High-purity CoO particles

Abstract

We provide high-purity CoO particles. [Solution] CoO particles with a purity of 99.9 wt% or higher.

Description

Technical Field

[0001] The present invention relates to high-purity CoO particles.

Background Art

[0002] Cobalt oxide is used in electronic components such as varistors and ceramic capacitors, magnetic materials such as ferrites, and electrode materials for lithium batteries, and already occupies an important position as an electronic material.

[0003] As cobalt oxide used in electronic materials, there is cobalt oxide in the form of particles, particularly particles of cobalt(II) oxide, that is, CoO particles. With the increasing high integration of electronic components, higher purity CoO particles have been increasingly demanded.

[0004] Patent Document 1 discloses a technique for producing lithium cobalt oxide aggregates as an electrode material for lithium batteries, and it is disclosed that spherical cobalt trioxide was prepared as a raw material for producing this lithium cobalt oxide aggregate. However, the purity of the spherical cobalt trioxide disclosed in Patent Document 1 is unknown, the main component is cobalt trioxide, and high-purity particles of cobalt(II) oxide are not disclosed.

[0005] Patent Document 2 discloses a method for producing fine cobalt oxide by firing cobalt hydroxide. However, the purity of the obtained fine cobalt oxide is unknown, and it is a mixture with an unknown oxidation number of cobalt oxide as the main component, and high-purity particles of cobalt(II) oxide are not disclosed.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

[0007] Thus, high-purity cobalt(II) oxide particles, i.e., high-purity CoO particles, have not been available until now.

[0008] Therefore, an object of the present invention is to provide high-purity CoO particles. [Means for solving the problem]

[0009] As a result of diligent research, the inventors have achieved the production of high-purity CoO particles and arrived at the present invention.

[0010] The present invention includes (1) the following: (1) CoO particles with a purity of 99.9 wt% or higher. [Effects of the Invention]

[0011] This invention provides high-purity particles of cobalt(II) oxide, i.e., high-purity CoO particles. The high-purity CoO particles of this invention have reduced content of impurity elements, as well as reduced content of cobalt oxides with different oxidation states, resulting in high-purity CoO particles in the strictest sense. Due to their high single-phase properties as a raw material, the high-purity CoO particles of this invention can be widely used as electronic materials. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a graph showing the particle size distribution of CoO particles from samples 1B, 2B, and 3B, prepared in Example 1, Example 2, and Reference Example 1, measured by laser diffraction / scattering particle size distribution analysis. [Figure 2] Figure 2 is a chart showing the results of measuring the XRD intensity of CoO particles from sample 1B, which was prepared in Example 1. [Figure 3]Figure 3 is a chart showing the results of measuring the XRD intensity of CoO particles from sample 2B, which was prepared in Example 2. [Figure 4] Figure 4 is a chart showing the results of measuring the XRD intensity of CoO particles from sample 3B, which was prepared in Reference Example 1. [Modes for carrying out the invention]

[0013] The present invention will be described in detail below with reference to embodiments. The present invention is not limited to the specific embodiments listed below.

[0014] [High purity CoO particles] The high-purity CoO particles of the present invention are high-purity CoO particles with a purity of 99.9 wt% or higher.

[0015] The reason why high-purity CoO particles of the same level as those of the present invention have not been provided until now is unknown, but the inventors believe that one reason may be the high technical difficulty of even producing them as cobalt oxide particles.

[0016] For example, in the example of Patent Document 1, when preparing spherical tricobalt tetroxide as a raw material for producing lithium cobalt oxide aggregates, cobalt hydroxide is further prepared as a raw material. In Reference Document 1, sodium hydroxide is used to prepare this cobalt hydroxide (see Example 1, paragraph 0034, etc., of Patent Document 1). According to the inventor's research, the Na in this sodium hydroxide is very likely to remain in subsequent processes, and once incorporated, it is difficult to remove, resulting in a low purity of the resulting cobalt oxide. Thus, the technology of Patent Document 1 cannot provide CoO particles of the same high purity as the present invention.

[0017] For example, Patent Document 2 discloses a method for producing fine cobalt oxide by firing cobalt hydroxide, but the purity of the obtained fine cobalt oxide is unknown, and it is a mixture with an unknown oxidation number of cobalt oxide as the main component. Patent Document 2 does not disclose high-purity particles of cobalt(II) oxide. The technique of Patent Document 2 cannot provide high-purity CoO particles at the same level as the present invention.

