by X-ray photoelectron spectroscopy (XPS) etc. as the ratio of cerium(III) to cerium(IV).

[0108] The cerium oxide nanoparticles of the present invention can further contain transition metals of Groups 3 to 12 in the periodic table. It can be expected that these metals, by taking valences of 2+ to 3+, form lattice defects when doped into the cerium oxide nanoparticles to improve performance, or cause a valence change of cerium oxide by accompanying valence changes such as 0 and 1+, 1+ and 2+, 2+ and 3+ of the redox potential to improve performance.

[0109] From the viewpoint of being easily doped into the cerium oxide nanoparticles and further improving the antibacterial and antiviral effects, these transition metals are preferably transition metals of the 4th to 6th periods, more preferably Ti, Mn, Fe, Co, Ni, Cu, Zn, Zr or Ag.

[0110] In addition to organic acid salts such as carboxylates and sulfonates, oxygen-containing acid salts of phosphorus such as phosphates and phosphonates, and inorganic acid salts such as nitrates, sulfates and carbonates, these transition metals can also be added as salts such as halides and hydroxides during synthesis (step a-1)). They only need to be soluble in the synthesis solvent.

[0111] When the cerium oxide nanoparticles of the present invention become a dispersion, for its hydrodynamic diameter, dynamic light scattering is measured to derive an autocorrelation function, and it is analyzed by the Non-Negative Least Squares method (NNLS method) to calculate the cumulative diameter as the particle diameter. When measuring dynamic light scattering, ELSZ-2000ZS of Otsuka Electronics Co., Ltd. is used. The hydrodynamic diameter shown by the cerium oxide nanoparticles only needs to be 1 to 1000 nm, preferably 1 to 300 nm, more preferably 1 to 200 nm, further preferably 1 to 150 nm, and most preferably 1 to 100 nm.

[0112] The hydrodynamic diameter is measured for a dispersion containing nanoparticles. The particle concentration is adjusted to 0.001 to 1% by mass, the salt concentration is adjusted to 100 mM or less, the pH is adjusted to 2 to 12, and the measurement is carried out at 25°C. In the case of a low particle concentration, membrane concentration and evaporation are performed, and in the case of a high particle concentration, dilution with a solvent is used to adjust the concentration. During the measurement, as long as the particle concentration of the dispersion is known, the concentration can be adjusted by the above method. In the case where the concentration of cerium oxide is unknown, for example, by inductively coupled plasma optical emission spectrometry (ICP-OES) or inductively coupled plasma mass spectrometry (ICP-MS), the cerium ion concentration is determined, and assuming that all of the cerium ions are CeO2, the cerium oxide concentration is determined and the concentration is adjusted. The nanoparticles are in a dispersion state. If there are no impurities that affect the value of the hydrodynamic diameter, the hydrodynamic diameter can be measured directly. In the case where the dispersion contains compounds other than the nanoparticles containing cerium oxide that affect the value of the hydrodynamic diameter, they are removed by membrane purification or the like and then measured. In the case where there are also fragments in addition to cerium oxide, the fragments are removed by centrifugation and the supernatant is measured. The dispersion can also be measured after ultrasonic treatment.

[0113] When the nanoparticles of the present invention are in powder form, their particle size can be measured using a particle size analyzer or an electron microscope. The particle size of the nanoparticles of the present invention is preferably 1 to 1000 nm, more preferably 1 to 300 nm, still more preferably 1 to 200 nm, further preferably 1 to 150 nm, and most preferably 1 to 100 nm. When the nanoparticles of the present invention form aggregates (secondary particles), the particle size is not the diameter of the aggregate, but the particle size of the particles constituting the aggregate (primary particles). The secondary particles can be observed using a particle size analyzer, and the primary particles can be observed using an electron microscope or the like.

[0114] The nanoparticles of the present invention exhibit dispersion stability in a wide pH range. In the present specification, when it is said that the nanoparticles have dispersion stability, it means that when the nanoparticles are made into a dispersion, even if the dispersion is left at room temperature, substantially no precipitation occurs. Specifically, it means that when the nanoparticles are prepared into a dispersion with a concentration of 0.1% by mass, even if centrifuged at 3000 G for 2 minutes, no precipitate can be visually confirmed. A preferred state of dispersion stability is a state where no precipitate can be visually confirmed even when centrifuged at 6000 G for 2 minutes, and more preferably a state where no precipitate can be visually confirmed even when centrifuged at 10000 G for 2 minutes. The nanoparticles of the present invention have dispersion stability at pH 6 or higher and 8 or lower, preferably at pH 5 or higher and 9 or lower, and still more preferably at pH 3 or higher and 9 or lower.

[0115] Since the nanoparticles of the present invention exhibit dispersion stability in a wide pH range, in addition to being easily made into products such as disinfectants as a dispersion, because the dispersion of the nanoparticles is stable, it also has the characteristic that the production of resin compositions, fiber products, coating compositions, etc. containing the nanoparticles becomes easy by applying the dispersion to resin compositions and fiber materials.

[0116] The reaction solution after adding the oxidizing agent of the present invention, the above-mentioned purified, dried and redispersed dispersion is colored. When the 0.1 mass% dispersion was evaluated by the Hazen colorimetric value (APHA), a value of 400 or more was shown. APHA is known as an index that can highly sensitively evaluate unknown coloring causative substances.

[0117] If the reaction solution after adding the oxidizing agent of the present invention is subjected to hydrothermal treatment, the dispersion containing the nanoparticles of the present invention becomes transparent or extremely light yellow, and the coloring is improved. In the dispersion of cerium oxide nanoparticles adjusted to 0.1 mass%, as the range in which the coloring is improved, it is sufficient that it is APHA 400 or less, preferably APHA 300 or less, more preferably APHA 250 or less, and most preferably APHA 200 or less.

[0118] The measurement method of APHA is measured according to the method specified in JIS, or measured with a commercially available measuring device. For the measurement of APHA, for example, OME2000 of Nippon Denshoku Industries Co., Ltd. can be used.

[0119] The measurement of APHA is carried out by preparing a dispersion containing nanoparticles. The particle concentration is adjusted to 0.1% by mass, the pH is adjusted to 2 - 12, and the measurement is carried out at 25°C. In the case of a low particle concentration, membrane concentration and evaporation are carried out, or in the case of a high particle concentration, dilution with a solvent is used to adjust the concentration. During the measurement, when the particle concentration of the dispersion is known, the concentration can be adjusted by the above method. When the concentration of cerium oxide is unclear, for example, by inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), the cerium ion concentration is determined, and assuming that all the cerium ions are CeO2, the cerium oxide concentration is determined and the concentration is adjusted. If the nanoparticles are in a dispersion and do not contain impurities that affect the APHA value, the APHA of only the solvent (e.g., water) constituting the dispersion can be used as a reference for measurement, and the APHA of the dispersion is measured. In the case where the dispersion contains compounds other than the cerium oxide-containing nanoparticles that affect the APHA value, they can be removed by membrane purification or the like before measurement. In the case where it is difficult to remove the compounds that affect the APHA value, the solution containing the compound can be used as a reference for measurement, and the APHA is determined by difference. In the case where there are also fragments in addition to cerium oxide, the fragments can also be removed by centrifugation and the supernatant can be measured. The dispersion can also be ultrasonically treated before measurement.

[0120] In addition, in the case where the nanoparticles are in powder form, they are redispersed in a solvent for measurement. As the solvent, hexane, ethyl acetate, chloroform, methanol, ethanol, DMSO, water, or a mixed solvent thereof is selected. Among them, water is preferably used, and in order to improve solubility, the pH can be adjusted, and a mixed solvent with an organic solvent such as methanol, ethanol, DMSO having compatibility with water can be used. In the case of using a mixed solvent, the mixing ratio only needs to be water:organic solvent = 1:99 - 99:1. In the case where the solubility of the nanoparticles in a polar solvent is low, hexane, ethyl acetate, or chloroform can also be used. In order to increase the solubility, heating / cooling or ultrasonic treatment can also be carried out.

[0121] The cerium oxide nanoparticles or their dispersion of the present invention can be sterilized before use. As the sterilization method, methods such as passing it through a sterilization filter, using an autoclave (for example, under the conditions of 120°C, 20 minutes), and using ultraviolet irradiation at 254 nm can be cited.

[0122] <C>Properties and Uses of Cerium Oxide Nanoparticles

[0123] The nanoparticles of cerium oxide or their dispersion of the present invention have high oxidation performance. Therefore, the nanoparticles of cerium oxide of the present invention can be used as an oxidizing agent. In this specification, "oxidizing agent" includes "oxidation catalyst". In this specification, "oxidation performance" includes both the performance of oxidizing a substance by the stoichiometric amount of cerium(IV) in the nanoparticles and the performance of oxidizing a substance by the nanoparticles acting as an oxidation catalyst (oxidation catalytic performance). The oxidation performance can be evaluated by methods such as measuring the oxidase activity and peroxidase activity described below. The oxidase activity can be obtained by the method shown in A. Asati, Angew. Chem. Int. Ed. 2009, 48, 2308-2312. Specifically, a dilution series is prepared using a reagent that develops color upon oxidation, such as TMBZ, and the same concentration of the solution of the nanoparticles of cerium oxide of the present invention is added to each to perform the color development reaction of 3,3',5,5'-tetramethylbenzidine (TMBZ). The Michaelis-Menten equation is applied to this reaction to calculate the oxidase activity. The reaction rate is calculated from the time-dependent change in absorbance at each TMBZ concentration, and the reciprocal of the reaction rate is plotted against the reciprocal of the TMBZ concentration corresponding to the substrate. A straight line is obtained by plotting for each substrate concentration, and the maximum reaction rate V is calculated from the reciprocal of the y-intercept. max This value is multiplied by the slope of the straight line to calculate the Michaelis constant K. m The maximum reaction rate V is used as the value showing the oxidase activity for comparison. Since TMBZ is only soluble under acidic conditions, the oxidase activity can also be measured by changing the pH using compounds such as 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (AzBTS), N,N'-bis(2-hydroxy-3-sulfopropyl)tolidine (SAT-3), or dopamine instead of TMBZ. max

[0124] The nanoparticles of cerium oxide of the present invention, their dispersions, resin compositions or molded articles using the nanoparticles or their dispersions, or fibrous materials using the nanoparticles or their dispersions can be used as oxidants. For example, they can be used in organic synthesis reactions, homogeneous catalysis in polymer polymerization, and wet etching solutions for semiconductors by utilizing the oxidation effect. In addition, by utilizing the oxidation effect, they can be used as a solution to replace the oxidase solution. Specifically, they can be used as a replacement for oxidase and peroxidase solutions in antibody-antigen reactions, detection reactions using nucleic acid hybridization, tissue staining, or electrochemical detection reactions by immobilizing the nanoparticles of cerium oxide on an electrode through coating. In addition to the above, they can be used as bleaching agents / disinfectants that utilize the oxidation effect for the decomposition / removal of contaminants, odors, allergens, bacteria, fungi, and molds. Specifically, they can be used as bleaching agents for the washing of clothes, tableware, kitchens, toilets, washrooms, bathrooms, medical instruments, etc. As washing methods, soaking washing, spraying, and spraying using a humidifier or atomizer can be mentioned. In addition, they can be added to swimming pools, bathtubs, hot springs as disinfectants, or used as beauty soaps, hand sanitizers, disinfectants, gargles, mouthwashes, hand sanitizing gels, antibacterial sprays, germicidal sprays, deodorant sprays, wet wipes, antibacterial tablets, etc. In addition, after the above washing and disinfection, the nanoparticles of cerium oxide of the present invention can be left on the object to maintain the deodorizing, antiviral, antibacterial, or antifungal effects. Such properties as an oxidant can be evaluated by the fading reaction of organic pigments described below.

