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

Abstract

Provided is a method for producing niobate particles with excellent productivity. Also provided are niobate particles having high crystallinity by the above production method. K x Na (1-x) Niobate particles containing a crystal structure of niobate represented by NbO3 (where 0 ≦ x ≦ 1), the crystal structure having 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. The crystal structure preferably includes a perovskite crystal structure.

Description

Technical Field

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

Background Art

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

[0003] Among them, the alkali metal niobate represented by K x Na 1-x NbO3 (0 ≦ x ≦ 1) has a perovskite crystal structure, and thus is applied as a piezoelectric ceramic. In addition, the alkali metal niobate is mixed with a resin and developed for use as a piezoelectric composite.

[0004] By the way, in order to enhance the versatility of the applications of alkali metal niobates, controlling the crystal growth of the alkali metal niobates is a very important technique. For example, as a piezoelectric material, it is expected that the larger the crystallite size, the more excellent piezoelectric effect can be exhibited.

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

[0006] Non-Patent Document 1 discloses a lead-free (K 0.50 Na 0.50 ) 0.94 Li 0.06A new two-step firing method capable of synthesizing NbO3 particles is disclosed.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Non-Patent Documents

[0008]

Non-Patent Document 1

[12] , 3957-3963.

Summary of the Invention

Problems to be Solved by the Invention

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

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

Means for Solving the Problems

[0011] The present invention has the following aspects.

[0012] (1) Niobate particles containing a crystal structure of K x Na (1-x) NbO3 (where 0 ≦ x ≦ 1), wherein 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.

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

[0014] (3) The 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, which is obtained from the peak at 2θ = 32.0 ± 1.2° of the niobate by X-ray diffraction measurement.

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

[0017] (6) The total content of niobium in the niobate particles is a content rate in terms of Nb2O5 conversion with respect to 100% by mass of the total mass of the niobate particles, which is obtained by XRF analysis of the niobate particles, and is 50 to 99% by mass, and the niobate particles according to any one of (1) to (5) above.

[0018] (7) The potassium and / or sodium content in the niobate particles is a content rate in terms of K2O conversion and Na2O conversion with respect to 100% by mass of the total mass of the niobate particles, which is obtained by XRF analysis of the niobate particles, and is 0.5 to 40% by mass, and the niobate particles according to any one of (1) to (6) above.

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

[0020] (9) The molybdenum content in the niobate particles is a content rate in terms of MoO3 conversion with respect to 100% by mass of the total mass of the niobate particles, which is obtained by XRF analysis of the niobate particles, and is 0.01 to 20% by mass, and the niobate particles according to (8) above.

[0021] (10) A method for producing niobate particles according to any one of (1) to (9) above, comprising firing 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 step of mixing a niobium compound, a molybdenum compound, a potassium compound and / or a sodium compound to form a mixture, and a step of firing the mixture, The method for producing niobate particles according to (10) or (11) above, wherein the ratio (Nb1) / (Na1 + K1 + Mo1) of the total mass of the sodium compound (Na1), potassium compound (K1), and molybdenum compound (Mo1), which are flux components, to the mass of the niobium compound (Nb1) in the mixture is 0.6 or more.

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

Advantages of the Invention

[0027] According to the present invention, a method for producing niobate particles with excellent productivity can be provided. Further, according to the present invention, niobate particles having high crystallinity and excellent piezoelectric performance, a resin composition containing the niobate particles, and a molded body thereof can be provided.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

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

[0030] <Niobate Particles> K x Na (1-x) The niobate particles include a crystal structure of niobate represented by K

[0031] Na x Na (1-x) NbO3 (where 0 ≦ x ≦ 1). 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. x Na (1-x) In NbO3, x is 0 ≦ x ≦ 1. When 0 < x < 1, K x Na (1-x) NbO3 is potassium sodium niobate (K x Na (1-x) NbO3). When x is 0, K x Na(1-x) NbO3 is sodium niobate (NaNbO3). When x is 1, K x Na (1-x) NbO3 is potassium niobate (KNbO3).

[0032] Piezoelectric materials are preferably characterized by including a composition called a morphotropic phase boundary (MPB) at the boundary between different crystal systems (such as monoclinic and orthorhombic, orthorhombic and tetragonal, etc.). The value of x can be adjusted so that the composition is near this phase boundary. K x Na (1-x) In KNaNbO3, for example, it is preferable that 0.4 ≦ x ≦ 0.6, and more preferably 0.45 ≦ x ≦ 0.55. Note that for improving characteristics other than piezoelectric performance, such as durability, it is possible to include a composition outside the MPB composition itself. Therefore, the composition of the niobate particles of the embodiment is not limited to this preferable range and is effective throughout the range of 0 ≦ x ≦ 1.

[0033] Also, for the purpose of suppressing leakage current and maintaining insulation, elements with a valence lower than that of Nb, such as Mn, Cr, Co, Ni, Zn, etc., may be appropriately included in an amount within a few moles (1 to 3 mol%) with respect to Nb. Also, as inevitable impurities in the raw materials, elements such as Fe may be included.

[0034] In this specification, even if the particles contain KNaNbO3 in any of the above cases, they may simply be referred to as "niobate particles". Also, the description of the numerical range of x may be omitted. x Na (1-x) The type, composition, and crystal structure of the niobate contained in the niobate particles of the embodiment can be specified by the XRD pattern of the spectrum obtained by XRD analysis.

[0035]

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

[0037] 〔Measurement of crystallite size〕 Using an X-ray diffractometer (for example, SmartLab manufactured by Rigaku Corporation), measurement is performed using analysis software. The measurement method is the 2θ / θ method, and the average crystallite size is calculated from the half-value width of the target peak (the peak having a peak top in the target 2θ range) using the Scherrer equation.

[0038] The average crystallite size determined from the peak at 2θ = 23.0 ± 1.0° of the crystal structure contained in the niobate particles of the embodiment 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 value, excellent piezoelectric performance is exhibited when the molded body described later is formed.

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

[0040] K x Na (1-x) NbO3 can exhibit a crystal system different from the monoclinic system, orthorhombic system, or tetragonal system depending on the composition, and the plane assignment differs 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] Regarding the target peak obtained by the above measurement of the crystallite size, when assigned assuming a cubic system without considering peak splitting, the peak at 2θ = 23.0 ± 1.0° described above corresponds to the position of the (100) plane of the cubic system. When the peak is split, the crystallite size is defined by the peak with the highest intensity.

