Niobate particles, method for producing same, resin composition, and molded body

Abstract

Provided is a method for producing niobate particles at exceptional productivity. Also provided are niobate particles having high crystallinity, the niobate particles being produced by means of the aforementioned production method. The present invention provides niobate particles containing a niobate crystal structure represented by KxNa(1−x)NbO3 (where 0≤x≤1), the crystal structure having an average crystallite size of 80 nm or greater as derived from the 2θ=23.0±1.0° peak of the niobate obtained by means of X-ray diffraction measurement. The crystal structure preferably includes a perovskite crystal structure.

Description

Niobate particles, method for producing the same, resin composition, and molded body

[0001] The present invention relates to niobate particles, a method for producing niobate particles, a resin composition, and a molded article.

[0002] Alkali metal niobates are widely used as piezoelectric materials, fillers, catalysts, water purification materials, and the like.

[0003] Among them, K ｘ Na １－ｘ NbO ３ The alkali metal niobate represented by (0≦x≦1) has a perovskite crystal structure and is therefore used as a piezoelectric ceramic. In addition, the alkali metal niobate is mixed with a resin and used to develop a piezoelectric composite.

[0004] In order to increase the versatility of alkali metal niobates, it is very important to control the crystal growth of the alkali metal niobates. For example, as piezoelectric materials, it is expected that the larger the crystallite size, the better the piezoelectric effect that can be exhibited.

[0005] Patent Document 1 discloses alkali niobate compound particles as a filler for piezoelectric materials having excellent piezoelectric properties, in which the ratio of the number of moles of potassium to the total number of moles of sodium and potassium (K / (Na+K)) is 0.460 to 0.495 in atomic terms, and the ratio of the total number of moles of alkali metal elements to the number of moles of niobium ((Li+Na+K) / Nb) is 0.995 to 1.005 in atomic terms. The particles are obtained by a manufacturing method involving a multi-stage firing process in which a step of dry mixing and firing is repeated twice so that the molar ratio of Nb to alkali metal elements falls within a specific range.

[0006] Non-Patent Document 1 describes a lead-free (K ０．５０ Na ０．５０ ) ０．９４ Li ０．０６ NbO ３ A new two-step calcination method is disclosed by which the particles can be synthesized.

[0007] JP 2018-198299 A

[0008] Nijesh K. James, et. al. J. Am. Ceram. Soc. , 99

[12] , 3957-3963.

[0009] Conventional methods for producing niobate particles require multi-stage mixing and firing steps, and there is still room for improvement in terms of productivity.

[0010] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for producing niobate particles with excellent productivity, and to provide niobate particles with high crystallinity by the production method.

[0011] The present invention has the following aspects.

[0012] (1) K ｘ Na （１－ｘ） NbO ３ (where 0≦x≦1), wherein the crystal structure has an average crystallite size of 80 nm or more, determined from a peak at 2θ=23.0±1.0° of the niobate obtained by X-ray diffraction measurement.

[0013] (2) The niobate particles according to (1) above, wherein the crystal structure includes a perovskite crystal structure.

[0014] (3) Niobate particles according to (1) or (2) above, which have a cubic shape.

[0015] (4) The niobate particles according to any one of (1) to (3) above, wherein the crystal structure has an average crystallite size of 50 nm or more, determined from a peak at 2θ=32.0±1.2° of the niobate obtained by X-ray diffraction measurement.

[0016] (5) Median diameter D calculated by laser diffraction / scattering method ５０ The niobate particles according to any one of (1) to (4) above, wherein the particle size is 0.1 to 100 μm.

[0017] (6) The total niobium content of the niobate particles is determined by XRF analysis of the niobate particles, and is expressed as Nb with respect to 100% by mass of the total mass of the niobate particles. ２ O ５ The niobate particles according to any one of (1) to (5) above, wherein the content in terms of niobate is 50 to 99 mass %.

[0018] (7) The potassium and / or sodium content in the niobate particles is determined by XRF analysis of the niobate particles, and is expressed as K relative to 100% by mass of the total mass of the niobate particles. ２ O equivalent and Na ２ The niobate particles according to any one of (1) to (6) above, wherein the content in terms of O is 0.5 to 40 mass %.

[0019] (8) Niobate particles according to any one of (1) to (7) above, which contain molybdenum.

[0020] (9) The molybdenum content in the niobate particles is determined by XRF analysis of the niobate particles, and is expressed as MoO relative to 100% by mass of the total mass of the niobate particles. ３ The niobate particles according to (8) above, having a content of 0.01 to 20 mass% in terms of converted niobate.

[0021] (10) A method for producing niobate particles according to any one of (1) to (9) above, comprising calcining a niobium compound in the presence of a molybdenum compound and a potassium compound and / or a sodium compound.

[0022] (11) The method for producing molybdate particles according to (10) above, wherein the molybdenum compound is at least one compound selected from the group consisting of molybdenum trioxide, potassium molybdate, and sodium molybdate.

[0023] (12) A method for producing a niobium-based composite oxide, comprising: a step of mixing a niobium compound, a molybdenum compound, and a potassium compound and / or a sodium compound to prepare a mixture; and a step of firing the mixture, wherein the niobium compound (Nb １ ) relative to the mass of the flux component sodium compound (Na１ ), potassium compounds (K １ ), molybdenum compounds (Mo １ ) total mass ratio (Nb １ ) / (Na １ +K １ +Mo １ ) is 0.6 or more.

[0024] (13) A method for producing niobate particles according to any one of (10) to (12) above, comprising the steps of mixing a niobium compound, a molybdenum compound, and a potassium compound and / or a sodium compound to form a mixture, and firing the mixture, wherein the molar ratio of potassium atoms to sodium atoms to molybdenum atoms to niobium atoms in the mixture satisfies (K+Na) / (2×Mo+Nb)>1.

[0025] (14) A resin composition comprising the niobate particles according to any one of (1) to (9) above and a resin.

[0026] (15) A molded article obtained by molding the resin composition according to (14) above.

[0027] According to the present invention, a method for producing niobate particles with excellent productivity can be provided. In addition, according to the present invention, it is possible to provide niobate particles with high crystallinity and excellent piezoelectric performance, a resin composition containing the niobate particles, and a molded product thereof.

[0028] K in Example 1 ｘ Na （１－ｘ） NbO ３ 1 is an SEM image of particles. ｘ Na （１－ｘ） NbO ３ 1 is a SEM image of particles of Example 1. ｘ Na （１－ｘ） NbO ３ 1 is an X-ray diffraction (XRD) pattern of the particles.

[0029] Hereinafter, embodiments of the niobate particles, the method for producing the niobate particles, the resin composition, and the molded article of the present invention will be described.

[0030] <Niobate particles> K ｘ Na（１－ｘ） NbO ３ (where 0≦x≦1), and the crystal structure has an average crystallite size of 80 nm or more, determined from the peak of the niobate at 2θ=23.0±1.0° obtained by X-ray diffraction measurement.

[0031] The niobate particles of the embodiment include K ｘ Na （１－ｘ） NbO ３ The niobate compound represented by the formula K ｘ Na （１－ｘ） NbO ３ In this case, x is 0≦x≦1. If x is 0<x<1, then K ｘ Na （１－ｘ） NbO ３ is potassium sodium niobate (K ｘ Na （１－ｘ） NbO ３ ) If x is 0, then K ｘ Na （１－ｘ） NbO ３ is sodium niobate (NaNbO ３ ) If x is 1, then K ｘ Na （１－ｘ） NbO ３ is potassium niobate (KNbO ３ )

[0032] It is known that piezoelectric materials have desirable properties when they contain a composition called the morphotropic phase boundary (MPB), which is the boundary between different crystal systems (monoclinic and orthorhombic, or orthorhombic and tetragonal, etc.). The value of x can be adjusted to obtain a composition near this phase boundary. ｘ Na （１－ｘ） NbO ３ In this formula, x is preferably 0.4≦x≦0.6, and more preferably 0.45≦x≦0.55. To improve characteristics other than piezoelectric performance, such as durability, the MPB composition may include compositions other than the MPB composition itself. Therefore, the composition of the niobate particles of the embodiment is not limited to this preferred range, and is effective throughout the entire range of 0≦x≦1.

[0033] Furthermore, for the purpose of suppressing leakage current and maintaining insulation properties, elements with a lower valence than Nb, such as Mn, Cr, Co, Ni, and Zn, may be appropriately contained within a range of several mole percent (1 to 3 moles) relative to Nb. Furthermore, elements such as Fe may be contained as inevitable impurities of the raw materials.

[0034] In this specification, the value of x is K in any of the above cases. ｘ Na （１－ｘ） NbO ３ In some cases, particles containing x may be simply referred to as "niobate particles." In addition, the numerical range of x may be omitted.

[0035] The type, composition, and crystal structure of the niobate contained in the niobate particles of the embodiment can be identified by the XRD pattern of the spectrum obtained by XRD analysis.

[0036] The average crystallite size of the crystal structure contained in the niobate particles of the embodiment can be determined by the following measurement method.