[0125] When the nanoparticles of cerium oxide or their dispersions of the present invention are used as oxidants, they can be used in combination with alcohols, surfactants, bactericides, or natural organic substances. As alcohols, for example, ethanol and isopropyl alcohol can be mentioned. As surfactants, for example, sodium alkylbenzenesulfonate, polyoxyethylene alkyl ether, and alkyl glucoside can be mentioned. As bactericides, for example, chlorhexidine, rivanol, mercurochrome, and crystal violet can be mentioned. As natural organic substances, for example, polyphenols, catechins, tannic acid, chitin, chitosan, isothiocyanate, hinokitiol, limonene, polylysine, terpenoids, saponins, flavonoids, and carotenoids can be mentioned. When using, multiple of them can be combined.

[0126] When the cerium oxide nanoparticles or their dispersion liquids of the present invention are used as oxidants, they can be used in combination with other known oxidants, detergents, disinfectants, antiviral agents or antibacterial agents. For example, hypochlorous acid, sodium hypochlorite, povidone iodine, hydrogen peroxide, ozone water, peracetic acid, ethanol, isopropanol, 2-phenoxyethanol, 1-phenoxypropanol, 2-phenoxypropanol, phenol, cresol, halogenated phenols, cationic germicides such as quaternary ammonium salts (benzalkonium chloride), anionic germicides such as sodium alkylbenzene sulfonate, detergents such as polyoxyethylene alkyl ethers, triclosan, triclocarban, zinc bis-(2-pyridylthio-1-oxide), polyhexamethylene biguanide hydrochloride, 8-hydroxyquinoline, polylysine, etc. can be combined in various ways. Examples of halogenated phenols include hexachlorophene, triclosan, trichlorophenol, tribromophenol, pentachlorophenol, 3,5-dibromo-4-hydroxybenzenesulfonic acid (Dibromol), and their salts.

[0127] The cerium oxide nanoparticles or their dispersion liquids of the present invention can be used for processing such as deodorization, anti-allergy, antibacterial, anti-mold, and antiviral by adding them as additives for imparting oxidation performance, antiviral performance, or antibacterial performance during the molding of fibers, tubes, beads, rubbers, films, plastics, etc., or by coating them on their surfaces as dispersion liquids. Examples of articles that can be processed with the cerium oxide nanoparticles or their dispersion liquids of the present invention include, for example, the radial hollow cover of the drain outlet for kitchen sinks, drain plugs, gaskets for fixing window glass, gaskets for fixing mirrors, waterproof gaskets for bathrooms, washbasins or kitchens, door linings for refrigerators, bath mats, anti-slip rubbers for washbasins or chairs, hoses, shower heads, gaskets used in water purifiers, plastic products of water purifiers, gaskets used in washing machines, plastic products of washing machines, masks, protective clothing, medical caps, medical shoe covers, filters for air conditioners, filters for air purifiers, filters for vacuum cleaners, filters for exhaust fans, filters for vehicles, filters for air conditioners, fans of air conditioners, plastic parts such as louvers at the air outlet of air conditioners and blower fans, fans of automotive air conditioners, plastic parts such as louvers at the air outlet of automotive air conditioners and blower fans, clothing, bedding, screens for window screens, nets for chicken coops, mosquito nets, wallpapers, windows, curtains, interior materials for buildings such as hospitals, interior materials for trams, automobiles, etc., vehicle seats, curtains, chairs, sofas, virus treatment equipment, doors, ceilings, floors, building materials such as windows, etc. In this way, the products processed with the cerium oxide nanoparticles or their dispersion liquids of the present invention can be utilized as sanitary materials in various fields.

[0128] The nanoparticles of cerium oxide or their dispersion of the present invention have high antiviral performance. In addition, the nanoparticles of cerium oxide of the present invention, their dispersion, the resin composition or its molded article using the nanoparticles or their dispersion, or the fibrous material using the nanoparticles or their dispersion can be used as an antiviral agent, antiviral resin or antiviral fiber. As a method for evaluating the performance as an antiviral agent, after contacting or mixing the nanoparticles of cerium oxide of the present invention, their dispersion, the resin composition or its molded article using the nanoparticles or their dispersion, or the fibrous material using the nanoparticles or their dispersion with a virus, the amount of the virus is quantified. As a method for quantifying the virus, methods such as measuring the amount of virus antigen by ELISA method, quantifying the viral nucleic acid by PCR, measuring the infectious titer by plaque method, and measuring the infectious titer by 50% infective dose method can be mentioned. In the present invention, the antiviral performance preferably uses the method of measuring the infectious titer by plaque method and 50% infective dose method. In the 50% infective dose method, the unit of the virus infection titer is expressed as TCID 50 (median tissue culture infective dose, Tissue culture infectious dose 50) when the test is carried out on cultured cells, and is expressed as EID 50 (median egg infective dose, Egg infectious dose 50) when using hatched eggs, and is expressed as LD 50 (median lethal dose, Lethal dose 50) in animals. In addition, as a method for calculating the infectious titer from the data obtained in the 50% infective dose method, there are Reed-Muench method, Behrens-Kaeber method, Spearman-Karber method, etc., but in the present invention, the Reed-Muench method is preferably used. Generally, the criterion for judging antiviral performance is that if the logarithmic reduction value of the infectious titer is 2.0 or more with respect to the infectious titer before the action of the nanoparticles of cerium oxide of the present invention, their dispersion or the resin composition or fibrous material using the nanoparticles or their dispersion, and the control not containing the nanoparticles of the present invention, the antiviral performance is judged to be effective.

[0129] In addition, a suitable embodiment of the dispersion containing the nanoparticles of cerium oxide of the present invention is that it contains condensed phosphoric acid or / and its salt and the nanoparticles of cerium oxide, and the logarithmic reduction value of the virus infection titer TCID 50 in the 50% infective dose method in the virus inactivation test using cell culture is 2.0 or more with respect to the infectious titer before the action of the nanoparticles of cerium oxide of the present invention and the control not containing the nanoparticles of the present invention. Through the virus infection titer TCID 50The logarithmic reduction value is 2.0 or more, so it can be used as an antiviral agent. The logarithmic reduction value of the virus infection titer is preferably 2.5 or more, and particularly preferably 3.0 or more.

[0130] Examples of the virus that can be inactivated with the cerium oxide nanoparticles or their dispersion of the present invention include, for example, rhinovirus, poliovirus, foot-and-mouth disease virus, rotavirus, norovirus, enterovirus, hepatitis virus, astrovirus, sapovirus, hepatitis E virus, influenza virus type A, B, C, parainfluenza virus, mumps virus (mumps), measles virus, human metapneumovirus, RSV, Nipah virus, Hendra virus, yellow fever virus, dengue virus, Japanese encephalitis virus, West Nile virus, hepatitis B, C virus, eastern and western equine encephalitis virus, Anopheles virus, rubella virus, Lassa virus, Junin virus, Machupo virus, Guanarito virus, Sabia virus, Crimean-Congo hemorrhagic fever virus, sandfly fever, hantavirus, Sin Nombre virus, rabies virus, Ebola virus, Marburg virus, bat lyssavirus, human T-cell leukemia virus, human immunodeficiency virus, human coronavirus, SARS coronavirus, SARS-CoV-2, human parvovirus, polyomavirus, human papillomavirus, adenovirus, herpes virus, varicella-zoster virus, Epstein-Barr virus, cytomegalovirus, smallpox virus, monkeypox virus, vaccinia virus, molluscum contagiosum virus, parapoxvirus, etc.

[0131] The cerium oxide nanoparticles or their dispersion of the present invention have high antibacterial properties. In addition, the cerium oxide nanoparticles of the present invention, their dispersion, the resin composition or its molded product using the nanoparticles or their dispersion, or the fiber material using the nanoparticles or their dispersion can be used as an antibacterial agent, antibacterial resin, antibacterial fiber.

[0132] As a method for evaluating antibacterial properties, for example, EN1040:2005 as the European Norm (EN) European standard test method can be cited. In this test method, a bacterial solution is added to a test solution containing the active ingredient of the antibacterial agent, and the number of bacteria is measured after a certain time. The bacterial solution contains 0.85% NaCl and 0.1% tryptone as culture medium components and is mixed so that the volume ratio of the test solution to the bacterial solution becomes 9:1. Generally, if the logarithmic reduction value of the number of bacteria is 2.0 or more with respect to the number of bacteria before the action of the cerium oxide nanoparticles of the present invention and the control not containing the nanoparticles of the present invention, it is determined that there is antibacterial performance. As a method for quantifying the number of bacteria, methods such as measuring the amount of bacteria by turbidity (OD600) measurement, measuring the amount of bacteria by colony formation method, and quantifying the nucleic acid of bacteria by PCR can be cited. In the present invention, antibacterial performance preferably uses the method of measuring the infection titer by turbidity measurement and colony formation method.

[0133] In addition, a suitable embodiment of the dispersion liquid containing the cerium oxide nanoparticles of the present invention is a dispersion liquid containing condensed phosphoric acid or / and its salts and the cerium oxide nanoparticles, and the logarithmic reduction value of the bacterial cell count is 2.0 or more relative to the infection titer before the action of the cerium oxide nanoparticles of the present invention and the control not containing the nanoparticles of the present invention. Since the logarithmic reduction value of the bacterial cell count in the antibacterial test is 2.0 or more, it can be used as an antibacterial agent. The logarithmic reduction value of the bacterial cell count is preferably 2.5 or more, and particularly preferably 3.0 or more.

[0134] As the microorganisms against which the cerium oxide nanoparticles or their dispersion liquid of the present invention exhibit antibacterial properties, the following microorganisms can be mentioned. As bacteria, Gram-positive bacteria and Gram-negative bacteria can be mentioned. As Gram-negative bacteria, for example, bacteria of the genus Escherichia such as Escherichia coli, bacteria of the genus Salmonella such as Salmonella, bacteria of the genus Pseudomonas such as Pseudomonas aeruginosa, bacteria of the genus Shigella such as Shigella, bacteria of the genus Klebsiella such as Klebsiella pneumoniae, bacteria of the genus Legionella such as Legionella pneumophila, etc. can be mentioned. As Gram-positive bacteria, for example, bacteria of the genus Staphylococcus such as Staphylococcus, bacteria of the genus Bacillus such as Bacillus subtilis, bacteria of the genus Mycobacterium such as Mycobacterium tuberculosis, etc. can be mentioned. As fungi, fungi and yeasts can be mentioned. As fungi, for example, filamentous fungi of the genus Aspergillus such as Aspergillus niger, filamentous fungi of the genus Penicillium such as Penicillium, filamentous fungi of the genus Cladosporium such as Cladosporium cladosporioides, filamentous fungi of the genus Alternaria such as Alternaria alternata, filamentous fungi of the genus Trichoderma such as Trichoderma, filamentous fungi of the genus Chaetomium such as Chaetomium globosum, etc. can be mentioned. As yeasts, for example, yeasts of the genus Saccharomyces such as baker's yeast and brewer's yeast and yeasts of the genus Candida such as Candida albicans, etc. can be mentioned.

[0135] By adding the cerium oxide nanoparticles or their dispersion liquid of the present invention to a disinfectant, an antiviral effect or an antibacterial effect can be imparted to the disinfectant solution. As the disinfectant, disinfectants containing disinfection components such as chlorine-based, iodine-based, peroxide-based, aldehyde-based, phenol-based, biguanide-based, mercury-based, alcohol-based, anionic surfactant-based, cationic surfactant-based, amphoteric surfactant-based, nonionic surfactant-based, natural source-based, etc. as active ingredients can be applied. In addition, by adding the cerium oxide nanoparticles or their dispersion liquid of the present invention to a liquid containing ultrafine bubbles, an antiviral effect or an antibacterial effect can be imparted.