[0018] In view of such a current situation of the prior art, the present invention aims to provide high-purity CoO particles that have not been achieved so far.

[0019] [Purity] The metal purity of the CoO particles of the present invention can be, for example, 99.9 wt% or more, preferably 99.95 wt% or more, preferably 99.99 wt% or more, preferably 99.991 wt% or more, preferably 99.992 wt% or more, preferably 99.993 wt% or more, preferably 99.994 wt% or more, preferably 99.995 wt% or more, or preferably 99.996 wt% or more, preferably 99.997 wt% or more, preferably 99.998 wt% or more. The metal purity of the CoO particles of the present invention can be calculated as the purity with 100 wt% when only Co is contained as a metal element in the CoO particles, and specifically, it can be calculated by the means described later in the examples.

[0020] [CoO single phase of CoO particles] In a preferred embodiment, the CoO particles of the present invention can be CoO particles determined to be a CoO single phase by an XRD measurement test. The determination of a CoO single phase by an XRD measurement test can be made by the means described later in the examples. That is, like the XRD measurement test described later, when all the peaks of the sample coincide with the peaks of CoO, no peak of 44.2 to 44.4° specific to Co is observed, and at the same time, no peak of 36.7 to 36.9° specific to Co₃O₄ is observed, it can be determined that a CoO single phase has been formed.

[0021] In a preferred embodiment, the CoO particles of the present invention may have a value of I(Co) / I(CoO), which is the ratio of the intensity I(Co) of the peak (the strongest line of Co) at 44.2≦2θ≦44.4 to the intensity I(CoO) of the peak (the strongest line of Co) at 42.3≦2θ≦42.5 in XRD measurement, for example, 0.05 or less, preferably 0.04 or less, preferably 0.03 or less, preferably 0.02 or less, preferably 0.01 or less, preferably 0.009 or less, preferably 0.008 or less, preferably 0.007 or less, preferably 0.006 or less, and preferably 0.005 or less.

[0022] In a preferred embodiment, the CoO particles of the present invention may have a value of I(Co3O4) / I(CoO), which is the ratio of the intensity I(CoO) of the peak (the strongest line of Co3O4) at 36.7≦2θ≦36.9 to the intensity I(CoO) of the peak (the strongest line of CoO) at 42.3≦2θ≦42.5 in XRD measurement, for example, 0.05 or less, preferably 0.04 or less, and preferably 0.03 or less.

[0023] In a preferred embodiment, the CoO particles of the present invention can be determined to be a single CoO phase by satisfying the above-mentioned range of intensity ratios in XRD measurements.

[0024] As described above, the CoO particles of the present invention are not only excellent in terms of purity, calculated using the case where only Co as the metallic element in the CoO particles is 100 wt%, but also in their high purity because they are single-phase CoO particles. Even if Co3O4 with different oxidation states were mixed in the CoO particles, it would not be detected as a metallic element impurity, so the metallic element purity of the CoO particles would remain high. However, if cobalt oxides with different oxidation states are mixed in, the raw material would have low purity as a CoO compound. The CoO particles of the present invention have high metallic element purity and are single-phase CoO, resulting in unprecedentedly high-purity CoO particles.

[0025] [Average particle size D50] In a preferred embodiment, the CoO particles of the present invention can have an average particle size D50 in the range of, for example, 1 to 20 μm, preferably 1 to 15 μm, preferably 1 to 10 μm, preferably 1 to 9 μm, preferably 1 to 8 μm, preferably 1 to 7 μm, preferably 1 to 6 μm, or for example, 2 to 20 μm, preferably 2 to 15 μm, preferably 2 to 10 μm, preferably 2 to 9 μm, preferably 2 to 8 μm, preferably 2 to 7 μm, preferably 2 to 6 μm, or for example, 3 to 20 μm, preferably 3 to 15 μm, preferably 3 to 10 μm, preferably 3 to 9 μm, preferably 3 to 8 μm, preferably 3 to 7 μm, preferably 3 to 6 μm, or for example, 4 to 20 μm, preferably 4 to 15 μm, preferably 4 to 10 μm, preferably 4 to 9 μm, preferably 4 to 8 μm, preferably 4 to 7 μm, preferably 4 to 6 μm. The average particle size D50 can be measured by the means described later in the examples.