[0042] The average crystallite size determined from the peak at 2θ = 32.0 ± 1.2° of the crystal structure included in the niobate particles of the embodiment 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 at least the above lower limit value, more excellent piezoelectric performance is exhibited.

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

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

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

[0046] The average crystallite size determined from the peak at 2θ = 57.0 ± 1.0° of the crystal structure included in the niobate particles of the embodiment 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 at least the above lower limit value, more excellent piezoelectric performance is exhibited.

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

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

[0049] According to the production method of the embodiment described later, it is excellent in controlling the crystal growth of the produced niobate particles, 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 the fluxing agent and the firing conditions in the production method described later.

[0051] The crystal structure of the niobate particles of the embodiment may include a perovskite crystal structure.

[0052] The niobate particles of the embodiment can have a cubic shape.

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

[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 becomes higher, niobate particles tend to be obtained in which the average crystallite size is larger and the particle size is also larger.

[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. The upper limit value of the particle size when the niobate particles have a cubic shape is not particularly limited. As an example, it may be 100 μm or less, may be 80 μm or less, and may be 50 μm or less. As an example of the upper limit numerical range of the particle size when the niobate particles have a cubic shape, it may be 0.1 to 100 μm, may be 0.5 to 80 μm, and may be 1 to 50 μm.

[0057] In this specification, the "particle size" of the niobate particles having a cubic shape is the length of one side of the hexahedron determined from the particle image of the primary particles of the niobate particles in the two-dimensional image taken by a scanning electron microscope (SEM). The value of the particle size of the niobate particles having the cubic shape is taken as the average value obtained from 50 or more niobate particles randomly selected from among the particles having the euhedral shape of the above measurement target.

[0058] When including niobate particles having a cubic shape, it is preferable that 50% or more of the particles have a cubic shape based on 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 the laser diffraction / scattering method50 may be 0.1 to 100 μm, may be 0.5 to 80 μm, and may be 1 to 50 μm.

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

[0061] The median diameter D of the niobate particles of the embodiment, calculated by the laser diffraction / scattering method 90 may be 0.5 to 150 μm, may be 1 to 100 μm, and 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 diameter at which the ratio of volume integration % is 50% in the particle diameter distribution measured dry using a laser diffraction particle size distribution analyzer. The D of the niobate particle sample, calculated by the laser diffraction / scattering method 10 can be determined as the particle diameter at the point where the distribution curve of volume integration % intersects 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 distribution curve of volume integration % intersects the horizontal axis at 90% from the small particle side.

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

[0064] The above specific surface area is measured with a specific surface area meter (for example, BELSORP-mini manufactured by MicrotracBEL Corporation), and the surface area per 1 g of the sample measured from the adsorption amount of nitrogen gas by the BET method (Brunauer-Emmett-Teller method) is calculated as the specific surface area (m 2 / g).

[0065] The niobate particles of the embodiment contain K x Na (1-x) NbO3 (where 0 ≤ x ≤ 1).

[0066] The niobate particles of the embodiment preferably contain the K x Na (1-x) NbO3 in an amount of 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, based on 100% by mass of the niobate particles.

[0067] Generally, since the niobate particles obtained after firing are a mixture with a flux (for example, potassium sodium molybdate, sodium oxide, potassium oxide, sodium carbonate, or potassium carbonate), it is preferable to perform washing to increase the purity. However, according to the manufacturing method described later, niobate particles within the above range can be obtained without going through a special washing process.

[0068] In the niobate particles, the content of niobium may be such that the total content rate in terms of Nb2O5 conversion and Ta2O5 conversion with respect to 100% by mass of the total mass of the niobate particles determined by XRF analysis of the niobate particles is 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] The content rate in terms of Nb2O5 conversion refers to a value obtained from the amount of Nb2O5 obtained by converting the niobium content determined by XRF analysis using a calibration curve in terms of Nb2O5 conversion.

[0070] The niobate particles of the embodiment contain potassium and / or sodium.

[0071] In the niobate particles, the potassium and / or sodium content may be such that the total content rate in terms of K2O conversion and Na2O conversion with respect to 100% by mass of the total mass of the niobate particles, which is determined by XRF analysis of the niobate particles, is 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] The total content rate in terms of K2O conversion and Na2O conversion refers to a value obtained from the sum of the amount of K2O obtained by converting the potassium content determined by XRF analysis using a calibration curve for K2O conversion and the amount of Na2O obtained by converting the sodium content determined by XRF analysis using a calibration curve for Na2O conversion. When the composition of the niobate particles is K x Na (1-x) NbO3 and x = 0 or 1, the potassium content or the sodium content may be 0.

[0073] The niobate particles of the embodiment may further contain molybdenum.

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

[0075] Regarding the molybdenum contained in the niobate particles of the embodiment, its state of existence and amount are not particularly limited, and in addition to molybdenum metal, molybdenum oxide or a molybdenum compound in which a part has been reduced may be contained in the niobate particles. Molybdenum is considered to be contained in the niobate particles as MoO3, but in addition to MoO3, it may also be contained in the niobate particles as MoO2 or MoO.

[0076] The form of molybdenum inclusion is not particularly limited, and it may be included in a form adhering to the surface of the niobate particles, may be included in a form substituted for a part of the crystal structure of the niobate particles, may be included in an amorphous state, or may be a combination thereof.

[0077] When the niobate particles of the embodiment contain molybdenum, the molybdenum content may be such that the content rate in terms of MoO3 with respect to 100% by mass of the total mass of the niobate particles, which is determined by XRF analysis of the niobate particles, is 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] The content rate in terms of MoO3 refers to a value obtained from the amount of MoO3 obtained by converting the molybdenum content determined by XRF analysis using a calibration curve in terms of MoO3.

