Low-valent titanium oxide powder

Abstract

The present invention relates to a low-valent titanium oxide powder containing TiOX (in the formula, X is in the range of 1.50 < = X < = 1.75), the low-valent titanium oxide powder containing base particles containing gamma-Ti3O5 and fine particles having a smaller particle diameter than the base particles, and the fine particles are particles not containing any one of Fe, Ta, Lu, Al, Nb, Sc, Zr, Hf and W. The low-valent titanium oxide powder is a low-valent titanium oxide powder containing TiOX (in the formula, X is in the range of 1.50 < = X < = 1.75). According to the present invention, a low-valent titanium oxide powder having excellent blackness is provided.

Description

Technical Field

[0001] The invention relates to low-valent titanium oxide powder. Background Art

[0002] It is known that suboxide titanium (also referred to as reduced titanium oxide) obtained by reducing titanium dioxide (TiO 2 ) exhibits different colors depending on the ratio of titanium and oxygen as constituent elements, and that it becomes black by appropriately adjusting the ratio.

[0003] For example, Patent Document 1 describes a method of obtaining black titanium oxide powder by heating and reducing titanium dioxide (white titanium oxide) at 600°C or above in a reducing atmosphere such as hydrogen or ammonia to produce black low-valent titanium oxide, and then mechanically crushing the sintered body (paragraph 0002 of Patent Document 1, etc.).

[0004] Furthermore, paragraph 0057 of Patent Document 2 describes that titanium oxide with a higher degree of reduction (for example, Ti 3 O 5 , Ti 4 O 7 , etc.) generally has a black tone.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 11-292536

[0008] Patent Document 2: Japanese Patent Application Publication No. 2019-002993 Summary of the Invention

[0009] However, the present inventors' research results have confirmed that the black titanium oxide powder described in Patent Document 1 has room for improvement in terms of blackness.

[0010] It is known that the crystal structure of Ti 3 O 5 , one of the suboxides, undergoes phase transformation into five phases: α phase, β phase, γ phase, δ phase, and λ phase.

[0011] If TiO2 is sintered together with a reducing agent at a high temperature of about 1000°C or above, high temperature stable phases such as α phase and λ phase are formed to obtain α-Ti3O5 or λ-Ti3O5. Then, by cooling to below about 200°C or applying mechanical stimulation such as pressing or friction at room temperature, part of the α phase or λ phase is transformed into the low temperature phase of β phase, thereby obtaining β-Ti3O5. However, these Ti3O5 are unable to fully reduce L * value.

[0012] The inventors of the present invention have further studied and found that when TiO2 is sintered with a reducing agent, the grain growth of particles containing Ti3O5 is suppressed, thereby stabilizing the metastable γ phase (γ-Ti3O5), thereby making the L of the obtained low-valent titanium oxide * The value is lower.

[0013] Based on this understanding, we conducted further research and found that by adding microparticles composed of a composition that is difficult to easily replace Ti in Ti3O5 during the reduction firing of TiO2, the particle size growth of particles containing Ti3O5 can be suppressed, thereby obtaining L * The present invention has been completed by obtaining a low-order titanium oxide powder containing γ-Ti3O5 having a sufficiently low value and excellent blackness.

[0014] According to one embodiment of the present invention, the following low-order titanium oxide powder is provided.

[0015] 1. A low-valent titanium oxide powder comprising TiO X (where X is in the range of 1.50≤X≤1.75) low-valent titanium oxide powder,

[0016] The subvalent titanium oxide powder comprises:

[0017] Base particles containing γ-Ti3O5, and

[0018] Microparticles having a particle size smaller than that of the base particles,

[0019] The fine particles are particles that do not contain any of Fe, Ta, Lu, Al, Nb, Sc, Zr, Hf, and W.

[0020] 2. The suboxide titanium powder according to 1., wherein

[0021] The microparticles include one or more selected from the group consisting of SiO2, Si3N4, B4C and MgO.

