Low-order titanium oxide powder

Abstract

The low-oxidation titanium powder of the present invention comprises TiO₂X (where X is in the range of 1.50≦X≦1.75), contains basic particles containing γ-Ti₃O₅, and is configured in a manner that satisfies the following conditions: In the X-ray diffraction pattern of the low-oxidation titanium powder using Cu-Kα rays, the peak area of ​​the γ(11-1) plane of γ-Ti₃O₅ in the range of diffraction angle 2θ being 30.0° to 31.0° is Iγ; when the sum of the peak areas of the (110) plane of α-Ti₃O₅, the (110) plane of β-Ti₃O₅, and the (110) plane of λ-Ti₃O₅ in the range of diffraction angle 2θ being 24.5° to 26.0° is Iα + Iβ + Iλ, Iα, Iβ, Iγ, and Iλ satisfy 0.001≦Iγ. γ / (I α+I β+I λ)

Description

Technical Field

[0001] The present invention relates to titanium suboxide powder. Prior Art

[0002] It is known that titanium suboxide (also called reduced titanium oxide) obtained by reducing titanium dioxide (TiO2) exhibits different colors depending on the ratio of titanium and oxygen as constituent elements, and can become black by appropriately adjusting the ratio. For example, Patent Document 1 describes a method for obtaining black titanium oxide powder by heating and reducing titanium dioxide (white titanium oxide) in a reducing atmosphere such as hydrogen or ammonia at 600° C. or higher to form black titanium suboxide, and then mechanically pulverizing the sintered body (paragraph 0002 of Patent Document 1, etc.). Furthermore, paragraph 0057 of Patent Document 2 states that titanium oxide with a higher degree of reduction (e.g., Ti 3 O 5 , Ti 4 O 7 , etc.) generally has a black color. [Prior Art Literature] [Patent Document]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 11-292536 [Patent Document 2] Japanese Patent Application Laid-Open No. 2019-002993 Summary of the Invention

[0004] [Problems to be solved by the invention]

[0005] However, the inventors of this case have found through research that the blackness of the black titanium oxide powder described in Patent Document 1 can still be improved. [Methods to solve the problem]

[0006] The crystal structure of Ti 3 O 5 , a type of titanium suboxide, is known to undergo phase transitions among five phases: α, β, γ, δ, and λ. If TiO2 is used as a reducing agent and fired at temperatures above approximately 1000°C, high-temperature stable phases of α and λ will form, resulting in α-Ti3O5 and λ-Ti3O5. Subsequently, by cooling to below approximately 200°C or subjecting the alloy to mechanical stimulation such as pressing or friction at room temperature, a portion of the α or λ phase will transition to the low-temperature β phase, resulting in β-Ti3O5. However, the L* values ​​of these Ti3O5 materials are not sufficiently low.

[0007] After further research, the inventors of this application realized that by using the abundance ratio of the γ phase of Ti₃O₅ (Iγ / (Iα+Iβ+Iλ)), represented by the peak area ratio in the X-ray diffraction pattern, as an indicator of the abundance ratio of γ-Ti₃O₅ in the titanium suboxide powder, the L* value in the titanium suboxide powder can be stably evaluated. Based on this insight, further diligent research revealed that by setting the lower limit of the above-mentioned indicator (Iγ / (Iα+Iβ+Iλ)) to above a predetermined value, it is possible to obtain a titanium suboxide powder containing γ-Ti3O5 with a sufficiently low L* value and excellent blackness, which led to the completion of the present invention.