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

[0080] As an example of the niobate particles of the embodiment, niobate particles can be exemplified in which the content rate in terms of MoO3 of molybdenum with respect to 100% by mass of the total mass of the niobate particles, which is determined by XRF analysis of the niobate particles, is 0 to 20% by mass, the content rate in terms of Nb2O5 of niobium is 50 to 99% by mass, and the content rates in terms of K2O and Na2O of potassium and sodium are 0.5 to 40% by mass. As another example of the niobate particles of the embodiment, niobate particles can be exemplified in which the content rate in terms of MoO3 of molybdenum with respect to 100% by mass of the total mass of the niobate particles, which is determined by XRF analysis of the niobate particles, is 0.01 to 20% by mass, the content rate in terms of Nb2O5 of niobium is 50 to 99% by mass, and the content rates in terms of K2O and Na2O of potassium and sodium are 0.5 to 40% by mass. As another example of the niobate particles of the embodiment, the content of molybdenum in terms of MoO3 is 0.05 to 15% by mass, the content of niobium in terms of Nb2O5 is 60 to 98% by mass, and the contents of potassium and sodium in terms of K2O and Na2O are 1 to 30% by mass with respect to 100% by mass of the total mass of the niobate particles, which are determined by XRF analysis of the niobate particles, can be exemplified. As another example of the niobate particles of the embodiment, the content of molybdenum in terms of MoO3 is 0.06 to 10% by mass, the content of niobium in terms of Nb2O5 is 70 to 95% by mass, and the contents of potassium and sodium in terms of K2O and Na2O are 3 to 25% by mass with respect to 100% by mass of the total mass of the niobate particles, which are determined by XRF analysis of the niobate particles, can be exemplified.

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

[0082] The niobate particles of the embodiment are produced by the production method described below. According to the production method described below, different from the conventional production method, desired niobate particles can be obtained only by a one-step firing and mixing process, so the production efficiency is high and preferable.

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

[0084] <Method for Producing Niobate Particles> The method for producing niobate particles of the embodiment includes firing 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 the present embodiment, it is possible to produce the niobate particles according to one embodiment of the present invention described above.

[0086] Further, according to the method for producing niobate particles of the present embodiment, by firing a niobium compound in the presence of a molybdenum compound and a potassium compound and / or a sodium compound, the degree of crystal growth of the produced niobate particles is excellent. Furthermore, according to the method for producing niobate particles of the present embodiment, by firing a niobium compound in the presence of potassium carbonate and / or sodium carbonate, the degree of crystal growth of the produced niobate particles is even more excellent.

[0087] A preferred method for producing niobate particles may 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, instead of at least a part of the molybdenum compound and the potassium compound, a compound containing molybdenum and potassium, such as potassium molybdate, can also be used. Similarly, instead of at least a part of the molybdenum compound and the sodium compound, a compound containing molybdenum and sodium, such as sodium molybdate, can also be used. Therefore, mixing a compound containing molybdenum, potassium, and / or sodium is also regarded as mixing a molybdenum compound, a potassium compound, and / or a 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 produced niobate particles contain potassium sodium niobate, 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) can be included.

[0091] When the produced niobate particles contain potassium niobate, a step of mixing a niobium compound, a molybdenum compound, and optionally a potassium compound to form a mixture (mixing step) can be included.

[0092] When the produced niobate particles contain sodium niobate, a step of mixing a niobium compound, a molybdenum compound, and optionally a sodium compound to form a mixture (mixing step) can be included.

[0093] Hereinafter, the content of the mixture will be described.

[0094] (Niobium compound) The niobium compound is not limited as long as it can be fired with a raw material compound to form a niobate, 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 alkoxide, etc. Niobium hydroxide and niobium oxide are preferred, and niobium oxide is more preferred. Examples of niobium oxide include niobium pentoxide (Nb2O5), niobium dioxide (NbO2), and niobium monoxide (NbO). In addition to the niobium oxides with the above oxidation numbers, any niobium oxides with different valences can be used. The physical forms such as the shape, particle size, and specific surface area of these niobium compounds as precursors are not particularly limited.

[0095] Since the shape after firing hardly reflects the shape of the raw material niobium compound, for example, it can be suitably used in any of spherical, amorphous, structured aspect (wire, fiber, ribbon, tube, etc.), sheet, etc.

[0096] (Molybdenum compound) Examples of the molybdenum compound include molybdenum oxide, molybdic acid, molybdenum sulfide, molybdate compounds, etc., and molybdenum oxide or molybdate compounds are preferred.

[0097] Examples of the molybdenum oxide include molybdenum dioxide (MoO2), molybdenum trioxide (MoO3), etc., and molybdenum trioxide is preferred.

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

[0099] In the method for producing the niobate particles of the present 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, which is suitable as a fluxing agent, can be produced, for example, from a molybdenum compound and a potassium compound, which are cheaper and more easily available, in the process of firing. Here, when a molybdenum compound and a potassium compound are used as a fluxing agent, and when a compound containing molybdenum and potassium is used as a fluxing agent, both cases are regarded as the case where a molybdenum compound and a potassium compound are used as a fluxing agent, that is, in the presence of a molybdenum compound and a potassium compound.

[0102] Compounds containing molybdenum and sodium, which are suitable as fluxes, can be produced, for example, from cheaper and more readily available molybdenum compounds and sodium compounds during the firing process. Here, when molybdenum compounds and sodium compounds are used as fluxes, and when compounds containing molybdenum and sodium are used as fluxes, both cases are considered as using molybdenum compounds and sodium compounds as fluxes, that is, in the presence of molybdenum compounds and sodium compounds.

[0103] In addition, the above-mentioned molybdenum compounds may be used alone or in combination of two or more.

[0104] Also, potassium molybdate (K2Mo n O 3n+1 , n = 1 to 3) contains potassium and thus may also have the function as a potassium compound described later.

[0105] Also, sodium molybdate (Na2Mo n O 3n+1 , n = 1 to 3) contains sodium and thus may also have the function as a sodium compound described later.

[0106] (Potassium compound) The potassium compound is not particularly limited, and examples thereof include 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, and the like. At this time, similar to the case of the molybdenum compound, the potassium compound contains isomers. Among these, it is preferable to use potassium carbonate, potassium hydrogen carbonate, potassium oxide, potassium hydroxide, potassium chloride, potassium sulfate, potassium molybdate, more preferably potassium carbonate, potassium hydrogen carbonate, potassium chloride, potassium sulfate, potassium molybdate, and even more preferably potassium carbonate and / or potassium molybdate.

[0107] In addition, the above-mentioned potassium compounds may be used alone or in combination of two or more.

[0108] Also, similar to the above, since potassium molybdate contains molybdenum, it may also have the function as the above-mentioned molybdenum compound.

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

[0110] In addition, the above-mentioned sodium compounds may be used alone or in combination of two or more.

[0111] Also, similar to the above, since sodium molybdate contains molybdenum, it may also have the function as the molybdenum compound described above.

