Titanium suboxide powder

Abstract

The present invention relates to a titanium suboxide powder that includes TiOX (wherein X is in the range of 1.50≤X≤1.75), the titanium suboxide powder including base particles that include γ-Ti3O5 and fine particles that have a smaller particle size than the base particles, the fine particles being particles that do not include Fe, Ta, Lu, Al, Nb, Sc, Zr, Hf, or W.　The present invention provides a titanium suboxide powder that has excellent blackness.

Description

Low-order titanium oxide powder

[0001] The present invention relates to a low-order titanium oxide powder.

[0002] Titanium dioxide (TiO ２ It is known that lower-order titanium oxide (also called reduced titanium oxide) obtained by reducing titanium dioxide (white titanium oxide) exhibits different colors depending on the ratio of the constituent elements titanium and oxygen, and can become black by appropriately adjusting this ratio. For example, Patent Document 1 describes a method in which titanium dioxide (white titanium oxide) is heated and reduced to 600°C or higher in a reducing atmosphere such as hydrogen gas or ammonia gas to produce black lower-order titanium oxide, and the sintered body is mechanically crushed to obtain black titanium oxide powder (paragraph 0002 of Patent Document 1, etc.). Furthermore, Patent Document 2, paragraph 0057, describes a method in which titanium oxides with a higher degree of reduction (for example, Ti ３ O ５ , Ti ４ O ７ etc.) are generally described as being black in color.

[0003] JP 11-292536 A JP 2019-002993 A

[0004] However, as a result of investigations by the present inventors, it has been found that the black titanium oxide powder described in Patent Document 1 has room for improvement in terms of blackness.

[0005] Ti, one of the low-order titanium oxides ３ O ５ It is known that the crystalline structure of TiO undergoes five phase transitions: α phase, β phase, γ phase, δ phase, and λ phase. ２ When sintered with a reducing agent at a high temperature of about 1000°C or higher, high-temperature stable phases called α-phase and λ-phase are formed, and α-Ti ３ O ５ and λ-Ti ３ O ５ Then, by lowering the temperature to below 200°C, or by applying mechanical stress such as pressing or rubbing at room temperature, a part of the α phase or λ phase will undergo a phase transition to a low-temperature phase called β phase, resulting in β-Ti. ３ O ５ These Ti ３ O５ Both of these are L ＊ The value could not be lowered sufficiently.

[0006] Further investigation by the present inventors revealed that TiO ２ When calcined with a reducing agent, Ti ３ O ５ By suppressing the grain growth of particles containing ３ O ５ ) can be stabilized, so that the L of the obtained low-order titanium oxide ＊ It was found that the value could be lower.

[0007] Based on this finding, further research was carried out and TiO ２ During the reduction firing, Ti ３ O ５ By adding fine particles that are difficult to replace Ti in the ３ O ５ Since the grain growth of particles containing L can be suppressed, ＊ γ-Ti with low value and excellent blackness ３ O ５ The present invention has been accomplished based on the discovery that a low-order titanium oxide powder containing the above-mentioned compound can be obtained.

[0008] According to one aspect of the present invention, there is provided the following low-order titanium oxide powder: 1. TiO Ｘ (wherein X is in the range of 1.50≦X≦1.75), ３ O ５ and fine particles having a particle size smaller than that of the base particles, wherein the fine particles do not contain any of Fe, Ta, Lu, Al, Nb, Sc, Zr, Hf, and W. 2. The low-order titanium oxide powder according to 1., wherein the fine particles are SiO ２ , Si ３ N ４ , B ４ 3. A low-order titanium oxide powder containing one or more selected from the group consisting of C and MgO. 3. The low-order titanium oxide powder according to 1. or 2., wherein the γ-Ti contained in the low-order titanium oxide powder３ O ５ The content of Ti ２ O ３ , α-Ti ３ O ５ , β-Ti ３ O ５ , γ-Ti ３ O ５ , λ-Ti ３ O ５ and Ti ４ O ７ 4. The low-order titanium oxide powder according to any one of 1. to 3., wherein the content of L is 10% by mass or more, based on a total of 100% by mass of the above. ＊ a ＊ b ＊ In color space, L ＊ The value is 15.0 or less, and a ＊ value is 5.0 or less, and b ＊ 5. The low-order titanium oxide powder according to any one of 1. to 4., wherein the specific surface area measured by the BET method is 1.0 m or less. ２ / g or more 30m ２ / g or less. 6. The low-order titanium oxide powder according to any one of 1. to 5., wherein the content of Si element contained in the low-order titanium oxide powder, as measured by ICP atomic emission spectroscopy, is 0.04 mass% or more and 20 mass% or less. 7. The low-order titanium oxide powder according to any one of 1. to 6., wherein, in the volume frequency particle size distribution of the low-order titanium oxide powder measured by laser diffraction scattering, when the particle diameter at which the cumulative value is 50% is defined as d50, the low-order titanium oxide powder has a d50 of 0.001 μm or more and 3.0 μm or less.