[0022] 3. The suboxide titanium powder according to 1. or 2., wherein

[0023] The content of γ-Ti3O5 contained in the suboxide titanium powder is 10 mass% or more in 100 mass% of the total of Ti2O3, α-Ti3O5, β-Ti3O5, γ-Ti3O5, λ-Ti3O5 and Ti4O7.

[0024] 4. The suboxide titanium powder according to any one of 1. to 3., wherein

[0025] L * a * b *In color space, L * The value is below 15.0, a * The value is below 5.0, b * The value is below 1.0.

[0026] 5. The suboxide titanium powder according to any one of 1. to 4., wherein

[0027] The specific surface area based on the BET method is 1.0 m 2 / g or more and 30m 2 / g or less.

[0028] 6. The suboxide titanium powder according to any one of 1. to 5., wherein

[0029] The content of Si element contained in the suboxide titanium powder measured by ICP emission spectrometry is 0.04 mass % or more and 20 mass % or less.

[0030] 7. The suboxide titanium powder according to any one of 1. to 6., wherein

[0031] In the volume frequency particle size distribution of the suboxide titanium powder measured by a laser diffraction scattering method, when the particle diameter at which the cumulative value becomes 50% is defined as d50, d50 is 0.001 μm or more and 3.0 μm or less.

[0032] According to the present invention, there is provided a low-order titanium oxide powder having excellent blackness. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a SEM image of the suboxide titanium powder of Example 1.

[0034] Figure 2 This is an SEM image of the suboxide titanium powder of Comparative Example 2.

[0035] Figure 3 This is a diagram showing the X-ray diffraction pattern of the suboxide titanium powder of Example 1.

[0036] Figure 4 This is a diagram showing the X-ray diffraction pattern of the suboxide titanium powder of Comparative Example 2. DETAILED DESCRIPTION

[0037] The outline of the sub-titanium oxide powder according to this embodiment will be described.

[0038] The suboxide titanium powder of this embodiment includes TiO X(where x is in the range of 1.50 ≤ x ≤ 1.75) a powder (group of particles), wherein the suboxide titanium powder comprises base particles containing γ-Ti3O5 and fine particles having a smaller particle size than the base particles. The fine particles do not contain any of Fe, Ta, Lu, Al, Nb, Sc, Zr, Hf, and W.

[0039] As Ti-substitutable metals that easily replace Ti in Ti3O5, in other words, with a lower formation energy, Fe, Ta, Lu, Al, Nb, Sc, Zr, Hf, and W are known.

[0040] According to the inventors' findings, it has been found that by adding the above-mentioned fine particles containing no Ti easily substitutable metal during the reduction calcination of TiO2, the grain growth of particles containing Ti3O5 can be suppressed, and the metastable phase γ-Ti3O5 can be stabilized. γ-Ti3O5 has a lower L than any of α, β or λ-Ti3O5. * Therefore, it was confirmed that a low-order titanium oxide powder containing γ-Ti3O5 with excellent blackness can be obtained.

[0041] The sub-titanium oxide powder of this embodiment is applicable to various applications and can be used as a black pigment (black filler) added to a dispersion medium such as a resin. Furthermore, compared to carbon black, a common black pigment, sub-titanium oxide powder is less likely to scatter in space and therefore has excellent low dust properties.

[0042] Each component of the suboxide titanium powder of this embodiment will be described in detail.

[0043] Subvalent titanium oxide powder has TiO X Represents the composition.

[0044] TiO x X in the formula (TiO) is a value in the range of 1.50≤X≤1.75. x X in ⁻¹ is represented by, for example, a weighted average using the mass ratio of the crystal composition contained in the suboxide titanium powder as a weight.

[0045] When the titanium suboxide powder contains two or more selected from the group consisting of Ti2O3, γ-Ti3O5 and Ti4O7, TiO x Indicates their average composition.

[0046] In this specification, the mass ratio of the crystal components contained in the sub-oxide 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 sub-oxide titanium powder.