[0112] Thus, although there may be overlapping notations as molybdenum compounds in classification, as an example, the molybdenum compound is at least one compound selected from the group consisting of molybdenum trioxide, potassium molybdate, and sodium molybdate. It is preferable that the sodium compound is sodium carbonate or sodium molybdate, and the potassium compound is potassium carbonate or potassium molybdate.

[0113] Preferably, a method for producing potassium sodium niobate particles can be exemplified, which includes firing a niobium compound in the presence of a molybdenum compound, a potassium compound, and a sodium compound.

[0114] Preferably, a method for producing sodium niobate particles can be exemplified, which includes firing a niobium compound in the presence of a molybdenum compound and a sodium compound.

[0115] Preferably, a method for producing potassium niobate particles can be exemplified, which includes firing a niobium compound in the presence of a molybdenum compound and a potassium compound.

[0116] In the method for producing niobate particles of the present embodiment, the potassium compound, the sodium compound, and the molybdenum compound are used as a fluxing agent. When a potassium compound and / or a sodium compound is used as a fluxing agent, it is presumed that oxides (Na2O or K2O) are formed from a part of the potassium compound and / or the sodium compound by such firing, and this functions as a flux, and the crystal growth of niobate proceeds.

[0117] Furthermore, when the niobium compound is calcined in the presence of potassium carbonate and / or sodium carbonate, oxides (Na2O or K2O) and / or CO2 are formed from a part of the potassium carbonate and / or sodium carbonate. It is presumed that these oxides and / or CO2 function as a flux and the crystal growth of niobate proceeds. By such calcination, the reaction forms oxides (Na2O or K2O) and / or CO2 that function as a flux, along with niobate particles (K x Na (1-x) NbO3). It is considered that the oxides (Na2O or K2O) and / or CO2 function as a flux, promoting the formation of niobate particles (K x Na (1-x) NbO3) with a large crystallite size.

[0118] The molybdate compound as the above flux does not vaporize even in the calcination temperature range and can be easily recovered by washing after calcination. Therefore, the amount of the molybdenum compound released outside the calcination furnace is also reduced, and the production cost can be significantly reduced.

[0119] In the method for producing niobate particles of the present embodiment, the total usage amounts of the raw material molybdenum compound, potassium compound, and sodium compound (hereinafter also referred to as the flux agent), which are considered to function as a flux agent, and the usage amount of the niobium compound are not particularly limited. Preferably, based on the mass of the niobium compound (Nb1), the ratio of the total mass of the sodium compound (Na1), potassium compound (K1), and molybdenum compound (Mo1) as the flux components, (Nb1) / (Na1 + K1 + Mo1), is 0.6 or more, and the mixture can be calcined. More preferably, the ratio of the total mass, (Nb1) / (Na1 + K1 + Mo1), is 0.64 or more, and the mixture can be calcined. Even more preferably, the ratio of the total mass, (Nb1) / (Na1 + K1 + Mo1), is 0.67 or more, and the mixture can be calcined.

[0120] From the viewpoint of efficient crystal growth, it is preferable that the amount of the flux agent used with respect to the niobium compound of the raw material is not less than the above mass ratio. By reducing the amount of the flux agent used with respect to the niobium compound of the raw material, although the detailed reason is not clear, the removability of the fired product from the firing container is improved, which is preferable. Further, 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, it is preferable that the molar ratio (K+Na) / (2×Mo+Nb) of potassium atoms, sodium atoms, molybdenum atoms, and niobium atoms in the mixture is greater than 1.0, more preferably 1.01 to 1.20, still more preferably 1.02 to 1.15, and particularly preferably 1.02 to 1.10.

[0122] When the molar ratio (K+Na) / (2×Mo+Nb) is within the above range, it is preferable because niobate particles with improved crystallite size can be easily obtained. In addition, when the molar ratio (K+Na) / (2×Mo+Nb) is 1.25 or less, crystal growth is promoted in the obtained niobate particles, and the amount of amorphous particles can be suppressed, which is particularly preferable.

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

[0124] According to the production method of the present invention, compared with the conventional production method, only one-step firing is required, and K x Na (1-x)While controlling the composition ratio of the niobate particles represented by NbO3, niobate particles can be obtained in a high yield, and furthermore, it becomes possible to control the particle diameter and crystallite diameter of the particles.

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

[0126] The method of firing is not particularly limited and can be performed by a known and commonly used method. When a molybdenum compound is used, if the firing temperature exceeds 500 °C, some niobium compounds react with the molybdenum compound to form niobium molybdate, etc., and from the molybdenum compound, molybdates (K a Mo b O c and Na a Mo b O c , K a Na a’ Mo b O c ) are considered to be formed. Furthermore, when the firing temperature reaches 800 °C or higher, some of the formed niobium molybdate, etc. decomposes, and it is considered that niobate particles are formed by the flux function of the molybdate. Also, in the niobate particles, it is considered that the molybdenum compound is incorporated into the niobate particles during the decomposition of niobium molybdate and the process of particle crystal growth.

[0127] Also, the states of the niobium compound, molybdenum compound, sodium compound, potassium compound, etc. that can be used during firing are not particularly limited, and it is sufficient that the raw material compounds such as the molybdenum compound, niobium compound, sodium compound, and potassium compound exist in the same space where they can act on each other. Specifically, it may be a simple mixing of the raw material compound powders, mechanical mixing using a pulverizer, etc., or mixing using a mortar, etc., and it may be mixing in a dry state or a wet state.

[0128] There is no particular limitation on the firing temperature conditions, and it is appropriately determined in consideration of the particle size of the target niobate particles, the formation of molybdenum compounds 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 molybdate can function as a flux, 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 improved crystallite size, the above firing temperature is preferably 800 °C or higher, more preferably 900 °C or higher, and even more preferably 1000 °C or higher.

[0129] Generally, when attempting to control the shape of the niobate obtained after firing, it is necessary to perform high-temperature firing above 1500 °C, which is close to the melting point of niobium oxide. However, from the viewpoints of the burden on the firing furnace and fuel cost, there are major problems for industrial use.

[0130] According to an embodiment of the present invention, for example, even under the condition that the maximum firing temperature for firing a niobium compound is 1500 °C or lower, the formation of niobate particles can be efficiently performed at low cost. Further, according to the method for producing niobate particles of the embodiment, even at a temperature much lower than the melting point of niobium oxide, i.e., 1300 °C or lower, self-shaped niobate particles can be formed regardless of the shape of the precursor. Also, from the viewpoint of efficiently producing niobate particles, the above firing temperature is preferably 1200 °C or lower, more preferably 1100 °C or lower.