[0009] According to the present invention, a low-order titanium oxide powder having excellent blackness is provided.

[0010] 1 is an SEM image of the low-order titanium oxide powder of Example 1. FIG. 2 is an SEM image of the low-order titanium oxide powder of Comparative Example 2. FIG. 3 is a diagram showing the X-ray diffraction pattern of the low-order titanium oxide powder of Example 1. FIG. 4 is a diagram showing the X-ray diffraction pattern of the low-order titanium oxide powder of Comparative Example 2.

[0011] The low-order titanium oxide powder of this embodiment will be outlined below.

[0012] The low-order titanium oxide powder of this embodiment is TiO Ｘ (where X is in the range of 1.50≦X≦1.75), and ３ O ５ and fine particles having a particle diameter smaller than that of the base particles, the fine particles being free of any of Fe, Ta, Lu, Al, Nb, Sc, Zr, Hf, and W.

[0013] Ti ３ O ５ Known Ti-substitutable metals that are easily substituted for Ti in the TiO SiO 2 , in other words, that have a low formation energy, include Fe, Ta, Lu, Al, Nb, Sc, Zr, Hf, and W. According to the findings of the present inventors, fine particles that do not contain the Ti-substitutable metals are prepared by treating TiO SiO 2 with TiO SiO 2 . ２ By adding it during reduction firing, Ti ３ O ５ The grain growth of the particles containing γ-Ti can be suppressed, and the metastable phase ３ O ５ It was found that γ-Ti can be stabilized. ３ O ５ is α, β, or λ-Ti ３ O ５ L lower than either ＊ Therefore, γ-Ti with excellent blackness is ３ O ５ It was found that a low-order titanium oxide powder containing

[0014] The low-order titanium oxide powder of this embodiment can be used for various purposes, and can be used as a black pigment (black filler) to be added to a dispersion medium such as a resin. Furthermore, the low-order titanium oxide powder is less likely to scatter into space than carbon black, a common black pigment, and therefore has excellent low-dust properties.

[0015] Each component of the low-order titanium oxide powder of this embodiment will be described in detail.

[0016] The low-order titanium oxide powder is TiO Ｘ It has a composition represented by the formula:

[0017] TiO ｘ where X is a value in the range of 1.50≦X≦1.75. ｘ X in the formula (1) is expressed as a weighted average, for example, with the mass ratio of the crystalline composition contained in the low-order titanium oxide powder as the weight. ２ O ３ , γ-Ti ３ O ５ , and Ti ４ O ７ When two or more selected from the group consisting of ｘ means the average composition of these.

[0018] In this specification, Ti ２ O ３ , α-Ti ３ O ５ , β-Ti ３ O ５ , γ-Ti ３ O ５ , λ-Ti ３ O ５ , and Ti ４ O ７ The mass ratio of the crystalline composition contained in the low-order titanium oxide powder can be calculated by Rietveld analysis of the X-ray diffraction pattern of the low-order titanium oxide powder. Specifically, Rietveld method software (for example, Rigaku Corporation's integrated powder X-ray analysis software PDXL2) is used, and the crystal structure is obtained from the crystal structure database (Pearson's Crystal Data) by using Ti ２ O ３ 1243140 (Journal of Applied Physics 119, 014905(2016)), α-Ti ３ O ５ 1127327 (Chemistry An Asian Journal 6, 1886 (2011), β-Ti ３ O ５ 1944823 (Journal of Solid State Chemistry 192, 356(2012)), γ-Ti ３ O ５1900755 (Journal of Solid State Chemistry 20, 29(1977)), λ-Ti ３ O ５ The mass ratio (%) is calculated by using 1127325 (Chemistry An Asian Journal 6, 1886 (2011)) as the mass ratio.

