WO2023204235A1 - Tantalic acid salt particles, method for producing tantalic acid salt particles, resin composition, and molded object - Google Patents

Abstract

Tantalic acid salt particles including a crystal structure of a tantalic acid salt represented by KxNa(1-x)TaO3 (where 0≤x≤1), wherein the crystal structure has an average crystallite size of 80 nm or larger, the average crystallite size being determined from a peak at 2θ=23.0±1.0° of the tantalic acid salt obtained by X-ray diffractometry.

Description

Tantalate particles, method for producing tantalate particles, resin composition, and molded article

The present invention relates to tantalate particles, a method for producing tantalate particles, a resin composition, and a molded article.
This application claims priority based on Japanese Patent Application No. 2022-070230, filed in Japan on April 21, 2022, the contents of which are incorporated herein.

Alkali metal tantalate salts are widely used as piezoelectric bodies, fillers, catalysts, semiconductor photoelectrodes, etc.

Patent Document 1 describes a method for producing tantalate crystal particles having a layered perovskite structure and represented by a specific formula, in which crystals are precipitated and grown by mixing raw materials and flux and heating the mixture. A method for producing tantalate crystal particles is disclosed. Also. It is exemplified that the flux contains potassium chloride or strontium chloride.

Patent Document 2 shows a catalyst composition comprising sodium tantalate (NaTaO ₃ ) as a base catalyst, a modifier, and at least one cocatalyst as an application example for photocatalytic reduction of carbon dioxide.

JP2009-190927A Special table 2016-524534 publication

Controlling the crystal growth of tantalate particles is a very important technique for increasing the versatility of the tantalate particles obtained. K _x Na _(1-x) TaO ₃ (0≦x≦1) has a perovskite structure and can be used, for example, as a piezoelectric material. As a piezoelectric material, it is expected that the larger the crystallite size, the more excellent the piezoelectric effect can be exhibited. However, there is still room for investigation into improving the crystal growth of tantalate particles obtained by conventional methods for producing tantalate particles.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide tantalate particles having an excellent degree of crystal growth.

The present invention has the following aspects.

(1) Contains the crystal structure of tantalate represented by K _x Na _(1-x) TaO ₃ (0≦x≦1),
The crystal structure is a tantalate particle having an average crystallite size of 80 nm or more as determined from a peak at 2θ=23.0±1.0° of the tantalate obtained by X-ray diffraction measurement.
(2) The tantalate particles according to (1) above, wherein the crystal structure includes a perovskite crystal structure.
(3) The tantalate particles according to (1) or (2) above, which have a cubic shape.
(4) The crystal structure described in (1) above has an average crystallite size of 50 nm or more as determined from the peak of 2θ = 32.0 ± 1.2° of the tantalate obtained by X-ray diffraction measurement. - The tantalate particles according to any one of (3).
(5) The tantalate particles according to any one of (1) to (4) above, wherein the median diameter D ₅₀ calculated by a laser diffraction/scattering method is 0.1 to 100 μm.
(6) The content of tantalum in the tantalate particles is determined by XRF analysis of the tantalate particles, and is the content in terms of Ta ₂ O ₅ based on 100% by mass of the total mass of the tantalate particles. The tantalate particles according to any one of (1) to (5) above, wherein the tantalate particles are 50 to 99% by mass.
(7) The potassium and/or sodium content in the tantalate particles is determined by XRF analysis of the tantalate particles, calculated as K ₂ O and Na based on 100% by mass of the tantalate particles. The tantalate particles according to any one of (1) to (6) above, wherein the total content in terms of ₂ O is 0.5 to 40% by mass.
(8) The tantalate particles according to any one of (1) to (7) above, which contain molybdenum.
(9) The molybdenum content in the tantalate particles is determined by XRF analysis of the tantalate particles, and the content ratio in terms of MoO ₃ is 0.5% based on 100% by mass of the total mass of the tantalate particles. The tantalate particles according to (8) above, which have a content of 01 to 20% by mass.
(10) A method for producing tantalate particles according to any one of (1) to (9) above, comprising:
A method for producing tantalate particles, comprising firing a tantalum compound in the presence of a potassium compound and/or a sodium compound.
(11) The method for producing tantalate particles according to (10) above, wherein the sodium compound is sodium carbonate and the potassium compound is potassium carbonate.
(12) The method for producing tantalate particles according to (10) or (11) above, which comprises firing a tantalum compound in the presence of a molybdenum compound and a potassium compound and/or a sodium compound.
(13) The method for producing tantalate particles according to (12) above, wherein the molybdenum compound is at least one compound selected from the group consisting of molybdenum trioxide, potassium molybdate, and sodium molybdate.
(14) A step of mixing a tantalum compound and a potassium compound and/or a sodium compound to form a mixture, and a step of firing the mixture,
The tantalate salt according to any one of (10) to (13) above, wherein the molar ratio (K+Na)/Ta of potassium atoms and sodium atoms to tantalum atoms in the mixture is 1.1 or more. Method of manufacturing particles.
(15) tantalate particles according to any one of (1) to (9) above;
A resin composition comprising a resin.
(16) A molded article obtained by molding the resin composition according to (15) above.

According to the present invention, tantalate particles having an excellent degree of crystal growth can be provided.
Further, according to the present invention, a method for producing the tantalate particles can be provided.
Moreover, according to the present invention, a resin composition containing the tantalate particles and a molded article thereof can be provided.

3 is a SEM image of NaTaO ₃ particles of Example 1. 3 is a SEM image of KTaO ₃ particles of Example 2. 3 is a SEM image of K _x Na _(1-x) TaO ₃ particles of Example 3. 3 is a SEM image of K _x Na _(1-x) TaO ₃ particles of Example 4. 3 is a SEM image of K _x Na _(1-x) TaO ₃ particles of Example 5. 3 is a SEM image of K _x Na _(1-x) TaO ₃ particles of Example 6. 3 is a SEM image of KTaO ₃ particles of Example 7. 3 is a SEM image of K _x Na _(1-x) TaO ₃ particles of Example 8. 3 is a SEM image of K _x Na _(1-x) TaO ₃ particles of Example 9. 3 is a SEM image of K _x Na _(1-x) TaO ₃ particles of Example 10. 3 is a SEM image of K _x Na _(1-x) TaO ₃ particles of Example 11. 3 is a SEM image of K _x Na _(1-x) TaO ₃ particles of Example 12. 1 is an X-ray diffraction (XRD) pattern of powder samples of Examples 1-2. 3 is an X-ray diffraction (XRD) pattern of powder samples of Examples 3 to 6. 3 is an X-ray diffraction (XRD) pattern of powder samples of Examples 7-8. Figure 3 is an X-ray diffraction (XRD) pattern of powder samples of Examples 9-12.