[0136] In the case of a liquid disinfectant, the concentration of the cerium oxide nanoparticles of the present invention can be arbitrarily set between 0.0001% by mass and 10% by mass.

[0137] As examples of the chlorine-based disinfection component, sodium hypochlorite, chlorine gas, chlorinated isocyanuric acid, etc. can be mentioned.

[0138] Examples of iodine-based disinfection components include iodine, povidone iodine, iodine oxyquinoline, phenoxyiodine, etc.

[0139] Examples of peroxide-based disinfection components include hydrogen peroxide, potassium permanganate, peracetic acid, organic peracids, sodium percarbonate, sodium perborate, ozone, etc.

[0140] Examples of aldehyde-based disinfection components include glutaraldehyde, phthalaldehyde, formaldehyde, etc.

[0141] Examples of phenolic disinfection components include isopropylmethylphenol, thymol, eugenol, triclosan, cresol, phenol, chlorocresol, parachlorometacresol, parachlorometaxylenol, o-phenylphenol, alkyl p-hydroxybenzoates, resorcinol, hexachlorophene, salicylic acid or its salts, etc.

[0142] Examples of biguanide-based disinfection components include chlorhexidine, chlorhexidine gluconate, chlorhexidine hydrochloride, etc.

[0143] Examples of mercury-based disinfection components include mercurochrome, mercuric chloride, thimerosal, etc.

[0144] Examples of alcohol-based disinfection components include ethanol, isopropanol, etc. In this case, the concentration of the alcohol-based disinfection component can be 30 to 80% by mass.

[0145] Examples of anionic surfactant-based disinfection components include alkylbenzene sulfonates, fatty acid salts, higher alcohol sulfates, polyoxyethylene alkyl ether sulfates, α-sulfo fatty acid esters, α-olefin sulfonates, monoalkyl phosphate salts, alkane sulfonates, etc.

[0146] Examples of cationic surfactant-based disinfection components include alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, polyhexamethylene biguanide, benzethonium chloride, etc.

[0147] Examples of amphoteric surfactant-based disinfection components include alkylamino fatty acid salts, alkyl betaines, alkylamine oxides, etc.

[0148] Examples of nonionic surfactant disinfection components include polyoxyethylene alkyl ethers, polyoxyethylene / polyoxypropylene alkyl ethers, polyoxyethylene / polyoxybutylene alkyl ethers, alkylamine ethoxylates, alkylamine alkoxylates, polyoxyethylene-polyoxypropylene block copolymers, polyoxyethylene-polyoxypropylene block copolymers (reverse type), ethylene oxide / propylene oxide adducts of polyols, alkyl glucosides, fatty acid alkanolamides, etc.

[0149] Examples of disinfection components of natural source systems include hinokitiol, anethole, anise oil, borneol, camphor, carvone, cinnamon oil, chenopodium oil, eucalyptol, citral, citronellal, eugenol, pinene, geraniol, lemon oil, linalool, menthol, orange oil, safrole, thymol, polyphenols (flavanols, gallotannins, ellagitannins, phlorotannins), etc., plant-based agents, chitin, chitosan, which are made from the shells of crustaceans, and calcined shell powder obtained by calcining the shells of scallops and oysters, etc., animal-based agents, polylysine, etc., microbial-based agents, and enzyme-based agents such as lysozyme. In addition, antibacterial peptides produced by organisms to defend themselves against external microorganisms can also be used. For example, there are histatin, defensin, lactoferrin, lactoferrcin, which is a decomposition product of lactoferrin, magainin, cecropin, melititin, etc.

[0150] In addition, plant extracts can also be used as disinfection components of natural sources. As specific examples, there can be mentioned grapefruit seed extract, plant extracts extracted from Kochia scoparia of Chenopodiaceae, Belamcanda chinensis of Iridaceae, Hypericum perforatum of Hypericaceae, Boswellia carterii of Burseraceae, Populus of Salicaceae, Adenophora triphylla of Campanulaceae, Echinacea purpurea, Matricaria recutita, Arctium lappa, Solidago virgaurea, Atractylodes lancea, etc. of Asteraceae, Coptis chinensis of Ranunculaceae, Lonicera japonica of Caprifoliaceae, Laurus nobilis of Lauraceae, Humulus lupulus of Moraceae, Scutellaria baicalensis, Origanum vulgare, Schizonepeta tenuifolia, Salvia officinalis, Thymus vulgaris, Melissa officinalis, Mosla japonica, Lavandula angustifolia, Rosmarinus officinalis, etc. of Lamiaceae, Hedychium coronarium, Zingiber officinale, etc. of Zingiberaceae, Sambucus nigra of Caprifoliaceae, Cryptomeria japonica of Taxodiaceae, Angelica dahurica, Saposhnikovia divaricata, etc. of Apiaceae, Polygonum aviculare of Polygonaceae, Arctostaphylos uva-ursi of Ericaceae, Houttuynia cordata of Saururaceae, Tribulus terrestris of Zygophyllaceae, Cayratia japonica of Vitaceae, Pimenta dioica, Camellia sinensis, Eucalyptus globulus, Syzygium aromaticum, etc. of Myrtaceae, Maackia amurensis, Sophora japonica, Sophora flavescens, Dalbergia cochinchinensis, Millettia pendula, etc. of Fabaceae, Liquidambar formosana of Hamamelidaceae, Phellodendron amurense, Citrus reticulata, etc. of Rutaceae, Symphytum officinale of Boraginaceae, Berberis vulgaris, Nandina domestica, etc. of Berberidaceae, Magnolia obovata of Magnoliaceae, Sanguisorba officinalis, Rosa multiflora, etc. of Rosaceae, Viscum album of Loranthaceae, Anemarrhena asphodeloides, Aspidistra elatior, Glycyrrhiza glabra, etc. of Liliaceae, Gentiana macrophylla of Gentianaceae, Phyllostachys edulis of Poaceae, brown algae of Fucaceae, etc.

[0151] Examples of ultrafine bubbles include bubbles with a particle size of 500 nm or less that contain one or more gases selected from air, oxygen, hydrogen, nitrogen, carbon dioxide, argon, neon, xenon, fluorinated gases, ozone, and inert gases. Ultrafine bubbles are also known as nanobubbles. The concentration can be 100,000 / ml or more.

[0152] In addition to the above-described disinfection components, the disinfectant containing the cerium oxide nanoparticles or a dispersion thereof according to the present invention may be admixed with appropriate optional components according to its dosage form. Specifically, it may contain a solvent, a wetting agent, a thickening agent, an antioxidant, a pH adjuster, an amino acid, a preservative, a sweetening agent, a fragrance, a surfactant, a colorant, an auxiliary agent for enhancing the bactericidal effect, a chelating agent, an ultraviolet absorber, an antifoaming agent, an enzyme, a formulation stabilizer, and the like.

[0153] The disinfectant added with the cerium oxide nanoparticles or a dispersion thereof according to the present invention can be provided in various forms such as liquid, gel, powder, etc. The liquid disinfectant can be provided as a lotion, a spray, a foaming agent, etc., and can be filled in a bottle with a metering cap, a trigger-type spray container, a squeeze-type or dispenser-type pump spray container, etc., and used by spraying or atomizing. The liquid disinfectant can be impregnated in a sheet of paper, cloth, etc., filled in a container such as a bottle or a barrel, and provided as a wet sheet.

[0154] By adding the cerium oxide nanoparticles or a dispersion thereof according to the present invention to a coating material, oxidation performance, antiviral performance, and antibacterial performance can be imparted to the coating material. At this time, for the purpose of immobilizing the cerium oxide nanoparticles of the present invention in the coating film, a resin emulsion composition may be included in the coating material.

[0155] The nanoparticles of the present invention have oxidation performance, antiviral performance, and antibacterial performance. On the other hand, since an anionic stabilizer is used in the nanoparticles of the present invention, it has the characteristic of not impairing the dispersion stability of the resin emulsion before the addition of the nanoparticles in a wide pH range.

[0156] Examples of the resin emulsion composition include an ethylene vinyl acetate resin emulsion, a vinyl chloride resin emulsion, an epoxy resin emulsion, an acrylic resin emulsion, a urethane resin emulsion, an acrylic silicone resin emulsion, a fluororesin emulsion, or a synthetic resin emulsion composed of resin components such as a composite system thereof. The mass ratio of the cerium oxide nanoparticles of the present invention added to the coating material to the solid component in the resin emulsion can be arbitrarily set between 0.01:99.99 and 99.99:0.01.

[0157] The ethylene vinyl acetate copolymer resin emulsion is obtained by copolymerizing ethylene and vinyl acetate monomers, and may further copolymerize vinyl monomers having functional groups such as a primary amino group, a secondary amino group, a tertiary amino group, a quaternary amino group, a carboxyl group, an epoxy group, a sulfonic acid group, a hydroxyl group, a hydroxymethyl group, and an alkoxy acid group.

[0158] The vinyl chloride copolymer resin emulsion is obtained by polymerizing vinyl chloride, and may further copolymerize vinyl monomers having functional groups such as an amino group, a secondary amino group, a tertiary amino group, a quaternary amino group, a carboxyl group, an epoxy group, a sulfonic acid group, a hydroxyl group, a hydroxymethyl group, and an alkoxy acid group.

[0159] In this specification, the term “(meth)” means that the description of acrylic derivatives (including acrylamide and acrylonitrile) includes not only the acrylic derivatives but also the corresponding methacrylic derivatives and their copolymers.

[0160] Examples of the resin that can be used in the preparation of the epoxy resin emulsion include bisphenol resins. The bisphenol resins are not particularly limited, and examples thereof include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD type epoxy resins, bisphenol S type epoxy resins, flame-retardant epoxy resins such as glycidyl ethers of tetrabromobisphenol A, glycidyl ether type epoxy resins of bisphenol A propylene oxide adducts, and hydrogenated bisphenol A (or F) type epoxy resins. Examples of other epoxy resins include glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, novolac type epoxy resins, fluorinated epoxy resins, rubber-modified epoxy resins containing polybutadiene or NBR, glycidyl ether ester type epoxy resins of p-hydroxybenzoic acid, m-aminophenol type epoxy resins, diaminodiphenylmethane series epoxy resins, urethane-modified epoxy resins having urethane bonds, various alicyclic epoxy resins, glycidyl ethers of polyols, epoxides of unsaturated polymers such as hydantoin type epoxy resins and petroleum resins, and amino-containing glycidyl ether resins.

[0161] Examples of monomers that can be used in the preparation of acrylic resin emulsions include (meth)acrylate monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, octadecyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, nonyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentyl (meth)acrylate, phenyl (meth)acrylate, and benzyl (meth)acrylate; monomers containing unsaturated bonds with carboxyl groups such as acrylic acid, methacrylic acid, β-carboxyethyl (meth)acrylate, 2-(meth)acryloyloxypropionic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, itaconic acid semi-ester, maleic acid semi-ester, maleic anhydride, and itaconic anhydride; polymerizable monomers containing glycidyl groups such as glycidyl (meth)acrylate and allyl glycidyl ether; polymerizable monomers containing hydroxyl groups such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, and glycerol mono(meth)acrylate; and ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, diallyl phthalate, divinylbenzene, and allyl (meth)acrylate, etc.

[0162] As monomers that can be used in the preparation of urethane resin emulsions, as polyisocyanate components, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-biphenyl diisocyanate, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 3,3'-dichloro-4,4'-biphenyl diisocyanate, 1,5-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, diisocyanate tetramethylene ester, 1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, trimethylhexamethylene diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, benzene dimethylene diisocyanate, tetramethylbenzene dimethylene diisocyanate, hydrogenated benzene dimethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 3,3'-dimethyl-4,4'-dicyclohexylmethane diisocyanate, etc. can be mentioned. As diol components, polyester polyols, polyether polyols, polycarbonate polyols, polyacetal polyols, polyacrylate polyols, polyester amide polyols, polysulfide polyols, polyolefin polyols such as polybutadiene series, etc. can be mentioned.