[0037] [Measurement of Crystallite Size] Measurement is performed using an X-ray diffractometer (e.g., SmartLab, manufactured by Rigaku Corporation) and analysis software. The measurement method is the 2θ / θ method, and the average crystallite size is calculated using the Scherrer equation from the half-width of the target peak (a peak having a peak top within the target 2θ range).

[0038] The average crystallite size of the crystal structure contained in the niobate particles of the embodiment, as determined from the peak at 2θ=23.0±1.0°, is 80 nm or more, preferably 90 nm or more, and more preferably 100 nm or more. When the average crystallite size of the niobate particles is equal to or greater than the above lower limit, excellent piezoelectric performance is exhibited when the niobate particles are formed into a molded product, as described below.

[0039] The upper limit of the average crystallite size of the crystal structure contained in the niobate particles of the embodiment, calculated from the peak at 2θ=23.0±1.0°, is not particularly limited, but may be 1000 nm or less, 800 nm or less, or 500 nm or less.

[0040] K ｘ Na（１－ｘ） NbO ３ Depending on the composition, it may exhibit a crystal system different from monoclinic, orthorhombic, or tetragonal, and the assignment of planes varies depending on the crystal system. Unless otherwise specified in this specification, the notation of plane indices indicates the case where the crystal structure is assumed to be a cubic system.

[0041] When the target peak obtained by the above crystallite size measurement is assigned assuming a cubic crystal system without considering peak splitting, the peak at 2θ = 23.0 ± 1.0° corresponds to the (100) plane of the cubic crystal system. When the peak is split, the crystallite size is defined by the peak with the strongest intensity.

[0042] The average crystallite size of the crystal structure contained in the niobate particles of the embodiment, as determined from the peak at 2θ=32.0±1.2°, is preferably 50 nm or more, more preferably 80 nm or more, and even more preferably 100 nm or more. When the average crystallite size of the niobate particles is equal to or greater than the lower limit, even better piezoelectric performance is exhibited.

[0043] The upper limit of the average crystallite size of the crystal structure contained in the niobate particles of the embodiment, calculated from the peak at 2θ=32.0±1.2°, is not particularly limited, but may be 1000 nm or less, 800 nm or less, or 700 nm or less.

[0044] An example of the above-mentioned numerical range of the average crystallite size of the crystal structure contained in the niobate particles of the embodiment, calculated from the peak at 2θ=32.0±1.2°, may be 50 nm or more and 1000 nm or less, 80 nm or more and 800 nm or less, or 100 nm or more and 700 nm or less.

[0045] When the target peak obtained by the above crystallite size measurement is assigned assuming a cubic crystal system without considering peak splitting, the peak at 2θ = 32.0 ± 1.2 ° corresponds to the (110) plane of the cubic crystal system. If the peak is split, the crystallite size is defined by the peak with the strongest intensity.

[0046] The average crystallite size of the crystal structure contained in the niobate particles of the embodiment, as determined from the peak at 2θ=57.0±1.0°, is preferably 55 nm or more, more preferably 60 nm or more, and even more preferably 65 nm or more. When the average crystallite size of the niobate particles is equal to or greater than the lower limit, even better piezoelectric performance is exhibited.

[0047] The upper limit of the average crystallite size determined from the peak at 2θ = 57.0 ± 1.0 ° of the crystal structure contained in the niobate particles of the embodiment is not particularly limited, but may be 500 nm or less, 400 nm or less, or 300 nm or less. An example of the numerical range of the average crystallite size determined from the peak at 2θ = 57.0 ± 1.0 ° of the crystal structure contained in the niobate particles of the embodiment may be 55 nm or more and 500 nm or less, 60 nm or more and 400 nm or less, or 65 nm or more and 300 nm or less.

[0048] When the target peak obtained by the above crystallite size measurement is assigned assuming a cubic crystal system without considering peak splitting, the peak at 2θ = 57.0 ± 1.0 ° corresponds to the (211) plane of the cubic crystal system. When the target peak is split, the crystallite size is defined by the peak with the strongest intensity.

[0049] According to the manufacturing method of the embodiment described below, the crystal growth of the manufactured niobate particles can be well controlled, and niobate particles with an improved average crystallite size can be easily obtained.

[0050] The average crystallite size can be controlled by the amount and type of flux agent used and the firing conditions in the production method described below.

[0051] The crystalline structure of the niobate particles of embodiments may include a perovskite crystalline structure.

[0052] Niobate particles of embodiments can have a cubic shape.

[0053] In this specification, the term "cubic" refers to a shape derived from a perovskite structure, and preferably has a substantially cubic hexahedral shape, and each face constituting the hexahedron may be flat or may be curved or uneven.

[0054] According to the manufacturing method of the embodiment described below, it is possible to manufacture niobate particles having a perovskite crystal structure and a cubic shape.

[0055] As the firing temperature increases, the average crystallite size and particle size of the niobate particles tend to increase.

[0056] When the niobate particles have a cubic shape, the particle size is preferably 0.1 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more. When the niobate particles have a cubic shape, the upper limit of the particle size is not particularly limited, but may be, for example, 100 μm or less, 80 μm or less, or 50 μm or less. When the niobate particles have a cubic shape, the upper limit of the particle size may be, for example, 0.1 to 100 μm, 0.5 to 80 μm, or 1 to 50 μm.

[0057] In this specification, the "particle size" of a cubic-shaped niobate particle is the length of one side of a hexahedron determined from a particle image of a primary particle of the niobate particle in a two-dimensional image taken with a scanning electron microscope (SEM). The value of the particle size of the cubic-shaped niobate particle is the average value obtained from 50 or more niobate particles randomly selected from the idiomorphic particles to be measured.

[0058] When niobate particles having a cubic shape are contained, it is preferable that 50% or more of the particles have a cubic shape by mass or number, more preferably 80% or more of the particles have a cubic shape, and even more preferably 90% or more of the particles have a cubic shape.

[0059] The median diameter D of the niobate particles of the embodiment calculated by a laser diffraction / scattering method ５０ may be 0.1 to 100 μm, may be 0.5 to 80 μm, or may be 1 to 50 μm.

[0060] D calculated by laser diffraction / scattering method of the niobate particles of the embodiment １０ may be 0.05 to 70 μm, may be 0.1 to 50 μm, or may be 0.5 to 20 μm.

[0061] The median diameter D of the niobate particles of the embodiment calculated by a laser diffraction / scattering method ９０ may be 0.5 to 150 μm, may be 1 to 100 μm, or may be 3 to 70 μm.

[0062] The median diameter D of the niobate particle sample calculated by the laser diffraction / scattering method ５０ can be determined as the particle size at which the volume cumulative percentage is 50% in the particle size distribution measured in a dry state using a laser diffraction particle size distribution analyzer. １０ can be calculated as the particle diameter at the point where the volume cumulative % distribution curve intersects with the horizontal axis at 10% from the small particle side, and D ９０ can be determined as the particle diameter at the point where the volume cumulative % distribution curve intersects with the horizontal axis representing 90% from the small particle side.

[0063] The niobate particles of the embodiment have a specific surface area of ​​0.02 to 20 m as determined by the BET method. ２ / g, and 0.04 to 10 m ２ / g, and 0.05 to 3m ２ / g.

[0064] The specific surface area is measured using a specific surface area meter (for example, BELSORP-mini manufactured by Microtrac-Bell Co., Ltd.), and the surface area per 1 g of sample measured from the amount of nitrogen gas adsorbed by the BET method (Brunauer-Emmett-Teller method) is defined as the specific surface area (m ２ / g).

[0065] The niobate particles of the embodiment include K ｘ Na （１－ｘ） NbO ３ (where 0≦x≦1).

[0066] The niobate particles of the embodiment contain the K with respect to 100 mass% of the niobate particles. ｘ Na （１－ｘ） NbO ３ It is preferable that the content is 65% by mass or more, preferably 65 to 99.999% by mass, more preferably 70 to 99.97% by mass, and even more preferably 75 to 99.95% by mass.

[0067] Generally, since the niobate particles obtained after firing are a mixture with flux (e.g., potassium sodium molybdate, sodium oxide or potassium oxide, sodium carbonate or potassium carbonate), it is preferable to wash them to increase their purity. However, according to the production method described below, niobate particles within the above range can be obtained without any special washing step.

[0068] The niobium content of the niobate particles is determined by XRF analysis of the niobate particles, and is expressed as Nb % relative to 100% by mass of the total mass of the niobate particles. ２ O ５ Conversion and Ta ２ O ５ The total content in terms of the total amount of the components may be 50% by mass or more, may be 50 to 99% by mass, may be 60 to 98% by mass, or may be 70 to 95% by mass.

[0069] Nb ２ O ５ The content in terms of Nb is calculated by converting the niobium content determined by XRF analysis into Nb ２ O ５ Nb converted using the calibration curve ２ O ５ It refers to a value calculated from a quantity.

[0070] Niobate particles in embodiments include potassium and / or sodium.