[0008] According to one aspect of the present invention, the following titanium suboxide powder can be provided. 1. A titanium suboxide powder comprising TiO X (where X is in the range of 1.50≦X≦1.75), Contains basic particles containing γ-Ti 3O 5 and is constructed in a manner that satisfies the following conditions: In the X-ray diffraction pattern of the titanium suboxide powder using Cu-Kα radiation, Let the peak area of ​​the γ(11-1) plane of γ-Ti 3O 5 within the range of diffraction angle 2θ from 30.0° to 31.0° be I γ, When the sum of the peak areas of the (110) plane of α-Ti 3O 5, the (110) plane of β-Ti 3O 5, and the (110) plane of λ-Ti 3O 5 within the range of diffraction angle 2θ of 24.5° to 26.0° is I α + I β + I λ, I α, I β, I γ, and I λ satisfy 0.001≦I γ / (I α+I β+I λ). 2. The titanium suboxide powder as in 1. is formulated so as to satisfy 0 ≤ (I α + I β + I λ) / I γ ≤ 1000. 3. The titanium suboxide powder according to 1. or 2., wherein the content of γ-Ti 3 O 5 contained in the titanium suboxide powder is 10% by mass or more based on 100% by mass of the total of Ti 2 O 3, γ-Ti 3 O 5, and Ti 4 O 7. 4. The titanium suboxide powder according to any one of 1. to 3., wherein, in the L*a*b* color space, the L* value is 15.0 or less, the a* value is 5.0 or less, and the b* value is 1.0 or less. 5. The titanium suboxide powder according to any one of 1. to 4., wherein the specific surface area obtained by the BET method is not less than 1.0 m2 / g and not more than 30 m2 / g. 6. The titanium suboxide powder according to any one of 1. to 5., wherein the content of Si element contained in the titanium suboxide powder measured by ICP emission spectrometry is 0.04 mass % to 20 mass %. 7. The titanium suboxide powder according to any one of 1. to 6., wherein, when the particle size at which the cumulative value reaches 50% in the volume frequency particle size distribution of the titanium suboxide powder measured by laser diffraction scattering is d50, the particle size d50 is not less than 0.001 μm and not more than 3.0 μm. [Effects of the Invention]

[0009] According to the present invention, a titanium suboxide powder having excellent blackness can be provided. Simple diagram description

[0010] [Figure 1] SEM image of titanium suboxide powder of Example 1. [Figure 2] SEM image of the titanium suboxide powder of Comparative Example 2. FIG3 is a diagram showing the X-ray diffraction pattern of the titanium suboxide powder of Example 1. FIG4 is a diagram showing the X-ray diffraction pattern of the titanium suboxide powder of Comparative Example 2. Implementation Method

[0011] The outline of the titanium suboxide powder of this embodiment will be described.

[0012] The titanium suboxide powder of this embodiment comprises a powder (particle group) of TiO X (where X is in the range of 1.50≦X≦1.75) and contains base particles containing γ-Ti 3O 5. Furthermore, in the X-ray diffraction pattern of the suboxide titanium powder using Cu-Kα radiation, when the peak area of ​​the (11-1) plane of γ-Ti 3 O 5 within the diffraction angle 2θ range of 30.0° to 31.0° is denoted as I γ, and the sum of the peak areas of the (110) plane of α-Ti 3 O 5, the (110) plane of β-Ti 3 O 5, and the (110) plane of λ-Ti 3 O 5 within the diffraction angle 2θ range of 24.5° to 26.0° is denoted as I α(α(110))+I β(β(110))+I λ(λ(110)), the suboxide titanium powder of this embodiment is constructed so as to satisfy I α, I β, I γ, and I λ of 0.001≦I γ / (I α+I β+I λ).

[0013] In this embodiment, the X-ray diffraction pattern of the titanium suboxide powder can be measured by the powder X-ray diffraction method under the following measurement conditions. (Measurement conditions) X-ray source: Cu-Kα ray (λ=1.54184Å) Tube voltage: 40kV, tube current: 40mA Optical conditions during measurement: Divergence slit = 2 / 3° Scattering slit: 8mm Light receiving slit = 0.15mm The position of the diffraction peak = 2θ (diffraction angle) Scanning speed: 4.0°(2θ) / min, continuous scanning Measuring range: 2θ = 10°~80° The peak area of ​​each crystalline phase is analyzed using XRD analysis software (eg, JADE, manufactured by LightStone Co., Ltd.), and the range of the peak area can be calculated from the range of a pseudo-triangle drawn along the baseline.

[0014] The inventors have discovered that by using the abundance ratio of the γ phase of Ti₃O₅ (Iγ / (Iα+Iβ+Iλ)), represented by the peak area ratio in the X-ray diffraction pattern, as an indicator of the abundance ratio of γ-Ti₃O₅ in the titanium suboxide powder, the L* value of the titanium suboxide powder can be evaluated more stably than when the mass ratio of γ-Ti₃O₅ is used as an indicator. Furthermore, by setting this indicator (Iγ / (Iα+Iβ+Iλ)) above the lower limit, the L* value of the titanium suboxide powder can be sufficiently reduced. γ-Ti₃O₅ has a lower L* value than any of α-, β-, or λ-Ti₃O₅. Therefore, a titanium suboxide powder containing γ-Ti₃O₅ with excellent blackness can be achieved.

[0015] Here, in the X-ray diffraction pattern, the α, β, and λ phases all appear as a single peak within the range of 2θ = 24.5° to 26.0°. A detailed analysis of this X-ray diffraction pattern revealed that the range of 30.0° to 31.0° was defined as the range where the γ phase is not overlapped by peaks of other TiOx components, such as Ti₃O₅. In addition, the above-mentioned (11-1) and (110) refer to the crystal planes of titanium suboxide.