Hereinafter, embodiments of tantalate particles, a method for producing tantalate particles, a resin composition, and a molded article of the present invention will be described.

≪Tantalate particles≫
The tantalate particles of the embodiment include a tantalate crystal structure represented by K _x Na _(1-x) TaO ₃ (where 0≦x≦1), and the crystal structure is represented by The average crystallite size determined from the peak at 2θ=23.0±1.0° of the tantalate obtained by line diffraction measurement is 80 nm or more.

The tantalate particles of embodiments include a tantalate compound represented by K _x Na _(1-x) TaO ₃ . In the above formula K _x Na _(1-x) TaO ₃ , x satisfies 0≦x≦1.
When x is 0<x<1, K _x Na _(1-x) TaO ₃ is potassium sodium tantalate.
If x=0, K _x Na _(1-x) TaO ₃ is sodium tantalate (NaTaO ₃ ).
If x=1, K _x Na _(1-x) TaO ₃ is potassium tantalate (KTaO ₃ ).

In addition, for the purpose of suppressing leakage current and maintaining insulation, several moles (1 to 3 moles) of elements with a lower valence than Ta, such as Mn, Cr, Co, Ni, and Zn, are added to Ta. It may be included as appropriate within a range of %. Furthermore, the raw material may contain an element such as Fe as an unavoidable impurity.

In this specification, the description of the numerical range of x in K _x Na _(1-x) TaO ₃ may be omitted.

The type, composition, and crystal structure of the tantalate contained in the tantalate particles of the embodiment can be specified by the XRD pattern of the spectrum obtained by XRD analysis.

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

[Measurement of crystallite size]
Measurement is performed using an X-ray diffractometer (for example, SmartLab, manufactured by Rigaku Corporation), a high-intensity, high-resolution crystal analyzer (CALSA) as a detector, and 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 (a peak having a peak top in the target 2θ range) using the Scherrer equation. The measurement conditions are: scan speed is 0.05 degrees/min, scan range is 20 to 70 degrees, step is 0.002 degrees, and device standard width is 0.028 degrees (Si). .

The average crystallite size determined from the peak at 2θ = 23.0 ± 1.0° of the crystal structure contained in the tantalate particles of the embodiment is 80 nm or more, preferably 90 nm or more, and 100 nm or more. It is more preferable that it be 140 nm or more, and even more preferably that it is 140 nm or more.

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

As an example of the above numerical range of the average crystallite size determined from the peak of 2θ = 23.0 ± 1.0° of the crystal structure contained in the tantalate particles of the embodiment, it may be 80 nm or more and 1000 nm or less. , may be 90 nm or more and 800 nm or less, 100 nm or more and 500 nm or less, and 140 nm or more and 500 nm or less.

K _x Na _(1-x) TaO ₃ can exhibit a crystal system different from monoclinic, rectangular, or tetragonal depending on the composition, and the plane assignment differs depending on the crystal system.
In this specification, unless otherwise specified, plane indices are expressed assuming that the crystal structure is a cubic system.

When assigning the target peak obtained in the crystallite size measurement above to the cubic system without considering peak splitting, the peak at 2θ = 23.0 ± 1.0° above is the cubic system. The position corresponds to the (100) plane of If the peak is split, define the crystallite size using the peak with the highest intensity.

The average crystallite size determined from the peak at 2θ = 32.0 ± 1.2° of the crystal structure contained in the tantalate particles of the embodiment is preferably 50 nm or more, more preferably 70 nm or more. , more preferably 220 nm or more.
When the average crystallite size of the tantalate particles is greater than or equal to the above lower limit, even more excellent piezoelectric performance is exhibited.

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

As an example of the above numerical range of the average crystallite size determined from the peak of 2θ = 32.0 ± 1.2° of the crystal structure included in the tantalate particles of the embodiment, it may be 50 nm or more and 1000 nm or less. , may be 70 nm or more and 800 nm or less, and may be 220 nm or more and 700 nm or less.

When assigning the target peak obtained in the above crystallite size measurement assuming that it is a cubic system without considering peak splitting, the peak at 2θ = 32.0 ± 1.2° above is a cubic system. The position corresponds to the (110) plane of If the peak is split, define the crystallite size using the peak with the highest intensity.

The average crystallite size determined from the peak at 2θ = 57.0 ± 1.0° of the crystal structure contained in the tantalate particles of the embodiment is preferably 15 nm or more, more preferably 30 nm or more. , more preferably 80 nm or more.
When the average crystallite size of the tantalate particles is greater than or equal to the above lower limit, even more excellent piezoelectric performance is exhibited.

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 tantalate particles of the embodiment is not particularly limited, but is 500 nm or less. It 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 of 2θ = 57.0 ± 1.0° of the crystal structure included in the tantalate particles of the embodiment, it may be 15 nm or more and 500 nm or less. , may be 30 nm or more and 400 nm or less, and may be 80 nm or more and 300 nm or less.

When assigning the target peak obtained in the crystallite size measurement above to a cubic system without considering peak splitting, the peak at 2θ = 57.0 ± 1.0° above is a cubic system. The position corresponds to the (211) plane of If the target peak is split, the crystallite size is defined by the peak with the highest intensity.

According to the manufacturing method of the embodiment described below, the crystal growth of the tantalate particles to be manufactured is excellently controlled, and tantalate particles with an improved average crystallite size can be easily obtained.

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

The crystal structure of the tantalate particles of the embodiment can include a perovskite crystal structure.