[0071] The potassium and / or sodium content in the niobate particles is determined by XRF analysis of the niobate particles, and is expressed as K based on 100% by mass of the total mass of the niobate particles. ２ O equivalent and Na ２ The total content calculated as O may be 0.5% by mass or more, may be 0.5 to 40% by mass, may be 1 to 30% by mass, or may be 3 to 25% by mass.

[0072] K ２ O equivalent and Na ２ The total content in terms of O is the potassium content determined by XRF analysis. ２ K converted using the O calibration curve ２ The amount of O and the sodium content determined by XRF analysis are expressed as Na ２ Na converted using the O conversion calibration curve ２ The value is calculated from the sum of the amount of K and the amount of O. ｘ Na （１－ｘ） NbO ３ When x=0 or 1 in the formula (I), the potassium content or sodium content may be 0.

[0073] The niobate particles of embodiments may further include molybdenum.

[0074] The niobate particles of the embodiment may contain molybdenum derived from a molybdenum compound that may be used in the manufacturing method described below. Furthermore, the niobate particles of the embodiment can achieve highly efficient crystal growth by using a molybdenum compound in the manufacturing method described below.

[0075] The state and amount of molybdenum contained in the niobate particles of the embodiment are not particularly limited, and may be contained in the niobate particles as molybdenum metal, molybdenum oxide, a partially reduced molybdenum compound, or the like. ３ It is thought that MoO ３ Besides, MoO ２ or MoO may be contained in the niobate particles.

[0076] The form in which molybdenum is contained is not particularly limited, and may be contained in a form in which it is attached to the surface of the niobate particle, in a form in which it is substituted as part of the crystal structure of the niobate particle, in an amorphous state, or a combination thereof.

[0077] When the niobate particles of the embodiment contain molybdenum, the molybdenum content is determined by XRF analysis of the niobate particles, and is expressed as MoO relative to 100% by mass of the total mass of the niobate particles. ３ The content in terms of the converted amount may be 0.01% by mass or more, may be 0.01 to 20% by mass, may be 0.05 to 15% by mass, or may be 0.06 to 10% by mass.

[0078] MoO ３ The molybdenum content calculated by XRF analysis is expressed as MoO ３ MoO converted using the calibration curve ３ It refers to a value calculated from a quantity.

[0079] The above values ​​of the molybdenum content, the niobium content, and the total content of potassium and sodium can be freely combined.

[0080] As an example of niobate particles of the embodiment, the ratio of molybdenum (MoO) to the total mass of the niobate particles (100 mass%) determined by XRF analysis of the niobate particles is: ３ The content of niobium in terms of Nb is 0 to 20 mass %. ２ O ５ The content of potassium and sodium in terms of potassium is 50 to 99 mass %. ２ O equivalent and Na ２ An example of the niobate particles of the embodiment is a niobate particle having a molybdenum content of 0.5 to 40 mass % calculated as O. As another example of the niobate particles of the embodiment, the molybdenum content of MoO relative to 100 mass % of the total mass of the niobate particles, which is determined by XRF analysis of the niobate particles, can be given. ３ The content of niobium in terms of Nb is 0.01 to 20 mass %. ２ O ５The content of potassium and sodium in terms of potassium is 50 to 99 mass %. ２ O equivalent and Na ２ An example of the niobate particles of the embodiment is a niobate particle having a molybdenum content of 0.5 to 40 mass % calculated as O. As another example of the niobate particles of the embodiment, the molybdenum content of MoO relative to 100 mass % of the total mass of the niobate particles, which is determined by XRF analysis of the niobate particles, can be given. ３ The content of niobium in terms of Nb is 0.05 to 15 mass %. ２ O ５ The content of potassium and sodium in terms of K is 60 to 98 mass %. ２ O equivalent and Na ２ An example of the niobate particles of the embodiment is a niobate particle having a molybdenum content of 1 to 30 mass % calculated as O. As another example of the niobate particles of the embodiment, the molybdenum content of MoO relative to 100 mass % of the total mass of the niobate particles, which is determined by XRF analysis of the niobate particles, can be given. ３ The content of niobium in terms of Nb is 0.06 to 10 mass %. ２ O ５ The content of potassium and sodium is 70 to 95 mass % in terms of potassium and sodium. ２ O equivalent and Na ２ Niobate particles having an O content of 3 to 25 mass % can be exemplified.

[0081] The niobate particles of the embodiment can be provided as an aggregate of niobate particles. The crystallite size, particle size distribution, specific surface area, the value of x, the molybdenum content, the niobium content, the potassium content, and the sodium content can be values ​​determined using the aggregate as a sample.

[0082] The niobate particles of the embodiment are manufactured by the manufacturing method described below. Unlike conventional manufacturing methods, the manufacturing method described below allows the desired niobate particles to be obtained through only one firing and mixing step, which is preferable because it has high production efficiency.

[0083] The niobate particles of the embodiment can be used as a piezoelectric material, a catalyst, a water purification material, and the like.

[0084] <Method for Producing Niobate Particles> A method for producing niobate particles according to an embodiment includes calcining a niobium compound in the presence of a molybdenum compound and a potassium compound and / or a sodium compound.

[0085] According to the method for producing niobate particles of this embodiment, it is possible to produce the niobate particles according to one embodiment of the present invention described above.

[0086] According to the method for producing niobate particles of this embodiment, the niobium compound is calcined in the presence of a molybdenum compound and a potassium compound and / or a sodium compound, thereby producing niobate particles with an excellent degree of crystal growth. Furthermore, according to the method for producing niobate particles of this embodiment, the niobium compound is calcined in the presence of potassium carbonate and / or sodium carbonate, thereby producing niobate particles with an excellent degree of crystal growth.

[0087] A preferred method for producing niobate particles can include a step of mixing a niobium compound, a molybdenum compound, and a potassium compound and / or a sodium compound to form a mixture (mixing step), and a step of firing the mixture (firing step).

[0088] Here, at least a portion of the molybdenum compound and potassium compound may be replaced with a compound containing molybdenum and potassium, such as potassium molybdate. Similarly, at least a portion of the molybdenum compound and sodium compound may be replaced with a compound containing molybdenum and sodium, such as sodium molybdate. Therefore, mixing molybdenum with a compound containing potassium and / or sodium is also considered to be mixing a molybdenum compound with a potassium compound and / or sodium compound.

[0089] [Mixing Step] The mixing step is a step of mixing a niobium compound, a molybdenum compound, and a potassium compound and / or a sodium compound to form a mixture.

[0090] When the niobate particles to be produced contain potassium sodium niobate, the method may include a step of mixing a niobium compound, a molybdenum compound, and, optionally, a potassium compound and a sodium compound to form a mixture (mixing step).

[0091] When the niobate particles to be produced contain potassium niobate, the method may include a step of mixing a niobium compound, a molybdenum compound, and, if desired, a potassium compound to form a mixture (mixing step).

[0092] When the niobate particles to be produced contain sodium niobate, the method may include a step of mixing a niobium compound, a molybdenum compound, and, if desired, a sodium compound to form a mixture (mixing step).

[0093] The contents of the mixture will be explained below.

[0094] (Niobium Compound) The niobium compound is not limited as long as it is a compound that can be converted into a niobate by firing together with the raw material compound, and examples thereof include niobium oxide, niobium hydroxide, niobium sulfide, niobium nitride, niobium fluoride, niobium chloride, niobium bromide, niobium iodide and other niobium halides, niobium alkoxides, etc. Niobium hydroxide and niobium oxide are preferred, and niobium oxide is more preferred. Niobium oxide includes niobium pentoxide (Nb ２ O ５ ), niobium dioxide (NbO ２ ), and niobium monoxide (NbO). In addition to the niobium oxides with the above oxidation numbers, any niobium oxide with a different valence can be used. The physical form of these niobium compounds as precursors, such as their shape, particle size, and specific surface area, is not particularly limited.

[0095] The shape of the niobium compound after firing hardly reflects the shape of the raw material niobium compound, and therefore, for example, any shape such as a sphere, an amorphous structure with an aspect (wire, fiber, ribbon, tube, etc.), or a sheet can be suitably used.

[0096] (Molybdenum Compound) Examples of the molybdenum compound include molybdenum oxide, molybdic acid, molybdenum sulfide, and molybdate compounds, with molybdenum oxide and molybdate compounds being preferred.

[0097] The molybdenum oxide may be molybdenum dioxide (MoO ２ ), molybdenum trioxide (MoO ３ ) and the like, with molybdenum trioxide being preferred.

[0098] The molybdate compound is preferably an alkali metal salt of a molybdenum oxoanion, more preferably lithium molybdate, potassium molybdate or sodium molybdate, and even more preferably potassium molybdate or sodium molybdate.

[0099] In the method for producing niobate particles of this embodiment, the molybdenum compound may be a hydrate.

[0100] The molybdenum compound is preferably at least one compound selected from the group consisting of molybdenum trioxide, lithium molybdate, potassium molybdate, and sodium molybdate, and more preferably at least one compound selected from the group consisting of molybdenum trioxide, potassium molybdate, and sodium molybdate.