[0047] Specifically, Rietveld method software (e.g., integrated powder X-ray analysis software PDXL2 manufactured by Rigaku Corporation) was used, and regarding the crystal structure, 1243140 (Journal of Applied Physics 119, 014905 (2016)) was used as Ti2O3, 1127327 (Chemistry An Asian Journal 6, 1886 (2011)) was used as α-Ti3O5, 1944823 (Journal of Solid State Chemistry 192, 356 (2012)) was used as β-Ti3O5, 1900755 (Journal of Solid State Chemistry 20, 29 (1977)) was used as γ-Ti3O5, and 1127325 (Chemistry An Asian Journal 6, 1886 (2011)) was used as α-Ti3O5. 6,1886(2011)) as λ-Ti3O5, and the above mass ratio (%) was calculated therefrom.

[0048] The crystal composition of the suboxide titanium powder may contain at least γ-Ti 3 O 5 , and may contain two or more selected from the group consisting of Ti 2 O 3 , γ-Ti 3 O 5 , and Ti 4 O 7 .

[0049] The lower limit of the content of γ-Ti3O5 contained in the suboxide titanium powder is, for example, 10% by mass or more, preferably 20% by mass or more, and more preferably 30% by mass or more, based on 100% by mass of the total of Ti2O3, α-Ti3O5, β-Ti3O5, γ-Ti3O5, λ-Ti3O5, and Ti4O7. This can further reduce the L * value.

[0050] On the other hand, from the perspective of blackness, the upper limit of the γ-Ti3O5 content is preferably as high as possible. Therefore, without particular limitation, the content of γ-Ti3O5, α-Ti3O5, β-Ti3O5, γ-Ti3O5, λ-Ti3O5, and Ti4O7, totaling 100% by mass, may be, for example, 90% by mass or less, 85% by mass or less, or even 80% by mass or less. This allows for adjustment of chroma, resulting in a powder with optimal blackness and chroma.

[0051] The sub-valent titanium oxide powder may contain other sub-valent titanium oxides in addition to the above-mentioned Ti2O3, Ti3O5 and Ti4O7 within the range that does not impair the effects of the present invention, for example, Ti 2.5One or more of other low-valent titanium oxides such as O4, TiO, and Ti3O.

[0052] The total content of Na, K, and P contained in the suboxide titanium 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.

[0053] Furthermore, the total content of Pb, Cd, and Cr contained in the suboxide titanium 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 facilitates obtaining a desired crystal phase.

[0054] The content (in terms of mass) of the elements contained in the suboxide titanium powder can be calculated from the analysis results of the elemental composition obtained by ICP emission spectrometry using, for example, Agilent 5110 ICP-OES (manufactured by Agilent Technologies Japan, Ltd.).

[0055] The suboxide titanium powder includes base particles containing γ-Ti 3 O 5 and fine particles.

[0056] The base particles may be configured to include primary particles and / or secondary particles.

[0057] The shape of the primary particles included in the base particles may be any of spherical, plate-like, needle-like, polygonal, and irregular shapes, and may include one or more of these shapes.

[0058] The secondary particles may include aggregates formed by agglomeration of a plurality of primary particles, links formed by linking a plurality of primary particles, and the like.

[0059] The fine particles may include particles in a state of being attached to a portion of the surface of the base particles in the suboxide titanium powder and / or particles in a state of being not attached to the base particles.

[0060] Furthermore, one or more of the microparticles attached to a portion of the base particle surface are present discontinuously on that portion of the base particle surface. In other words, the microparticles are scattered on the base particle surface. The microparticles do not continuously cover the entire surface of the base particle.

[0061] In this embodiment, as long as the base particles and the fine particles are in simple physical contact, the fine particles are considered to be attached to the base particles. The base particles and the fine particles may or may not be chemically bonded.

[0062] The fine particles are composed of particles that do not contain any Ti-substitutable metals such as Fe, Ta, Lu, Al, Nb, Sc, Zr, Hf, and W. Specifically, the fine particles do not contain any single metal, metal oxide, or metal nitride of a Ti-substitutable metal.