The tantalate particles of embodiments can have a cubic shape.

In this specification, "cubic shape" may be a shape derived from a perovskite structure, preferably a substantially cubic hexahedral shape, and each face constituting the hexahedron may be a flat surface. , it may be a curved or uneven surface.

According to the manufacturing method of the embodiment described below, tantalate particles having a perovskite crystal structure and a cubic shape can be manufactured.

As the firing temperature becomes higher, tantalate particles with a larger average crystallite size and larger particle size tend to be obtained.

When the tantalate 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 of the particle size when the tantalate particles have a cubic shape is not particularly limited, but may be, for example, 100 μm or less, 80 μm or less, 50 μm or less. It's good.
An example of the upper numerical range of the particle size when the tantalate particles have a cubic shape is 0.1 to 100 μm, 0.5 to 80 μm, and 1 to 50 μm. It's fine.

In this specification, the "particle size" of tantalate particles having a cubic shape refers to the particle size of the tantalate particles as determined from the particle image of the primary particles of the tantalate particles in a two-dimensional image taken with a scanning electron microscope (SEM). This is the length of one side of the hexahedron to be determined.
The value of the tantalate particle size having a cubic shape is the average value obtained from 50 or more tantalate particles randomly selected from among the euhedral particles to be measured above. do.

When tantalate particles having a cubic shape are included, it is preferable that 50% or more of the particles have a cubic shape based on mass or number, and it is preferable that 80% or more of the particles have a cubic shape. More preferably, 90% or more of the particles have a cubic shape.

The median diameter _D50 of the tantalate particles of the embodiment calculated by a laser diffraction/scattering method may be 0.1 to 100 μm, may be 0.5 to 80 μm, and may be 1 to 50 μm. good.

D ₁₀ of the tantalate particles of the embodiments calculated by laser diffraction/scattering method may be 0.05 to 70 μm, may be 0.1 to 50 μm, and may be 0.5 to 20 μm. good.

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

The median diameter D ₅₀ of the tantalate particle sample calculated by the laser diffraction/scattering method is based on the particle size distribution measured dry using a laser diffraction particle size distribution analyzer when the volume integrated % ratio is 50%. It can be determined as the particle size. _D10 , which is calculated by the laser diffraction/scattering method of a tantalate particle sample, can be determined as the particle diameter at the point where the volume integration % distribution curve intersects the horizontal axis of 10% from the small particle side. ₉₀ can be determined as the particle diameter at the point where the volume integration % distribution curve intersects the 90% horizontal axis from the small particle side.

The specific surface area of the tantalate particles of the embodiment determined by the BET method may be 0.02 to 20 m ² /g, 0.04 to 10 m ² /g, 0.05 to 10 m 2 /g. It may be 3 m ² /g.

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

The tantalate particles of the embodiment include K _x Na _(1-x) TaO ₃ (0≦x≦1).

The tantalate particles of the embodiment preferably contain 65% by mass or more, and preferably 65 to 99.999% by mass, of the K _x Na _(1-x) TaO ₃ based on 100% by mass of the tantalate particles. The content is preferably from 70 to 99.97% by mass, and even more preferably from 75 to 99.95% by mass.

The tantalum content in the tantalate particles is determined by XRF analysis of the tantalate particles, and the content in terms of Ta ₂ O ₅ based on 100% by mass of the tantalate particles is: It may be 50% by mass or more, 50 to 99% by mass, 60 to 98% by mass, or 70 to 95% by mass.

The content in terms of Ta ₂ O ₅ refers to the value obtained from the amount of Ta ₂ O ₅ obtained by converting the tantalum content determined by XRF analysis using a calibration curve in terms of Ta ₂ O ₅ .

The tantalate particles of embodiments include potassium and/or sodium.

The potassium and/or sodium content in the tantalate particles is determined by XRF analysis of the tantalate particles, calculated in terms of _K2O and _Na2O based on 100% by mass of the tantalate particles. The total content in terms of conversion may be 0.5% by mass or more, 0.5 to 40% by mass, 1 to 30% by mass, or 3 to 25% by mass. It's okay.

The total content in terms of K ₂ O and Na ₂ O is the potassium content determined by XRF analysis, the amount of K _{2 O calculated using the calibration curve of K 2} O, and the amount of K ₂ O calculated by XRF analysis. This is the value determined from the sum of the sodium content determined by this method and the Na ₂ O amount converted using a calibration curve for Na ₂ O conversion. Note that when the composition of the tantalate particles is K _x Na _(1-x) TaO ₃ where x=0 or 1, the potassium content or sodium content may be 0.

The tantalate particles of embodiments can further include molybdenum.

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

The molybdenum contained in the tantalate particles of the embodiment is not particularly limited in its existence state or amount, and may be contained in the tantalate particles as molybdenum metal, molybdenum oxide, partially reduced molybdenum compounds, etc. It's fine. Molybdenum is considered to be contained in the tantalate particles as MoO ₃ , but it may also be contained in the tantalate particles as MoO ₂ , MoO, etc. in addition to MoO ₃ .

The form in which molybdenum is contained is not particularly limited, and even if it is contained in a form attached to the surface of the tantalate particles or in a form substituted with a part of the crystal structure of the tantalate particles, It may be contained in an amorphous state or a combination thereof.

When the tantalate particles of the embodiment contain molybdenum, the molybdenum content is determined by XRF analysis of the tantalate particles, and is calculated as MoO ₃ based on 100% by mass of the tantalate particles. The ratio may be 0.01% by mass or more, 0.01 to 20% by mass, 0.05 to 15% by mass, or 0.06 to 10% by mass. Good too.

The content in terms of MoO ₃ is a value obtained from the amount of MoO ₃ obtained by converting the molybdenum content determined by XRF analysis using a calibration curve in terms of MoO ₃ .

The above values of molybdenum content, tantalum content, and total potassium and sodium content can be freely combined.