[0101] A compound containing molybdenum and potassium suitable as a fluxing agent can be produced, for example, during the firing process using a molybdenum compound and a potassium compound, which are cheaper and more readily available as raw materials. Here, both the case where a molybdenum compound and a potassium compound are used as fluxing agents and the case where a compound containing molybdenum and potassium is used as fluxing agents are collectively referred to as the case where a molybdenum compound and a potassium compound are used as fluxing agents, i.e., in the presence of a molybdenum compound and a potassium compound.

[0102] A compound containing molybdenum and sodium suitable as a fluxing agent can be produced, for example, during the firing process using a molybdenum compound and a sodium compound, which are cheaper and more readily available as raw materials. Here, the use of a molybdenum compound and a sodium compound as fluxing agents and the use of a compound containing molybdenum and sodium as fluxing agents are both collectively referred to as the use of a molybdenum compound and a sodium compound as fluxing agents, i.e., in the presence of a molybdenum compound and a sodium compound.

[0103] The above molybdenum compounds may be used alone or in combination of two or more.

[0104] In addition, potassium molybdate (K ２ Mo ｎ O ３ｎ＋１ , n=1 to 3) contains potassium and can therefore also function as a potassium compound, which will be described later.

[0105] In addition, sodium molybdate (Na ２ Mo ｎ O ３ｎ＋１ , n=1 to 3) contains sodium and can therefore function as a sodium compound, which will be described later.

[0106] (Potassium Compound) The potassium compound is not particularly limited, but includes potassium chloride, potassium chlorite, potassium chlorate, potassium sulfate, potassium hydrogen sulfate, potassium sulfite, potassium hydrogen sulfite, potassium nitrate, potassium carbonate, potassium hydrogen carbonate, potassium acetate, potassium oxide, potassium bromide, potassium bromate, potassium hydroxide, potassium silicate, potassium phosphate, potassium hydrogen phosphate, potassium sulfide, potassium hydrogen sulfide, potassium molybdate, potassium tungstate, etc. In this case, the potassium compound includes isomers, as in the case of molybdenum compounds. Among these, potassium carbonate, potassium hydrogen carbonate, potassium oxide, potassium hydroxide, potassium chloride, potassium sulfate, and potassium molybdate are preferably used, potassium carbonate, potassium hydrogen carbonate, potassium chloride, potassium sulfate, and potassium molybdate are more preferably used, and potassium carbonate and / or potassium molybdate are more preferably used.

[0107] The potassium compounds described above may be used alone or in combination of two or more.

[0108] As described above, potassium molybdate contains molybdenum and can therefore also function as the molybdenum compound described above.

[0109] (Sodium Compound) The sodium compound is not particularly limited, and examples thereof include sodium carbonate, sodium molybdate, sodium oxide, sodium hydrogencarbonate, sodium sulfate, sodium hydroxide, sodium nitrate, sodium chloride, metallic sodium, etc. Among these, from the viewpoints of industrial ease of availability and ease of handling, it is preferable to use sodium carbonate, sodium molybdate, sodium oxide, or sodium sulfate, and it is more preferable to use sodium carbonate and / or sodium molybdate.

[0110] The above-mentioned sodium compounds may be used alone or in combination of two or more.

[0111] As described above, sodium molybdate contains molybdenum and can therefore also function as the molybdenum compound described above.

[0112] As described above, there may be cases where the molybdenum compounds are classified in a redundant manner, but as an example, it is preferable that the molybdenum compound is at least one compound selected from the group consisting of molybdenum trioxide, potassium molybdate, and sodium molybdate, the sodium compound is sodium carbonate or sodium molybdate, and the potassium compound is potassium carbonate or potassium molybdate.

[0113] A preferred example of the method for producing potassium sodium niobate particles includes calcining a niobium compound in the presence of a molybdenum compound, a potassium compound, and a sodium compound.

[0114] A preferred example of the method for producing sodium niobate particles includes calcining a niobium compound in the presence of a molybdenum compound and a sodium compound.

[0115] A preferred example of the method for producing potassium niobate particles includes calcining a niobium compound in the presence of a molybdenum compound and a potassium compound.

[0116] In the method for producing niobate particles of this embodiment, a potassium compound, a sodium compound, and a molybdenum compound are used as fluxing agents. When a potassium compound and / or a sodium compound is used as a fluxing agent, the firing converts a part of the potassium compound and / or the sodium compound into an oxide (Na ２ O and K ２ O) is formed, which acts as a flux to promote the crystal growth of niobate.

[0117] Furthermore, when a niobium compound is calcined in the presence of potassium carbonate and / or sodium carbonate, a portion of the potassium carbonate and / or sodium carbonate is converted into an oxide (Na ２ O and K ２ O) and / or CO ２ are formed, and these oxides and / or CO ２It is assumed that the oxide (Na) acts as a flux, and the crystal growth of niobate proceeds. ２ O and K ２ O) and / or CO ２ With the formation of niobate particles (K ｘ Na （１－ｘ） NbO ３ ) is thought to be formed. ２ O and K ２ O) and / or CO ２ The flux function allows the niobate particles (K ｘ Na （１－ｘ） NbO ３ ) is thought to be promoted.

[0118] The molybdate compound used as the flux does not vaporize even in the firing temperature range and can be easily recovered by washing after firing. This reduces the amount of molybdenum compound released outside the firing furnace, and also significantly reduces production costs.

[0119] In the method for producing niobate particles of the present embodiment, the total amount of the raw materials, molybdenum compound, potassium compound, and sodium compound (hereinafter also referred to as fluxing agent), which are thought to function as a fluxing agent, and the amount of the niobium compound used are not particularly limited. However, it is preferable that the niobium compound (Nb １ ) relative to the mass of the flux component sodium compound (Na １ ), potassium compounds (K １ ), molybdenum compounds (Mo １ ) total mass ratio (Nb １ ) / (Na １ +K １ +Mo １ ) is 0.6 or more, and the mixture can be fired. １ ) / (Na １ +K １ +Mo １ ) is 0.64 or more, and the mixture can be fired. １) / (Na １ +K １ +Mo １ ) can be 0.67 or more, and the mixture can be fired.

[0120] From the viewpoint of efficient crystal growth, it is preferable that the amount of fluxing agent used relative to the niobium compound raw material is equal to or greater than the above mass ratio. By reducing the amount of fluxing agent used relative to the niobium compound raw material, the ease of removal of the fired product from the firing vessel is improved, although the detailed reason is not clear. In addition, it is preferable that the K / Na ratio of the niobate particles can be adjusted within a desired range.

[0121] From the same viewpoint, in the method for producing niobate particles of the embodiment, the molar ratio of potassium atoms and sodium atoms to molybdenum atoms and niobium atoms in the mixture, (K+Na) / (2×Mo+Nb), is preferably greater than 1.0, more preferably 1.01 to 1.20, even more preferably 1.02 to 1.15, and particularly preferably 1.02 to 1.10.

[0122] It is preferable that the molar ratio (K+Na) / (2×Mo+Nb) is within the above range, since niobate particles with improved crystallite size can be easily obtained. Note that it is particularly preferable that the molar ratio (K+Na) / (2×Mo+Nb) is 1.25 or less, since crystal growth can be promoted in the obtained niobate particles and the amount of irregular particles can be suppressed.

[0123] In the method for producing niobate particles according to the embodiment, the molar ratio of potassium atoms and / or sodium atoms to molybdenum atoms in the mixture is preferably (K+Na) / Mo=1 to 4, more preferably 1.5 to 4. In particular, when (K+Na) / Mo=2 to 4, the molar ratio of potassium atoms and / or sodium atoms to molybdenum atoms in the mixture is preferably 1.5 to 4. ｘ Na （１－ｘ） Nb ｙ O ｚ A single composition of the above can be easily formed.

[0124] According to the manufacturing method of the present invention, compared to the conventional manufacturing method, K can be obtained by only one firing step. ｘ Na （１－ｘ） NbO３ While controlling the composition ratio of the niobate particles represented by the formula (1), it is possible to obtain niobate particles in high yield, and further to control the particle size and crystallite size of the particles.

[0125] [Firing step] The firing step is a step of firing the mixture. The niobate particles according to the embodiment can be obtained by firing the mixture. As described above, this manufacturing method is called a flux method.

[0126] The calcination method is not particularly limited, and can be carried out by a known, commonly used method. When a molybdenum compound is used, if the calcination temperature exceeds 500°C, a part of the niobium compound reacts with the molybdenum compound to form niobium molybdate, etc., and the molybdenum compound produces molybdate (K a Mo ｂ O ｃ and Na ａ Mo ｂ O ｃ , K. a Na ａ’ Mo ｂ O ｃ ) is thought to be formed. Furthermore, when the firing temperature reaches 800°C or higher, the partially formed niobium molybdate and the like decompose, and niobate particles are formed due to the flux function of the molybdate. Furthermore, in the niobate particles, it is thought that molybdenum compounds are incorporated into the niobate particles during the decomposition of niobium molybdate and the process of particle crystal growth.