[0063] In this specification, the microparticles do not contain Ti easily replaceable metals means that the main raw material constituting the microparticles is not Ti easily replaceable metals, and may contain Ti easily replaceable metals that are inevitably mixed into the raw materials and the manufacturing process. Specifically, it can be defined as the total content of Ti easily replaceable metals in the entire low-valent titanium oxide powder in terms of oxide conversion, for example, 3.0% by mass or less. When the total amount of Ti easily replaceable metals in terms of oxide conversion exceeds 3.0% by mass, λ-Ti3O5 may be stabilized and easily generated. As a result, the proportion of γ-Ti3O5 decreases and L * The value increases, so it may lead to an increase in blackness.

[0064] The fine particles may be composed of one or more selected from the group consisting of SiO2, Si3N4, B4C, and MgO. It is speculated that since Si, B, or Mg are metal elements that are difficult to replace Ti in Ti3O5, the oxides or nitrides of Si, B, or Mg adhere to the surface of the particles containing Ti3O5 during the reduction calcination of TiO2, thereby suppressing the grain growth of the particles.

[0065] The lower limit of the content of Si element contained in the suboxide titanium powder is, for example, 0.04 mass % or more, preferably 0.5 mass % or more, and more preferably 0.7 mass % or more. * value.

[0066] On the other hand, the upper limit of the content of the Si element is, for example, 20 mass % or less, preferably 15 mass % or less, and more preferably 8 mass % or less. This allows for a smaller particle size.

[0067] Furthermore, when the fine particles contain B4C, the content of the B element in the suboxide titanium powder can be, for example, 0.02 mass% to 20 mass%. When the fine particles contain MgO, the content of the Mg element in the suboxide titanium powder can be, for example, 0.01 mass% to 20 mass%.

[0068] The content of Si, B, or Mg elements contained in the suboxide titanium powder can be measured by the above-mentioned ICP emission spectrometry analysis.

[0069] The lower limit of the specific surface area of ​​the suboxide titanium powder by the BET method is, for example, 1.0 m 2 / g or more, preferably 3.0m2 / g or more, more preferably 5.0m 2 / g or more. This can further reduce the L * value.

[0070] On the other hand, the upper limit of the specific surface area of ​​the suboxide titanium powder by the BET method is, for example, 30 m 2 / g or less, preferably 20m 2 / g or less, more preferably 10m 2 This can improve the handling properties of the powder.

[0071] 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 under a nitrogen flow (atmospheric pressure) and adsorbing nitrogen at an equilibrium relative pressure of about 0.3 under the condition of n=2.

[0072] In the volume frequency particle size distribution of the suboxide titanium powder measured by a laser diffraction scattering method, the particle diameter at which the cumulative value becomes 50% is defined as d50.

[0073] The upper limit of d50 of the sub-oxide titanium powder is, for example, 3.0 μm or less, preferably 1.5 μm or less, and more preferably 1.0 μm or less. * value.

[0074] On the other hand, the lower limit of d50 of the suboxide titanium powder is, for example, 0.001 μm or more, preferably 0.01 μm or more, and more preferably 0.23 μm or more. This can improve the coloring power when mixed with a medium.

[0075] The particle size distribution of the suboxide titanium powder was measured according to the following procedure.

[0076] First, 100 mg of sub-titanium oxide powder and 50 mL of ion-exchanged water are placed in a polystyrene sample vial (capacity: 100 mL (e.g., AS ONE Corporation, PS-100)). Ultrasonic dispersion is performed for 60 seconds using an ultrasonic homogenizer (e.g., Branson Ultrasonics Corporation, model: DIGITALSONIFIE ER450) at an output amplitude of 10%. Then, within 30 seconds after the completion of the ultrasonic dispersion, the volume-based particle size distribution of the dispersed sub-titanium oxide powder is measured using a particle size distribution analyzer using a laser diffraction scattering method (e.g., Beckman Coulter, model: LS13320) under the following measurement conditions.