[0026] [Average particle size D90] In a preferred embodiment, the CoO particles of the present invention may have an average particle size D90 in the range of, for example, 1 to 30 μm, preferably 5 to 30 μm, preferably 10 to 30 μm, or for example, 1 to 20 μm, preferably 5 to 20 μm, preferably 10 to 20 μm. The value of the average particle size D90 can be measured by means described later in the examples.

[0027] [Average particle size D10] In a preferred embodiment, the CoO particles of the present invention may have an average particle size D10 in the range of, for example, 0.5 to 10 μm, preferably 0.5 to 9 μm, preferably 0.5 to 8 μm, preferably 0.5 to 7 μm, preferably 0.5 to 6 μm, preferably 0.5 to 5 μm, preferably 0.5 to 4 μm, preferably 0.5 to 3 μm, preferably 0.5 to 2 μm, or for example, 1 to 10 μm, preferably 1 to 9 μm, preferably 1 to 8 μm, preferably 1 to 7 μm, preferably 1 to 6 μm, preferably 1 to 5 μm, preferably 1 to 4 μm, preferably 1 to 3 μm, preferably 1 to 2 μm. The value of the average particle size D10 can be measured by means described later in the examples.

[0028] [Span value] In a preferred embodiment, the CoO particles of the present invention are given by the following formula: Span value = (Average particle size D90 - Average particle size D10) / Average particle size D50 The values ​​represented by, the so-called span values, are, for example, 0.5 to 2.5, preferably 0.6 to 2.5, preferably 0.7 to 2.5, preferably 0.8 to 2.5, preferably 0.9 to 2.5, or, for example, 0.5 to 2.4, preferably 0.6 to 2.4, preferably 0.7 to 2.4, preferably 0.8 to 2.4, preferably 0.9 to 2.4, or, for example, 0.5 to 2.0, preferably 0.6 to 2.0, preferably 0.7 to 2.0, preferably 0.8 to 2.0, preferably 0.9 to 2.0, or, for example, 0.5 to 1.5, preferably 0.6 to 1.5, preferably 0.7 to 1.5, preferably 0.8 to 1.5, preferably 0.9 to 1.5, Alternatively, the range can be, for example, 0.5 to 1.4, preferably 0.6 to 1.4, preferably 0.7 to 1.4, preferably 0.8 to 1.4, preferably 0.9 to 1.4, or, for example, 0.5 to 1.3, preferably 0.6 to 1.3, preferably 0.7 to 1.3, preferably 0.8 to 1.3, preferably 0.9 to 1.3, or, for example, 0.5 to 1.2, preferably 0.6 to 1.2, preferably 0.7 to 1.2, preferably 0.8 to 1.2, preferably 0.9 to 1.2, or, for example, 0.5 to 1.1, preferably 0.6 to 1.1, preferably 0.7 to 1.1, preferably 0.8 to 1.1, preferably 0.9 to 1.1.

[0029] [Processing for fine grinding] As is well known, when metal oxide particles are calcined, various particles sinter and bond together, so it is common to perform a fine grinding treatment on these particles to obtain particles of the desired size. When such a fine grinding treatment is performed on metal oxide particles obtained by calcination, impurity metal elements originating from the medium and equipment used for fine grinding inevitably become mixed in. Therefore, even if the metal oxide obtained by calcination has a low content of metal element impurities, it is not possible to maintain high purity after processing to obtain particles of the desired size. However, as will be described later in the examples, the CoO particles according to the present invention are obtained as fine particles with the above-mentioned excellent particle size distribution immediately after calcination, and there is no need to perform additional fine grinding treatment. As a result, the CoO particles according to the present invention are free from the risk of impurity elements originating from the fine grinding treatment and can be used for subsequent purposes while maintaining the above-mentioned high purity.

[0030] Examples of metal elements used in the media and equipment for the fine grinding process include Al (aluminum), Cr (chromium), Fe (iron), Ni (nickel), Cu (copper), Zr (zirconium), and W (tungsten). The CoO particles according to the present invention are high-purity particles in which the content of these metal elements is kept to a minimum, and there is no possibility of contamination of these metal elements after calcination.

[0031] [Impurity content] In a preferred embodiment, the impurity content of metal elements in the CoO particles of the present invention may be within the following ranges for each element. Unless otherwise specified, the values ​​below are in wtppm. The impurity content of each of these elements can be measured by the means described later in the examples.