[0163] As silicon-containing acrylic monomers that can be used in the preparation of acrylic silicone resin emulsions, γ-(meth)acryloyloxypropyltrimethoxysilane, γ-(meth)acryloyloxypropyltriethoxysilane, γ-(meth)acryloyloxypropylmethyldimethoxysilane, γ-(meth)acryloyloxypropylmethyldiethoxysilane, etc. can be mentioned.

[0164] As monomers that can be used in the preparation of fluororesin emulsions, fluoroolefins (1,1-difluoroethylene, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, pentafluoroethylene, hexafluoropropylene, etc.), fluorine-containing (meth)acrylates ((meth)acrylic acid trifluoroethyl ester, (meth)acrylic acid pentafluoropropyl ester, (meth)acrylic acid perfluorocyclohexyl ester, etc.) can be mentioned.

[0165] The coating containing the cerium oxide nanoparticles or its dispersion of the present invention may contain pigments, matting materials, aggregates, fibers, crosslinking agents, plasticizers, preservatives, mildew-proof agents, antibacterial agents, defoaming agents, viscosity regulators, leveling agents, pigment dispersants, anti-settling agents, anti-sagging agents, ultraviolet absorbers, light stabilizers, antioxidants, adsorbents, etc. as needed. These components can be mixed into the coating composition alone or in combination.

[0166] The coating material containing the cerium oxide nanoparticles or its dispersion of the present invention can be used for coating the interior surfaces of buildings, for example. As the interior surfaces, substrates such as mortar, concrete, gypsum board, siding, extruded board, slate board, asbestos cement board, fiber-reinforced cement board, calcium silicate board, ALC board, metal, wood, glass, rubber, ceramics, fired tile, porcelain tile, plastic, synthetic resin, etc., cloth, wallpaper, or a coating film formed on these substrates can be cited. In addition, it can also be applied to the exterior surfaces of buildings and structures other than buildings.

[0167] The nanoparticles of the present invention can be made into a resin composition containing nanoparticles by adding a dispersion of the cerium oxide particles or cerium oxide nanoparticles of the present invention to a base resin. Such a resin composition exhibits oxidative decomposition performance against harmful substances such as viruses and bacteria. In the case of using nanoparticles manufactured through a hydrothermal treatment process, a resin composition having the further characteristic of excellent hue can be made.

[0168] The type of the base resin is not limited and can be either a thermoplastic resin or a thermosetting resin, can be a homopolymer, can be a copolymer, or can be a blend of two or more polymers. From the viewpoint of good moldability, a thermoplastic resin is preferred.

[0169] As the thermoplastic resin, polyolefins such as polyethylene, polypropylene, polystyrene, polymethylpentene, alicyclic polyolefins, styrene resins such as acrylonitrile styrene resin (AS resin), acrylonitrile butadiene styrene resin (ABS resin), polyamides such as nylon 6 and nylon 66, polyesters such as polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polybutylene succinate, polycarbonate, polyarylate, polyacetal, polyphenylene sulfide, vinyl chloride, tetrafluoroethylene, trifluoroethylene, 3-fluorochloroethylene, tetrafluoroethylene - hexafluoropropylene copolymer, 1,1-difluoroethylene and other fluorine-based resins, aromatic polyamide, polyimide, acrylic resin, methacrylic resin, polyacetal, polyglycolic acid, polylactic acid, etc. can be used. As examples of the thermosetting resin, phenolic resin, epoxy resin, urea resin, melamine resin, unsaturated polyester, polyurethane, polyimide, silicone resin, etc. can be used.

[0170] The resin composition of the present invention is obtained by adding the cerium oxide nanoparticles of the present invention to a base resin. The addition method is not particularly limited. For example, it can be added to the base resin that has been melted by heat or the like and then kneaded, or it can be melt-kneaded after being mixed with the base resin at a specified ratio. It can also be added to the base resin together with additives such as flame retardants, plasticizers, antistatic agents, antioxidants, light-resistant agents, hydrolysis inhibitors, pigments, and lubricants. In addition, by exposing the cerium oxide nanoparticles of the present invention to the resin surface and making them biased, the contact efficiency with harmful substances such as viruses and bacteria is improved, and thus sufficient effects are exerted. The biasing method is not particularly limited, but in the case of using additives in combination, by selecting additives with relatively higher affinity for the cerium oxide nanoparticles of the present invention compared to the base resin, the biasing efficiency can be enhanced. Examples of such additives include higher fatty acids, esters of acids, amides of acids, higher alcohols, low-molecular / high-molecular polymers of surfactants, etc., but as long as they have affinity for the cerium oxide nanoparticles of the present invention, there is no particular limitation, and they can be preferably applied. In addition, one or more of them can be combined and added. In addition, the nanoparticles can be added by attaching the nanoparticles or their dispersion liquid of the present invention after the base resin has been molded. In this case, in order to make the nanoparticles efficiently adhere to the molded base resin, additives can be used. Examples of the additives used at this time include binder components such as acrylic resin systems, epoxy resins, melamine resins, urethane resins, polyamide resins, polyimide resins, polyester resins, urea resins, phenolic resins, and silicone resins. In addition, in the case of adding by attaching the dispersion liquid to the base resin, it is preferable to remove the liquid component contained in the dispersion liquid after the addition of the nanoparticles. As a method for removing the liquid component contained in the dispersion liquid, air drying, heat drying, or vacuum drying can be carried out as the drying process.

[0171] The cerium oxide nanoparticles of the present invention added to the base resin can be in any form such as powder, granular, paste, aqueous dispersion or organic solvent dispersion, and can be melt-kneaded by a known method without particular limitation. In addition, the cerium oxide nanoparticles of the present invention can be added to the base resin together with a dispersant or as a mixture with a dispersant. The dispersant for the cerium oxide nanoparticles of the present invention is not particularly limited, but a surfactant is preferred, and cationic surfactants such as quaternary ammonium salts, anionic surfactants such as higher fatty acid salts and alkyl sulfate salts, amphoteric surfactants such as alkyl betaines, and nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters and polyoxyethylene alkyl ethers can all be applied, but cationic surfactants or nonionic surfactants are more preferred. The mixing ratio of the dispersant relative to the cerium oxide nanoparticles of the present invention is not particularly limited as long as it does not significantly impair the compatibility with the added base resin and the oxidation performance, and can be adjusted arbitrarily.

[0172] Regarding the content rate of the cerium oxide nanoparticles of the present invention relative to the entire resin composition of the present invention, as long as harmful substances such as viruses and bacteria can be decomposed, there is no particular limitation, but it is preferably 0.01% by mass or more and 60% by mass or less. If the content rate is less than 0.01% by mass, sufficient effects cannot be exerted. In addition, if it is more than 60% by mass, mechanical properties such as the strength and durability of the resin may sometimes be impaired. It is preferably 0.05% by mass or more and 50% by mass or less. More preferably, it is 0.1% by mass or more and 30% by mass or less. Further preferably, it is 3% by mass or more and 10% by mass or less. In addition, the resin composition of the present invention can be kneaded with a resin identical to or different from the base resin at a specified ratio as a masterbatch. In the case of making a masterbatch, the content rate of the cerium oxide nanoparticles of the present invention is preferably 10% by mass or more.

[0173] The manufacturing method of the resin composition of the present invention is not particularly limited, and examples include a method of mixing the respective components constituting the resin composition using a mixer, a method of uniformly melt-kneading them, etc. As the mixer, for example, a V-type stirrer, a high-speed mixer, a suspension high-speed stirring mixer, and a Henschel mixer can be cited. The melt-kneading temperature is preferably 200°C to 320°C, more preferably 200°C to 300°C. The obtained resin composition can be granulated by a granulator and used.

[0174] The resin composition of the present invention can be molded by any molding method. As the molding method, injection molding, extrusion molding, blow molding, blow molding, vacuum molding, compression molding, gas-assisted molding, etc. can be cited.

[0175] When the resin composition of the present invention uses cerium oxide nanoparticles manufactured through a hydrothermal treatment process, it has excellent hue characteristics. The value of the Yellowness Index of the resin composition containing 1% by mass of the nanoparticles manufactured through hydrothermal treatment of the present invention is preferably 15 or less, more preferably 10 or less, and further preferably 5 or less. The so-called yellowness here is a value measured using a color computer (manufactured by Suga Test Instruments Co., Ltd.) in accordance with JIS-K7373.

[0176] The resin composition of the present invention can be widely used as molded articles of any shape. Examples of the molded articles include injection molded articles, extrusion molded articles, vacuum pressure molded articles, blow molded articles, sheets, fibers, cloths, non-woven fabrics, composites with other materials, and the like.

[0177] Using the resin composition of the present invention as a raw material, resin products such as automotive interior materials, electrical product housings, hanging ring handles, armrests, door handles, partitions, coatings, etc. can be manufactured.

[0178] The fibrous material containing the cerium oxide nanoparticles of the present invention can be obtained by a method of immobilizing the cerium oxide nanoparticles of the present invention on a fiber substrate, or a method of spinning using a resin composition incorporated with the cerium oxide nanoparticles of the present invention. The method of immobilizing the cerium oxide nanoparticles of the present invention on a fiber substrate is preferred because the cerium oxide nanoparticles are exposed on the surface of the obtained fibrous material, and it is easy to exhibit antiviral and antibacterial properties.

[0179] As a method of immobilizing the cerium oxide nanoparticles of the present invention on a fiber substrate, a method of immobilizing on a base fiber substrate using the cerium oxide particles of the present invention or a dispersion liquid containing cerium oxide particles by an impregnation method, a spraying method, or a coating method can be mentioned.

[0180] When immobilizing the cerium oxide nanoparticles of the present invention on the above-mentioned fiber substrate, it is preferred to add an adhesive component that serves as an adhesive to the fiber substrate in the dispersion liquid because it can inhibit the detachment of the cerium oxide nanoparticles from the fiber substrate.

[0181] Examples of the types of adhesive components include acrylic resin systems, epoxy resins, melamine resins, urethane resins, polyamide resins, polyimide resins, polyester resins, urea resins, phenolic resins, silicone resins, etc., but are not limited to these and can be preferably applied.

[0182] In addition, when immobilizing the cerium oxide nanoparticles of the present invention on the above-mentioned fiber substrate, additives for controlling the dispersibility and viscosity of the cerium oxide nanoparticles of the present invention can be added to the dispersion liquid.

[0183] As an additive, preferably a surfactant, cationic surfactants such as quaternary ammonium salts, anionic surfactants such as higher fatty acid salts and alkyl sulfates, amphoteric surfactants such as alkyl betaines, and nonionic surfactants such as polyoxyethylene sorbitan fatty acid esters and polyoxyethylene alkyl ethers can all be applied, but cationic surfactants or nonionic surfactants are more preferred.

[0184] The mixing ratio of the additive relative to the cerium oxide nanoparticles of the present invention is not particularly limited as long as it does not significantly impair the antiviral and antibacterial properties, and can be adjusted arbitrarily.

[0185] When spinning is carried out using the resin composition of the present invention, as the base resin, a thermoplastic resin is preferred. As a spinning method, for example, the resin composition of the present invention is made into a molten polymer and led to a spinning pack through a pipe. The polymer introduced from the polymer inlet of the spinning pack passes through a filter layer composed of a filter medium / filter for filtration, and is discharged from the discharge holes of the spinneret to obtain fibers.