[0016] The ratio Iγ / (Iα+Iβ+Iλ) in titanium suboxide powder can be controlled by appropriately selecting the types, blending amounts, and production methods of the various components. For example, factors for achieving the desired range of Iγ / (Iα+Iβ+Iλ) include, but are not limited to, the addition of fine particles of SiO2, which do not contain a metal that readily substitutes for Ti, during the reduction firing of TiO2. This suppresses grain growth of Ti3O5-containing particles and stabilizes the pseudo-stable γ-Ti3O5 phase.

[0017] The lower limit of Iγ / (Iα+Iβ+Iλ) is 0.001 or greater, preferably 0.01 or greater, and more preferably 0.03 or greater. This allows for the realization of a titanium suboxide powder containing γ-Ti3O5 with excellent blackness. The upper limit of Iγ / (Iα+Iβ+Iλ) is not particularly limited. A larger Iγ / (Iα+Iβ+Iλ) increases the ratio of the γ-Ti3O5 phase, thereby further reducing the L* value.

[0018] In other aspects, the titanium suboxide powder may be configured to satisfy 0≦(Iα+Iβ+Iλ) / Iγ≦1000. The upper limit of (I α + I β + I λ) / I γ is, for example, 1000 or less, preferably 500 or less, and more preferably 100 or less. This can further reduce the L * value. Furthermore, the closer the lower limit of (I α+I β+I λ) / I γ is to 0, the better, thereby further reducing the L* value.

[0019] The titanium suboxide powder of this embodiment can be used in a variety of applications, including as a black pigment (black filler) added to a dispersion medium such as resin. Furthermore, compared to carbon black, a common black pigment, titanium suboxide powder is less likely to disperse in space, resulting in excellent dust reduction.

[0020] Each component of the titanium suboxide powder of this embodiment will be described in detail.

[0021] Titanium suboxide powder has a composition represented by TiO X.

[0022] X in TiO x is a value within the range of 1.50≦X≦1.75. X in TiO x is, for example, a weighted average weighted by the mass ratio of the crystal components contained in the titanium suboxide powder. When the titanium suboxide powder contains two or more selected from the group consisting of Ti 2 O 3 , γ-Ti 3 O 5 , and Ti 4 O 7 , TiO x means the average composition thereof.

[0023] In this specification, the mass ratio of the crystal components contained in the suboxide titanium powder, such as Ti2O3, α-Ti3O5, β-Ti3O5, γ-Ti3O5, λ-Ti3O5, and Ti4O7, can be calculated by performing Rietveld analysis on the X-ray diffraction pattern of the suboxide titanium powder. Specifically, the crystal structure is determined based on the crystal structure database (Pearson's Crystal Data) using Rietveld method software (e.g., integrated powder X-ray analysis software PDXL2 manufactured by Rigaku Corporation) using 1243140 (Journal of Applied Physics 119, 014905 (2016)) as Ti 2 O 3, 1127327 (Chemistry An Asian Journal 6, 1886 (2011)) as α-Ti 3 O 5, 1944823 (Journal of Solid State Chemistry 192, 356 (2012)) as β-Ti 3 O 5, 1900755 (Journal of Solid State Chemistry 20, 29 (1977)) as γ-Ti 3 O 5, and 1127327 (Chemistry An Asian Journal 6, 1886 (2011) as λ-Ti 3O 5 to calculate the above mass ratio (%).

[0024] The crystalline composition of the titanium suboxide powder only needs to contain at least γ-Ti 3O 5, and may also contain two or more selected from the group consisting of Ti 2O 3, γ-Ti 3O 5, and Ti 4O 7.

[0025] The lower limit of the γ-Ti 3 O 5 content in the titanium suboxide powder is, for example, 10% by mass or greater, preferably 20% by mass or greater, and more preferably 30% by mass or greater, based on 100% by mass of the total 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 . This further reduces the L* value of the titanium suboxide powder. On the other hand, the upper limit of the γ-Ti 3 O 5 content is not particularly limited. For example, the content of γ-Ti 3 O 5 can be 90% by mass or less, 85% by mass or less, or even 80% by mass or less, based on the total of 100% by mass 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 . This allows the chroma (a* value, b* value) to be adjusted, resulting in a powder with the desired blackness and chroma.

[0026] The titanium suboxide powder may also contain other titanium suboxides besides the above-mentioned Ti2O3, Ti3O5, and Ti4O7 within a range that does not impair the effects of the present invention. For example, it may also contain one or more of other titanium suboxides such as Ti2.5O4, TiO, and Ti3O.