[0032] Li: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Be: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; B: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0033] Na: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 4 wtppm or less, preferably 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Mg: For example, 10 wtppm or less, preferably 8 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less; Al: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0034] Si: For example, 1000 wtppm or less, preferably 800 wtppm or less, preferably 600 wtppm or less, preferably 500 wtppm or less, preferably less than 500 wtppm; P: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; K: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0035] Ca: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Sc: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Ti: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0036] Cr: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Mn: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less; Fe: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0037] Ni: For example, 15 wtppm or less, preferably 10 wtppm or less, preferably 9 wtppm or less, preferably 8 wtppm or less; Cu: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Zn: for example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0038] Ga: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Ge: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; As: For example, 100 wtppm or less, preferably 80 wtppm or less, preferably 60 wtppm or less, preferably 50 wtppm or less, preferably less than 50 wtppm;

[0039] Se: For example, 50 wtppm or less, preferably 30 wtppm or less, preferably 10 wtppm or less, preferably less than 10 wtppm; Rb: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Sr: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0040] Y: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Zr: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Nb: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0041] Mo: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Ru: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Rh: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0042] Pd: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Ag: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Cd: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0043] Sn: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Sb: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Te: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0044] Cs: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Ba: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; La: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0045] Ce: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Pr: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Nd: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0046] Sm: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Eu: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Gd: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0047] Tb: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Dy: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Ho: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0048] Er: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Tm: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Yb: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0049] Lu: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Hf: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Ta: For example, 100 wtppm or less, preferably 50 wtppm or less, preferably 30 wtppm or less, preferably 10 wtppm or less, preferably less than 10 wtppm;

[0050] W: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 2 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Re: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Os: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0051] Ir: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Pt: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Au: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0052] Hg: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Tl: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Pb: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm;

[0053] Bi: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; Th: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm; U: For example, 10 wtppm or less, preferably 5 wtppm or less, preferably 3 wtppm or less, preferably 1 wtppm or less, preferably less than 1 wtppm.

[0054] [Preferred mode of implementation] In a preferred embodiment, the present invention includes the following embodiments: (1) (1) CoO particles with a purity of 99.9 wt% or higher. (2) CoO particles as described in (1), wherein the average particle size D50 is in the range of 1 to 20 μm. (3) CoO particles as described in (1), which are a single phase of CoO.

[0055] (4) The CoO particle described in (1), wherein, in XRD measurement, the ratio of the intensity I(Co) of the peak (strongest Co line) at 44.2≦2θ≦44.4 to the intensity I(Co) of the peak (strongest Co line) at 42.3≦2θ≦42.5, i.e., I(Co) / I(CoO), is 0.05 or less.

[0056] (5) The CoO particle described in (1), wherein the ratio of the intensity I(Co3O4) of the peak (the strongest line for Co3O4) at 36.7≦2θ≦36.9 to the intensity I(CoO) of the peak (the strongest line for CoO) at 42.3≦2θ≦42.5 in XRD measurement, i.e., I(Co3O4) / I(CoO), is 0.05 or less.

[0057] (6) CoO particles as described in (1), wherein the Na content is 5 wt ppm or less. (7) CoO particles as described in (1), wherein the Al content is 10 wt ppm or less. (8) CoO particles as described in (1), wherein the Cr content is 10 wt ppm or less. (9) CoO particles as described in (1), wherein the Fe content is 10 wt ppm or less.

[0058] (10) CoO particles as described in (1), wherein the Ni content is 10 wt ppm or less. (11) CoO particles as described in (1), wherein the Cu content is 10 wt ppm or less. (12) CoO particles as described in (1), wherein the Zr content is 10 wt ppm or less. (13) CoO particles as described in (1), wherein the W content is 10 wt ppm or less.

[0059] (14) The CoO particles described in (1) are such that the value of ("average particle size D90" - "average particle size D10") / "average particle size D50" is in the range of 0.5 to 2.5.

[0060] As described above, the present invention has been explained with specific embodiments, but each configuration and combination thereof in each embodiment is merely an example, and additions, omissions, substitutions, and other modifications can be made as appropriate without departing from the spirit of the present invention. [Examples]

[0061] The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples.

[0062] [Example 1: Production of CoO particles according to Examples 1 and 2 and Reference Example 1] [Example 1] [Synthesis of cobalt oxalate] Cobalt oxalate was synthesized using the following procedure and conditions. As raw materials, aqueous solutions of cobalt sulfate and oxalic acid were prepared. The oxalic acid solution was adjusted to pH 4 by adding ammonia water. The conditions, such as the concentration of the prepared cobalt sulfate aqueous solution and oxalic acid aqueous solution, are summarized in Table 1.