[0186] The type of the fiber substrate is not limited, and it can be any one of natural fibers, synthetic fibers or inorganic fibers, and can be a mixed fiber or composite fiber of two or more of them. As natural fibers, cellulose-based fibers such as cotton, hemp and rayon, and animal fibers such as wool, silk and down can be cited, but are not limited to these and can be preferably applied. As synthetic fibers, polyolefin-based fibers, polyester-based fibers, polyamide-based fibers, acrylic-based fibers, polyurethane-based fibers, polyvinyl alcohol-based fibers, etc. can be cited, but are not limited to these and can be preferably applied. As inorganic fibers, glass fibers, carbon fibers, ceramic fibers, etc. can be cited, but are not limited to these and can be preferably applied. In addition, fibers subjected to processing such as profiled cross-sections and hollow shapes can also be preferably applied. As fiber forms, filaments, fabrics, non-woven fabrics, etc. can be cited, but are not limited to these and can be preferably applied.

[0187] When a fiber material is obtained using nanoparticles manufactured through a hydrothermal treatment process, the fiber material and fiber products obtained from it as raw materials have the characteristic of low colorability.

[0188] Regarding the content rate of the cerium oxide nanoparticles of the present invention with respect to the entire fibrous material of the present invention, there is no particular limitation as long as harmful substances such as viruses and bacteria can be decomposed, but it is preferably 0.01% by mass or more and 60% by mass or less. If the content rate is less than 0.01% by mass, sufficient effects cannot be exerted. In addition, if it is more than 60% by mass, mechanical properties such as the strength and durability of the fiber may be impaired, or the air permeability when made into a cloth form may be impaired. It is preferably 0.05% by mass or more and 50% by mass or less. More preferably, it is 0.1% by mass or more and 30% by mass or less. Further preferably, it is 3% by mass or more and 10% by mass or less.

[0189] The fibrous material of the present invention obtained by such operation is characterized by exhibiting oxidative decomposition performance against harmful substances such as viruses and bacteria.

[0190] The fibrous material of the present invention can be used as a raw material to produce fibrous products such as masks, protective clothing, filters, mats, chairs, gowns, lab coats, curtains, bed sheets, automotive interior materials, and dishcloths.

[0191] Examples

[0192] The present invention will be further specifically described by the following examples.

[0193] <Materials and Methods>

[0194] Cerium(III) nitrate hexahydrate, sodium tripolyphosphate, sodium hexametaphosphate, and 30% by mass hydrogen peroxide solution were obtained from FUJIFILM Wako Pure Chemical Corporation. Sodium pyrophosphate was obtained from Alfa Aesar, sodium trimetaphosphate was obtained from Merck, and TMBZ·HCl was obtained from Dojindo Laboratories. The commercially available cerium oxide dispersion (289744) used in the comparative example was obtained from Merck. The Amicon Ultra 15 (10kD) used for purification was purchased from Merck Millipore.

[0195] Regarding other reagents, they were purchased from FUJIFILM Wako Pure Chemical Corporation, Tokyo Chemical Industry Co., Ltd., or Sigma-Aldrich Japan K.K., and used directly without special purification.

[0196] In the measurement of the hydrodynamic diameter of the cerium oxide nanoparticles, the Zeta potential / particle measurement system ELSZ-2000ZS of Otsuka Electronics Co., Ltd. was used, and the microplate reader for absorbance measurement used the SpectraMax iD3 of MOLECULAR DEVICE.

[0197] (Example 1) Preparation of a dispersion of cerium oxide nanoparticles using pyrophosphoric acid as a stabilizer

[0198] 50 ml of water was added to a beaker, and 0.54 g of pyrophosphoric acid was dissolved. 2 ml of a 10 mass% aqueous solution of cerium(III) nitrate hexahydrate was added, and the mixture was stirred at room temperature for 10 minutes. Then, 2 ml of a 1.2 mass% aqueous hydrogen peroxide solution was added dropwise, and the reaction was carried out overnight at room temperature. The reaction solution was purified using an ultrafiltration membrane with a molecular weight cut-off of 10 kD to obtain an orange dispersion containing cerium oxide nanoparticles.

[0199] (Example 2) Preparation of a dispersion of cerium oxide nanoparticles using tripolyphosphoric acid as a stabilizer

[0200] Instead of 0.54 g of sodium pyrophosphate in Example 1, 0.54 g of sodium tripolyphosphate was used, and the reaction was carried out under the same conditions as in Example 1 to obtain an orange dispersion containing cerium oxide nanoparticles.

[0201] (Example 3) Preparation of a dispersion of cerium oxide nanoparticles using metaphosphoric acid as a stabilizer

[0202] Instead of 0.54 g of sodium pyrophosphate in Example 1, 0.54 g of sodium metaphosphate was used, and the reaction was carried out under the same conditions as in Example 1 to obtain an orange dispersion containing cerium oxide nanoparticles.

[0203] (Example 4) Preparation of a dispersion of cerium oxide nanoparticles using hexametaphosphoric acid as a stabilizer

[0204] Instead of 0.54 g of sodium pyrophosphate in Example 1, 0.54 g of sodium hexametaphosphate was used, and the reaction was carried out under the same conditions as in Example 1 to obtain an orange dispersion containing cerium oxide nanoparticles.

[0205] (Example 5) Preparation of a dispersion of cerium oxide nanoparticles obtained by hydrothermal treatment using pyrophosphoric acid as a stabilizer

[0206] The dispersion obtained in Example 1 was transferred to a pressure-resistant container, and hydrothermal treatment was carried out at 120 °C (199 kPa) for 20 minutes to obtain a dispersion of cerium oxide nanoparticles using pyrophosphoric acid as a stabilizer. The resulting dispersion was light brown.

[0207] (Example 6) Preparation of a dispersion of cerium oxide nanoparticles obtained by hydrothermal treatment using tripolyphosphoric acid as a stabilizer

[0208] The dispersion obtained in Example 2 was transferred to a pressure-resistant container, and hydrothermal treatment was carried out at 120 °C (199 kPa) for 20 minutes to obtain a dispersion of cerium oxide nanoparticles using tripolyphosphoric acid as a stabilizer. The resulting dispersion was light brown.

[0209] (Example 7) Preparation of a dispersion of cerium oxide nanoparticles obtained by hydrothermal treatment using tripolyphosphoric acid as a stabilizer

[0210] The dispersion obtained in Example 3 was transferred to a pressure-resistant container and subjected to hydrothermal treatment at 120 °C (199 kPa) for 20 minutes to obtain a dispersion of cerium oxide nanoparticles using tripolyphosphoric acid as a stabilizer. The resulting dispersion was light brown.

[0211] (Example 8) Preparation of a dispersion of cerium oxide nanoparticles obtained by hydrothermal treatment using hexametaphosphoric acid as a stabilizer

[0212] The dispersion obtained in Example 4 was transferred to a pressure-resistant container and subjected to hydrothermal treatment at 120 °C (199 kPa) for 20 minutes to obtain a dispersion of cerium oxide nanoparticles using hexametaphosphoric acid as a stabilizer. The resulting dispersion was light brown.

[0213] (Comparative Example 1) Attempt to prepare a dispersion of cerium oxide nanoparticles using phosphoric acid as a stabilizer

[0214] Instead of 0.54 g of sodium pyrophosphate in Example 1, 0.54 g of phosphoric acid or 0.54 g of disodium hydrogen phosphate was used, and the reaction was carried out under the same conditions as in Example 1. White precipitates formed in any of the reaction solutions, and a dispersion of cerium oxide nanoparticles could not be obtained.

[0215] A manufacturing method of adding a stabilizer later is disclosed in Patent Document 2 (Japanese Patent Application Laid-Open No. 2005-500436). Various phosphoric acid compounds are listed as stabilizers in

[0021] to

[0022] , and phosphoric acid is exemplified as a preferred stabilizer in

[0023] . However, phosphoric acid cannot be used as a stabilizer in the manufacturing method of the present invention. From this result, it is speculated that the cerium oxide nanoparticles obtained by the method of adding a stabilizer later disclosed in Patent Document 2 have different properties from the nanoparticles of the present invention.

[0216] (Comparative Example 2) Preparation of a dispersion of cerium oxide nanoparticles with phosphoric acid added later

[0217] With reference to Patent Document 2 (Japanese Patent Application Laid-Open No. 2005-500436), a dispersion was prepared by a manufacturing method of adding phosphoric acid later to a dispersion of cerium oxide nanoparticles for adsorption. A commercially available 20 wt% dispersion of cerium oxide nanoparticles (Merck, 289744) was diluted to 1 wt%, 0.1 g of phosphoric acid was added to 20 ml of the diluted solution, and the mixture was stirred at room temperature for 2 hours. Then, the reaction solution was purified using an ultrafiltration membrane with a molecular weight cut-off of 10 kD to obtain a dispersion containing cerium oxide nanoparticles.

[0218] (Comparative Example 3) Preparation of Dispersion of Cerium Oxide Nanoparticles with Pyrophosphate Added Later

[0219] In Comparative Example 2, 0.1 of sodium pyrophosphate was used instead of 0.1 g of phosphoric acid, and the reaction was carried out under the same conditions as in Comparative Example 2, obtaining a dispersion containing cerium oxide nanoparticles.

[0220] (Comparative Example 4) Preparation of Dispersion of Cerium Oxide Nanoparticles with Tripolyphosphate Added Later

[0221] In Comparative Example 2, 0.1 of sodium tripolyphosphate was used instead of 0.1 g of phosphoric acid, and the reaction was carried out under the same conditions as in Comparative Example 2, obtaining a dispersion containing cerium oxide nanoparticles.

[0222] (Comparative Example 5) Preparation of Dispersion of Cerium Oxide Nanoparticles with Metaphosphate Added Later

[0223] In Comparative Example 2, 0.1 of sodium metaphosphate was used instead of 0.1 g of phosphoric acid, and the reaction was carried out under the same conditions as in Comparative Example 2, obtaining a dispersion containing cerium oxide nanoparticles.

[0224] (Comparative Example 6) Preparation of Dispersion of Cerium Oxide Nanoparticles with Hexametaphosphate Added Later

[0225] In Comparative Example 2, 0.1 of sodium hexametaphosphate was used instead of 0.1 g of phosphoric acid, and the reaction was carried out under the same conditions as in Comparative Example 2, obtaining a dispersion containing cerium oxide nanoparticles.

[0226] (Example 9) Measurement of Hydrodynamic Diameter of Cerium Oxide Nanoparticles

[0227] The hydrodynamic diameters of the cerium oxide nanoparticles prepared in Examples 1 to 8 were measured by dynamic light scattering (DLS). The solvent during measurement was set as water, and the average particle diameter (cumulant diameter) of the hydrodynamic diameter was obtained. The obtained values are shown in Table 1.

[0228] It was confirmed that the average particle diameters were 11.2 to 51.4 nm, all being nanoparticles.

[0229] (Example 10) Measurement of Zeta Potential of Dispersion Containing Cerium Oxide Nanoparticles

[0230] The Zeta potentials of the cerium oxide nanoparticles manufactured in Examples 1 to 8 were measured. The solvent during measurement was set as water, and the pH of each sample was adjusted to 7 with nitric acid or sodium hydroxide. The obtained values are shown in Table 1.

[0231] The zeta potential was confirmed to be -37.7 to -46.6 mV, and any nanoparticles had a high negative charge.

[0232] (Table 1)

[0233]

[0234] (Example 11) Dispersion stability of cerium oxide nanoparticles

[0235] The dispersion stability of the cerium oxide nanoparticles produced in Examples 1, 2, 5, and 6 was evaluated. The pH of each sample was adjusted to 3 - 9 with nitric acid or sodium hydroxide. Centrifugation was performed at 10000G for 2 minutes at a concentration of 0.1 wt%, and the dispersion stability was evaluated by the formation of a precipitate.

[0236] The results are shown in Table 2. If the precipitate could not be visually confirmed, it was determined to be dispersion stable ("none" in the table), and if it was sufficient to be confirmed, it was determined to be dispersion unstable ("yes" in the table). Any nanoparticles showed high dispersion stability in a wide pH range.