[0077] [Measurement conditions]

[0078] Dispersion medium: water

[0079] Refractive index: 2.71

[0080] Measurement interval: log(d2 / d1)=0.04

[0081] Subvalent titanium oxide powder can be composed of L * a * b * L in color space * The value is below 15.0, a * The value is below 5.0, b * The value is 1.0 or less. Thus, a low-order titanium oxide powder having excellent blackness can be obtained.

[0082] The above L * 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 further preferably 11.2 or less. * The lower limit of the value may be, for example, 8.0 or more, 8.5 or more, or 9.0 or more.

[0083] Furthermore, the above a * 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.

[0084] Furthermore, the above b * 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 further 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.

[0085] L * a * b * L in color space * value, a * Value and b *The values ​​were measured using a colorimeter (e.g., ZE-2000 (manufactured by Nippondenshoku Industries Co., Ltd.)). More specifically, after zero-point calibration using a dark-field cylinder, standard calibration was performed using a standard white plate (X = 91.71, Y = 93.56, Z = 110.52). Next, approximately 3 g of subatomic titanium oxide powder was placed in a 35φ x 15H circular sample cell and measured.

[0086] The low-order titanium oxide powder of this embodiment can be preferably used as a pigment (coloring filler) such as a black pigment, but is not limited to this application. Pigments (coloring fillers) are used, for example, in cosmetics, electronic parts such as semiconductors, and coatings such as paints and inks.

[0087] The subvalent titanium oxide powder can be dispersed in a dispersion medium for use. That is, the dispersion of this embodiment contains the subvalent titanium oxide powder and a dispersion medium. Thus, even a small amount of addition can sufficiently improve the blackness of the dispersion.

[0088] The dispersion medium can be appropriately selected depending on the application of the dispersion, and may be, for example, water, alcohol, ketone, ester, resin, etc. Examples of the resin include epoxy resin, silicone resin, phenolic resin, melamine resin, urea-formaldehyde resin, unsaturated polyester, fluororesin, polyimide, polyamide-imide, 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, and AES (acrylonitrile-ethylene-propylene-diene rubber-styrene) resin.

[0089] Next, the method for producing the subatomic titanium oxide powder according to this embodiment will be described.

[0090] An example of a method for producing suboxide titanium powder includes a calcination step in which a mixture containing TiO2 powder as a raw material and fine powder of a metal that does not easily replace Ti, such as SiO2, and TiH2 powder as a reducing agent is heated in an inert gas atmosphere.

[0091] The calcination process reduces TiO2 to form suboxide titanium. Furthermore, the SiO2 particles, which do not contain a Ti-substitutable metal, can suppress the growth of Ti3O5 contained in the particles of the suboxide titanium powder.

[0092] Powders are classified into, for example, large fine powders with a particle size of greater than 5 μm and less than 100 μm, medium fine powders with a particle size of greater than 0.1 μm and less than 5 μm, and small fine powders with a particle size of less than 0.1 μm. The particle size is defined as the median particle size (d50 is the particle size at which the cumulative value reaches 50% in the volume frequency particle size distribution measured by laser diffraction scattering).

[0093] The particle size and specific surface area of ​​the raw material, reducing agent, etc. can be selected based on the desired particle size of the suboxide titanium powder. For example, the raw material and the fine powder containing no Ti-substitutable metal can be selected so that the particle size of the TiO2 powder is greater than the particle size of the SiO2 powder or the specific surface area of ​​the TiO2 powder is less than the specific surface area of ​​the SiO2 powder.

[0094] As long as the particles do not contain Ti-substitutable metals, the powder that can be used is not limited to SiO 2. For example, powders containing one or more selected from the group consisting of SiO 2, Si 3 N 4, B 4 C, and MgO can be used as such particles.

[0095] The molar ratio of TiO2 to TiH2 contained in the mixture (TiO2 content (mole) / TiH2 content (mole)) 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.

[0096] The heating temperature in the calcining 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 calcining step is performed by placing the mixture in a known calcining furnace such as an electric furnace.