[0131] As an example, the numerical range of the firing temperature for firing the niobium compound in the firing step may be 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 the charging amount of a specific flux and the firing temperature, desired particles can be easily obtained.

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

[0133] Regarding the firing time, it is preferable to carry out the temperature rising time to a predetermined firing temperature in the range of 15 minutes to 10 hours, and to carry out the holding time at the firing temperature in the range of 5 minutes to 30 hours. In order to efficiently form niobate particles, it is preferable that the holding time at the firing temperature is 2 hours or more, and more preferably 2 to 15 hours. By selecting the conditions that the firing temperature is 700 to 1100 °C and the holding time at the firing temperature is 2 to 15 hours, niobate particles with 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 preferable, and an air atmosphere is more preferable in consideration of cost.

[0135] The apparatus for firing is not necessarily limited, and a so-called firing furnace can be used. The firing furnace is preferably made of a material that does not react with sublimated molybdenum oxide, and more preferably, a highly airtight firing furnace is used so as to efficiently utilize molybdenum oxide.

[0136] [Cooling step] The method for producing niobate particles may include a cooling step. The cooling step is a step of cooling the niobate particles that have grown crystals in the firing step.

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

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

[0139] [Post-treatment step] The manufacturing method of the present embodiment may include a post-treatment step. The post-treatment step may be a step of separating the niobate particles and the fluxing agent contained in the fired product, and can be performed by taking out the fired product from the firing container. The post-treatment step can be performed after the above-described firing step. Further, if necessary, it may be repeated two or more times.

[0140] Examples of the method for removing the fluxing agent include washing and high-temperature treatment. These can be performed in combination.

[0141] The washing method is not particularly limited, but when the flux is water-soluble such as the above potassium compound, sodium compound, and molybdate compound, water washing or the like can be mentioned.

[0142] Further, examples of the high-temperature treatment method include a method of raising the temperature to a temperature equal to or higher than the sublimation point or boiling point of the flux.

[0143] [Grinding step] The fired product obtained through the firing step may have niobate particles aggregated and not satisfy the range of suitable particle diameters for the intended use. Therefore, the niobate particles may be ground as necessary so as to satisfy the range of suitable particle diameters. The method for pulverizing the fired product is not particularly limited, and conventionally known pulverization methods such as a ball mill, jaw crusher, jet mill, disk mill, spectromill, grinder, mixer mill, etc. can be applied.

[0144] [Classification step] The fired product containing niobate particles obtained by the firing step may be appropriately classified for adjusting the particle size range. "Classification treatment" refers to an operation of grouping particles according to their size. The classification can be either wet or dry, but from the viewpoint of productivity, dry classification is preferred. For dry classification, in addition to classification by a sieve, there is air classification that classifies by the difference between centrifugal force and fluid resistance. 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 cyclone air classifier, a forced vortex centrifugal classifier, a semi-free vortex centrifugal classifier, etc. The above-mentioned pulverization step and classification step can be performed at necessary stages. By the presence or absence of these pulverization and classification and the selection of their conditions, for example, the average particle size of the obtained niobate particles can be adjusted.

[0145] In the above-mentioned production method, by combining the ratio (Nb1) / (Na1 + K1 + Mo1) of the total mass of the sodium compound (Na1), potassium compound (K1), and molybdenum compound (Mo1) which are flux components to the mass of the niobium compound (Nb1) with a firing temperature in a specific range, 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 production method of the embodiment, which have little or no aggregation, are likely to exhibit their original properties, are excellent in their own handleability, and are preferable from the viewpoint of being more excellent in dispersibility when dispersed in a dispersion medium and used.

[0147] According to the method for producing niobate particles of the above embodiment, since niobate particles with little or no aggregation can be easily produced, excellent niobate particles with the desired properties can be produced with high productivity without performing the above-mentioned grinding step or classification step, which has excellent advantages.

[0148] ≪Resin Composition≫ The niobate particles of the embodiment can be blended with a resin and provided as a resin composition. As 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, and may be a thermosetting resin, a thermoplastic resin, or an active energy ray curable resin.

[0149] (Thermosetting Resin) A thermosetting resin is a resin having a property that it can be substantially insolubilized and infusibilized when cured by heating or means such as radiation or a catalyst. For example, it may be a known and commonly used resin used in molding materials and the like. Specifically, for example, novolak type phenol resins such as phenol novolak resin and cresol novolak resin; resol type phenol resins such as unmodified resol phenol resin, tung oil, linseed oil, walnut oil, and other oil-modified resol phenol resins; bisphenol type epoxy resins such as bisphenol A epoxy resin and bisphenol F epoxy resin; novolak type epoxy resins such as aliphatic chain modified bisphenol type epoxy resin, novolak epoxy resin, and cresol novolak epoxy resin; epoxy resins such as biphenyl type epoxy resin and polyalkylene glycol type epoxy resin; resins having a triazine ring such as urea (urethane) 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. can be mentioned, and it may be a polymer, an oligomer, or a monomer.

[0150] The above-mentioned thermosetting resin 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 of the compounds commonly used as curing agents can be used. Examples include amine compounds, amide compounds, acid anhydride compounds, phenolic compounds, etc. Specifically, examples of amine compounds include diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenylsulfone, isophoronediamine, imidazole, BF3-amine complex, guanidine derivatives, etc. Examples of amide compounds include dicyandiamide, polyamide resins synthesized from dimers of linolenic acid and ethylenediamine, etc. Examples of acid anhydride compounds include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, etc. Examples of phenolic compounds include phenol novolak resins, cresol novolak resins, aromatic hydrocarbon formaldehyde resin-modified phenolic resins, dicyclopentadiene phenol addition-type resins, phenol aralkyl resins (zylox resins), polyhydric phenol novolak resins synthesized from polyhydric hydroxy compounds typified by resorcinol novolak resins and formaldehyde, naphthol aralkyl resins, trimethylolmethane resins, tetraphenylol ethane resins, naphthol novolak resins, naphthol-phenol co-condensed novolak resins, naphthol-cresol co-condensed novolak resins, biphenyl-modified phenolic resins (polyhydric phenolic compounds in which phenolic nuclei are linked by bismethylene groups), biphenyl-modified naphthol resins (polyhydric naphtholic compounds in which phenolic nuclei are linked by bismethylene groups), aminotriazine-modified phenolic resins (polyhydric phenolic compounds in which phenolic nuclei are linked by melamine, benzoguanamine, etc.), alkoxy group-containing aromatic ring-modified novolak resins (polyhydric phenolic compounds in which phenolic nuclei and alkoxy group-containing aromatic rings are linked by formaldehyde), and other polyhydric phenolic compounds. These curing agents may be used alone or in combination of two or more kinds.