[0019] The crystal composition of the low-order titanium oxide powder is at least γ-Ti ３ O ５ Any material containing Ti may be used. ２ O ３ , γ-Ti ３ O ５ , and Ti ４ O ７ It may contain two or more selected from the group consisting of:

[0020] γ-Ti contained in low-order titanium oxide powder ３ O ５ The lower limit of the content of Ti ２ O ３ , α-Ti ３ O ５ , β-Ti ３ O ５ , γ-Ti ３ O ５ , λ-Ti ３ O ５ and Ti ４ O ７ In the total of 100% by mass, the content of the low-order titanium oxide powder is, for example, 10% by mass or more, preferably 20% by mass or more, and more preferably 30% by mass or more. ＊ On the other hand, the above γ-Ti ３ O ５ The upper limit of the content of Ti is preferably as high as possible from the viewpoint of blackness. ２ O ３ , α-Ti ３ O ５ , β-Ti ３ O ５ , γ-Ti ３ O ５ , λ-Ti ３ O ５ and Ti ４ O７ The content of the pigments may be, for example, 90% by mass or less, 85% by mass or less, or 80% by mass or less, based on a total of 100% by mass of the pigments. This allows the chroma to be adjusted, and a powder having a desired blackness and chroma can be obtained.

[0021] The low-order titanium oxide powder may contain the above-mentioned Ti within a range that does not impair the effects of the present invention. ２ O ３ , Ti ３ O ５ , and Ti ４ O ７ Other low-order titanium oxides may be included, for example, Ti ２．５ O ４ , TiO, Ti ３ It may also contain one or more other lower titanium oxides such as 0.

[0022] The total content of Na, K, and P contained in the low-order titanium oxide powder is, for example, 2000 ppm by mass or less, preferably 1000 ppm by mass or less, more preferably 500 ppm by mass or less, and even more preferably 100 ppm by mass or less. This improves reactivity and makes it easier to obtain the desired crystalline phase. The total content of Pb, Cd, and Cr contained in the low-order titanium oxide powder may be, for example, 200 ppm by mass or less, preferably 100 ppm by mass or less, more preferably 50 ppm by mass or less, and even more preferably 30 ppm by mass or less. This improves reactivity and makes it easier to obtain the desired crystalline phase. The content (mass equivalent) of elements contained in the low-order titanium oxide powder can be calculated from the analysis results of the elemental composition obtained by ICP atomic emission spectroscopy using, for example, an Agilent 5110 ICP-OES (manufactured by Agilent Technologies, Inc.).

[0023] The low-order titanium oxide powder is composed of γ-Ti particles. ３ O ５ and fine particles.

[0024] The base particle may be configured to include primary particles and / or secondary particles. The shape of the primary particles included in the base particle may be any of spherical, plate-like, needle-like, polygonal, and irregular shapes, and one or more of these may be included. The secondary particles may include aggregates formed by aggregating multiple primary particles, or linked bodies formed by linking multiple primary particles, etc.

[0025] The microparticles in the low-order titanium oxide powder may include particles that are attached to a portion of the surface of the base particle, and / or particles that are not attached to the base particle. Furthermore, one or more of the microparticles that are attached to a portion of the surface of the base particle are discontinuously present on that portion of the surface of the base particle. In other words, the microparticles are scattered on the surface of the base particle. The microparticles do not continuously cover the entire surface of the base particle. In this embodiment, the microparticles are considered to be attached to the base particle if they are simply in physical contact with each other. The base particle and the microparticles may or may not be chemically bonded.

[0026] The fine particles are composed of particles that do not contain any of the metals that are easily substituted for Ti, such as Fe, Ta, Lu, Al, Nb, Sc, Zr, Hf, and W. Specifically, the fine particles do not contain any of the metals that are easily substituted for Ti, metal oxides, or metal nitrides of the metals that are easily substituted for Ti. In this specification, "the fine particles do not contain any of the metals that are easily substituted for Ti" means that the main raw material that constitutes the fine particles is not a metal that is easily substituted for Ti, and the fine particles may contain metals that are easily substituted for Ti that are inevitably mixed in the raw materials and during the manufacturing process. Specifically, the total content of metals that are easily substituted for Ti in terms of oxides in the entire low-order titanium oxide powder may be defined as, for example, 3.0 mass% or less. When the total amount of metals that are easily substituted for Ti exceeds 3.0 mass% in terms of oxides, λ-Ti is not considered to be a λ-Ti. ３ O ５ As a result, γ-Ti ３ O ５ The proportion of L ＊ The value increases, which may result in an increase in blackness.