[0127] Furthermore, the state of the niobium compound, molybdenum compound, sodium compound, potassium compound, etc. that can be used during firing is not particularly limited, as long as the raw material compounds, such as the molybdenum compound, niobium compound, sodium compound, potassium compound, etc., are present in the same space so that they can interact with each other. Specifically, simple mixing in which powders of the raw material compounds are mixed together, mechanical mixing using a grinder or the like, or mixing using a mortar or the like may be used, and mixing may be performed in a dry state or a wet state.

[0128] The firing temperature is not particularly limited and is appropriately determined taking into consideration the particle size of the target niobate particles, the formation of the molybdenum compound in the niobate particles, the shape of the niobate particles, etc. The firing temperature may be 700°C or higher, which is close to the temperature at which the molybdate can function as a flux, or may be 750°C or higher, 800°C or higher, 850°C or higher, or 900°C or higher. From the viewpoint of efficiently producing niobate particles with an improved crystallite size, the firing temperature is preferably 800°C or higher, more preferably 900°C or higher, and even more preferably 1000°C or higher.

[0129] Generally, in order to control the shape of the niobate obtained after firing, it is necessary to perform firing at a high temperature of over 1500°C, which is close to the melting point of niobium oxide. However, this poses a significant challenge for industrial use in terms of the burden on the firing furnace and fuel costs.

[0130] According to one embodiment of the present invention, niobate particles can be formed efficiently at low cost, even under conditions such as a maximum firing temperature of 1500°C or lower for firing a niobium compound. Furthermore, according to the method for producing niobate particles of the embodiment, idiomorphous niobate particles can be formed regardless of the shape of the precursor, even at a firing temperature of 1300°C or lower, which is much lower than the melting point of niobium oxide. Furthermore, from the viewpoint of efficiently producing niobate particles, the firing temperature is preferably 1200°C or lower, and more preferably 1100°C or lower.

[0131] The numerical range of the firing temperature for firing the niobium compound in the firing step may be, for example, 700 to 1300° C., 750 to 1300° C., 800 to 1200° C., 850 to 1200° C., 900 to 1100° C., or 1000 to 1100° C. By combining a specific amount of flux and firing temperature, desired particles can be easily obtained.

[0132] From the viewpoint of production efficiency, the temperature rise rate may be 20 to 600° C. / h, 40 to 500° C. / h, or 80 to 400° C. / h.

[0133] Regarding the firing time, it is preferable that the time required to raise the temperature to a predetermined firing temperature is in the range of 15 minutes to 10 hours, and that the holding time at the firing temperature is in the range of 5 minutes to 30 hours. To efficiently form niobate particles, the firing temperature is preferably held for 2 hours or more, and more preferably for 2 to 15 hours. By selecting conditions of a firing temperature of 700 to 1100°C and a firing temperature holding time of 2 to 15 hours, niobate particles with an improved crystallite size can be easily obtained.

[0134] The firing atmosphere is not particularly limited as long as the effects of the present invention can be obtained. For example, an oxygen-containing atmosphere such as air or oxygen, or an inert atmosphere such as nitrogen, argon, or carbon dioxide is preferred, and an air atmosphere is more preferred when cost is taken into consideration.

[0135] The calcination apparatus is not necessarily limited, and a so-called calcination furnace can be used. The calcination furnace is preferably made of a material that does not react with the sublimated molybdenum oxide, and it is preferable to use a highly airtight calcination furnace so that the molybdenum oxide can be efficiently utilized.

[0136] [Cooling Step] The method for producing niobate particles may include a cooling step, in which the niobate particles whose crystals have grown in the firing step are cooled.

[0137] The cooling rate is not particularly limited, but is preferably 1 to 1000°C / hour, more preferably 5 to 500°C / hour, and even more preferably 50 to 100°C / hour. A cooling rate of 1°C / hour or more is preferable because it can shorten the manufacturing time. On the other hand, a cooling rate of 1000°C / hour or less is preferable because the firing container is less likely to crack due to heat shock and can be used for a long time.

[0138] The cooling method is not particularly limited, and may be natural cooling or a cooling device may be used.

[0139] [Post-treatment step] The manufacturing method of this embodiment may include a post-treatment step. The post-treatment step may be a step of separating the niobate particles and the flux agent contained in the fired product, and may be performed after removing the fired product from the firing container. The post-treatment step may be performed after the above-mentioned firing step. Furthermore, the post-treatment step may be repeated two or more times as necessary.

[0140] Methods for removing the fluxing agent include washing, high-temperature treatment, etc. These may be performed in combination.

[0141] The cleaning method is not particularly limited, but when the flux is water-soluble, such as the potassium compounds, sodium compounds, and molybdate compounds, washing with water may be used.

[0142] Moreover, examples of the high-temperature treatment method include a method in which the temperature is raised to the sublimation point or boiling point of the flux or higher.

[0143] [Pulverization step] The niobate particles in the sintered product obtained through the sintering step may aggregate and not satisfy the particle size range suitable for the intended application. Therefore, the niobate particles may be pulverized as necessary to satisfy the particle size range suitable for the intended application. The pulverization method for the sintered product is not particularly limited, and conventionally known pulverization methods such as a ball mill, jaw crusher, jet mill, disk mill, spectromill, grinder, and mixer mill can be used.

[0144] [Classification Process] The fired product containing niobate particles obtained in the firing process may be classified as appropriate to adjust the particle size range. "Classification process" refers to the operation of grouping particles according to their size. Classification may be either wet or dry, but dry classification is preferred from the viewpoint of productivity. Dry classification includes sieving and air classification, which classifies particles based on the difference between centrifugal force and fluid drag. From the viewpoint of classification accuracy, air classification is preferred, and can be performed using a classifier such as an air classifier utilizing the Coanda effect, a swirling air classifier, a forced vortex centrifugal classifier, or a semi-free vortex centrifugal classifier. The above-mentioned pulverization and classification processes can be performed at any necessary stage. For example, the average particle size of the obtained niobate particles can be adjusted by selecting whether or not to perform pulverization or classification and the conditions for performing them.

[0145] In the above-mentioned production method, the niobium compound (Nb １ ) relative to the mass of the flux component sodium compound (Na １ ), potassium compounds (K １ ), molybdenum compounds (Mo １ ) total mass ratio (Nb １ ) / (Na １ +K １ +Mo １ By combining the above-mentioned nitrite powder with a specific range of firing temperature, niobate particles having a desired average particle size and particle size distribution can be obtained without performing a pulverization step or a classification step.

[0146] The niobate particles of the embodiment or the niobate particles obtained by the manufacturing method of the embodiment are preferably those with little or no aggregation, as these particles are more likely to exhibit their inherent properties, are easier to handle, and have better dispersibility when dispersed in a dispersion medium.

[0147] According to the method for producing niobate particles of the above embodiment, niobate particles with little or no agglomeration can be easily produced, and therefore, there is an excellent advantage that niobate particles having the desired excellent properties can be produced with high productivity without performing the above-mentioned crushing step or classification step.

[0148] <<Resin Composition>> The niobate particles of the embodiment can be blended with a resin to provide a resin composition. In one embodiment, a resin composition containing the niobate particles of the embodiment and a resin is provided. The resin is not particularly limited, and may be a polymer, an oligomer, or a monomer, a thermosetting resin, a thermoplastic resin, or an active energy ray-curable resin.

[0149] (Thermosetting resin) The thermosetting resin is a resin that has the property of becoming substantially insoluble and infusible when cured by means of heat, radiation, a catalyst, etc. For example, it may be a known and commonly used resin used in molding materials, etc. Specific examples of the resin include novolac-type phenolic resins such as phenol novolac resin and cresol novolac resin; phenolic resins such as unmodified resol phenolic resin and resol-type phenolic resin such as oil-modified resol phenolic resin modified with tung oil, linseed oil, walnut oil, etc.; bisphenol-type epoxy resins such as bisphenol A epoxy resin and bisphenol F epoxy resin; novolac-type epoxy resins such as aliphatic chain-modified bisphenol-type epoxy resin, novolac epoxy resin, cresol novolac epoxy resin; epoxy resins such as biphenyl-type epoxy resin and polyalkylene glycol-type epoxy resin; resins having a triazine ring such as urea resin and melamine resin; vinyl resins such as (meth)acrylic resin and vinyl ester resin; unsaturated polyester resin, bismaleimide resin, polyurethane resin, diallyl phthalate resin, silicone resin, resin having a benzoxazine ring, cyanate ester resin, etc., and they may be polymers, oligomers, or monomers.