[0151] In the resin composition of the embodiment, the compounding amounts of the thermosetting resin and the above-mentioned curing agent are not particularly limited. For example, when the curable resin is an epoxy resin, from the viewpoint of good properties of the obtained cured product, it is preferable to use an amount such that the active groups in the curing agent are 0.7 to 1.5 equivalents with respect to a total of 1 equivalent of the epoxy groups of the epoxy resin.

[0152] Also, if necessary, a curing accelerator can be appropriately 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. Examples include phosphorus compounds, tertiary amines, imidazoles, organic acid metal salts, Lewis acids, amine complex salts, and the like.

[0153] Also, if necessary, a curing catalyst can be used in combination with the thermosetting resin in a timely manner, and examples include known and commonly used thermal polymerization initiators and active energy ray polymerization initiators.

[0154] (Thermoplastic resin) Examples of the thermoplastic resin that may be used in the resin composition of the embodiment include known and commonly used resins used in molding materials and the like. Specifically, for example, 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, polyethersulfone resin, polyetheretherketone 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 kind of thermoplastic resin can be selected and used, but depending on the purpose, it is also possible to use a combination of two or more kinds of thermoplastic resins.

[0155] When provided for piezoelectric applications, it is preferable that the resin exhibits a high dielectric constant. As the resin, a polymer having an electron-withdrawing group is preferable, and fluorine-containing polymers such as polyvinylidene fluoride (PVDF), vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, etc., and polymers 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 hydroxy pullulan, 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 and cyanoethyl sorbitol are preferably used.

[0156] The resin composition of the embodiment may contain other formulations as necessary, and within the range where the effects of the invention can be obtained, external lubricants, internal lubricants, antioxidants, flame retardants, light stabilizers, ultraviolet absorbers, coupling agents of silane-based, titanate-based, and aluminate-based, reinforcing materials such as glass fibers and carbon fibers, fillers, various colorants, etc. may be added. Also, the use of stress relaxation agents (low stress agents) such as silicone oil, liquid rubber, rubber powder, butadiene-based copolymer rubbers such as methyl methacrylate-butadiene-styrene copolymer, methyl methacrylate-butadiene-styrene copolymer, and silicone-based compounds is also possible.

[0157] The resin composition of the embodiment is obtained by mixing the niobate particles of the embodiment, the resin, and further other formulations as necessary. There is no particular limitation on the mixing method, and they are mixed by known and commonly used methods.

[0158] As a general method when the resin is a thermosetting resin, the thermosetting resin, the niobate particles of the embodiment, and other components as required are sufficiently mixed by a mixer or the like, and then kneaded by a three-roll mill or the like to obtain a fluid liquid composition, or a thermosetting resin in a predetermined blending amount, the niobate particles of the embodiment, and other components as required are sufficiently mixed by a mixer or the like, and then melt-kneaded by a mixing roll, an extruder, or the like, and then cooled to obtain a solid composition. In the case where a curing agent, a catalyst, or the like is blended, it is preferable that the curable resin and the blend thereof are sufficiently and uniformly mixed, and it is more preferable that the niobate particles of the embodiment are also uniformly dispersed and mixed.

[0159] As a general method when the resin is a thermoplastic resin, the thermoplastic resin, the niobate particles of the embodiment, and other components as required are premixed using various mixers such as a tumbler and a Henschel mixer, and then melt-kneaded using a mixer such as a Banbury mixer, a roll, a Brabender, a single-screw kneading extruder, a twin-screw kneading extruder, a kneader, and a mixing roll. The temperature of the melt-kneading is not particularly limited, but a range of 240 to 320 °C can be mentioned.

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

[0161] The proportion of the content of the niobate particles with respect 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%, and may be 30 to 85 vol%.

[0162] ≪Molded article≫ A molded article can be obtained by molding the resin composition of the embodiment. As one embodiment, a molded article obtained by molding the resin composition of the embodiment is provided. To obtain a resin molded article, it can be carried out by a known and commonly used method.

[0163] For example, when the resin contained in the resin composition is a thermosetting resin, it may conform to the curing method of a thermosetting resin composition such as a general epoxy resin composition. For example, a resin composition in which the resin is an epoxy resin can be cured by heat, and the heating temperature conditions at that time can be appropriately selected according to the type and use of the curing agent to be combined, and it may be heated in a temperature range of room temperature to about 250°C. In the case of an active energy ray curable resin, it can be cured and molded by irradiating active energy rays such as ultraviolet rays and infrared rays.

[0164] Also, when the resin of the embodiment is a thermoplastic resin, it can be made into a molded product by a known and commonly used molding method. For example, injection molding method, ultra-high speed injection molding method, injection compression molding method, two-color molding method, hollow molding methods such as gas assist, molding method using a heat-insulating mold, molding method using a rapid heating mold, foam molding (including supercritical fluid), insert molding, IMC (in-mold coating molding) molding method, extrusion molding method, sheet molding method, rotational molding method, lamination molding method, press molding method, etc. can be mentioned. Also, a molding method using a hot runner system can be used. There is no limitation on the shape, pattern, color, dimensions, etc. of the molded product, and it can be arbitrarily set according to the use of the molded product.

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

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

Examples

[0167] Next, examples will be shown to explain the present invention in more detail, but the present invention is not limited to the following examples. That is, each configuration in each embodiment and their combinations, etc. are examples, and additions, omissions, substitutions, and other changes of the configuration are possible without departing from the gist of the present invention. Further, the present invention is not limited by each embodiment, but is limited only by the scope of the claims.