[0027] The total content of Na, K, and P in the titanium suboxide powder is, for example, 2000 mass ppm or less, preferably 1000 mass ppm or less, more preferably 500 mass ppm or less, and even more preferably 100 mass ppm or less. This improves reactivity and makes it easier to obtain a desired crystal phase. Furthermore, the total content of Pb, Cd, and Cr in the titanium suboxide powder can be, for example, 200 mass ppm or less, preferably 100 mass ppm or less, more preferably 50 mass ppm or less, and even more preferably 30 mass ppm or less. This improves reactivity and makes it easier to obtain the desired crystal phase. The content (in terms of mass) of the elements contained in the titanium suboxide powder can be calculated from the analysis results of the elemental composition obtained by ICP emission spectrometry using, for example, an Agilent 5110 ICP-OES (manufactured by Agilent Technologies, Inc.).

[0028] The titanium suboxide powder includes base particles containing γ-Ti 3O 5 as particles.

[0029] The base particles may be composed of primary particles and / or secondary particles. The primary particles contained in the basic particles may be in the shape of spheres, plates, needles, polygons, or irregular shapes, or may contain one or more of these shapes. Secondary particles may include aggregates formed by agglomerating a plurality of primary particles, and linked bodies formed by linking a plurality of primary particles.

[0030] The fine particles may also include particles in the titanium suboxide powder that are attached to a portion of the surface of the base particles and / or particles that are not attached to the base particles. Furthermore, one or more of the microparticles attached to a portion of the base particle's surface are present discontinuously on that portion of the base particle's surface. In other words, the microparticles are dispersed on the base particle's surface. The microparticles do not continuously cover the entire surface of the base particle. In this embodiment, the microparticles will adhere to the base particles as long as the base particles and the microparticles are in simple physical contact. The base particles and the microparticles may or may not be chemically bonded.

[0031] As for the fine particles, they can be composed of particles that do not contain any metal that can easily replace Ti. For example, SiO2, Si3N4, B4C, and MgO can be mentioned. These can be used alone or in combination of two or more. The detailed mechanism is unclear, but it is speculated that because Si, B, or Mg are metal elements that are not easy to replace Ti in Ti 3 O 5, the oxides and nitrides of Si, B, or Mg will adhere to the surface of Ti 3 O 5-containing particles during the reduction firing of TiO 2, thereby inhibiting the grain growth of the particles. In this specification, the microparticles do not contain a metal that can easily replace Ti, which means that the main raw material constituting the microparticles is not a metal that can easily replace Ti. The microparticles may also contain a metal that can easily replace Ti that is inevitably mixed into the raw materials and during the manufacturing process. Specifically, it can also be defined as the total content of metals that can easily replace Ti in the entire low-oxide titanium powder, calculated as oxides, being, for example, 3.0% by mass or less.

[0032] The lower limit of the Si content in the titanium suboxide powder is, for example, 0.04 mass % or more, preferably 0.5 mass % or more, and more preferably 0.7 mass % or more. This can further reduce the L* value of the titanium suboxide powder. On the other hand, the upper limit of the Si content is, for example, 20% by mass or less, preferably 15% by mass or less, and more preferably 8% by mass or less. This allows for a smaller particle size. When the fine particles contain B₄C, the content of the B element in the titanium suboxide powder may be, for example, 0.02 mass% to 20 mass%. When the fine particles contain MgO, the content of the Mg element in the titanium suboxide powder may be, for example, 0.01 mass% to 20 mass%. Furthermore, the content of Si, B, or Mg elements contained in the titanium suboxide powder can be measured using the above-mentioned ICP emission spectrometry.

[0033] The lower limit of the specific surface area of ​​the titanium suboxide powder obtained by the BET method is, for example, 1.0 m² / g or greater, preferably 3.0 m² / g or greater, and more preferably 5.0 m² / g or greater. This can further reduce the L* value of the titanium suboxide powder. On the other hand, the upper limit of the specific surface area of ​​the titanium suboxide powder obtained by the BET method is, for example, 30 m2 / g or less, preferably 20 m2 / g or less, and more preferably 10 m2 / g or less. This can improve the handleability of the powder.

[0034] The specific surface area can be measured using a specific surface area meter (e.g., Macsorb HM model-1201, manufactured by Mountech) by degassing at 200°C for 10 minutes using a nitrogen flow (atmospheric pressure), and by balancing the relative pressure of about 0.3 under nitrogen adsorption and using n=2.