[0150] The thermosetting resins described above may be used together with a curing agent. The curing agent used in this case can be used in a known and commonly used combination with the thermosetting resin. For example, when the thermosetting resin is an epoxy resin, any compound commonly used as a curing agent can be used, such as amine compounds, amide compounds, acid anhydride compounds, and phenol compounds. Specific examples of amine compounds include diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenylsulfone, isophoronediamine, imidazole, BF3-amine complex, and guanidine derivatives. Examples of amide compounds include dicyandiamide and polyamide resins synthesized from a linoleic acid dimer and ethylenediamine. Examples of acid anhydride compounds include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride. Examples of phenolic compounds include phenol novolac resin, cresol novolac resin, aromatic hydrocarbon formaldehyde resin modified phenol resin, dicyclopentadiene phenol addition type resin, phenol aralkyl resin (Zylok resin), polyhydric phenol novolac resin synthesized from polyhydric hydroxy compounds such as resorcinol novolac resin and formaldehyde, naphthol aralkyl resin, trimethylolmethane resin, tetraphenylolethane resin, naphthol novolac resin, naphthol-phenol co-condensed novolac resin, naphthol-c Examples of the curing agent include polyhydric phenol compounds such as resole-co-condensed novolac resin, biphenyl-modified phenol resin (a polyhydric phenol compound in which phenol nuclei are linked by bismethylene groups), biphenyl-modified naphthol resin (a polyhydric naphthol compound in which phenol nuclei are linked by bismethylene groups), aminotriazine-modified phenol resin (a polyhydric phenol compound in which phenol nuclei are linked by melamine, benzoguanamine, or the like), and alkoxy group-containing aromatic ring-modified novolac resin (a polyhydric phenol compound in which phenol nuclei and alkoxy group-containing aromatic rings are linked by formaldehyde). These curing agents may be used alone or in combination of two or more.

[0151] The blending amounts of the thermosetting resin and the curing agent in the resin composition of the embodiment are not particularly limited. For example, when the curable resin is an epoxy resin, it is preferable to use an amount such that the active groups in the curing agent are 0.7 to 1.5 equivalents per total equivalent of epoxy groups in the epoxy resin, in view of the good properties of the resulting cured product.

[0152] If necessary, a curing accelerator can be used in combination with the thermosetting resin in the resin composition of the embodiment. For example, when the curable resin is an epoxy resin, various curing accelerators can be used, including, for example, phosphorus compounds, tertiary amines, imidazoles, organic acid metal salts, Lewis acids, and amine complex salts.

[0153] If necessary, a curing catalyst may be used in combination with the thermosetting resin at appropriate times, and examples of such a catalyst include known and commonly used thermal polymerization initiators and active energy ray polymerization initiators.

[0154] (Thermoplastic Resin) Examples of thermoplastic resins that may be used in the resin composition of the embodiment include well-known and commonly used resins used in molding materials, etc. Specific examples include polyethylene resin, polypropylene resin, polymethyl methacrylate resin, polyvinyl acetate resin, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, polyvinyl chloride resin, polystyrene resin, polyacrylonitrile resin, polyamide resin, polycarbonate resin, polyacetal resin, polyethylene terephthalate resin, polyphenylene oxide resin, polyphenylene sulfide resin, polysulfone resin, polyether sulfone resin, polyether ether ketone resin, polyallylsulfone resin, thermoplastic polyimide resin, thermoplastic urethane resin, polyaminobismaleimide resin, polyamideimide resin, polyetherimide resin, bismaleimide triazine resin, polymethylpentene resin, fluorinated resin, liquid crystal polymer, olefin-vinyl alcohol copolymer, ionomer resin, polyarylate resin, acrylonitrile-ethylene-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-styrene copolymer, and the like. At least one thermoplastic resin can be selected and used, but two or more thermoplastic resins can also be used in combination depending on the purpose.

[0155] When the resin is used for a piezoelectric body, it is preferable that the resin exhibits a high dielectric constant, and the resin is preferably a polymer having an electron-withdrawing group, and is preferably a fluorine-containing polymer such as polyvinylidene fluoride (PVDF), vinylidene fluoride-tetrafluoroethylene copolymer, or vinylidene fluoride-trifluoroethylene copolymer, or a polymer having a cyano group or a cyanoethyl group such as cyanoethylated polyvinyl alcohol, vinylidene cyanide-vinyl acetate copolymer, cyanoethyl cellulose, cyanoethyl hydroxysucrose, cyanoethyl hydroxycellulose, cyanoethyl hydroxypullulan, cyanoethyl methacrylate, cyanoethyl acrylate, cyanoethyl hydroxyethyl cellulose, cyanoethyl amylose, cyanoethyl hydroxypropyl cellulose, cyanoethyl dihydroxypropyl cellulose, cyanoethyl hydroxypropyl amylose, cyanoethyl polyacrylamide, cyanoethyl polyacrylate, cyanoethyl pullulan, cyanoethyl polyhydroxymethylene, cyanoethyl glycidol pullulan, cyanoethyl sucrose, or cyanoethyl sorbitol.

[0156] The resin composition of the embodiment may contain other compounds as needed, and may contain external lubricants, internal lubricants, antioxidants, flame retardants, light stabilizers, ultraviolet absorbers, silane-based, titanate-based, or aluminate-based coupling agents, reinforcing materials such as glass fiber or carbon fiber, fillers, various colorants, etc. In addition, stress-reducing agents (stress relaxation agents) such as silicone oil, liquid rubber, rubber powder, butadiene copolymer rubbers such as methyl acrylate-butadiene-styrene copolymers and methyl methacrylate-butadiene-styrene copolymers, and silicone compounds may also be used, as long as the effects of the invention are achieved.

[0157] The resin composition of the embodiment can be obtained by mixing the niobate particles of the embodiment, a resin, and, if necessary, other ingredients. The mixing method is not particularly limited, and the ingredients can be mixed by a known or commonly used method.

[0158] When the resin is a thermosetting resin, a typical method is to thoroughly mix the thermosetting resin, the niobate particles of the embodiment, and other components as needed using a mixer or the like, and then knead using a three-roll mill or the like to obtain a fluid liquid composition, or to thoroughly mix a predetermined amount of the thermosetting resin, the niobate particles of the embodiment, and other components as needed using a mixer or the like, and then melt-knead using a mixing roll, extruder, or the like, and then cool to obtain a solid composition. When a curing agent, catalyst, or the like is blended, it is preferable that the curable resin and the blend are thoroughly and uniformly mixed, and it is even more preferable that the niobate particles of the embodiment are also uniformly dispersed and mixed.

[0159] A typical method when the resin is a thermoplastic resin is to premix the thermoplastic resin, the niobate particles of the embodiment, and other components as needed using various mixers such as a tumbler or a Henschel mixer, and then melt-knead them using a mixer such as a Banbury mixer, a roll, a Brabender, a single-screw kneading extruder, a twin-screw kneading extruder, a kneader, a mixing roll, etc. The melt-kneading temperature is not particularly limited, but may be in the range of 240 to 320°C.

[0160] When preparing the resin composition of the embodiment, the mixing ratio of the niobate particles of the embodiment to the non-volatile content of the resin is not particularly limited, but may be, for example, in the range of 0.1 to 1800 parts by mass of the niobate particles, or may be in the range of 10 to 900 parts by mass, per 100 parts by mass of the non-volatile content of the resin.

[0161] The content ratio of the niobate particles relative to the total volume (100 vol%) of the resin composition of the embodiment may be 10 vol% or more, may be 20 to 90 vol%, or may be 30 to 85 vol%.

[0162] <<Molded Article>> A molded article can be obtained by molding the resin composition of the embodiment. In one embodiment, a molded article is provided by molding the resin composition of the embodiment. The resin molded article can be obtained by a known, commonly used method.

[0163] For example, when the resin contained in the resin composition is a thermosetting resin, the curing method may conform to the curing method for a thermosetting resin composition such as a general epoxy resin composition. For example, a resin composition containing an epoxy resin can be cured by heat, and the heating temperature conditions may be appropriately selected depending on the type of curing agent to be combined, the application, etc., and heating may be performed within a temperature range of about room temperature to 250°C. In the case of an active energy ray-curable resin, it can be cured and molded by irradiating it with active energy rays such as ultraviolet rays or infrared rays.

[0164] Furthermore, even when the resin of the embodiment is a thermoplastic resin, a molded product can be obtained by a known and commonly used molding method. For example, injection molding, ultra-high speed injection molding, injection compression molding, two-color molding, gas-assisted hollow molding, molding using an insulated mold, molding using a rapidly heated mold, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating molding), extrusion molding, sheet molding, rotational molding, laminate molding, press molding, etc. can be mentioned. A molding method using a hot runner system can also be used. There are no limitations on the shape, pattern, color, dimensions, etc. of the molded product, and they can be set arbitrarily depending on the application of the molded product.

[0165] When the molded article of the resin composition is in the form of a sheet or layer, the thickness thereof may be 10 to 1000 μm, or 10 to 500 μm.

[0166] The resin composition of the embodiment and its molded body can be provided and used as a piezoelectric body by appropriately performing a polarization treatment.