[0027] The fine particles are SiO ２ , Si３ N ４ , B ４ The composition may be configured to contain one or more selected from the group consisting of C and MgO. Si, B, or Mg may be Ti ３ O ５ Since these metal elements are difficult to replace with Ti in the matrix, oxides and nitrides of Si, B, or Mg are not TiO ２ During the reduction firing of Ti ３ O ５ It is presumed that the particles adhere to the surface of the particles containing the compound, thereby suppressing the grain growth of the particles.

[0028] The lower limit of the content of the Si element contained in the low-order titanium oxide powder is, for example, 0.04 mass% or more, preferably 0.5 mass% or more, and more preferably 0.7 mass% or more. ＊ On the other hand, the upper limit of the content of the Si element is, for example, 20% by mass or less, preferably 15% by mass or less, and more preferably 8% by mass or less. This allows the particle size to be reduced. ４ When C is contained, the content of B element contained in the low-order titanium oxide powder may be, for example, 0.02% by mass or more and 20% by mass or less. When the fine particles contain MgO, the content of Mg element contained in the low-order titanium oxide powder may be, for example, 0.01% by mass or more and 20% by mass or less. The content of Si, B, or Mg element contained in the low-order titanium oxide powder can be measured by the above-mentioned ICP atomic emission spectroscopy.

[0029] The lower limit of the specific surface area of ​​the low-order titanium oxide powder measured by the BET method is, for example, 1.0 m ２ / g or more, preferably 3.0m ２ / g or more, more preferably 5.0m ２ / g or more. ＊ On the other hand, the upper limit of the specific surface area of ​​the low-order titanium oxide powder measured by the BET method is, for example, 30 m ２ / g or less, preferably 20m ２ / g or less, more preferably 10m ２ / g or less, thereby improving the handling properties of the powder.

[0030] The specific surface area can be measured using a specific surface area measuring device (e.g., Macsorb HM model-1201, manufactured by Mountech) under the conditions of n=2, where degassing is performed with a nitrogen gas flow (atmospheric pressure) at 200°C for 10 minutes, and equilibrium relative pressure by nitrogen gas adsorption is about 0.3.

[0031] In the volume frequency particle size distribution of the low-order titanium oxide powder measured by the laser diffraction scattering method, the particle size at which the cumulative value is 50% is defined as d50. The upper limit of d50 of the low-order titanium oxide powder is, for example, 3.0 μm or less, preferably 1.5 μm or less, and more preferably 1.0 μm or less. This allows the L of the low-order titanium oxide powder to be ＊ On the other hand, the lower limit of the d50 of the low-order titanium oxide powder is, for example, 0.001 μm or more, preferably 0.01 μm or more, and more preferably 0.23 μm or more. This improves the coloring power when mixed with a medium.

[0032] The particle size distribution of low-order titanium oxide powder is measured by the following procedure. First, 100 mg of low-order titanium oxide powder and 50 mL of ion-exchanged water are placed in a polystyrene sample vial (volume: 100 mL (e.g., AS ONE, PS-100)), and an ultrasonic homogenizer (e.g., Branson Ultrasonics Corporation, model: DIGITALSONIFIER 450) is used to perform ultrasonic dispersion treatment for 60 seconds at an output of 10% amplitude. Next, within 30 seconds after the ultrasonic dispersion treatment is completed, a particle size distribution measuring device using a laser diffraction scattering method (e.g., Beckman Coulter, model LS 13 320) is used to measure the volume-based particle size distribution of the dispersed low-order titanium oxide powder under the following measurement conditions: (Measurement conditions) Dispersion medium: water Refractive index: 2.71 Measurement interval: interval at which log(d2 / d1) = 0.04