[0097] The inert gas atmosphere may contain, for example, Ar gas or He gas, preferably Ar gas. Alternatively, a vacuum atmosphere may be used instead of an inert gas atmosphere. A gaseous reducing agent may be introduced as needed.

[0098] From the perspective of fully carrying out the reduction reaction, the heating time in the calcination process can be, for example, more than 1 hour, more than 2 hours, or more than 4 hours. From the perspective of moderately suppressing the growth of low-order titanium oxide powder and facilitating recovery in a powder state, the heating time can be, for example, less than 24 hours, less than 18 hours, or less than 12 hours.

[0099] The method for producing the subatomic titanium oxide powder of this embodiment may further include a washing step of washing the subatomic titanium oxide powder obtained in the calcining step. The washing step can remove impurities in the subatomic titanium oxide powder.

[0100] Washing is performed, for example, with at least one selected from the group consisting of hot water, alcohol, and an organic acid. Examples of the alcohol include methanol, ethanol, or a mixture thereof. Examples of the organic acid include acetic acid. Washing with an organic acid is preferred from the perspective of suppressing the incorporation of ionic impurities such as halide ions into the suboxide titanium powder.

[0101] The method for producing the suboxide titanium powder of the present embodiment may further include a particle size adjustment step after the calcination step, if necessary. In this particle size adjustment step, the suboxide titanium powder is pulverized and classified.

[0102] The pulverization method includes 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 suboxide titanium powder can be adjusted.

[0103] When the manufacturing method of the present embodiment has other well-known processes such as a cleaning process and a crushing process, the order of these processes is arbitrary. That is, the manufacturing method may have a sintering process, a cleaning process and a crushing process in sequence, or may have a sintering process, a crushing process and a cleaning process in sequence. In the former case, a process (drying process) for drying the low-valent titanium oxide powder may be further implemented between the cleaning process and the crushing process. The drying temperature in the drying process may be, for example, above 100°C or below 200°C. The drying time may be, for example, above 10 hours or below 20 hours.

[0104] The embodiments of the present invention are described above, but these are examples of the present invention, and various configurations other than the above can be adopted. Furthermore, the present invention is not limited to the above embodiments, and modifications and improvements within the scope of achieving the purpose of the present invention are included in the present invention.

[0105] Example

[0106] Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited at all to the descriptions of these Examples.

[0107] Production of low-cost titanium oxide powder

[0108] [Example 1]

[0109] TiO2 powder (product of Toho Titanium Co., Ltd., HT0514, TiO2 purity 99.9%, average particle size about 0.7 μm, specific surface area 6-7 m 2 / g), TiH2 powder (TOHO TECHNICAL SERVICE CO., LTD. product, TCH450, Ti purity 99.8%, average particle size ~45μm), SiO2 fine powder (Evonik Industries AG, AEROSIL NX90G, SiO2 purity 99.0%, specific surface area 50~80m 2 / g), and was mixed with a mixture of TiO2:TiH2=4:1 (molar ratio) using an Eirich mixer (manufactured by Nippon Eirich Co., Ltd.) to give 0.1 wt% to obtain a mixture.

[0110] The obtained mixture was transferred to an alumina crucible and heated in an electric furnace (Fujidempa Kogyo Co., Ltd., Himulti 10000) under Ar atmosphere at a temperature of 10°C / min from room temperature to 1100°C (sintering temperature) for 12 hours.

[0111] After heating, the obtained powder was pulverized in a mortar for 5 minutes to obtain a suboxide titanium powder.

[0112] [Examples 2 to 16]

[0113] Sub-titanium oxide powder was obtained in the same manner as in Example 1 except that the molar ratio of TiO2:TiH2, the proportion of fine powder added to the mixture of TiO2 and TiH2 (weight %), the calcination temperature and the calcination time were changed to the values ​​shown in Table 1.

[0114] In Example 16, Si 3 N 4 fine powder (manufactured by HC Starck, α phase:β phase=13:87) was used instead of SiO 2 fine powder, and Himulti 5000 was used as the electric furnace instead of Himulti 10000.