[0063] [Table 1]

[0064] While maintaining a cobalt sulfate aqueous solution at 25°C and stirring, a pH 4 oxalic acid aqueous solution was added dropwise to the cobalt sulfate aqueous solution over 2 minutes. After the addition was complete, the mixture was kept at 25°C for 2 hours while continuing to stir.

[0065] After stirring and holding were completed, solid-liquid separation was performed by filtration. Suction filtration was used. The precipitate obtained from the solid-liquid separation was repulped and washed to obtain a cobalt oxalate slurry (Sample 1A).

[0066] [Catalization of cobalt oxalate] A cobalt oxalate slurry (sample 1A) was heated and dried, then calcined by heating it to 900°C in an Ar atmosphere and maintaining the temperature for 2 hours. In this way, cobalt oxalate was calcined to obtain CoO particles according to Example 1 (Sample 1B).

[0067] [Example 2] [Synthesis of cobalt oxalate] Using the conditions described in Table 1, cobalt oxalate was synthesized according to Example 2 in the same manner as in Example 1. In Example 2, the pH of the oxalic acid aqueous solution to be added was adjusted to pH 9. In this way, cobalt oxalate was synthesized according to Example 2 (Sample 2A).

[0068] [Catalization of cobalt oxalate] The synthesized cobalt oxalate (sample 2A) was calcined using the same procedure and conditions as in Example 1. In this way, cobalt oxalate was calcined to obtain CoO particles according to Example 2 (Sample 2B).

[0069] [Reference example 1] [Synthesis of cobalt oxalate] Using the conditions described in Table 1, cobalt oxalate was synthesized according to Reference Example 1 in the same manner as in Example 1. In Reference Example 1, the pH of the oxalic acid solution to be added was not adjusted by adding ammonia water, but was used as is. As a result, the pH of the added oxalic acid solution was pH 0.4. In this way, cobalt oxalate was synthesized according to Reference Example 1 (Sample 3A).

[0070] [Catalization of cobalt oxalate] The synthesized cobalt oxalate (sample 3A) was calcined using the same procedure and conditions as in Example 1. In this way, cobalt oxalate was calcined to obtain CoO particles according to Reference Example 1 (Sample 3B).

[0071] [Example 2: Evaluation of manufactured CoO particles] Samples 1B, 2B, and 3B, which are CoO particles produced in Example 1, Example 2, and Reference Example 1, were evaluated as follows. These CoO particles were measured directly after calcination, without any processing for fine grinding.

[0072] [Particle size distribution] The particle size distribution was measured for the CoO particles of Sample 1B, Sample 2B, and Sample 3B prepared in Example 1, Example 2, and Reference Example 1. The measurements were performed using laser diffraction / scattering particle size distribution analysis (using a HORIBA LA-920). The results obtained are shown in Figure 1 and Table 2 below.

[0073] [Table 2]

[0074] Thus, sample 1B from Example 1 is D 50 The size was 5.41 μm. Sample 2B from Example 2 was D 50 The size was 11.96 μm. On the other hand, sample 3B according to Reference Example 1 was D 50 The particle size was 22.67 μm. Thus, the CoO particles according to the present invention, when manufactured using the above procedure, were obtained as fine particles without any subsequent processing for fine grinding.

[0075] Furthermore, to evaluate the distribution, we calculated the so-called span value, which is expressed by the following formula: Span value = (Average particle size D90 - Average particle size D10) / Average particle size D50

[0076] The obtained span values ​​were 2.338 for sample 1B from Example 1, 1.010 for sample 2B from Example 2, and 1.045 for sample 3B from Reference Example 1.

[0077] [XRD intensity ratio] XRD intensity was measured for CoO particles of samples 1B, 2B, and 3B prepared in Example 1, Example 2, and Reference Example 1. The equipment and conditions used for the measurements are summarized in Table 3.

[0078] [Table 3]

[0079] The results obtained are shown in Figures 2, 3, and 4, and in Table 4 below. Figures 2, 3, and 4 show the peak positions of Co, CoO, and Co3O4, respectively, for comparison with the peak positions of the measured samples (Sample 1B from Example 1, Sample 2B from Example 2, and Sample 3B from Reference Example 1). In Figures 2, 3, and 4, the peak at 42.3 ≤ 2θ ≤ 42.5 is the strongest line for CoO, the peak at 44.2 ≤ 2θ ≤ 44.4 is the strongest line for Co, and the peak at 36.7 ≤ 2θ ≤ 36.9 is the strongest line for Co3O4.