[0035] In the volume frequency particle size distribution of titanium suboxide powder measured by laser diffraction scattering, the particle size at which the cumulative value becomes 50% is defined as d50. The upper limit of the d50 of the titanium suboxide powder is, for example, 3.0 μm or less, preferably 1.5 μm or less, and more preferably 1.0 μm or less. This can further reduce the L* value of the titanium suboxide powder. On the other hand, the lower limit of the d50 of the titanium suboxide 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.

[0036] The particle size distribution of titanium suboxide powder was determined by the following procedure. First, place 100 mg of titanium suboxide powder and 50 mL of ion-exchanged water into a polystyrene sample vial (100 mL capacity, e.g., AS ONE, PS-100) and ultrasonically disperse the powder for 60 seconds using an ultrasonic homogenizer (e.g., Branson Ultrasonics Corporation, Model: DIGITALSONIFIER450) at an output amplitude of 10%. Then, within 30 seconds of the completion of the ultrasonic dispersion, measure the volume-based particle size distribution of the dispersed titanium suboxide powder using a laser diffraction scattering particle size analyzer (e.g., Beckman Coulter, Model: LS13320) under the following measurement conditions. (Measurement conditions) Dispersant: Water Refractive index: 2.71 Measurement interval: satisfy the interval of log(d2 / d1)=0.04

[0037] The titanium suboxide powder may be configured such that the L* value in the L*a*b* color space is 15.0 or less, the a* value is 5.0 or less, and the b* value is 1.0 or less. This allows for the production of titanium suboxide powder with excellent blackness. The upper limit of the L* 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. On the other hand, the lower limit of the L* value may be, for example, 8.0 or more, 8.5 or more, or 9.0 or more. The upper limit of the a* value is, for example, 5.0 or less, preferably 2.0 or less, and more preferably 1.5 or less. On the other hand, the lower limit of the a* 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 b* 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. On the other hand, the lower limit of the b* value is, for example, -6.0 or greater, preferably -5.0 or greater, and even more preferably -4.0 or greater.

[0038] L*, a*, and b* values ​​in the L*a*b* color space can be measured using a colorimeter (e.g., the ZE-2000 (manufactured by Nippon Denshoku Industries, Ltd.)). Specifically, after performing zero point calibration using a dark field cylinder, standard alignment is performed using a standard white plate (X=91.71, Y=93.56, Z=110.52). Then, approximately 3g of titanium suboxide powder is placed in a 35φ x 15H circular container for measurement.

[0039] The titanium suboxide powder of this embodiment is preferably used as a pigment (coloring filler) such as a black pigment, but its application is not limited to this. Furthermore, the pigment (coloring filler) can be used, for example, in cosmetic raw materials, electronic components such as semiconductors, and coatings such as paints and inks.

[0040] Titanium suboxide powder can also be dispersed in a dispersant, for example. That is, the dispersion of this embodiment contains the titanium suboxide powder and a dispersant. This allows the blackness of the dispersion to be sufficiently enhanced even with a small amount of addition.

[0041] The dispersion medium can be appropriately selected according to the use of the dispersion. For example, it can be water, alcohol, ketone, ester, resin, etc. In the case of resin, for example, it can be epoxy resin, polysiloxane resin, phenolic 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.

[0042] Next, a method for manufacturing the titanium suboxide powder of the present embodiment will be described.

[0043] An example of the method for manufacturing the titanium suboxide powder includes a firing step of heating a mixture of a powder containing TiO2 as a raw material, a fine powder containing no metal that can easily displace Ti such as SiO2, and a powder of TiH2 as a reducing agent in an inert gas environment. By the firing step, TiO2 is reduced to form titanium suboxide. Also, the growth of the Ti3O5 crystal grains contained in the particles of the titanium suboxide powder can be suppressed by the fine particles containing no metal that can easily displace Ti such as SiO2.

[0044] The powder is classified, for example, into large fine powders with a particle diameter exceeding 5 μm and 100 μm or less, medium fine powders with a particle diameter exceeding 0.1 μm and 5 μm or less, and small fine powders with a particle diameter of 0.1 μm or less. The particle diameter is defined as the median diameter (let the particle diameter at which the cumulative value becomes 50% in the volume frequency particle size distribution measured by the laser diffraction scattering method be d50). The particle diameter and specific surface area of the raw material, reducing agent, etc. can be selected according to the desired particle diameter of the titanium suboxide powder. For example, the raw material and the fine powder containing no metal that can easily displace Ti can also be selected by satisfying the particle diameter of the TiO2 powder > the particle diameter of the SiO2 powder, or the specific surface area of the TiO2 powder < the specific surface area of the SiO2 powder.