[0237] (Table 2)

[0238]

[0239] (Example 12) Measurement of APHA of a dispersion of cerium oxide-containing nanoparticles

[0240] The cerium oxide nanoparticles produced in Examples 5 - 8 that had undergone hydrothermal treatment were adjusted to a 0.1 mass% dispersion, and the APHA was measured. The results are shown in Table 3.

[0241] It was confirmed that the APHA was 41 - 94, and any nanoparticles had low coloring properties.

[0242] (Reference Example 1) Measurement of APHA of a dispersion of cerium oxide-containing nanoparticles

[0243] The cerium oxide produced in Comparative Examples 2 - 6 that had not undergone hydrothermal treatment was adjusted to a 0.1 mass% dispersion, and the APHA was measured. The results are shown in Table 3.

[0244] (Example 13) Measurement of APHA of a dispersion of cerium oxide-containing nanoparticles

[0245] The cerium oxide produced in Examples 1 - 4 that had not undergone hydrothermal treatment was adjusted to a 0.1 mass% dispersion, and the APHA was measured. The results are shown in Table 3.

[0246] The APHA was 500 or more. Compared with Example 12, it was confirmed that the coloring properties of the nanoparticles were improved by hydrothermal treatment.

[0247] (Table 3)

[0248]

[0249] (Example 14) Determination of the oxidation performance using TMBZ

[0250] The oxidation performance was calculated as the oxidase activity by the method using the oxidation chromogenic reagent (TMBZ) described in A. Asati, Angew. Chem. Int. Ed. 2009, 48, 2308 - 2312.

[0251] TMBZ·HCl was dissolved in water to prepare a dilution series of 10, 5, 2.5, 1.25, 0.625 mM. 160 μl of 50 mM citrate buffer (pH 4) was mixed with 20 μl of the TMBZ solution at each concentration and added to a 96 - well plate. 20 μl of the aqueous solution of the cerium oxide nanoparticles of the present invention prepared in Examples 1 - 8 adjusted to 1 mg / ml was added thereto, and immediately placed in a microplate reader, and the time - course change of the absorbance at 652 nm accompanying the blue color development of TMBZ was measured. The measurement interval was set to 30 seconds and the measurement period was set to 10 minutes.

[0252] The Michaelis - Menten equation was applied in the calculation of the oxidase activity. In this oxidase activity measurement, since there was no change in the concentration of nano - cerium dioxide, a steady - state approximation was performed to obtain the Michaelis constant K m and the maximum reaction rate V max . The analysis of the Michaelis - Menten equation used a Lineweaver plot (double - reciprocal plot). Among the obtained results, the maximum reaction rate V max shown as the value indicating the oxidase activity is shown in Table 4.

[0253] (Comparative Example 7) Determination of the oxidation performance using TMBZ

[0254] For the cerium oxide nanoparticles prepared in Comparative Examples 2 - 6, the oxidase activity was also measured under the same operations and conditions, and the maximum reaction rate Vmax was calculated and shown in Table 4.

[0255] From the results of comparing Example 14 with Comparative Example 7, it was confirmed that the cerium oxide nanoparticles of the present invention have high oxidase activity. Due to such characteristics, the cerium oxide nanoparticles of the present invention can be used as an oxidant.

[0256] On the other hand, compared with the cerium oxide nanoparticles of Examples 1 - 8, the oxidase activity of the cerium oxide nanoparticles of Comparative Examples 2 - 6 was a low value.

[0257] (Table 4)

[0258]

[0259] (Example 15) Virus inactivation test

[0260] 0.1 ml of a virus solution (influenza virus, ATCC, VR - 1679, Influenza A virus (H3N2)) was mixed with 0.9 ml of a dispersion of cerium oxide nanoparticles prepared in Examples 1 - 8 adjusted to 5 mg / ml, and allowed to act for 1 hour. Then, PBS was added as a reaction - stopping solution to stop the action on the virus. The original solution of the sample for virus titer measurement was used to measure the infectious titer by the plaque assay method. The logarithm reduction value of the infectious titer relative to the infectious titer before the action of the cerium oxide nanoparticles is shown in Table 5.

[0261] (Comparative Example 8) Virus inactivation test

[0262] In Example 15, the cerium oxide nanoparticles of Comparative Examples 2 - 6 were used, and except for this, the same operations as in Example 15 were carried out, and the logarithm reduction value of the infectious titer is shown in Table 5.

[0263] From the results of comparing Example 15 with Comparative Example 8, it can be confirmed that the nanoparticles of the present invention have high antiviral activity. Due to such characteristics, the cerium oxide nanoparticles of the present invention can be used as antiviral agents.

[0264] On the other hand, compared with the cerium oxide nanoparticles of Examples 1 - 8, the antiviral activities of the cerium oxide nanoparticles of Comparative Examples 2 - 6 are lower values.

[0265] (Table 5)

[0266]

[0267] (Example 16) Antibacterial test against Escherichia coli

[0268] Escherichia coli pre - cultured in LB medium was suspended in a bacterial solution preparation (0.1% tryptone, 0.85% NaCl) to prepare a bacterial solution of 10 8 CFU / ml. 0.1 ml of this bacterial solution was mixed with 0.9 ml of a dispersion of cerium oxide nanoparticles prepared in Examples 1 - 8 at 1 mg / ml, and allowed to stand at room temperature for one hour. Then, a dilution series was made with this mixed solution as the original solution, inoculated on LB agar medium, and the number of colonies was measured. The logarithm reduction value of the number of colonies relative to the number of colonies before the action of the cerium oxide nanoparticles was used as the antibacterial activity value and is shown in Table 6.

[0269] (Comparative Example 9) Antibacterial test against Escherichia coli

[0270] In Example 16, the cerium oxide nanoparticles of Comparative Examples 2 to 6 were used, and except for this, the same operations as in Example 16 were carried out, and the antibacterial activity values are shown in Table 6.

[0271] From the results of comparing Example 16 with Comparative Example 9, it was confirmed that the nanoparticles of the present invention have high antibacterial activity. Due to such characteristics, the cerium oxide nanoparticles of the present invention can be used as antibacterial agents.

[0272] On the other hand, the antibacterial activity of the cerium oxide nanoparticles of Comparative Examples 2 to 6 was lower than that of the cerium oxide nanoparticles of Examples 1 to 8.

[0273] (Table 6)

[0274]

[0275] (Example 17) Preparation of resin composition (ABS resin)

[0276] The dispersion of the cerium oxide nanoparticles produced in Example 2 was freeze-dried at -45°C and 20 Pa. 99 parts by mass of ABS resin particles (manufactured by Toray, general-purpose resin "Toyolac (registered trademark)" 100-322), 1 part by mass of the cerium oxide nanoparticles obtained by freeze-drying, and 0.5 part by mass of pure water as a spreading agent were mixed, and using a Henschel mixer, after mixing at 230°C for 60 seconds, the resulting mixture was passed through an extruder with an exhaust port, melt-kneaded at an extrusion temperature of 230°C, and extruded into strips for granulation to obtain a resin composition. Then, the obtained granules were molded into a square plate with a thickness of 3 mm using an injection molding machine with a barrel temperature set at 230°C.

[0277] (Example 18) Preparation of resin composition (ABS resin)

[0278] In Example 17, instead of the dispersion of the cerium oxide nanoparticles produced in Example 2, the dispersion of the cerium oxide nanoparticles produced in Example 4 was used, and except for this, a resin composition was obtained and a square plate was molded under the same conditions as in Example 17.

[0279] (Example 19) Preparation of resin composition (ABS resin)

[0280] In Example 17, instead of the dispersion of the cerium oxide nanoparticles produced in Example 2, the dispersion of the cerium oxide nanoparticles produced in Example 6 was used, and except for this, a resin composition was obtained and a square plate was molded under the same conditions as in Example 17.

[0281] (Example 20) Preparation of Resin Composition (ABS Resin)

[0282] In Example 17, instead of the dispersion of cerium oxide nanoparticles produced in Example 2, the dispersion of cerium oxide nanoparticles produced in Example 8 was used, and under the same conditions as in Example 17, a resin composition was obtained and formed into a square plate.

[0283] (Example 21) Preparation of Resin Composition (Nylon 6 Resin)

[0284] The dispersion of cerium oxide nanoparticles produced in Example 2 was freeze-dried at -45°C and 20 Pa. 99 parts by mass of nylon 6 resin particles (manufactured by Toray) and 1 part by mass of cerium oxide nanoparticles obtained by freeze-drying were mixed, and through an extruder with a vent, melt-kneaded at an extrusion temperature of 250°C, extruded stripwise and pelletized to obtain a resin composition. Then, the obtained pellets were formed into a square plate with a thickness of 3 mm using an injection molding machine set at a barrel temperature of 250°C.

[0285] (Example 22) Preparation of Resin Composition (Nylon 6 Resin)

[0286] In Example 21, instead of the dispersion of cerium oxide nanoparticles produced in Example 2, the dispersion of cerium oxide nanoparticles produced in Example 6 was used, and under the same conditions as in Example 21, a resin composition was obtained and formed into a square plate.

[0287] (Example 23) Preparation of Resin Composition (PBT Resin)

[0288] 99 parts by mass of polybutylene terephthalate (PBT) resin particles (manufactured by Toray) and 1 part by mass of the dispersion of cerium oxide nanoparticles produced in Example 2 were mixed, and through an extruder with a vent, melt-kneaded at an extrusion temperature of 250°C, extruded stripwise and pelletized to obtain a resin composition. Then, the obtained pellets were formed into a square plate with a thickness of 3 mm using an injection molding machine set at a barrel temperature of 250°C.

[0289] (Example 24) Preparation of Resin Composition (PBT Resin)

[0290] In Example 23, instead of the dispersion of cerium oxide nanoparticles produced in Example 2, the dispersion of cerium oxide nanoparticles produced in Example 6 was used, and under the same conditions as in Example 23, a resin composition was obtained and formed into a square plate.

[0291] (Comparative Example 10) Preparation of Resin Composition (ABS Resin)

[0292] In Example 17, instead of the dispersion of cerium oxide nanoparticles produced in Example 2, a dispersion of cerium oxide nanoparticles produced in Comparative Example 4 was used, and under the same conditions as in Example 17, a resin composition was obtained and formed into a square plate.

[0293] (Comparative Example 11) Preparation of Resin Composition (ABS Resin)

[0294] In Example 17, instead of the dispersion of cerium oxide nanoparticles produced in Example 2, a dispersion of cerium oxide nanoparticles produced in Comparative Example 6 was used, and under the same conditions as in Example 17, a resin composition was obtained and formed into a square plate.

[0295] (Comparative Example 12) Preparation of Resin Composition (Nylon 6 Resin)

[0296] In Example 21, instead of the dispersion of cerium oxide nanoparticles produced in Example 2, a dispersion of cerium oxide nanoparticles produced in Comparative Example 4 was used, and under the same conditions as in Example 21, a resin composition was obtained and formed into a square plate.

[0297] (Comparative Example 13) Preparation of Resin Composition (PBT Resin)

[0298] In Example 23, instead of the nanoparticles of the cerium oxide dispersion produced in Example 2, a dispersion of cerium oxide nanoparticles produced in Comparative Example 4 was used, and under the same conditions as in Example 23, a resin composition was obtained and formed into a square plate.

[0299] (Example 25) Virus Inactivation Test

[0300] The virus inactivation test was conducted as follows. The molded products of the resin compositions of Examples 17 to 24 were made into square plates of 50 mm × 50 mm × 1 mm and placed in a humidified petri dish. 0.4 ml of a virus solution (influenza virus, ATCC, VR-1679, Influenza A virus (H3N2)) was dropped onto the molded products of the resin composition, and it was allowed to act for 24 hours in a state where a 4 cm × 4 cm membrane (made of PP) was placed. Then, SDLP was added as a reaction stopping solution to stop the action on the virus, and the virus on the molded products of the resin composition was washed off and recovered. The recovered solution was used as the stock solution of the virus titer measurement sample, and the infectious titer was measured by the TCID 50 method.