As an example of the tantalate particles of the embodiment, the content rate of molybdenum in terms of MoO ₃ is 0 to 100% by mass of the tantalate particles, as determined by XRF analysis of the tantalate particles. 20% by mass, the content of tantalum in terms of Ta ₂ O ₅ is 50 to 99% by mass, and the content of potassium and sodium in terms of K ₂ O and Na ₂ O is 0.5 to 40% by mass % of tantalate particles.
As another example of the tantalate particles of the embodiment, the content of molybdenum in terms of MoO ₃ based on 100% by mass of the total mass of the tantalate particles is determined by XRF analysis of the tantalate particles. The content of tantalum in terms of Ta ₂ O ₅ is 50 to 99% by mass, and the content of potassium and sodium in terms of K ₂ O and Na ₂ O is 0.01 to 20% by mass. An example is tantalate particles having a content of 5 to 40% by mass.
As another example of the tantalate particles of the embodiment, the content of molybdenum in terms of MoO ₃ based on 100% by mass of the total mass of the tantalate particles is determined by XRF analysis of the tantalate particles. The content of tantalum in terms of Ta ₂ O ₅ is 60 to 98% by mass, and the content of potassium and sodium in terms of K ₂ O and Na ₂ O is 1 to 1. An example may be tantalate particles having a content of 30% by mass.
As another example of the tantalate particles of the embodiment, the content of molybdenum in terms of MoO ₃ based on 100% by mass of the total mass of the tantalate particles is determined by XRF analysis of the tantalate particles. The content of tantalum in terms of Ta ₂ O ₅ is 70 to 95% by mass, and the content of potassium and sodium in terms of K ₂ O and Na ₂ O is 3 to 10% by mass. An example may be tantalate particles having a content of 25% by mass.

The tantalate particles of the embodiments can be provided as an aggregate of tantalate particles. For the above values of crystallite size, particle size distribution, specific surface area, value of x, molybdenum content, tantalum content, potassium content, and sodium content, adopt the values determined using the above aggregate as a sample. I can do it.

The tantalate particles of the embodiment can be manufactured, for example, by the <<method for manufacturing tantalate particles>> described below.
Note that the tantalate particles of the present invention are not limited to those produced by the method for producing tantalate particles of the embodiment below.

The tantalate particles of the embodiments can be used as piezoelectric bodies, catalysts, water purification materials, and the like.

≪Method for producing tantalate particles≫
A method for producing tantalate particles of an embodiment includes firing a tantalum compound in the presence of a potassium compound and/or a sodium compound.

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

Further, according to the method for producing tantalate particles of the present embodiment, by firing the tantalum compound in the presence of a potassium compound and/or a sodium compound, the degree of crystal growth of the tantalate particles produced can be controlled. Excellent.
Furthermore, according to the method for producing tantalate particles of the present embodiment, by firing the tantalum compound in the presence of potassium carbonate and/or sodium carbonate, the degree of crystal growth of the tantalate particles produced depends on the degree of crystal growth. Excellent.

A preferred method for producing tantalate particles includes a step of mixing a tantalum compound and a potassium compound and/or a sodium compound to form a mixture (mixing step), and a step of firing the mixture (calcination step). can be included.

In the method for producing tantalate particles of the embodiment, it is preferable to further use a molybdenum compound. By using a molybdenum compound, crystal growth of tantalate particles can be further promoted and tantalate particles can be manufactured with high efficiency.

An example of a method for producing such tantalate particles is a method that includes firing a tantalum compound in the presence of a molybdenum compound and a potassium compound and/or a sodium compound.

A preferred method for producing tantalate particles includes a step of mixing a tantalum compound, a molybdenum compound, a potassium compound and/or a sodium compound to form a mixture (mixing step), and a step of firing the mixture (calcining step). ) and can include.

Here, a compound containing molybdenum and potassium, such as potassium molybdate, can also be used in place of at least some of the molybdenum compounds and potassium compounds. Similarly, in place of at least some of the molybdenum and sodium compounds, it is also possible to use compounds containing molybdenum and sodium, such as sodium molybdate.
Therefore, mixing molybdenum and a compound containing potassium and/or sodium is also considered to be mixing a molybdenum compound and a potassium compound and/or a sodium compound.

[Mixing process]
The mixing step is a step of mixing a tantalum compound, optionally a molybdenum compound, and a potassium compound and/or a sodium compound to form a mixture.

When the tantalate particles to be produced include potassium sodium tantalate, it may include a step (mixing step) of mixing the tantalum compound, optionally a molybdenum compound, a potassium compound, and a sodium compound to form a mixture. .

When the tantalate particles to be produced contain potassium tantalate, it may include a step (mixing step) of mixing the tantalum compound, optionally a molybdenum compound, and a potassium compound to form a mixture.

When the tantalate particles to be produced contain sodium tantalate, it may include a step (mixing step) of mixing the tantalum compound, optionally a molybdenum compound, and a sodium compound to form a mixture.

The contents of the mixture will be explained below.

(Tantalum compound)
The tantalum compound is not limited as long as it can be fired with a raw material compound to form a tantalate, and includes tantalum oxide, tantalum hydroxide, tantalum sulfide, tantalum nitride, tantalum fluoride, tantalum chloride, tantalum bromide, Examples include tantalum halides such as tantalum iodide, tantalum alkoxides, tantalum hydroxide and tantalum oxide are preferred, and tantalum oxide is more preferred.
Examples of tantalum oxide include tantalum pentoxide (Ta ₂ O ₅ ), tantalum dioxide (TaO ₂ ), and tantalum monoxide (TaO). In addition to tantalum oxide having the above-mentioned oxidation number, any tantalum oxide having a different valence can be used.
There are no particular limitations on the physical form, such as the shape, particle size, specific surface area, etc. of the tantalum compound as a precursor.

The shape after firing hardly reflects the shape of the raw tantalum compound, so it may be spherical, amorphous, a structure with an aspect (wire, fiber, ribbon, tube, etc.), or a sheet. can also be suitably used.

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

Examples of the molybdenum oxide include molybdenum dioxide (MoO ₂ ), molybdenum trioxide (MoO ₃ ), and molybdenum trioxide is preferred.

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

In the method for producing tantalate particles of the present embodiment, the molybdenum compound may be a hydrate.

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 preferably from the group consisting of molybdenum trioxide, potassium molybdate, and sodium molybdate. More preferably, it is at least one selected compound.