[0033] The low-order titanium oxide powder is L ＊ a ＊ b ＊ L in color space ＊ The value is 15.0 or less, and a ＊ value is 5.0 or less, and b ＊The L value may be 1.0 or less. This allows for the production of low-order titanium oxide powder with excellent blackness. ＊ The upper limit of the value may be, for example, 15.0 or less, 14.0 or less, or 13.0 or less, preferably 12.0 or less, more preferably 11.6 or less, and even more preferably 11.2. ＊ The lower limit of the value may be, for example, 8.0 or more, 8.5 or more, or 9.0 or more. ＊ The upper limit of the value is, for example, 5.0 or less, preferably 2.0 or less, and more preferably 1.5 or less. ＊ The lower limit of the value is, for example, −2.0 or more, preferably −1.5 or more, and more preferably −1.0 or more. ＊ The upper limit of the value is, for example, 1.0 or less, preferably −0.1 or less, more preferably −1.0 or less, and even more preferably −2.0 or less. ＊ The lower limit of the value is, for example, −6.0 or more, preferably −5.0 or more, and more preferably −4.0 or more.

[0034] L ＊ a ＊ b ＊ L in color space ＊ Value, a ＊ value and b ＊ The value is measured using a colorimeter (for example, a ZE-2000 (manufactured by Nippon Denshoku Industries Co., Ltd.)). More specifically, after zeroing using a dark field cylinder, standardization is performed using a standard white plate (X = 91.71, Y = 93.56, Z = 110.52). Next, approximately 3 g of low-order titanium oxide powder is placed in a 35φ x 15H round cell and measurement is performed.

[0035] The low-order titanium oxide powder of this embodiment is preferably used as a pigment (colored filler) such as a black pigment, but its use is not limited to this. The pigment (colored filler) is also used in, for example, cosmetics, electronic components such as semiconductors, coating materials such as paints and inks, etc.

[0036] The low-order titanium oxide powder may be used, for example, by dispersing it in a dispersion medium. That is, the dispersion of this embodiment contains the above-mentioned low-order titanium oxide powder and a dispersion medium. This makes it possible to sufficiently improve the blackness of the dispersion even with the addition of a small amount.

[0037] The dispersion medium is appropriately selected depending on the application of the dispersion, and may be, for example, water, alcohol, ketone, ester, resin, etc. Examples of the resin may include epoxy resin, silicone resin, phenol resin, melamine resin, urea resin, unsaturated polyester, fluororesin, polyimide, polyamideimide, polyetherimide, polybutylene terephthalate, polyethylene terephthalate, polyphenylene sulfide, wholly aromatic polyester, polysulfone, liquid crystal polymer, polyethersulfone, polycarbonate, maleimide-modified resin, ABS (acrylonitrile butadiene styrene) resin, AAS (acrylonitrile acrylic rubber styrene) resin, AES (acrylonitrile ethylene propylene diene rubber styrene) resin, etc.

[0038] Next, a method for producing the low-order titanium oxide powder of this embodiment will be described.

[0039] An example of a method for producing low-order titanium oxide powder is to use TiO as a raw material. ２ powder and SiO ２ and TiH as a reducing agent. ２ and a powder of TiO. ２ is reduced to form low-order titanium oxide. ２ The Ti particles contained in the low-order titanium oxide powder are removed by using fine particles that do not contain easily substituted Ti metals such as ３ O ５ The grain growth can be suppressed.

[0040] The powder is classified into, for example, large fine powders with particle sizes of more than 5 μm and not more than 100 μm, medium fine powders with particle sizes of more than 0.1 μm and not more than 5 μm, and small fine powders with particle sizes of not more than 0.1 μm. The particle size is the median diameter (the particle size at which the cumulative value reaches 50% in the volume frequency particle size distribution measured by the laser diffraction scattering method is called d50). The particle size and specific surface area of ​​the raw materials, reducing agent, etc. can be selected depending on the particle size of the desired low-order titanium oxide powder. For example, TiO ２ Particle size of powder > SiO ２ The particle size of the powder or TiO ２ Specific surface area of ​​powder <SiO ２ The raw material and the fine powder that does not contain the metal that is easily substituted for Ti may be selected so that the specific surface area of ​​the powder is equal to or greater than the above.

[0041] If the fine particles do not contain the above-mentioned Ti-substitutable metal, SiO ２ For example, such fine particles can be used without being limited to powders such as SiO ２ , Si ３ N ４ , B ４ Powder containing one or more elements selected from the group consisting of C and MgO can be used.