[0301] When testing the molded article using the resin composition of the present invention, the difference between the common logarithm of the virus infection titer and the common logarithm of the virus infection titer when testing the resin composition (blank) without using cerium oxide nanoparticles was set as the virus inactivation index, and the antiviral property was evaluated. In addition, the larger the virus inactivation index, the higher the antiviral property. Specifically, a logarithmic reduction value of the infection titer (virus inactivation index) of 2.0 or more was determined to be effective in antiviral performance.

[0302] The evaluation results are shown in Table 7.

[0303] (Comparative Example 14) Virus inactivation test

[0304] For the molded articles of the resin compositions prepared in Comparative Examples 10 to 13, virus inactivation tests were also carried out under the same operations and conditions as in Example 25, and the antiviral activities are shown in Table 7.

[0305] The resin compositions of Examples 17 to 24 showed higher antiviral activities compared to the resin compositions of Comparative Examples 10 to 13.

[0306] (Table 7)

[0307]

[0308] (Example 26) Measurement of YI

[0309] The YI value as the yellowness degree (YI) of the color tone of the square plates obtained in Examples 19, 20, 22, and 24, which contained cerium oxide nanoparticles that had been hydrothermally treated, was measured using a color computer manufactured by Suga Test Instruments Co., Ltd. The evaluation results are shown in Table 8.

[0310] (Example 27) Measurement of YI

[0311] The YI value of the color tone of the square plates obtained in Examples 17, 18, 21, and 23, which contained cerium oxide nanoparticles that had not been hydrothermally treated, was measured as the yellowness degree (YI) using a color computer manufactured by Suga Test Instruments Co., Ltd. The evaluation results are shown in Table 8.

[0312] By comparing Example 26 with Example 27, it was confirmed that the YI of the resin composition prepared using cerium oxide nanoparticles that had been hydrothermally treated decreased, that is, the color tone improved.

[0313] (Table 8)

[0314]

[0315] (Example 28) Production of non-woven fabric (polypropylene spunbond non-woven fabric)

[0316] The dispersion of cerium oxide nanoparticles produced in Example 2 was freeze-dried at -45°C and 20 Pa. The mass of the nanoparticles thus obtained was measured to determine the concentration of the nanoparticles contained in the above dispersion.

[0317] The dispersion of cerium oxide nanoparticles produced in Example 2 was concentrated or diluted with water based on the concentration of the nanoparticles contained in the above dispersion to prepare an aqueous dispersion containing 3 parts by mass of nanoparticles, 3 parts by mass of a self-crosslinking acrylic binder (Boncoat AN-1170, manufactured by DIC Corporation), and 94 parts by mass of water.

[0318] A polypropylene spunbond nonwoven fabric (manufactured by Toray) was cut into squares with a side length of 5 cm and immersed in the above aqueous dispersion for 1 hour. Then, after gently squeezing, it was dried in an oven at 130°C for 2 hours. The coloring of the nonwoven fabric with the immobilized cerium oxide nanoparticles was visually confirmed.

[0319] (Example 29) Production of nonwoven fabric (polypropylene spunbond nonwoven fabric)

[0320] In Example 28, instead of the dispersion of cerium oxide nanoparticles produced in Example 2, the dispersion of cerium oxide nanoparticles produced in Example 4 was used, and a nonwoven fabric with immobilized cerium oxide nanoparticles was produced by the same method as in Example 28.

[0321] (Example 30) Production of nonwoven fabric (polypropylene spunbond nonwoven fabric)

[0322] In Example 28, instead of the dispersion of cerium oxide nanoparticles produced in Example 2, the dispersion of cerium oxide nanoparticles produced in Example 6 was used, and a nonwoven fabric with immobilized cerium oxide nanoparticles was produced by the same method as in Example 28.

[0323] (Example 31) Production of nonwoven fabric (polypropylene spunbond nonwoven fabric)

[0324] In Example 28, instead of the dispersion of cerium oxide nanoparticles produced in Example 2, the dispersion of cerium oxide nanoparticles produced in Example 8 was used, and a nonwoven fabric with immobilized cerium oxide nanoparticles was produced by the same method as in Example 28.

[0325] (Example 32) Production of nonwoven fabric (viscose nonwoven fabric)

[0326] Instead of using the spunbond nonwoven fabric made of polypropylene (manufactured by Toray), a rayon nonwoven fabric (manufactured by Kurarayflex) was used. Except for this point, a nonwoven fabric with cerium oxide nanoparticles immobilized thereon was obtained by the same method as in Example 28.

[0327] (Example 33) Production of nonwoven fabric (rayon nonwoven fabric)

[0328] In Example 32, instead of the dispersion of cerium oxide nanoparticles produced in Example 2, the dispersion of cerium oxide nanoparticles produced in Example 6 was used. Except for this, a nonwoven fabric with cerium oxide nanoparticles immobilized thereon was produced by the same method as in Example 32.

[0329] (Comparative Example 15) Production of nonwoven fabric (spunbond nonwoven fabric made of polypropylene)

[0330] In Example 28, instead of the dispersion of cerium oxide nanoparticles produced in Example 2, the dispersion of cerium oxide nanoparticles produced in Comparative Example 4 was used. Except for this, a nonwoven fabric with cerium oxide nanoparticles immobilized thereon was produced by the same method as in Example 28.

[0331] (Comparative Example 16) Production of nonwoven fabric (spunbond nonwoven fabric made of polypropylene)

[0332] In Example 28, instead of the dispersion of cerium oxide nanoparticles produced in Example 2, the dispersion of cerium oxide nanoparticles produced in Comparative Example 6 was used. Except for this, a nonwoven fabric with cerium oxide nanoparticles immobilized thereon was produced by the same method as in Example 28.

[0333] (Comparative Example 17) Production of nonwoven fabric (rayon nonwoven fabric)

[0334] In Example 32, instead of the dispersion of cerium oxide nanoparticles produced in Example 2, the dispersion of cerium oxide nanoparticles produced in Comparative Example 4 was used. Except for this, a nonwoven fabric with cerium oxide nanoparticles immobilized thereon was produced by the same method as in Example 32.

[0335] (Example 34) Virus inactivation test

[0336] The virus inactivation test was conducted as follows. The non-woven fabrics of Examples 28 to 33 were made into 20 mm × 20 mm, and 0.4 g was placed in an Erlenmeyer flask. 0.2 ml of a virus solution (influenza virus, ATCC, VR-1679, Influenza A virus (H3N2)) was added dropwise to the non-woven fabric and allowed to act for 2 hours. Then, SDLP was added as a reaction stop solution to stop the action on the virus, and the virus was washed off and recovered from the non-woven fabric. The recovered solution was used as the stock solution of the test sample for virus titer determination, and the infectious titer was measured by the TCID 50 method for infectious titer measurement.

[0337] The common logarithm of the infectious titer of the virus in the case of conducting the test using the fiber material of the present invention was set as the virus inactivation index, and the antiviral property was evaluated. Additionally, the larger the virus inactivation index, the higher the antiviral property. Specifically, when the logarithmic reduction value of the infectious titer (virus inactivation index) was 2.0 or more, the antiviral performance was determined to be effective.

[0338] The evaluation results are shown in Table 9.

[0339] (Comparative Example 18) Virus inactivation test

[0340] For the fiber materials produced in Comparative Examples 15 to 17, the virus inactivation test was conducted under the same operations and conditions as in Example 34, and the antiviral activities are shown in Table 9.

[0341] The fiber materials of Examples 28 to 33 showed higher antiviral activities compared to the fiber materials of Comparative Examples 15 to 17.

[0342] (Table 9)

[0343]

[0344] (Example 35) Confirmation of colorability

[0345] For the non-woven fabrics obtained in Examples 30, 31, and 33 containing the nanoparticles of cerium oxide that had been hydrothermally treated, the colorability was visually confirmed. The results are shown in Table 10.

[0346] (Example 36) Confirmation of colorability

[0347] For the non-woven fabrics obtained in Examples 28, 29, and 32 containing the nanoparticles of cerium oxide that had not been hydrothermally treated, the colorability was visually confirmed. The results are shown in Table 10.

[0348] Comparing Example 35 with Example 36, it was confirmed that the YI of the fiber material produced using the cerium oxide nanoparticles subjected to hydrothermal treatment decreased, that is, the hue improved.

[0349] (Table 10)

[0350]

[0351] (Example 37) Preparation of a dispersion of cerium oxide nanoparticles using tetrapolyphosphoric acid as a stabilizer

[0352] Instead of 0.54 g of sodium pyrophosphate in Example 1, 0.54 g of sodium tetrapolyphosphate was used, and the reaction was carried out under the same conditions as in Example 1 to obtain an orange dispersion containing cerium oxide nanoparticles.

[0353] (Example 38) Preparation of a dispersion of cerium oxide nanoparticles using pentapolyphosphoric acid as a stabilizer

[0354] Instead of 0.54 g of sodium pyrophosphate in Example 1, 0.54 g of sodium pentapolyphosphate was used, and the reaction was carried out under the same conditions as in Example 1 to obtain an orange dispersion containing cerium oxide nanoparticles.

[0355] (Example 39) Preparation of a dispersion of cerium oxide nanoparticles using polyphosphoric acid as a stabilizer

[0356] Instead of 0.54 g of sodium pyrophosphate in Example 1, 0.54 g of sodium polyphosphate (Wako Pure Chemical Industries, 194 - 05935) was used, and the reaction was carried out under the same conditions as in Example 1 to obtain an orange dispersion containing cerium oxide nanoparticles.

[0357] (Example 40) Preparation of a dispersion of cerium oxide nanoparticles using metaphosphoric acid as a stabilizer

[0358] Instead of 0.54 g of sodium pyrophosphate in Example 1, 0.54 g of sodium metaphosphate (Wako Pure Chemical Industries, 199 - 08165) was used, and the reaction was carried out under the same conditions as in Example 1 to obtain an orange dispersion containing cerium oxide nanoparticles.

[0359] (Example 41) Preparation of a dispersion of cerium oxide nanoparticles obtained by hydrothermal treatment using tetrapolyphosphoric acid as a stabilizer

[0360] The dispersion obtained in Example 1 was transferred to a pressure - resistant container and subjected to hydrothermal treatment at 120 °C (199 kPa) for 20 minutes to obtain a dispersion of cerium oxide nanoparticles using tetrapolyphosphoric acid as a stabilizer. The resulting dispersion was light brown.

[0361] (Example 42) Preparation of a dispersion of cerium oxide nanoparticles obtained by hydrothermal treatment using pentaphosphoric acid as a stabilizer

[0362] The dispersion obtained in Example 1 was transferred to a pressure-resistant container and subjected to hydrothermal treatment at 120 °C (199 kPa) for 20 minutes to obtain a dispersion of cerium oxide nanoparticles using pentaphosphoric acid as a stabilizer. The resulting dispersion was light brown.

[0363] (Example 43) Preparation of a dispersion of cerium oxide nanoparticles obtained by hydrothermal treatment using polyphosphoric acid as a stabilizer

[0364] The dispersion obtained in Example 1 was transferred to a pressure-resistant container and subjected to hydrothermal treatment at 120 °C (199 kPa) for 20 minutes to obtain a dispersion of cerium oxide nanoparticles using polyphosphoric acid as a stabilizer. The resulting dispersion was light brown.