[0045] As long as it is the above-mentioned fine particles containing no metal that can easily displace Ti, the use of the SiO2 powder is not limited. For example, for the fine particles, a powder containing one or more selected from the group consisting of SiO2, Si3N4, B4C, and MgO can be used.

[0046] The molar ratio of TiO2 to TiH2 contained in the mixture (TiO2 content (molar) / TiH2 content (molar)) is, for example, greater than 3.2 and less than 6.0, preferably greater than 3.5 and less than 5.5, and more preferably greater than 3.8 and less than 5.2.

[0047] The heating temperature in the firing step is, for example, 800° C. to 1200° C., preferably 900° C. to 1150° C., and more preferably 950° C. to 1100° C. For example, the firing step is carried out by placing the mixture in a known firing furnace such as an electric furnace.

[0048] The inert gas environment may include, for example, Ar or He, preferably Ar. Furthermore, the inert gas environment may be replaced with a vacuum environment. If necessary, a gaseous reducing agent may also be introduced.

[0049] The heating time in the firing step may be, for example, 1 hour or longer, 2 hours or longer, or 4 hours or longer, in order to ensure sufficient reduction reaction. It may be, for example, 24 hours or shorter, 18 hours or shorter, or 12 hours or shorter, in order to appropriately suppress the growth of the titanium suboxide powder and facilitate recovery in a powdered state.

[0050] The method for producing titanium suboxide powder of this embodiment may further include a cleaning step for cleaning the titanium suboxide powder obtained in the sintering step. The cleaning step can remove impurities in the titanium suboxide powder. Cleaning is performed, for example, using at least one selected from the group consisting of hot water, alcohol, and an organic acid. Alcohols, for example, may be methanol, ethanol, or mixtures thereof. Organic acids, for example, may be acetic acid. Cleaning with an organic acid is preferred to suppress the incorporation of ionic impurities such as halide ions into the titanium suboxide powder.

[0051] The method for producing the titanium suboxide powder of this embodiment may further include a particle size adjustment step of pulverizing / classifying the titanium suboxide powder after the sintering step, as needed. The pulverization method can include methods using various pulverizers, such as a mortar, ball mill, jet mill, and fine grinder. The pulverization step can be performed once or twice or more. When the pulverization step is performed twice or more, the pulverization method used in each pulverization step can be different. By performing the pulverization step, the chromaticity and specific surface area of ​​the titanium suboxide powder can be adjusted.

[0052] While the production method of this embodiment includes other known steps such as a washing step and a pulverizing step, the order of these steps is arbitrary. Specifically, the production method may include a sintering step, a washing step, and a pulverizing step in that order, or a sintering step, a pulverizing step, and a washing step in that order. In the former case, a drying step (drying step) may be further performed between the washing step and the pulverizing step. The drying temperature in the drying step may be, for example, 100°C or higher but 200°C or lower. The drying time may be, for example, 10 hours or higher but 20 hours or lower.

[0053] While the embodiments of the present invention have been described above, these are merely illustrative examples of the present invention, and various configurations other than those described above may be employed. Furthermore, the present invention is not limited to the embodiments described above, and modifications and improvements within the scope of achieving the objectives of the present invention are also encompassed by the present invention. [Example]

[0054] Hereinafter, the present invention will be described in detail with reference to the embodiments, but the present invention is not limited to the description of any of these embodiments.

[0055] <Production of titanium suboxide powder> [Example 1] TiO2 powder (HT0514, manufactured by Toho Titanium Co., Ltd., TiO2 purity 99.9%, average particle size of approximately 0.7 μm, specific surface area 6~7 m2 / g), TiH2 powder (TCH450, manufactured by TOHO TEC Co., Ltd., Ti purity 99.8%, average particle size ~45 μm), and SiO2 fine powder (AEROSIL NX90G, manufactured by Aerosil Co., Ltd., Japan, SiO2 purity 99.0%, specific surface area 50~80 m2 / g) were mixed using an Eirich mixer (manufactured by Eirich Co., Ltd., Japan) in a mixture of TiO2:TiH2=4:1 (molar ratio) to obtain a mixture at 0.1 wt%. The obtained mixture was transferred to an alumina crucible and heated in an electric furnace (Fuji Electric Industrial Co., Ltd., Himulti 10000) under an Ar atmosphere at a rate of 10°C / min from room temperature to 1100°C (firing temperature) for 12 hours. After heating, the obtained powder was pulverized in a mortar for 5 minutes to obtain titanium suboxide powder.