[0042] TiH contained in the mixture ２ TiO ２ The molar ratio (TiO ２ Content (mol) / TiH ２ The content (mol) of (I) is, for example, 3.2 or more and 6.0 or less, preferably 3.5 or more and 5.5 or less, and more preferably 3.8 or more and 5.2 or less.

[0043] The heating temperature in the firing step is, for example, 800° C. or higher and 1200° C. or lower, preferably 900° C. or higher and 1150° C. or lower, and more preferably 950° C. or higher and 1100° C. For example, the mixture is placed in a known firing furnace such as an electric furnace, and the firing step is carried out.

[0044] The inert gas atmosphere may contain, for example, Ar gas or He gas, preferably Ar gas. Note that instead of the inert gas atmosphere, a vacuum atmosphere may be used. If necessary, a gaseous reducing agent may be introduced.

[0045] The heating time in the calcination step may be, for example, 1 hour or more, 2 hours or more, or 4 hours or more from the viewpoint of allowing the reduction reaction to proceed sufficiently, and may be, for example, 24 hours or less, 18 hours or less, or 12 hours or less from the viewpoint of appropriately suppressing the growth of the low-order titanium oxide powder and making it easy to collect it in a powder state.

[0046] The method for producing low-order titanium oxide powder of this embodiment may further include a washing step of washing the low-order titanium oxide powder obtained in the calcination step. The washing step can remove impurities from the low-order titanium oxide powder. The washing is carried out, for example, with at least one selected from the group consisting of hot water, alcohol, and organic acid. The alcohol may be, for example, methanol, ethanol, or a mixture thereof. The organic acid may be, for example, acetic acid. Washing with an organic acid is preferable from the viewpoint of suppressing the incorporation of ionic impurities such as halide ions into the low-order titanium oxide powder.

[0047] The method for producing low-order titanium oxide powder of this embodiment may further include a particle size adjustment step of pulverizing and classifying the low-order titanium oxide powder after the firing step, as necessary. Examples of the pulverization method include methods using various pulverizers such as a mortar, a ball mill, a jet mill, and a fine mill. The pulverization step may be performed once or two or more times. When the pulverization step is performed two or more times, the pulverization method used in each pulverization step may be different from each other. By performing the pulverization step, the chromaticity and specific surface area of ​​the low-order titanium oxide powder can be adjusted.

[0048] When the manufacturing method of this embodiment includes other known steps such as a washing step and a pulverization step, the order of these steps is arbitrary. That is, this manufacturing method may include a calcination step, a washing step, and a pulverization step in this order, or may include a calcination step, a pulverization step, and a washing step in this order. In the former case, a step of drying the low-order titanium oxide powder (drying step) may be further carried out between the washing step and the pulverization step. The drying temperature in the drying step may be, for example, 100°C or higher and 200°C or lower. The drying time may be, for example, 10 hours or higher and 20 hours or shorter.

[0049] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention.

[0050] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the descriptions of these examples.

[0051] <Preparation of low-order titanium oxide powder> [Example 1] TiO ２ Powder (product of Toho Titanium Co., Ltd., HT0514, TiO ２ Purity 99.9%, average particle size approximately 0.7μm, specific surface area 6-7m ２ / g), TiH ２ Powder (Toho Tech product, TCH450, Ti purity 99.8%, average particle size 45 μm), SiO ２ Fine powder (manufactured by Nippon Aerosil Co., Ltd., AEROSIL NX90G, SiO ２ Purity 99.0%, specific surface area 50-80m ２ / g) to TiO ２ : TiH ２ The mixture was mixed using an Eirich mixer (manufactured by Nippon Eirich Co., Ltd.) to a concentration of 0.1 wt% with a 4:1 (molar ratio) mixture. The resulting mixture was transferred to an alumina crucible and heated in an electric furnace (Fuji Denpa Kogyo Co., Ltd., Hi-Multi 10000) under an Ar atmosphere, with the temperature increased from room temperature at a rate of 10°C / min, to 1100°C (calcination temperature) for 12 hours (calcination time). After heating, the resulting powder was pulverized in a mortar for 5 minutes to obtain a low-order titanium oxide powder.