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

[0169] [XRF (X-ray fluorescence) analysis] Using a fluorescence X-ray analyzer Supermini200 (manufactured by Rigaku Corporation), about 5 g of the sample powder was set in a PP container covered with a polypropylene film to prepare a sample measurement container, and XRF (X-ray fluorescence) analysis was performed under the following conditions. Measurement conditions EZ scan mode Measured elements: F to U Measurement time: Standard Measurement diameter: 30 mm Residual fraction (balance component): None

[0170] The XRF analysis of the sample powder was performed to determine the niobium content in the sample powder, and it was calculated as the content rate (% by mass) in terms of Nb2O5 conversion with respect to 100% by mass of the total mass of the sample powder. The XRF analysis of the sample powder was performed to determine the molybdenum content in the sample powder, and it was calculated as the content rate (% by mass) in terms of MoO3 conversion with respect to 100% by mass of the total mass of the sample powder. The XRF analysis of the sample powder was performed to determine the potassium content in the sample powder, and it was calculated as the content rate (% by mass) in terms of K2O conversion with respect to 100% by mass of the total mass of the sample powder. The XRF analysis of the sample powder was performed to determine the sodium content in the sample powder, and it was calculated as the content rate (% by mass) in terms of Na2O conversion with respect to 100% by mass of the total mass of the sample powder. K x Na (1-x)It was calculated from the contents (%) of K2O and Na2O obtained from the XRF with respect to x of NbO3.

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

[0172] [Measurement of particle size] (In the case of particles having a cubic shape) The sample powder was photographed with a scanning electron microscope (SEM). For the smallest unit of particles (i.e., primary particles) recognized on the two-dimensional image, when it was recognized to have a cubic shape, the length of one side of the hexahedron discriminated from the particle image of the primary particle was measured as the particle size. The same operation was performed on 50 primary particles, and each average value was obtained.

[0173] [Measurement of crystallite size] Using SmartLab (manufactured by Rigaku Corporation) as the X-ray diffractometer and PDXL as the analysis software, measurement was performed. The measurement method was the 2θ / θ method, and the average crystallite size was calculated using the Scherrer equation from the half-value widths of the peaks that appear at 2θ = 23.0 ± 1.0°, the peaks that appear at 2θ = 32.0 ± 1.2°, and the peaks that appear at 2θ = 57.0 ± 1.0°. Note that as the measurement conditions, the scan speed was 10 degrees / minute, the scan range was 10 to 90 degrees, and the step was 0.02 degrees.

[0174] [Measurement of particle size distribution] A small amount of the particle powder was placed in a beaker, 50 mL of a 0.5% aqueous sodium hexametaphosphate solution was added, and then the sample for measurement was prepared by subjecting it to a dispersion treatment for 2 minutes using an ultrasonic homogenizer sonifier 450D (manufactured by BRANSON). This sample for measurement was measured for D 10 , D 50 , D 90 using a laser diffraction / scattering particle size distribution analyzer MT3300EXII (manufactured by Microtrac Bel Co., Ltd).

[0175] <K x Na (1-x) Production of NbO3 Particles

[0176] [Example 1] 40.0 g of niobium oxide (Nb2O5, manufactured by Mitsui Mining & Smelting Co., Ltd.), 22.6 g of potassium carbonate (K2CO3, manufactured by AGC Inc.), 9.7 g of sodium carbonate (Na2CO3, manufactured by Tokuyama Corporation), and 13.6 g of molybdenum trioxide (MoO3, manufactured by Nippon Inorganic Chemical Industry Co., Ltd.) were mixed in an absolute mill (manufactured by Osaka Chemical Co., Ltd.) for 30 seconds to obtain a mixture. The obtained mixture was placed in a crucible and fired in a ceramic electric furnace at 850 °C for 5 hours. Subsequently, the obtained fired product was placed in 250 mL of pure water, ultrasonic cleaning was repeated 4 times, and then the washing water was removed by filtration, followed by water washing 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 amount of potassium carbonate was changed to 18.4 g, the amount of sodium carbonate was changed to 9.2 g, and the amount of molybdenum trioxide was changed to 9.1 g.

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

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

[0180] [Example 5] 40.0 g of niobium oxide (manufactured by Mitsui Mining & Smelting Co., Ltd., Nb2O5), 12.1 g of potassium carbonate (manufactured by AGC Inc., K2CO3), 8.6 g of sodium carbonate (manufactured by Tokuyama Corporation, Na2CO3), 19.8 g of potassium molybdate (manufactured by Fujifilm Wako Pure Chemical Corporation, K2MoO4), and 2.7 g of sodium molybdate (manufactured by Fujifilm Wako Pure Chemical Corporation, Na2MoO4) were mixed in an absolute mill (manufactured by Osaka Chemical Co., Ltd.) for 30 seconds to obtain a mixture. The obtained mixture was placed in a crucible and fired in a ceramic electric furnace at 850 °C for 5 hours. Subsequently, the obtained fired product was placed in 250 mL of pure water, and ultrasonic cleaning was repeated 4 times. Then, the cleaning water was removed by filtration, followed by water washing and drying to remove the remaining fluxing agent, thereby obtaining the powder of Example 5.

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

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

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

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

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

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

[0187] [Comparative Example 1] 80.0 g of niobium oxide (manufactured by Mitsui Mining & Smelting Co., Ltd., Nb2O5), 20.0 g of potassium carbonate (manufactured by AGC Inc., K2CO3), and 16.9 g of sodium carbonate (manufactured by Tokuyama Corporation) were mixed in an absolute mill (manufactured by Osaka Chemical Co., Ltd.) for 30 seconds to obtain a mixture. The obtained mixture was placed in a crucible and fired in a ceramic electric furnace at 850 °C for 5 hours to obtain the powder of Comparative Example 1.

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

[0189]

Table 1

[0190] The evaluation results of each particle obtained from the formulation table in Table 1 are shown in Table 2. The removability from the crucible was evaluated as "〇", "△", or "×". "〇" indicates that the fired product can be easily removed without sticking to the crucible, "△" indicates that a part of the fired product is sticking to the crucible, and "×" indicates that the fired product is sticking to the crucible and cannot be removed. In the table, "N.D." is an abbreviation for not detected, indicating non-detection.

[0191]

Table 2

[0192] Table 2 shows the shapes and sizes of the particles of each example and comparative example, as determined from the SEM images. When particles of different shapes are observed to be mixed, the representative shape (the most frequently observed shape) is described. Aggregates of cubic particles are also included in those having a cubic shape. When no specific shape is observed, it is determined to be amorphous. In Example 1, as shown in FIG. 1, the shape of the particles was cubic. The same was true for Examples 2 to 11, where the particles were also cubic. In Comparative Example 1, as shown in FIG. 2, the shape of the particles was amorphous, and some cubic particles were observed.