[0056] [Examples 2 to 16] Except for changing the molar ratio of TiO₂:TiH₂, the addition ratio (weight %) of the fine powder to the mixture of TiO₂ and TiH₂, the firing temperature, and the firing time to the values described in Table 1, it was carried out in the same manner as in Example 1, and low titanium oxide powder was obtained. However, in Example 16, the SiO₂ fine powder was replaced with Si₃N₄ fine powder (manufactured by H.C. Starck, α-phase:β-phase = 13:87), and Himulti10000 was replaced with Himulti5000 electric furnace.

[0057] [Comparative Examples 1-7] Low titanium oxide powder was obtained by carrying out in the same manner as in Example 1 except that no SiO₂ fine powder was added and using firing conditions other than those in Table 1.

[0058] [Table 1]

[0059] [X-ray Diffraction Measurement] Powder X-ray diffraction measurement was performed on the obtained low titanium oxide powder. Specifically, a sample horizontal multi-purpose X-ray diffractometer (manufactured by Rigaku, RINT-UltimaIV) was used, and the X-ray diffraction pattern was measured under the following measurement conditions. From the obtained X-ray diffraction pattern, it was confirmed that each low titanium oxide powder had the crystal composition shown in Table 1. From the results of the X-ray diffraction pattern, it was found that the low titanium oxide powders of Examples 1-16 contained a peak corresponding to γ-Ti₃O₅ (a peak within the range of diffraction angle 2θ of 30.0° or more and 31.0° or less), but the low titanium oxide powders of Comparative Examples 1-7 did not contain a peak corresponding to γ-Ti₃O₅. As an example, the X-ray diffraction patterns of Example 1 and Comparative Example 2 are shown in FIGS. 3 and 4, respectively. Furthermore, for the obtained X-ray diffraction pattern, the peak area of the γ(11-1) plane of γ-Ti₃O₅ within the range of diffraction angle 2θ of 30.0° or more and 31.0° or less was defined as Iγ, and the sum of the peak areas of the (110) plane of α-Ti₃O₅, the (110) plane of β-Ti₃O₅, and the (110) plane of λ-Ti₃O₅ within the range of diffraction angle 2θ of 24.5° or more and 26.0° or less was defined as Iα+Iβ+Iλ. Furthermore, the peak area ratio γ was calculated from Iγ / (Iα+Iβ+Iλ), and the peak area ratio αβλ was calculated from (Iα+Iβ+Iλ) / Iγ. Also, in Table 1, “∞” represents “a / 0 (a is any number)”. Also, for the peak area of each crystal phase, using XRD analysis software (for example, JADE manufactured by LightStone Co., Ltd.), the range of the peak area is calculated from the range of the pseudo-triangle drawn along the baseline. (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 Position of diffraction peak = 2θ (diffraction angle) Scanning speed: 4.0° (2θ) / min, continuous scanning Measurement range: 2θ = 10° to 80°

[0060] Then, the mass fraction (mass %) of each crystal composition in the obtained titanium suboxide powder is calculated using Rietveld method software (manufactured by Rigaku Corporation, integrated powder X-ray analysis software PDXL2). The crystal structure is based on the crystal structure database (Pearson's Crystal Data), using 1243140 (Journal of Applied Physics 119, 014905 (2016)) for Ti₂O₃, 1127327 (Chemistry An Asian Journal 6, 1886 (2011)) for α-Ti₃O₅, 1944823 (Journal of Solid State Chemistry 192, 356 (2012)) for β-Ti₃O₅, 1900755 (Journal of Solid State Chemistry 20, 29 (1977)) for γ-Ti₃O₅, 1127327 (Chemistry An Asian Journal 6, 1886 (2011)) for λ-Ti₃O₅. Also, in Table 1, α-Ti₃O₅ was not confirmed in each of the examples and comparative examples.

[0061] <SEM image> For the obtained titanium suboxide powder, a scanning electron microscope was used for observation to obtain SEM images. In Examples 1 to 16, a plurality of fine particles having a smaller particle size than the base particle were observed to be attached to the surface of a single base particle. On the other hand, in Comparative Examples 1 to 7, no fine particles were observed to be attached to the surface of a single base particle. For example, the SEM images of Example 1 and Comparative Example 2 are shown in FIG1 and FIG2 , respectively.

[0062] <Determination of specific surface area> The specific surface area of ​​the resulting titanium suboxide powder was measured using a Macsorb HM model-1201, manufactured by Mountech. Degassing was performed at 200°C for 10 minutes using a nitrogen flow (atmospheric pressure). Measurement conditions were nitrogen adsorption, an equilibrium relative pressure of approximately 0.3, and n = 2. The results are shown in Table 1.