A compound containing molybdenum and potassium that is suitable as a fluxing agent can be produced, for example, in the firing process using cheaper and more easily available molybdenum compounds and potassium compounds as raw materials. Here, when using a molybdenum compound and a potassium compound as a fluxing agent, when using a compound containing molybdenum and potassium as a fluxing agent, when using a combination of both, when using a molybdenum compound and a potassium compound as a fluxing agent, that is, Considered to be in the presence of molybdenum compounds and potassium compounds.

A compound containing molybdenum and sodium suitable as a fluxing agent can be produced, for example, in the firing process using cheaper and more easily available molybdenum compounds and sodium compounds as raw materials. Here, when using a molybdenum compound and a sodium compound as a fluxing agent, when using a compound containing molybdenum and sodium as a fluxing agent, when using a combination of both, when using a molybdenum compound and a sodium compound as a fluxing agent, that is, Considered to be in the presence of molybdenum compounds and sodium compounds.

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

Furthermore, since potassium molybdate (K ₂ Mon _{O 3n+1} , n=1 to 3) contains potassium, it can also function as a potassium compound, which will be described later.

Furthermore, since sodium molybdate (Na _{2 Mon} O _3n+1 , n=1 to 3) contains sodium, it can also function as a sodium compound as described below.

(potassium compound)
Potassium compounds include, but are not limited to, 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, and 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. In this case, the potassium compound includes isomers as in the case of the molybdenum compound. Among these, it is preferable to use potassium carbonate, potassium hydrogen carbonate, potassium oxide, potassium hydroxide, potassium chloride, potassium sulfate, and potassium molybdate. It is more preferable to use potassium carbonate and/or potassium molybdate.

Note that the above-mentioned potassium compounds may be used alone or in combination of two or more.

Furthermore, similarly to the above, since potassium molybdate contains molybdenum, it can also function as the above-mentioned molybdenum compound.

(sodium compound)
Examples of the sodium compound include, but are not limited to, sodium carbonate, sodium molybdate, sodium oxide, sodium sulfate, sodium hydroxide, sodium nitrate, sodium chloride, sodium metal, and the like. Among these, it is preferable to use sodium carbonate, sodium molybdate, sodium oxide, and sodium sulfate from the viewpoint of easy industrial availability and handling, and it is more preferable to use sodium carbonate and/or sodium molybdate. .

Note that the above-mentioned sodium compounds may be used alone or in combination of two or more.

Furthermore, similarly to the above, since sodium molybdate contains molybdenum, it can also function as the above-mentioned molybdenum compound.

In this way, the molybdenum compound may be described twice as a molybdenum compound in terms of classification, but as an example, the molybdenum compound is at least one compound selected from the group consisting of molybdenum trioxide, potassium molybdate, and sodium molybdate. can be,
Preferably, the sodium compound is sodium carbonate or sodium molybdate, and the potassium compound is potassium carbonate or potassium molybdate.

Preferably, a method for producing potassium sodium tantalate particles can be exemplified, which includes firing a tantalum compound in the presence of a molybdenum compound, a potassium compound, and a sodium compound.

An example of a method for producing sodium tantalate particles preferably includes firing a tantalum compound in the presence of a molybdenum compound and a sodium compound.

An example of a method for producing potassium tantalate particles preferably includes firing a tantalum compound in the presence of a molybdenum compound and a potassium compound.

In the method for producing tantalate particles of this embodiment, a potassium compound, a sodium compound, and a molybdenum compound are used as a fluxing agent.
When a potassium compound and/or a sodium compound is used as a fluxing agent, oxides (Na ₂ O and K ₂ O) are formed from a part of the potassium compound and/or sodium compound by such baking, which functions as a flux. However, it is assumed that tantalate crystal growth progresses.

Furthermore, when tantalum compounds are calcined in the presence of potassium carbonate and/or sodium carbonate, oxides (Na ₂ O and K ₂ O) and/or CO ₂ are formed from some potassium carbonate and/or sodium carbonate. It is presumed that these oxides and/or CO ₂ function as a flux to promote crystal growth of tantalate particles.
Through reaction during such calcination, tantalate particles (K _x Na _(1-x) TaO ₃ ) are formed along with the formation of oxides (Na ₂ O and K ₂ O) and/or CO ₂ that function as fluxes. it is conceivable that. The flux function of oxides (Na ₂ O and K ₂ O) and/or CO ₂ promotes the formation of tantalate particles (K _x Na _(1-x) TaO ₃ ) with large crystallite sizes. It is thought that there are.

When a molybdenum compound is used as a fluxing agent, by such baking, a tantalum compound, a molybdenum compound, a sodium compound or a potassium compound (a compound containing molybdenum and sodium, or a compound containing molybdenum and potassium) ), which react at high temperatures and function as fluxes (e.g., K _a Mo _b O _c , Na _a Mo _b O _c , K _a Na _a' Mo _b O _c ) is thought to form tantalate particles (K _x Na _(1-x) TaO ₃ ). It is believed that some molybdenum compounds are incorporated into the tantalate particles when they are formed (crystal growth). More specifically, regarding the formation mechanism of molybdenum compounds contained in tantalate particles, we will explain the formation and decomposition of Mo-O-Ta in the system during calcination, or the generation mechanism of molybdenum compounds contained in tantalate particles. It is believed that molybdenum compounds, such as molybdenum oxides, are formed during the crystal growth of the particles. Furthermore, considering the above mechanism, it is also possible that molybdenum oxide exists on the surface of the tantalate particles through Mo--O--Ta bonds. Inclusion of a molybdenum compound (for example, molybdenum oxide) in the tantalate particles leads to improvement in the physical properties of the tantalate particles, and for example, the catalytic performance of the tantalate particles can be improved.