[0115] [Comparative Examples 1 to 7]

[0116] Suboxide titanium powder was obtained in the same manner as in Example 1 except that SiO2 fine powder was not added and the calcination conditions in Table 1 were adopted.

[0117] [Comparative Examples 8-9]

[0118] Instead of SiO2 fine powder, Al2O3 fine powder (manufactured by Denka Company Limited, product name: ASFP-20, Al2O3 purity 99.9%, specific surface area 10.8m 2 / g, average particle size 0.3 μm) and the calcination conditions in Table 1 were used. Suboxide titanium powder was obtained in the same manner as in Example 1.

[0119] [Table 1]

[0120]

[0121] <X-ray diffraction measurement>

[0122] The obtained sub-titanium oxide powder was subjected to powder X-ray diffraction measurement. Specifically, an X-ray diffraction pattern was measured under the following measurement conditions using a sample-horizontal multi-purpose X-ray diffractometer (RINT-Ultima IV manufactured by Rigaku Corporation).

[0123] The obtained X-ray diffraction patterns confirmed that each subatomic titanium oxide powder had the crystal composition shown in Table 1. The X-ray diffraction pattern results show that the subatomic titanium oxide powders of Examples 1 to 16 contained a peak corresponding to γ-Ti3O5 (a peak with a diffraction angle 2θ in the range of 30.0° to 31.0°), but the subatomic titanium oxide powders of Comparative Examples 1 to 9 did not contain a peak corresponding to γ-Ti3O5.

[0124] As an example, the X-ray diffraction patterns of Example 1 and Comparative Example 2 are shown in FIG. Figure 3 、 Figure 4 .

[0125] [Measurement conditions]

[0126] X-ray source: Cu-Kα ray

[0127] Tube voltage: 40kV, tube current: 40mA

[0128] Optical conditions during measurement: Divergence slit = 2 / 3°

[0129] Scattering slit: 8mm

[0130] Light receiving slit = 0.15mm

[0131] The position of the diffraction peak = 2θ (diffraction angle)

[0132] Scanning speed: 4.0°(2θ) / min, continuous scanning

[0133] Measuring range: 2θ = 10° to 80°

[0134] Next, the mass fraction (mass %) of each crystal component in the obtained suboxide titanium powder was calculated using Rietveld method software (manufactured by Rigaku Corporation, integrated powder X-ray analysis software PDXL2). Regarding the crystal structure, 1243140 (Journal of Applied Physics 119, 014905 (2016)) was used as Ti2O3, 1127327 (Chemistry An Asian Journal 6, 1886 (2011)) was used as α-Ti3O5, 1944823 (Journal of Solid State Chemistry 192, 356 (2012)) was used as β-Ti3O5, 1900755 (Journal of Solid State Chemistry 20, 29 (1977)) was used as γ-Ti3O5, and 1127325 (Chemistry An Asian Journal 6, 1886 (2011)) was used as λ-Ti3O5 from the crystal structure database (Pearson's Crystal Database).

[0135] In addition, in Table 1, α-Ti 3 O 5 was not confirmed in each of the Examples and Comparative Examples.

[0136] SEM image

[0137] The obtained suboxide titanium powder was observed using a scanning electron microscope to obtain a SEM image.

[0138] In Examples 1 to 16, fine particles having a particle size smaller than that of the base particles were confirmed.

[0139] As an example, the SEM images of Example 1 and Comparative Example 2 are shown in FIG. Figure 1 、 Figure 2 .

[0140] <Measurement of specific surface area>

[0141] The specific surface area of ​​the resulting sub-titanium oxide powder was measured using a specific surface area meter (Macsorb HM model-1201, manufactured by Mountech). Degassing was performed at 200°C for 10 minutes under a nitrogen flow (atmospheric pressure). The measurement conditions were set to achieve an equilibrium relative pressure of approximately 0.3 and n = 2 through nitrogen adsorption. The results are shown in Table 1.