[0052] [Examples 2 to 16] TiO ２ : TiH ２ Molar ratio of TiO ２ and TiH ２ A low-order titanium oxide powder was obtained in the same manner as in Example 1, except that the ratio (wt%) of the fine powder added to the mixture, the firing temperature, and the firing time were changed to the values ​​shown in Table 1. However, in Example 16, SiO ２ Instead of fine powder, Si ３ N ４Fine powder (manufactured by H.C. Starck, α phase:β phase=13:87) was used, and Himulti 5000 was used in place of Himulti 10000 in the electric furnace.

[0053] [Comparative Examples 1 to 7] SiO ２ A low-order titanium oxide powder was obtained in the same manner as in Example 1, except that the fine powder was not added and the firing conditions in Table 1 were adopted.

[0054] [Comparative Examples 8-9] SiO ２ Instead of fine powder, Al ２ O ３ Fine powder (manufactured by Denka Co., Ltd., trade name: ASFP-20, Al ２ O ３ Purity 99.9%, specific surface area 10.8m ２ A low-order titanium oxide powder was obtained in the same manner as in Example 1, except that a titanium dioxide powder (0.3 μm / g, average particle size: 0.3 μm) was added and the firing conditions in Table 1 were adopted.

[0055]

[0056] <X-ray diffraction measurement> Powder X-ray diffraction measurement was carried out on the obtained low-order titanium oxide powder. Specifically, an X-ray diffraction pattern was measured under the following measurement conditions using a horizontal sample multipurpose X-ray diffractometer (Rigaku Corporation, RINT-Ultima IV). The obtained X-ray diffraction patterns confirmed that each low-order titanium oxide powder had the crystalline composition shown in Table 1. The results of the X-ray diffraction patterns showed that the low-order titanium oxide powders of Examples 1 to 16 were γ-Ti ３ O ５ The low-order titanium oxide powders of Comparative Examples 1 to 9 contain a peak corresponding to γ-Ti (a peak where the diffraction angle 2θ is in the range of 30.0° to 31.0°). ３ O ５As an example, the X-ray diffraction patterns of Example 1 and Comparative Example 2 are shown in Figures 3 and 4, respectively. (Measurement conditions) X-ray source: Cu-Kα ray (λ = 1.54184 Å) Tube voltage: 40 kV, Tube current: 40 mA Optical conditions during measurement: Divergence slit = 2 / 3° Scattering slit: 8 mm Receiving slit = 0.15 mm Diffraction peak position = 2θ (diffraction angle) Scan speed: 4.0° (2θ) / min, continuous scan Measurement range: 2θ = 10° to 80°

[0057] Subsequently, the mass fraction (mass%) of each crystalline composition in the obtained low-order titanium oxide powder was calculated using Rietveld method software (Rigaku Corporation, integrated powder X-ray analysis software PDXL2). The crystal structure was calculated from the crystal structure database (Pearson's Crystal Data) as follows: Ti ２ O ３ 1243140 (Journal of Applied Physics 119, 014905(2016)), α-Ti ３ O ５ 1127327 (Chemistry An Asian Journal 6, 1886 (2011), β-Ti ３ O ５ 1944823 (Journal of Solid State Chemistry 192, 356(2012)), γ-Ti ３ O ５ 1900755 (Journal of Solid State Chemistry 20, 29(1977)), λ-Ti ３ O ５ 1127325 (Chemistry An Asian Journal 6, 1886 (2011)) was used. In Table 1, in each example and each comparative example, α-Ti ３ O ５ was not confirmed.

[0058] <SEM Images> The obtained low-order titanium oxide powder was observed using a scanning electron microscope, and SEM images were obtained. In Examples 1 to 16, fine particles having a particle size smaller than that of the base particles were confirmed. As examples, SEM images of Example 1 and Comparative Example 2 are shown in Figures 1 and 2, respectively.

[0059] <Measurement of Specific Surface Area> The specific surface area of ​​the obtained low-order titanium oxide powder was measured using a specific surface area measuring device (Macsorb HM model-1201, manufactured by Mountech). Degassing was performed at 200°C for 10 minutes using a nitrogen gas flow (atmospheric pressure). The measurement conditions were nitrogen gas adsorption with an equilibrium relative pressure of approximately 0.3 and n = 2. The results are shown in Table 1.