[0063] <Determination of Particle Size Distribution> The particle size distribution of the obtained titanium suboxide powder was measured using the following procedure, and the measurement results of the particle size (d50) at which the cumulative value becomes 50% are shown in Table 1. First, place 100 mg of titanium suboxide powder and 50 mL of ion-exchanged water in a polystyrene sample vial (100 mL capacity, e.g., AS ONE, PS-100) and ultrasonically disperse the powder for 60 seconds using an ultrasonic homogenizer (e.g., Branson Ultrasonics Corporation, Model: DIGITALSONIFIER450) at an output amplitude of 10%. Within 30 seconds of the ultrasonic dispersion, measure the volume-based particle size distribution of the dispersed titanium suboxide powder using a laser diffraction scattering particle size analyzer (e.g., Beckman Coulter, Model LS13320) under the following measurement conditions. (Measurement conditions) Dispersant: Water Refractive index: 2.71 Measurement interval: satisfy the interval of log(d2 / d1)=0.04

[0064] <Elemental Analysis> The resulting titanium suboxide powder was analyzed using an Agilent 5110 ICP-OES (Agilent Technologies, Inc.). Specifically, 0.1 g of the powder was weighed into a platinum crucible, 1 ml of HF and 1 ml of HCl were added, and pressurized acid decomposition was performed at 150°C for 4 hours. The volume was then fixed to 6 ml, and after confirming the absence of unwanted residue, ICP emission spectrometry analysis was performed. The results are shown in Table 1.

[0065] <Chroma Measurement> The resulting titanium suboxide powder was measured for chromaticity (L*, a*, and b* values ​​in the L*a*b* color space) using a colorimeter ZE-2000 (manufactured by Nippon Denshoku Industries, Ltd.). Specifically, zero-point calibration was performed using a dark field cylinder, followed by standard alignment using a standard white plate (X=91.71, Y=93.56, Z=110.52). Approximately 3g of powder was then placed in a 35φ x 15H circular container, and the chromaticity was measured. The results are shown in Table 1.

[0066] The results show that the titanium suboxide powders in Examples 1 to 16 have lower L* values ​​in the L*a*b* color space than those in Comparative Examples 1 to 7, indicating better blackness.

[0067] The present invention claims priority based on Japanese application No. 2023-019367, filed on February 10, 2023, the disclosure of which is incorporated herein in its entirety.

[0068] none

Claims

1. A low-titanium oxide powder comprising TiOX (where X is in the range of 1.50 ≤ X ≤ 1.75), containing basic particles containing γ-Ti3O5, and configured in a manner satisfying the following conditions: In the X-ray diffraction pattern of the low-titanium oxide powder using Cu-Kα rays, the peak area of ​​the γ(11-1) plane of γ-Ti3O5 in the range of diffraction angle 2θ being 30.0° to 31.0° is Iγ; when the sum of the peak areas of the (110) plane of α-Ti3O5, the (110) plane of β-Ti3O5, and the (110) plane of λ-Ti3O5 in the range of diffraction angle 2θ being 24.5° to 26.0° is Iα + Iβ + Iλ, Iα, Iβ, Iγ, and Iλ satisfy 0.001 ≤ Iγ / (Iα + Iβ + Iλ). And it satisfies 0<(Iα+Iβ+Iλ) / Iγ≦1000.

2. The low-titanium oxide powder as claimed in claim 1, wherein, The content of γ-Ti3O5 in this low-oxidation titanium powder is more than 10% by mass out of a total of 100% by mass of Ti2O3, α-Ti3O5, β-Ti3O5, γ-Ti3O5, λ-Ti3O5 and Ti4O7.

3. The low-oxidation titanium powder as claimed in claim 1 or 2, wherein, In the L*a*b* color space, L* values ​​are below 15.0, a* values ​​are below 5.0, and b* values ​​are below 1.

0.

4. The low-oxidation titanium powder as claimed in claim 1 or 2, wherein, The specific surface area obtained by the BET method is between 1.0 m² / g and 30 m² / g.

5. The low-oxidation titanium powder as claimed in claim 1 or 2, wherein, The Si content in this low-titanium oxide powder, as determined by ICP-N PLC analysis, is between 0.04% and 20% by mass.

6. The low-oxidation titanium powder as claimed in claim 1 or 2, wherein, In the volume frequency particle size distribution of the low titanium oxide powder measured by laser diffraction scattering, when the cumulative value is 50% of the particle size as d50, d50 is 0.001μm to 3.0μm.

Images