[0167] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to the following examples. That is, each configuration and their combination in each embodiment is merely an example, and addition, omission, substitution, and other modifications of the configuration are possible within the scope of the present invention. Furthermore, the present invention is not limited to each embodiment, but is limited only by the scope of the claims.

[0168] <Analysis and Evaluation> The powders of each example and comparative example were used as samples and the following measurements were carried out.

[0169] [XRF (X-ray Fluorescence) Analysis] Using an X-ray fluorescence analyzer Supermini 200 (manufactured by Rigaku Corporation), approximately 5 g of sample powder was placed in a PP container lined with a propylene film to prepare a sample measurement container, and XRF (X-ray fluorescence) analysis was performed under the following conditions: Measurement conditions: EZ scan mode, Measurement elements: F to U, Measurement time: Standard, Measurement diameter: 30 mm, Remainder (balance component): None

[0170] The sample powder is subjected to XRF analysis to determine the niobium content in the sample powder, and the Nb content relative to 100% by mass of the total mass of the sample powder is calculated. ２ O ５ The sample powder was subjected to XRF analysis to determine the molybdenum content in the sample powder, and the molybdenum content was calculated as the content (mass%) of MoO relative to 100 mass% of the total mass of the sample powder. ３ The sample powder was subjected to XRF analysis to determine the potassium content in the sample powder, and the potassium content was calculated as a percentage by mass (mass %) of the total mass of the sample powder (100 mass %). ２ The sample powder was subjected to XRF analysis to determine the sodium content in the sample powder, and the sodium content was calculated as a percentage by mass of 0 based on 100% by mass of the total mass of the sample powder. ２ The content (mass%) was calculated in terms of O. ｘ Na （１－ｘ） NbO ３ With respect to x, K obtained from the XRF ２ O, Na ２ It was calculated from the O content (mass %).

[0171] [Crystal structure analysis: XRD (X-ray diffraction) method] The sample powder was filled into a measurement sample holder with a depth of 0.5 mm, and the holder was set in an X-ray diffraction (XRD) device (SmartLab manufactured by Rigaku Corporation), and measurement was performed under the conditions of Cu / Kα radiation, 40 kV / 50 mA, a scan speed of 10° / min, and a scan range of 10 to 90°.

[0172] [Particle size measurement] (Cubic particles) The sample powder was photographed using a scanning electron microscope (SEM). When the smallest particle (i.e., primary particle) observed in the two-dimensional image was observed to have a cubic shape, the length of one side of a hexahedron determined from the particle image of the primary particle was measured as the particle size. The same procedure was performed on 50 primary particles, and the average value was calculated.

[0173] [Measurement of crystallite size] An X-ray diffractometer was used, SmartLab (manufactured by Rigaku Corporation), and PDXL was used as analysis software. The measurement method was the 2θ / θ method, and the average crystallite size was calculated using the Scherrer method from the half-width of the peak appearing at 2θ = 23.0 ± 1.0 °, the peak appearing at 2θ = 32.0 ± 1.2 °, and the peak appearing at 2θ = 57.0 ± 1.0 °. The measurement conditions were a scan speed of 10 degrees / min, a scan range of 10 to 90 degrees, and a step of 0.02 degrees.

[0174] [Particle size distribution measurement] A small amount of particle powder was placed in a beaker, 50 mL of 0.5% sodium hexametaphosphate aqueous solution was added, and then the mixture was dispersed for 2 minutes using an ultrasonic homogenizer, Sonifier 450D (manufactured by Branson Corporation) to prepare a measurement sample. This measurement sample was measured using a laser diffraction / scattering particle size distribution measuring device MT3300EXII (manufactured by Microtrac Bell Corporation) to measure the volume cumulative standard D １０ , D ５０ , D ９０ was measured.

[0175] <K ｘ Na （１－ｘ） NbO ３ Production of particles>

[0176] [Example 1] Niobium oxide (manufactured by Mitsui Mining & Smelting Co., Ltd., Nb ２ O ５ ) 40.0 g, potassium carbonate (AGC Co., Ltd., K ２ CO ３ ) 22.6 g, sodium carbonate (Tokuyama Corporation, Na ２ CO ３) 9.7 g, molybdenum trioxide (manufactured by Nippon Inorganic Chemical Industry Co., Ltd., MoO ３ 13.6 g of the powder was mixed in an Absolute Mill (Osaka Chemical Co., Ltd.) for 30 seconds to obtain a mixture. The resulting mixture was placed in a crucible and fired in a ceramic electric furnace at 850°C for 5 hours. The fired product was then placed in 250 mL of pure water and subjected to ultrasonic cleaning four times, followed by water washing to remove the cleaning water by filtration and drying to remove the remaining fluxing agent, thereby obtaining the powder of Example 1.

[0177] Example 2 A powder was obtained in the same manner as in Example 1, except that the amounts of potassium carbonate, sodium carbonate, and molybdenum trioxide were changed to 18.4 g, 9.2 g, and 9.1 g, respectively.

[0178] Example 3 A powder was obtained in the same manner as in Example 1, except that the amounts of potassium carbonate, sodium carbonate, and molybdenum trioxide were changed to 16.3 g, 9.0 g, and 6.8 g, respectively.

[0179] Example 4 A powder was obtained in the same manner as in Example 1, except that the amount of potassium carbonate was changed to 21.8 g and the amount of sodium carbonate was changed to 10.2 g.

[0180] [Example 5] Niobium oxide (manufactured by Mitsui Mining & Smelting Co., Ltd., Nb ２ O ５ ) 40.0 g, potassium carbonate (AGC Co., Ltd., K ２ CO ３ ) 12.1 g, sodium carbonate (Tokuyama Corporation, Na ２ CO ３ 8.6 g of potassium molybdate (K2MoO4, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), 19.8 g of potassium molybdate (K2MoO4, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.), and 2.7 g of sodium molybdate (Na2MoO4, manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.) were mixed for 30 seconds in an Absolute Mill (manufactured by Osaka Chemical Co., Ltd.) to obtain a mixture. The resulting mixture was placed in a crucible and fired at 850°C for 5 hours in a ceramic electric furnace. The fired product was then placed in 250 mL of pure water and subjected to ultrasonic cleaning four times. After that, the remaining fluxing agent was removed by water washing, which was filtered, and the powder was dried to obtain the powder of Example 5.

[0181] Example 6 A powder was obtained in the same manner as in Example 1, except that the amounts of potassium carbonate, sodium carbonate, and molybdenum trioxide were changed to 28.8 g, 10.3 g, and 20.4 g, respectively.

[0182] Example 7 A powder was obtained in the same manner as in Example 1, except that the calcination was carried out at 950° C. for 5 hours.

[0183] Example 8 A powder was obtained in the same manner as in Example 1, except that the calcination was carried out at 750° C. for 5 hours.

[0184] Example 9 A powder was obtained in the same manner as in Example 1, except that the amount of potassium carbonate was changed to 16.7 g and the amount of sodium carbonate was changed to 14.1 g.

[0185] Example 10 A powder was obtained in the same manner as in Example 1, except that the amount of potassium carbonate was changed to 29.2 g and the amount of sodium carbonate was changed to 4.5 g.

[0186] Example 11 A powder was obtained in the same manner as in Example 1, except that the amounts of potassium carbonate, sodium carbonate, and molybdenum trioxide were changed to 30.1 g, 10.5 g, and 21.8 g, respectively.

[0187] Comparative Example 1 Niobium oxide (manufactured by Mitsui Mining & Smelting Co., Ltd., Nb ２ O ５ ) 80.0 g, potassium carbonate (AGC Co., Ltd., K ２ CO ３ 20.0 g of ammonium nitrate (manufactured by Tokuyama Corporation) and 16.9 g of sodium carbonate (manufactured by Tokuyama Corporation) were mixed for 30 seconds in an Absolute Mill (manufactured by Osaka Chemical Co., Ltd.) to obtain a mixture. The obtained mixture was placed in a crucible and fired at 850°C for 5 hours in a ceramic electric furnace to obtain a powder of Comparative Example 1.

[0188] The synthesis conditions are shown in Table 1.

[0189]

[0190] The evaluation results for each particle obtained from the formulation in Table 1 are shown in Table 2. The ease of removal from the crucible was evaluated using "Good", "Average", or "Poor". "Good" indicates that the fired product could be easily removed without adhering to the crucible, "Average" indicates that a portion of the fired product adhered to the crucible, and "Poor" indicates that the fired product adhered to the crucible and could not be removed. In the table, "N.D." stands for "not detected" and indicates that it was not detected.

[0191]

[0192] Table 2 shows the particle shape and size of each example and comparative example as determined from SEM images. When particles of different shapes were observed to be mixed, the representative shape (the shape most commonly observed) was recorded. Cubic particle aggregates were also recorded as having a cubic shape. When no specific shape was observed, the particles were determined to be amorphous. In Example 1, the particles had a cubic shape as shown in Figure 1. In each of Examples 2 to 11, the particles were cubic like in Example 1. In Comparative Example 1, the particles had an amorphous shape as shown in Figure 2, with some cubic particles observed.