[0142] <Measurement of particle size distribution>

[0143] The particle size distribution of the obtained suboxide titanium powder was measured according to the following procedure, and the measurement results of the particle size (d50) at which the cumulative value becomes 50% are shown in Table 1.

[0144] First, 100 mg of sub-titanium oxide powder and 50 mL of ion-exchanged water were placed in a polystyrene sample vial (capacity: 100 mL (e.g., AS ONE Corporation, PS-100)). Ultrasonic dispersion was performed for 60 seconds using an ultrasonic homogenizer (e.g., Branson Ultrasonics Corporation, Model: DIGITALSONIFIE ER450) at an output amplitude of 10%. Within 30 seconds after the completion of the ultrasonic dispersion, the volume-based particle size distribution of the dispersed sub-titanium oxide powder was measured using a particle size distribution analyzer using a laser diffraction scattering method (e.g., Beckman Coulter, Model: LS13320) under the following measurement conditions.

[0145] [Measurement conditions]

[0146] Dispersion medium: water

[0147] Refractive index: 2.71

[0148] Measurement interval: log(d2 / d1)=0.04

[0149] Elemental Analysis

[0150] The resulting sub-titanium oxide powder was subjected to elemental analysis using an Agilent 5110 ICP-OES (manufactured by Agilent Technologies Japan, Ltd.). Specifically, 0.1 g of the powder was weighed into a platinum crucible, and 1 ml of each of HF and HCl was added. Pressure acid decomposition was performed at 150°C for 4 hours. The volume was then adjusted to 6 ml, and after confirming the absence of unnecessary residue, ICP emission spectroscopy analysis was performed. The results are shown in Table 1.

[0151] In Table 1, the total amount of Ti-substitutable metals represents the total amount (mass %) of Fe, Ta, Lu, Al, Nb, Sc, Zr, Hf, and W in terms of metal oxides.

[0152] <Measurement of chromaticity>

[0153] The chromaticity (L * a *b * L in color space * value, a * Value and b * More specifically, after performing zero-point calibration using a dark-field cylinder, standard calibration was performed using a standard white plate (X = 91.71, Y = 93.56, Z = 110.52). Next, approximately 3 g of powder was placed in a 35φ × 15H circular sample cell, and the chromaticity was measured. The results are shown in Table 1.

[0154] Compared with the low-order titanium oxide powders in Examples 1 to 16 and Comparative Examples 1 to 9, L * a * b * L in color space * The value is low, thus showing excellent blackness.

[0155] This application claims priority based on Japanese patent application No. 2023-019373, filed on February 10, 2023, and all the disclosures thereof are incorporated herein by reference.

Claims

1. A low-valent titanium oxide powder comprising TiO X Wherein X is a low-valent titanium oxide powder in the range of 1.50≤X≤1.75, The subvalent titanium oxide powder comprises: Base particles containing γ-Ti3O5, and Microparticles having a particle size smaller than that of the base particles, The fine particles are particles that do not contain any of Fe, Ta, Lu, Al, Nb, Sc, Zr, Hf, and W.

2. The suboxide titanium powder according to claim 1, wherein The microparticles include one or more selected from the group consisting of SiO2, Si3N4, B4C and MgO.

3. The suboxide titanium powder according to claim 1 or 2, wherein The content of γ-Ti3O5 contained in the suboxide titanium powder is 10 mass% or more in 100 mass% of the total of Ti2O3, γα-Ti3O5, β-Ti3O5, γ-Ti3O5, λ-Ti3O5 and Ti4O7.

4. The suboxide titanium powder according to claim 1 or 2, wherein L * a * b * In color space, L * The value is below 15.0, a * The value is below 5.0, b * The value is below 1.

0.

5. The suboxide titanium powder according to claim 1 or 2, wherein The specific surface area based on the BET method is 1.0 m 2 / g or above and 30m 2 / g or less.

6. The suboxide titanium powder according to claim 1 or 2, wherein The content of Si element contained in the suboxide titanium powder measured by ICP emission spectrometry is 0.04 mass % or more and 20 mass % or less.

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

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