[0193] From the XRD analysis results, in the sample of Example 1, as shown in FIG. 3, peaks at 2θ = 23.0 ± 1.0°, 2θ = 32.0 ± 1.2°, and 2θ = 57.0 ± 1.0° corresponding to the (100), (110), and (221) planes of the perovskite structure of K x Na (1-x) NbO3 were observed. Similarly, in the samples of Examples 2 to 11 and Comparative Example 1, peaks corresponding to the (100), (110), and (221) planes of the perovskite structure of K x Na (1-x) NbO3 were observed.

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

[0195] Focusing on each particle size (SEM observation, D 50 ) and crystallite size, the particles of Examples 1 to 11 had larger primary particle sizes and crystallite sizes than those of the comparative example. This is considered to be the result that most of the raw material compounds used in the production methods of the respective examples, including MoO3, Na2CO3, K2CO3, Na2MoO4, and K2MoO4 (including their products and decomposition products), functioned as a fluxing agent, enabling good crystal growth of the particles.

[0196] Also, there was a tendency that larger-sized particles were obtained as the firing temperature was higher (Examples 1, 7, 8).

[0197] From the results of Examples 1 to 11, by firing a niobium compound in the presence of a molybdenum compound and a potassium compound and / or a sodium compound, high-quality K x Na (1-x) NbO3 particles were shown to be capable of being fired.

[0198] <Manufacture of Piezoelectric Composite Sheet>

[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 rotating and revolving mixer ARV-200 (manufactured by Shinky Co., Ltd.). After stirring, it was poured into a mold with a size of 5.5 cm square and a depth of 0.3 mm and pressed at 120°C and 1 MPa for 30 minutes. In this way, a piezoelectric composite sheet with a volume fraction of the particles of 60 vol% was obtained.

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

[0201] [Comparative Example 2] A piezoelectric composite sheet with a volume fraction of the particles of 60 vol% was obtained in the same manner as in Example 12, except that the particles were changed to the particles 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 volume fraction of the particles was 40 vol%, and kneaded with a Laboplastmill mixer (manufactured by Toyo Seiki Seisakusho Co., Ltd., model number: 4C150) under the 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. Then, the kneaded resin composition was compression-molded 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 to obtain a sheet with a thickness of 0.5 mm. The sheet was further compressed three times at a temperature of 240°C, a preheating time of 30 seconds, a compression time of 30 seconds, and a pressure of 100 kgf / cm 2 to obtain a piezoelectric composite sheet.

[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 the particles produced in Comparative Example 1.

[0205] [Evaluation of Piezoelectric Composite Sheet] On one side of the piezoelectric composite sheet, a 100-nm aluminum electrode was formed by a vapor deposition apparatus, 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 corona discharge treatment was performed for 3 minutes. After removing the sheet from the hot plate, a 100-nm aluminum electrode was formed by a vapor deposition apparatus on the surface where the corona discharge treatment was performed, and a laminated body of a polarized aluminum electrode / piezoelectric composite sheet / aluminum electrode was obtained. The obtained laminated body was cut into 10 mm × 2 mm with an NT cutter. Then, the complex dielectric constant of the obtained 10 mm × 2 mm laminated body sheet was measured with an Agilent impedance analyzer 4294A, and the electromechanical coupling coefficient kt in the thickness direction was calculated. The electromechanical coupling constant kt varies in a practical range depending on the resin used. In the case of silicone resin, it can be used without practical problems if it is 0.03 or more, more preferably 0.04 or more, and particularly preferably 0.08 or more. On the other hand, in the case of polyvinylidene fluoride (PVDF) resin, it can be used without practical problems if it is 0.05 or more, more preferably 0.09 or more, and particularly preferably 0.15 or more. Table 3 shows the thickness electromechanical coupling constant kt of the piezoelectric composite sheet.

[0206]

Table 3

[0207] It was revealed that the piezoelectric composite sheet containing the particles of Example 1 exhibited a higher electromechanical coupling constant kt and an excellent piezoelectric effect as compared with the piezoelectric composite sheet containing the particles of Comparative Example 1. The K contained in the powder of Example 1 x Na (1-x) The crystallite size of the NbO3 particles was larger than that of the K contained in the powder of Comparative Example 1 x Na (1-x) NbO3 particles, so it is considered that excellent piezoelectric performance was exhibited.

Claims

1. K ｘ Na （１－ｘ） NbO ３ (wherein 0.4≦x≦0.6) 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, Niobate particles having a median diameter D50 of 5.3 to 100 μm as calculated by a laser diffraction / scattering method.

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. The niobate particles according to claim 1 or 2, 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.

5. The total niobium content in the niobate particles is determined by XRF analysis of the niobate particles, and the content in terms of Nb2O5 relative to 100% by mass of the total mass of the niobate particles is 50 to 99% by mass. The niobate particles according to claim 1 or 2.

6. The niobate particles according to claim 1 or 2, wherein the potassium and / or sodium content in the niobate particles is determined by XRF analysis of the niobate particles, and the content in terms of K2O and Na2O is 0.5 to 40 mass% relative to 100 mass% of the total mass of the niobate particles.

7. The niobate particle of claim 1 comprising molybdenum.

8. The niobate particles according to claim 7, wherein the molybdenum content in the niobate particles is determined by XRF analysis of the niobate particles, and the content in terms of MoO3 is 0.01 to 20 mass% relative to 100 mass% of the total mass of the niobate particles.

9. 2. 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.

10. 10. The method for producing molybdate particles according to claim 9, wherein the molybdenum compound is at least one compound selected from the group consisting of molybdenum trioxide, potassium molybdate, and sodium molybdate.

11. The method includes a step of mixing a niobium compound, a molybdenum compound, and a potassium compound and / or a sodium compound to obtain a mixture, and a step of calcining the mixture, The method for producing niobate particles according to claim 9 or 10, wherein the ratio (Nb1) / (Na1+K1+Mo1) of the total mass of the flux components, sodium compound (Na1), potassium compound (K1) and molybdenum compound (Mo1), to the mass of the niobium compound (Nb1) in the mixture is 0.6 or more.

12. The method includes a step of mixing a niobium compound, a molybdenum compound, and a potassium compound and / or a sodium compound to obtain a mixture, and a step of calcining the mixture, The method for producing niobate particles according to claim 9 or 10, wherein a molar ratio of potassium atoms, sodium atoms, molybdenum atoms, and niobium atoms in the mixture satisfies (K+Na) / (2×Mo+Nb)>1.

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

14. A molded article obtained by molding the resin composition according to claim 13.

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