The molybdate compound used as the above-mentioned flux does not vaporize even in the firing temperature range and can be easily recovered by cleaning after firing, which reduces the amount of molybdenum compound released outside the firing furnace and significantly reduces production costs. can be reduced to

In the method for producing tantalate 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) and the amount of tantalum compound used, which are considered to function as fluxing agents. Although not particularly limited, preferably, 10 parts by mass or more of a fluxing agent is mixed with 100 parts by mass of the tantalum compound used as a raw material to form a mixture, and the mixture is fired. can. More preferably, 20 to 5,000 parts by mass of a fluxing agent are mixed with 100 parts by mass of the tantalum compound used to form a mixture, and the mixture is fired. More preferably, 100 to 1000 parts by mass of a fluxing agent is mixed with 100 parts by mass of the tantalum compound used to form a mixture, and the mixture is fired.

From the viewpoint of efficient crystal growth, it is preferable that the amount of fluxing agent used with respect to the tantalum compound as a raw material is equal to or more than the above lower limit. By increasing the amount of fluxing agent used with respect to the tantalum compound as a raw material, the crystallite size of the tantalate particles to be produced can be easily controlled, and tantalate particles with improved crystallite size can be easily obtained. . On the other hand, from the viewpoint of reducing the amount of fluxing agent used and improving production efficiency, the above upper limit or less is preferable. If the amount of flux agent is large, large single crystals may be produced, which may reduce productivity. Therefore, select the amount of flux appropriately so that the particle size of the tantalate particles produced is the desired size. can do.

From the same viewpoint, in the method for producing tantalate particles of the embodiment, it is preferable that the molar ratio (K+Na)/Ta of potassium atoms and sodium atoms to tantalum atoms in the mixture is 1.1 or more. , more preferably from 1.5 to 10, and even more preferably from 2.0 to 5.
When the molar ratio (K+Na)/Ta is within the above range, tantalate particles with improved crystallite size can be easily obtained.
The ratio of (K+Na)/Ta in the manufactured tantalate particles (K _x Na _(1-x) TaO ₃ ) having a perovskite structure is usually around (K+Na)/Ta=1 (within the range having a perovskite structure). However, the excess (K+Na) in the mixture is considered to contribute to good crystal growth of tantalate as so-called self-flux.

In the method for producing tantalate 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=0.8 to 4, and 0. More preferably, it is between 9 and 4.

In the method for producing tantalate particles of the embodiment, the K/Na ratio of the tantalate particles to be produced can be changed depending on the K/Na blending ratio of the raw materials. The molar ratio of potassium and/or sodium atoms to molybdenum atoms in the mixture depends on the desired values of X and 1-X of K _x Na _(1-x) TaO ₃ in the tantalate particles produced. You may set it as appropriate. When the X is 0<X<1, the molar ratio of potassium atoms to sodium atoms in the mixture may be, for example, K/Na=0.01 to 10, and 0.1 to 5. It may be. Moreover, the larger the value of K/Na, the larger the particle size of the tantalate particles produced tends to be.

By using various compounds within the above range, the amount of molybdenum compound contained in the obtained tantalate particles becomes more appropriate, and tantalate particles with a controlled crystal shape can be easily obtained.

[Firing process]
The firing step is a step of firing the mixture. The tantalate particles according to the embodiment are obtained by firing the mixture. As mentioned above, this manufacturing method is called the flux method.

The flux method is classified as a solution method. More specifically, the flux method is a crystal growth method that utilizes the fact that a crystal-flux binary phase diagram shows a eutectic type. The mechanism of the flux method is presumed to be as follows. That is, when a mixture of solute and flux is heated, the solute and flux become a liquid phase. At this time, since the flux is a flux, in other words, the solute-flux binary phase diagram shows a eutectic type, so the solute melts at a temperature lower than its melting point and forms a liquid phase. becomes. In this state, when the flux is evaporated, the concentration of the flux decreases, in other words, the effect of the flux on lowering the melting point of the solute is reduced, and the evaporation of the flux becomes a driving force to cause crystal growth of the solute (flux evaporation method). Note that crystal growth of the solute and flux can also be caused by cooling the liquid phase (slow cooling method).

The flux method has advantages such as being able to grow crystals at a temperature much lower than the melting point, being able to precisely control the crystal structure, and being able to form euhedral crystals.

In the production of tantalate particles by the flux method, when tantalum compounds are calcined in the presence of potassium compounds and/or sodium compounds, oxides (Na ₂ O and K ₂ O ) is formed, which functions as a flux and is presumed to promote the crystal growth of tantalate particles.
Furthermore, when tantalum compounds are calcined in the presence of potassium carbonate and/or sodium carbonate, oxides (Na ₂ O and K ₂ O) and/or CO ₂ are formed from some potassium carbonate and/or sodium carbonate. It is presumed that these oxides and/or CO ₂ function as a flux to promote crystal growth of tantalate particles.

Although the mechanism for producing tantalate particles using a molybdenum compound as a flux is not necessarily clear, it is assumed that the following mechanism is involved, for example. That is, when a tantalum compound is calcined in the presence of a molybdenum compound, tantalum molybdate is formed from a part of the tantalum compound, and molybdate salts (for example, K _a Mo _b O _c and Na _a Mo _b O _{c )} are formed from the molybdenum compound. , K _a Na _a' Mo _b O _c ) are formed. At this time, as understood from the above explanation, tantalate crystals can be grown at a temperature lower than the melting point of tantalate due to the flux function of molybdate. Also, for example, partially formed tantalum molybdate decomposes and promotes crystal growth of tantalate particles. That is, a molybdenum compound (molybdate) functions as a flux, and tantalate particles are produced via an intermediate called tantalum molybdate.

The firing method is not particularly limited and can be performed by any known and commonly used method. When a molybdenum compound is used, when the firing temperature exceeds 500°C, some tantalum compounds react with the molybdenum compound to form tantalum molybdate, etc., and the molybdenum compound produces molybdate (K _a Mo _b O _c , Na _a Mo _b O _c , K _a Na _a' Mo _b O _c ) are thought to be formed. Furthermore, when the firing temperature reaches 800° C. or higher, it is thought that the partially formed tantalum molybdate and the like decomposes, and tantalate particles are formed due to the flux function of the molybdate. Furthermore, in tantalate particles, molybdenum compounds are considered to be incorporated into the tantalate particles during the decomposition of tantalum molybdate and the growth of particle crystals.