[0060] <Measurement of particle size distribution> The particle size distribution of the obtained low-order titanium oxide powder was measured by the following procedure, and the measurement results of the particle diameter (d50) at which the cumulative value becomes 50% are shown in Table 1. First, 100 mg of the low-order titanium oxide powder and 50 mL of ion-exchanged water were placed in a polystyrene sample bottle (capacity: 100 mL (e.g., AS ONE Corporation, PS-100)), and subjected to ultrasonic dispersion treatment for 60 seconds at an output of 10% amplitude using an ultrasonic homogenizer (e.g., Branson Ultrasonics Corporation, model: DIGITALSONIFIER 450). Subsequently, within 30 seconds after the ultrasonic dispersion treatment was completed, the volumetric particle size distribution of the dispersed low-order titanium oxide powder was measured using a particle size distribution measuring device (e.g., Beckman Coulter, Model LS 13 320) using a laser diffraction scattering method under the following measurement conditions: (Measurement conditions) Dispersion medium: Water Refractive index: 2.71 Measurement interval: interval at which log(d2 / d1) = 0.04

[0061] <Elemental Analysis> Elemental analysis was performed on the obtained low-order titanium oxide powder using an Agilent 5110 ICP-OES (manufactured by Agilent Technologies, Inc.). Specifically, 0.1 g of the powder was weighed into a platinum crucible, and 1 ml each of HF and HCl was added, followed by pressurized acid decomposition at 150°C for 4 hours. The volume was then adjusted to 6 ml, and after confirming that no unnecessary residue remained, ICP optical emission spectroscopy was performed. The results are shown in Table 1. In Table 1, the total amount of metals easily substituted for Ti indicates the total amount (mass%) of Fe, Ta, Lu, Al, Nb, Sc, Zr, Hf, and W in terms of metal oxide.

[0062] <Measurement of chromaticity> The chromaticity (L ＊ a ＊ b ＊ L in color space ＊ Value, a ＊ value and b ＊ The chromaticity was measured. More specifically, the zero point was first corrected using a dark field cylinder, and then standardization was performed using a standard white plate (X = 91.71, Y = 93.56, Z = 110.52). Next, approximately 3 g of the powder was placed in a 35φ x 15H round cell, and the chromaticity was measured. The results are shown in Table 1.

[0063] The low-order titanium oxide powders in Examples 1 to 16 were found to have a L ＊ a ＊ b ＊ L in color space ＊ The low value indicates excellent blackness.

[0064] This application claims priority based on Japanese Patent Application No. 2023-019373, filed February 10, 2023, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. TiO Ｘ (wherein X is in the range of 1.50≦X≦1.75), γ-Ti ３ O ５ a base particle comprising: and fine particles having a particle size smaller than that of the base particles, The low-order titanium oxide powder, wherein the fine particles are particles that do not contain any of Fe, Ta, Lu, Al, Nb, Sc, Zr, Hf, and W.

2. The low-order titanium oxide powder according to claim 1, The fine particles are SiO ２ , Si ３ N ４ , B ４ A low-order titanium oxide powder containing one or more elements selected from the group consisting of C and MgO.

3. The low-order titanium oxide powder according to claim 1 or 2, γ-Ti contained in the low-order titanium oxide powder ３ O ５ The content of Ti ２ O ３ , α-Ti ３ O ５ , β-Ti ３ O ５ , γ-Ti ３ O ５ , λ-Ti ３ O ５ and Ti ４ O ７ A low-order titanium oxide powder that is 10% by mass or more based on a total of 100% by mass of the above.

4. The low-order titanium oxide powder according to claim 1 or 2, L ＊ a ＊ b ＊ In color space, L ＊ The value is 15.0 or less, and a ＊ value is 5.0 or less, and b ＊ A low-order titanium oxide powder having a value of 1.0 or less.

5. The low-order titanium oxide powder according to claim 1 or 2, The specific surface area measured by the BET method is 1.0 m ２ / g or more 30m ２ / g or less.

6. The low-order titanium oxide powder according to claim 1 or 2, A low-order titanium oxide powder, in which the content of elemental Si contained in the low-order titanium oxide powder as measured by ICP emission spectroscopy is 0.04% by mass or more and 20% by mass or less.

7. The low-order titanium oxide powder according to claim 1 or 2, A low-order titanium oxide powder in which, when the particle diameter at which the cumulative value reaches 50% in the volume frequency particle size distribution of the low-order titanium oxide powder measured by a laser diffraction scattering method is defined as d50, the d50 is 0.001 μm or more and 3.0 μm or less.