[0193] From the results of XRD analysis, as shown in FIG. 3, in the sample of Example 1, K ｘ Na （１－ｘ） NbO ３ Peaks at 2θ = 23.0 ± 1.0°, 2θ = 32.0 ± 1.2°, and 2θ = 57.0 ± 1.0° were observed, which were derived from the (100) plane, (110) plane, and (221) plane of the perovskite structure of Example 1. ｘ Na （１－ｘ） NbO ３ Peaks originating from the (100) plane, (110) plane, and (221) plane of the perovskite structure were observed.

[0194] Furthermore, the powder samples of Examples 1 to 11 and Comparative Example 1 were found to contain niobium, molybdenum, potassium, and sodium in the oxide-equivalent amounts shown in Table 2, as determined by XRF analysis.

[0195] Each particle size (SEM observation, D ５０), and crystallite size, the particles of Examples 1 to 11 had larger primary particle size and crystallite size than the particles of the Comparative Example. This is because the raw material compound MoO ３ , Na ２ CO ３ , K. ２ CO ３ , Na ２ MoO ４ and K. ２ MoO ４ This is thought to be because most of the compounds (including their products and decomposition products) functioned as fluxing agents, allowing the crystal growth of particles to proceed smoothly.

[0196] Furthermore, the higher the firing temperature, the larger the particles tended to be (Examples 1, 7, and 8).

[0197] From the results of Examples 1 to 11, it can be seen that by firing a niobium compound in the presence of a molybdenum compound and a potassium compound and / or a sodium compound, a high-quality K niobium oxide having a large average crystallite size and a perovskite structure can be obtained. ｘ Na （１－ｘ） NbO ３ It was shown that the particles could be calcined.

[0198] <Manufacturing of piezoelectric composite sheets>

[0199] Example 12 26.1 g of the particles produced in Example 1, 3.54 g of silicone resin KE-106 (Shin-Etsu Chemical Co., Ltd.), and 0.35 g of CAT-RG (Shin-Etsu Chemical Co., Ltd.) were weighed into a container and stirred at 2000 rpm for 120 seconds using a planetary centrifugal mixer ARV-200 (Thinky Corporation). After stirring, the mixture was poured into a 5.5 cm square, 0.3 mm deep mold and pressed at 120°C and 1 MPa for 30 minutes. In this way, a piezoelectric composite sheet with a particle volume fraction of 60 vol% was obtained.

[0200] [Example 13] A piezoelectric composite sheet with a particle volume fraction of 64 vol% was obtained in the same manner as in Example 12, except that the particles produced in Example 1 were changed to 26.6 g, silicone resin KE-106 (Shin-Etsu Chemical Co., Ltd.) to 3.05 g, and CAT-RG (Shin-Etsu Chemical Co., Ltd.) to 0.31 g.

[0201] Comparative Example 2 A piezoelectric composite sheet having a particle volume fraction of 60 vol % was obtained in the same manner as in Example 12, except that the particles were changed to those produced in Comparative Example 1.

[0202] [Example 14] The particles produced in Example 1 and PVDF (Kureha Corporation, model number #850) were weighed so that the particle volume fraction was 40 vol%, and kneaded in a Labo Plastomill Mixer (Toyo Seiki Seisaku-sho, Ltd., model number: 4C150) under conditions of a temperature of 220°C, a screw rotation speed of 60 ppm, and a kneading time of 3 minutes to obtain a kneaded resin composition. Thereafter, the kneaded resin composition kneaded body was compressed in a compression molding machine at a temperature of 230°C, a preheating time of 1 minute, a compression time of 1 minute, and a pressure of 100 kgf / cm. ２ The sheet was further heated at 240°C for 30 seconds, compressed for 30 seconds, and compressed under a pressure of 100 kgf / cm. ２ The sheet was compressed three times at 1000 kJ / cm². A piezoelectric composite sheet was obtained.

[0203] Example 15 A piezoelectric composite sheet was obtained in the same manner as in Example 14, except that the volume fraction of the particles was changed to 60 vol %.

[0204] Comparative Example 3 A piezoelectric composite sheet was obtained in the same manner as in Example 14, except that the particles were changed to those produced in Comparative Example 1.

[0205] [Evaluation of Piezoelectric Composite Sheet] A 100 nm aluminum electrode was formed on one side of the piezoelectric composite sheet using a vapor deposition device, and the aluminum electrode was grounded. After heating the sheet to 120°C on a hot plate, a DC voltage of -10 kV was applied to a discharge needle placed directly above the sheet, and a corona discharge treatment was performed for 3 minutes. After removing the sheet from the hot plate, a 100 nm aluminum electrode was formed on the corona discharge treated side using a vapor deposition device, resulting in a polarized aluminum electrode / piezoelectric composite sheet / aluminum electrode laminate. The resulting laminate was cut into 10 mm x 2 mm pieces using an NT cutter. The complex dielectric constant of the resulting 10 mm x 2 mm laminate sheet was then measured using an Agilent Impedance Analyzer 4294A, and the electromechanical coupling constant kt in the thickness direction was calculated. The practical range of the electromechanical coupling constant kt varies depending on the resin used, but in the case of silicone resin, a value of 0.03 or higher can be used without practical problems, with a value of 0.04 or higher being more preferable, and a value of 0.08 or higher being particularly preferable. On the other hand, in the case of polyvinylidene fluoride (PVDF) resin, a value of 0.05 or higher can be used without practical problems, with a value of 0.09 or higher being more preferable, and a value of 0.15 or higher being particularly preferable. Table 3 shows the electromechanical coupling constant kt of the thickness of the piezoelectric composite sheet.

[0206]

[0207] It was revealed that the piezoelectric composite sheet containing the particles of Example 1 exhibited a higher electromechanical coupling constant kt than the piezoelectric composite sheet containing the particles of Comparative Example 1, and exhibited an excellent piezoelectric effect. ｘ Na （１－ｘ） NbO ３ The crystallite size of the particles is the same as that of the powder of Comparative Example 1. ｘ Na （１－ｘ） NbO ３ It is believed that the excellent piezoelectric performance was achieved because the size was larger than the crystallite size of the particles.

Claims

1. K ｘ Na （１－ｘ） NbO ３ (wherein 0≦x≦1), wherein the crystal structure has an average crystallite size of 80 nm or more, determined from a peak at 2θ=23.0±1.0° of the niobate obtained by X-ray diffraction measurement.

2. The niobate particle of claim 1, wherein the crystal structure comprises a perovskite crystal structure.

3. The niobate particles according to claim 1 or 2, having a cubic shape.

4. Niobate particles according to claim 1 or 2, wherein the crystal structure has an average crystallite size of 50 nm or more as determined from a peak at 2θ=32.0±1.2° of the niobate obtained by X-ray diffraction measurement.

5. Median diameter D calculated by laser diffraction / scattering method ５０ The niobate particles according to claim 1 or 2, wherein the average particle diameter is 0.1 to 100 μm.

6. The total niobium content in the niobate particles is determined by XRF analysis of the niobate particles, and is calculated by dividing the total mass of the niobate particles by 100% by weight of Nb. ２ O ５ The niobate particles according to claim 1 or 2, wherein the content in terms of niobium is 50 to 99 mass%.

7. The potassium and / or sodium content in the niobate particles is determined by XRF analysis of the niobate particles. The potassium and / or sodium content is calculated based on the total mass of the niobate particles (100 mass%). ２ O equivalent and Na ２ The niobate particles according to claim 1 or 2, wherein the content in terms of O is 0.5 to 40 mass %.

8. The niobate particles of claim 1, comprising molybdenum.

9. The molybdenum content in the niobate particles is determined by XRF analysis of the niobate particles, and is expressed as MoO ３ The niobate particles according to claim 8, wherein the content in terms of niobium is 0.01 to 20 mass%.

10. A method for producing the niobate particles according to claim 1, comprising calcining a niobium compound in the presence of a molybdenum compound and a potassium compound and / or a sodium compound.

11. The method for producing molybdate particles according to claim 10, wherein the molybdenum compound is at least one compound selected from the group consisting of molybdenum trioxide, potassium molybdate and sodium molybdate.

12. A method for producing a niobium compound (Nb １ ) relative to the mass of the flux component sodium compound (Na １ ), potassium compounds (K １ ), molybdenum compounds (Mo １ ) total mass ratio (Nb １ ) / (Na １ +K １ +Mo １ 12. The method for producing niobate particles according to claim 10 or 11, wherein the value of n is 0.6 or more.

13. A method for producing niobate particles according to claim 10 or 11, comprising the steps of mixing a niobium compound, a molybdenum compound, and a potassium compound and / or a sodium compound to obtain a mixture, and firing the mixture, wherein the molar ratio of potassium atoms, sodium atoms, molybdenum atoms, and niobium atoms in the mixture satisfies (K+Na) / (2×Mo+Nb)>1.

14. A resin composition comprising the niobate particles according to claim 1 or 2 and a resin.

15. A molded article obtained by molding the resin composition according to claim 14.

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