In addition, the state of the tantalum compound, molybdenum compound, sodium compound, potassium compound, etc. that can be used during firing is not particularly limited, and the raw material compounds such as the molybdenum compound, tantalum compound, sodium compound, potassium compound, etc. can interact with each other. It suffices if it exists in the space of Specifically, it may be simple mixing of powdered raw material compounds, mechanical mixing using a grinder or the like, mixing using a mortar or the like, and mixing in a dry state or a wet state. It's okay.

The firing temperature conditions are not particularly limited, and are appropriately determined in consideration of the target particle size of the tantalate particles, the formation of molybdenum compounds in the tantalate particles, the shape of the tantalate particles, and the like. The firing temperature may be 700°C or higher, which is close to the temperature at which the molybdate can function as a flux, may be 750°C or higher, 800°C or higher, or 850°C or higher. , 900°C or higher.
From the viewpoint of efficiently producing tantalate particles with 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.

Generally, in order to control the shape of the tantalate obtained after firing, it is necessary to perform high-temperature firing at over 1500°C, which is close to the melting point of tantalum oxide. There are major challenges in making full use of it.

According to one embodiment of the present invention, for example, tantalate particles can be formed efficiently at low cost even under conditions where the maximum firing temperature for firing a tantalum compound is 1500° C. or lower.
Further, according to the method for producing tantalate particles of the embodiment, even when the firing temperature is 1300° C. or lower, which is much lower than the melting point of tantalum oxide, the precursor has an automorphic shape regardless of the shape of the precursor. Tantalate particles can be formed. Moreover, from the viewpoint of efficiently producing tantalate particles, the above-mentioned firing temperature is preferably 1200°C or lower, more preferably 1100°C or lower.

In the firing process, the numerical range of the firing temperature for firing the tantalum compound may be, for example, 700 to 1300°C, 750 to 1300°C, 800 to 1200°C, and 850 to 1300°C. The temperature may be 1200°C to 1200°C, 900 to 1100°C, or 1000 to 1100°C.

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

Regarding the firing time, it is preferable that the heating time to a predetermined firing temperature be carried out in the range of 15 minutes to 10 hours, and the holding time at the firing temperature be carried out in the range of 5 minutes to 30 hours. In order to efficiently form tantalate particles, the firing temperature is preferably held for 2 hours or more, and more preferably from 2 to 15 hours.
Tantalate particles with improved crystallite size can be easily obtained by selecting the conditions of a calcination temperature of 700 to 1100° C. and a calcination temperature holding time of 2 to 15 hours.

The firing atmosphere is not particularly limited as long as the effects of the present invention can be obtained, but 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 from a cost perspective. Taking this into consideration, an air atmosphere is more preferable.

The device 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 it is also preferable to use a highly airtight firing furnace so that molybdenum oxide can be used efficiently.

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

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. It is preferable that the cooling rate is 1° C./hour or more because the manufacturing time can be shortened. On the other hand, it is preferable that the cooling rate is 1000° C./hour or less because the firing container is less likely to crack due to heat shock and can be used for a long time.

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

[Post-processing process]
The manufacturing method of this embodiment may include a post-processing step. The post-treatment step may be a step of separating the tantalate particles and the flux 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-mentioned firing step. Further, if necessary, the process may be repeated two or more times.

Methods for removing the fluxing agent include washing, high temperature treatment, etc. These can be done in combination.

The washing method is not particularly limited, but when the flux is water-soluble like the potassium compound, sodium compound, or molybdate compound mentioned above, washing with water may be used.

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

[Crushing process]
In the fired product obtained through the firing step, the tantalate particles may aggregate and the particle size may not meet the preferred particle size range for the intended use. Therefore, the tantalate particles may be pulverized to satisfy a suitable particle size range, if necessary.
The method for pulverizing the baked product is not particularly limited, and conventionally known pulverizing methods such as a ball mill, jaw crusher, jet mill, disk mill, spectro mill, grinder, mixer mill, etc. can be applied.

[Classification process]
The fired product containing tantalate particles obtained by the firing step may be appropriately classified in order to adjust the particle size range. "Classification processing" refers to an operation of dividing particles into groups according to their size.
Classification may be performed either wet or dry, but from the viewpoint of productivity, dry classification is preferred. In addition to classification using a sieve, dry classification includes wind classification that uses the difference between centrifugal force and fluid drag, but from the perspective of classification accuracy, wind classification is preferable, and air classifiers that use the Coanda effect, This can be carried out using a classifier such as a swirling airflow classifier, a forced vortex centrifugal classifier, or a semi-free vortex centrifugal classifier.
The above-described pulverization process and classification process can be performed at necessary stages. For example, the average particle size of the obtained tantalate particles can be adjusted by whether or not these pulverization and classification are performed and by selecting the conditions thereof.

The tantalate particles of the embodiment or the tantalate particles obtained by the production method of the embodiment have less agglomeration or are not agglomerated, which are more likely to exhibit their original properties and are easier to handle. Moreover, when used after being dispersed in a medium to be dispersed, it is preferable from the viewpoint of more excellent dispersibility.

In addition, according to the method for producing tantalate particles of the above embodiment, it is possible to easily produce tantalate particles with little or no agglomeration, so even if the above-mentioned crushing step and classification step are not performed, It has the excellent advantage that tantalate particles having the desired excellent properties can be produced with high productivity.

≪Resin composition≫
The tantalate particles of embodiments can be blended with a resin to provide a resin composition. As one embodiment, a resin composition containing the tantalate 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 or a thermoplastic resin, or an active energy ray-curable resin.