[0365] (Example 44) Preparation of a dispersion of cerium oxide nanoparticles obtained by hydrothermal treatment using metaphosphoric acid as a stabilizer

[0366] The dispersion obtained in Example 1 was transferred to a pressure-resistant container and subjected to hydrothermal treatment at 120 °C (199 kPa) for 20 minutes to obtain a dispersion of cerium oxide nanoparticles using metaphosphoric acid as a stabilizer. The resulting dispersion was light brown.

[0367] (Comparative Example 19) Dispersion of cerium oxide nanoparticles obtained by adding hexametaphosphoric acid after inclusion in cerium oxide nanoparticles using polyacrylic acid as a stabilizer

[0368] Using Non-Patent Document 1 as a reference, a manufacturing method using the same oxidizing agent as in the present invention was used to produce anionic cerium oxide nanoparticles using polyacrylic acid as a stabilizer. To 10 ml of a 1 mass% aqueous solution of sodium polyacrylate, 200 μl of a 10 mass% aqueous solution of cerium(III) nitrate hexahydrate was added, and the mixture was stirred at room temperature for 5 minutes. Then, 200 μl of a 1.2 mass% aqueous solution of hydrogen peroxide was added, and the mixture was heated to 40 °C and reacted for 1 hour. The reaction solution was purified using a 30 kD ultrafiltration membrane to obtain a yellow dispersion containing cerium oxide nanoparticles. Similar to Comparative Example 6, this dispersion was prepared to 1 wt%, 0.1 g of hexametaphosphoric acid was added to 20 ml, and the mixture was stirred at room temperature for 2 hours. Then, the reaction solution was purified using an ultrafiltration membrane with a molecular weight cut-off of 10 kD to obtain a dispersion containing cerium oxide nanoparticles.

[0369] (Example 45) Measurement of the ratio of phosphorus element to cerium element (P / Ce ratio) using XPS

[0370] The ratio of phosphorus to cerium (P / Ce ratio) of the cerium oxide nanoparticles obtained in Examples 1, 2, 4, 5, 6, and 8 was determined by X-ray photoelectron spectroscopy (XPS). In the measurement, the excitation X-ray was monochromatic AlK α1,2 rays (1486.6 eV), the X-ray diameter was 200 μm, and the photoelectron emission angle was 45°. The obtained spectrum was corrected for the horizontal axis so that the P2p main peak was 133.0 eV. At the time of measurement, the dispersion liquid of the cerium oxide nanoparticles produced in Examples 1, 2, 4, 5, 6, and 8 was added to a glass container and dried by hot air at 120 °C. The powder obtained by pulverizing the powder of the obtained cerium oxide nanoparticles with a mortar was used. The obtained values are shown in Table 11.

[0371] From these results, it can be seen that the ratio of phosphorus to cerium (P / Ce ratio) of the cerium oxide nanoparticles produced in Examples 1, 2, 4, 5, 6, and 8 is 0.72 or more, and the phosphorus ratio is high.

[0372] (Table 11)

[0373]

[0374] (Comparative Example 20) Measurement of the ratio of phosphorus to cerium (P / Ce ratio) using XPS

[0375] The ratio of phosphorus to cerium (P / Ce ratio) of the cerium oxide nanoparticles obtained in Comparative Examples 3, 4, 6, and 19 was determined by X-ray photoelectron spectroscopy (XPS). The measurement was carried out under the same conditions as in Example 45. The obtained values are shown in Table 12.

[0376] From these results, it can be seen that the ratio of phosphorus to cerium (P / Ce ratio) of the cerium oxide nanoparticles of Comparative Examples 3, 4, 6, and 19 is 0.71 or less, and the phosphorus ratio is low.

[0377] (Table 12)

[0378]

[0379] (Example 46) Measurement of the molar ratio of Ce 4+ relative to Ce 4+ and Ce 3+ as a whole

[0380] The Ce 4+ of the cerium oxide nanoparticles obtained in Examples 1, 2, 4, 5, 6, and 8 was determined by X-ray photoelectron spectroscopy (XPS) 3+Molar ratio. In the measurement, the exciting X-ray was monochromatic AlK α1,2 rays (1486.6 eV), the diameter of the X-ray was 200 μm, and the emission angle of the photoelectron was 45°. The obtained spectrum was corrected for the horizontal axis such that the main peak of P2p was 133.0 eV. During the measurement, the dispersion liquids of the cerium oxide nanoparticles produced in Examples 1, 2, 4, 5, 6, and 8 were added to a glass container and dried by hot air at 120°C. The powder obtained by pulverizing the powder of the obtained cerium oxide nanoparticles with a mortar was used. The obtained values are shown in Table 13.

[0381] From these results, it can be seen that the molar ratio of Ce in the cerium oxide nanoparticles produced in Examples 1, 2, 4, 5, 6, and 8 4+ relative to Ce 4+ and Ce 3+ as a whole is 0.070 or more and 0.89 or less.

[0382] (Table 13)

[0383]

[0384] (Comparative Example 21) Measurement of the molar ratio of Ce by XPS 4+ relative to Ce 4+ and Ce 3+ as a whole

[0385] The molar ratio of Ce in the cerium oxide nanoparticles obtained in Comparative Examples 3, 4, 6, and 19 was measured by X-ray photoelectron spectroscopy (XPS). The measurement was carried out under the same conditions as in Example 46. The obtained values are shown in Table 14. 4+ and Ce 3+ The obtained values are shown in Table 14.

[0386] From these results, it can be seen that the molar ratio of Ce in the cerium oxide nanoparticles of Comparative Examples 3, 4, 6, and 19 4+ and Ce 3+ is not 86:14 to 20:80.

[0387] (Table 14)

[0388]

[0389] (Example 47) XRD analysis of cerium oxide nanoparticles

[0390] The dispersion liquids of the cerium oxide nanoparticles of the present invention produced in Examples 5, 6, and 8 were added to a glass container and hot air dried at 120°C. The obtained powder of the cerium oxide nanoparticles was pulverized with a mortar and measured by X-ray Diffraction (XRD). The measurement conditions were as follows: the light source was CuKα ray, the output was 40 kV and 40 mA, the detector was LynxEye, and the measurement range was 2θ = 5 to 90°. The diffraction peak data of the obtained XRD spectra are shown in Table 15.

[0391] (Table 15)

[0392]

[0393] From these results, it was clarified that the nanoparticles of Example 5 had diffraction peaks at 2θ = 31.340° and 42.079°, the nanoparticles of Example 6 had diffraction peaks at 2θ = 31.460° and 42.020°, and the nanoparticles of Example 8 had diffraction peaks at 2θ = 31.341° and 42.021°. From these results, it was found that the cerium oxide nanoparticles of the present invention had diffraction peaks in the XRD spectrum in the range where the Bragg angle 2θ was 30.5° or more and 32.0° or less and in the range where it was 41.5° or more and 43.0° or less, respectively.

[0394] (Comparative Example 22) XRD Analysis of Cerium Oxide Nanoparticles

[0395] As a comparison with Examples 5, 6, and 8, XRD measurements were performed on the cerium oxide nanoparticles of Comparative Examples 3, 4, and 6 by the same operation as in Example 47. The diffraction peak data of the obtained XRD spectra are shown in Table 16. From these results, it was found that the nanoparticles of Comparative Examples 3, 4, and 6 did not have diffraction peaks in the XRD spectrum in the range where the Bragg angle 2θ was 30.5° or more and 32.0° or less and in the range where it was 41.5° or more and 43.0° or less.

[0396] (Table 16)

[0397]

Claims

1. A nanometer particle of cerium oxide with an inorganic acid adsorbed on its surface, having a Zeta potential of 0 mV or less at pH 7.

2. A nanometer particle of cerium oxide with a phosphorus compound adsorbed thereon, wherein the molar ratio of phosphorus element to cerium element in XPS measurement, i.e., the P / Ce ratio, is 0.72 or more.

3. The nanometer particle of cerium oxide according to claim 2, wherein the phosphorus compound is condensed phosphoric acid.

4. The nanometer particle of cerium oxide according to claim 2 or 3, having peaks in the range of 2θ = 30.5° or more and 32.0° or less and 41.5° or more and 43.0° or less in the XRD spectrum.

5. Particles of cerium oxide adsorbed with a phosphorus compound, Ce in XPS measurement 4+ Relative to Ce 4+ and Ce 3+ The overall molar ratio is 0.070 or more and 0.89 or less.

6. The nanometer particle of cerium oxide according to claim 5, wherein the phosphorus compound is condensed phosphoric acid.

7. The nanometer particle of cerium oxide according to claim 5 or 6, having peaks in the range of 2θ = 30.5° or more and 32.0° or less and 41.5° or more and 43.0° or less in the XRD spectrum.

8. A nanometer particle of cerium oxide, which is manufactured by the following step (a). Step (a) is a step of adding an oxidizing agent to a solution containing condensed phosphoric acid or / and its salt and cerium(III) ions.

9. The nanometer particle of cerium oxide according to claim 8, wherein the pH of the solution when adding the oxidizing agent is 5 or more.

10. The cerium oxide nanoparticles according to claim 8, characterized in that, The condensed phosphoric acid is polyphosphoric acid or metaphosphoric acid.

11. The cerium oxide nanoparticles according to claim 10, characterized in that, The polyphosphoric acid is pyrophosphoric acid, tripolyphosphoric acid, tetrapolyphosphoric acid, pentapolyphosphoric acid or hexapolyphosphoric acid.

12. The nanoparticles of cerium oxide according to claim 10, characterized in that, The metaphosphoric acid is trimetaphosphoric acid, tetrametaphosphoric acid, pentametaphosphoric acid or hexametaphosphoric acid.

13. The nanometer particle of cerium oxide according to claim 8, which is manufactured by a process including step (a) and step (b). Step (b) is a step of hydrothermally treating the solution obtained in step (a).

14. The nanometer particle of cerium oxide according to claim 8, wherein the APHA of a dispersion containing 0.1% by mass of the nanometer particle is 400 or less.

15. The nanometer particle of cerium oxide according to claim 8, having a Zeta potential of -20 mV or less at pH 7.

16. A dispersion, containing the nanometer particle of cerium oxide according to any one of claims 1 to 3, 5, 6, 8 to 15.

17. An oxidizing agent, containing the nanometer particle of cerium oxide according to any one of claims 1 to 3, 5, 6, 8 to 15.

18. An antiviral agent, containing the nanometer particle of cerium oxide according to any one of claims 1 to 3, 5, 6, 8 to 15.

19. An antibacterial agent, containing the nanometer particle of cerium oxide according to any one of claims 1 to 3, 5, 6, 8 to 15.

20. A resin composition, containing the nanometer particle of cerium oxide according to any one of claims 1 to 3, 5, 6, 8 to 15.

21. A resin product, which is made using the resin composition according to claim 20.

22. The resin product according to claim 21, wherein the resin product is a product selected from automotive interior materials, electrical product housings, grab handles, armrests, door handles, partitions and coatings.

23. A fiber material comprising the cerium oxide nanoparticles according to any one of claims 1 to 3, 5, 6, 8 to 15.

24. A fiber product made of the fiber material according to claim 23.

25. The fiber product according to claim 24, wherein the fiber product is a product selected from the group consisting of masks, protective clothing, filters, mats, chairs, gowns, lab coats, curtains, bed sheets, automotive interior materials, and dishcloths.

26. A method for manufacturing cerium oxide nanoparticles, comprising the following step (a), Step (a) is a step of adding an oxidizing agent to a solution containing a condensed phosphoric acid represented by the following general formula (I) and / or its salt and cerium (III) ions.

27. The method for manufacturing cerium oxide nanoparticles according to claim 26, further comprising step (b), Step (b) is a step of hydrothermally treating the solution obtained in step (a).

28. The method for manufacturing cerium oxide nanoparticles according to claim 26 or 27, wherein the APHA of a 0.1 mass% dispersion of the cerium oxide nanoparticles is 400 or less.

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