[0080] [Table 4]

[0081] Thus, in Sample 1B from Example 1, the peaks of Co and Co3O4 were significantly smaller than the peak of CoO. Similarly, in Sample 2B from Example 2, the peaks of Co and Co3O4 were significantly smaller than the peak of CoO. Thus, the CoO particles according to the present invention were in the form of a single CoO phase.

[0082] [Impurity element content] The content of impurity elements was measured in the CoO particles of Sample 1B and Sample 2B, which were prepared in Example 1 and Example 2, respectively. The measurements were performed using GDMS (measuring device: Astrum, manufactured by Nu Instruments). The results obtained are summarized in Tables 5-1 to 5-4 below. Values ​​indicated by the inequality sign (<) indicate that the values ​​were below the limit of quantification. The content of impurity elements (wtppm) is the value when the mass of Co is assumed to be 100 wt%.

[0083] [Table 5-1]

[0084] [Table 5-2]

[0085] [Table 5-3]

[0086] [Table 5-4]

[0087] The total content of impurity metal elements in sample 1B was 11 wt ppm. The total content of impurity metal elements in sample 2B was 26 wt ppm. From these values, the metal purity of sample 1B, taking into account the impurity metal elements, was calculated to be 99.9989 wt%, and the metal purity of sample 2B was calculated to be 99.9974 wt%. Thus, the CoO particles according to the present invention were high-purity CoO particles.

[0088] Since the CoO particles according to the present invention are obtained as fine particles without any processing for fine grinding, there is no risk of contamination with impurity elements originating from the medium used for fine grinding, and the CoO particles can be used thereafter while maintaining the high purity mentioned above.

[0089] [Summary of evaluations] The CoO particles obtained in Examples 1 and 2 were of high purity and had a small particle size. The CoO particles in the examples were of high purity in the sense that the metal impurity content was extremely reduced, and at the same time, the cobalt oxides other than CoO were extremely reduced, resulting in a single-phase CoO state.

[0090] [Potential contribution to the SDGs] One embodiment of the present invention provides high-purity CoO particles. Since high precision of materials and components is important for the development of IoT and AI technologies, one embodiment of the present invention has the potential to contribute to the development of IoT and AI technologies. For this reason, one embodiment of the present invention has the potential to contribute to Goal 9 of the United Nations Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation." [Industrial applicability]

[0091] According to the present invention, high-purity CoO particles can be provided. This invention is industrially useful.

Claims

1. CoO particles with a purity of 99.9 wt% or higher.

2. The CoO particles according to claim 1, wherein the average particle size D50 is in the range of 1 to 20 μm.

3. The CoO particles according to claim 1, which are a single phase of CoO.

4. The CoO particle according to claim 1, wherein, in XRD measurement, the value of I(Co) / I(CoO), which is the ratio of the intensity I(Co) of the peak (strongest Co line) at 44.2 ≤ 2θ ≤ 44.4 to the intensity I(CoO) of the peak (strongest Co line) at 42.3 ≤ 2θ ≤ 42.5, is 0.05 or less.

5. In XRD measurements, the intensity I(CoO) of the peak (strongest CoO line) at 42.3 ≤ 2θ ≤ 42.5 is compared with the peak (CoO) at 36.7 ≤ 2θ ≤ 36.

9. ３ O ４ The strength of the strongest line (Co ３ O ４ I(Co) is the ratio of ) ３ O ４ The CoO particle according to claim 1, wherein the value of ) / I(CoO) is 0.05 or less.

6. The CoO particles according to claim 1, wherein the Na content is 5 wt ppm or less.

7. The CoO particles according to claim 1, wherein the Al content is 10 wt ppm or less.

8. The CoO particles according to claim 1, wherein the Cr content is 10 wt ppm or less.

9. The CoO particles according to claim 1, wherein the Fe content is 10 wt ppm or less.

10. The CoO particles according to claim 1, wherein the Ni content is 10 wt ppm or less.

11. The CoO particles according to claim 1, wherein the Cu content is 10 wt ppm or less.

12. The CoO particles according to claim 1, wherein the Zr content is 10 wt ppm or less.

13. The CoO particles according to claim 1, wherein the W content is 10 wt ppm or less.

14. The CoO particles according to claim 1, wherein the value of ("average particle size D90" - "average particle size D10") / "average particle size D50" is in the range of 0.5 to 2.5.

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