(thermosetting resin)
Thermosetting resins are resins that have the property of becoming substantially insoluble and infusible when cured by means such as heating, radiation, or catalysts. For example, it may be a known and commonly used resin used for molding materials and the like. Specifically, for example, novolac-type phenolic resins such as phenol novolac resins and cresol novolac resins; resol-type phenolic resins such as unmodified resol phenolic resins, oil-modified resol phenolic resins modified with tung oil, linseed oil, walnut oil, etc. Phenol resins such as bisphenol A epoxy resin, bisphenol F epoxy resin, etc.; novolac epoxy resins such as fatty chain modified bisphenol epoxy resins, novolac epoxy resins, cresol novolac epoxy resins; biphenyl epoxy resins, Epoxy resins such as alkylene glycol type epoxy resins; resins with triazine rings such as urea resins and melamine resins; vinyl resins such as (meth)acrylic resins and vinyl ester resins: unsaturated polyester resins, bismaleimide resins, Examples include polyurethane resins, diallyl phthalate resins, silicone resins, resins having benzoxazine rings, cyanate ester resins, and they may be polymers, oligomers, or monomers.

The thermosetting resin 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 a 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, phenol compounds, etc. Can be mentioned. Specifically, examples of the amine compound include diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenylsulfone, isophoronediamine, imidazole, BF ₃ -amine complex, and guanidine derivatives. Examples of the amide compound include dicyandiamide, a polyamide resin synthesized from a dimer of linolenic acid, and ethylenediamine, and the like. Examples of acid anhydride compounds include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydro. Examples include phthalic anhydride. Examples of phenolic compounds include polyhydric hydroxyl compounds such as phenol novolak resin, cresol novolac resin, aromatic hydrocarbon formaldehyde resin-modified phenol resin, dicyclopentadiene phenol addition type resin, phenol aralkyl resin (Zyrock resin), and resorcin novolak resin. Polyhydric phenol novolac resins synthesized from chemical compounds and formaldehyde, naphthol aralkyl resins, trimethylolmethane resins, tetraphenylolethane resins, naphthol novolac resins, naphthol-phenol condensed novolac resins, naphthol-cresol condensed novolac resins, biphenyl modified resins 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 (phenol with melamine, benzoguanamine, etc.) Polyhydric phenol compounds such as a polyhydric phenol compound in which a phenol nucleus and an alkoxy group-containing aromatic ring are linked with formaldehyde) and alkoxy group-containing aromatic ring-modified novolac resins (a polyhydric phenol compound in which a phenol nucleus and an alkoxy group-containing aromatic ring are linked with formaldehyde) are mentioned. These curing agents may be used alone or in combination of two or more types.

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

Further, 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, including phosphorus compounds, tertiary amines, imidazole, organic acid metal salts, Lewis acids, amine complex salts, etc. It will be done.

Furthermore, if necessary, a curing catalyst can be used in combination with the thermosetting resin, including known and commonly used thermal polymerization initiators and active energy ray polymerization initiators.

(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, polyether sulfone resin, polyether ether ketone resin, polyallyl sulfone resin, thermoplastic polyimide resin, thermoplastic urethane resin , polyamino bismaleimide 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, etc. At least one type 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 types of thermoplastic resins.

When provided as a piezoelectric material, the resin preferably exhibits a high dielectric constant, and the resin is preferably a polymer having an electron-withdrawing group, such as polyvinylidene fluoride (PVDF), vinylidene fluoride-tetrafluoroethylene, etc. Copolymers, fluorine-containing polymers such as vinylidene fluoride-trifluoroethylene copolymers, cyanoethylated polyvinyl alcohol, vinylidene cyanide-vinyl acetate copolymers, cyanoethylcellulose, cyanoethylhydroxysucrose, cyanoethylhydroxycellulose, cyanoethylhydroxypullulan , 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 Preferred are polymers having a cyano group or cyanoethyl group, such as saccharose and cyanoethyl sorbitol.

The resin composition of the embodiment may contain other compounds as necessary, and may contain an external lubricant, an internal lubricant, an antioxidant, a flame retardant, a light stabilizer, and ultraviolet rays to the extent that the effects of the invention can be obtained. An absorbent, a silane-based, titanate-based, or aluminate-based coupling agent, a reinforcing material such as glass fiber or carbon fiber, a filler, various coloring agents, etc. may be added. In addition, stress reducing agents such as silicone oil, liquid rubber, rubber powder, butadiene copolymer rubber such as methyl acrylate-butadiene-styrene copolymer, methyl methacrylate-butadiene-styrene copolymer, and silicone compounds (stress relaxation agents) can also be used.

The resin composition of the embodiment can be obtained by mixing the tantalate particles of the embodiment, a resin, and, if necessary, other compounds. There is no particular limitation on the mixing method, and the mixing may be carried out by any known and commonly used method.

When the resin is a thermosetting resin, the general method is to thoroughly mix the thermosetting resin, the tantalate particles of the embodiment, and other components as necessary using a mixer, etc., and then mix the three Knead with a roll or the like to form a fluid liquid composition, or mix a predetermined amount of thermosetting resin, the tantalate particles of the embodiment, and other components as necessary with a mixer or the like. After that, the mixture is melt-kneaded using a mixing roll, an extruder, etc., and then cooled to obtain a solid composition. Regarding the mixing state, when a curing agent, a catalyst, etc. are blended, it is preferable that the curable resin and those compounds are sufficiently uniformly mixed, and the tantalate particles of the embodiment are also uniformly dispersed and mixed. It is more preferable.

When the resin is a thermoplastic resin, a common method is to mix the thermoplastic resin, the tantalate particles of the embodiment, and other ingredients as necessary using various mixers such as a tumbler or a Henschel mixer. Examples include a method of premixing and then melt-kneading with 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. Note that the melt-kneading temperature is not particularly limited, but may be in the range of 240 to 320°C.

In preparing the resin composition of the embodiment, the mixing ratio of the tantalate particles of the embodiment and the nonvolatile content of the resin is not particularly limited, but per 100 parts by mass of the nonvolatile content of the resin, For example, it may range from 0.1 to 1800 parts of tantalate particles, and it may range from 10 to 900 parts.

The content ratio of the tantalate particles to the total mass (100% by mass) of the resin composition of the embodiment may be 30% by mass or more, 50 to 90% by mass, and 60 to 85% by mass. It may be %.

≪Molded object≫
A molded article can be obtained by molding the resin composition of the embodiment. As one embodiment, a molded article formed by molding the resin composition of the embodiment is provided. The resin molded article can be obtained by any known and commonly used method.

For example, when the resin contained in the resin composition is a thermosetting resin, a general curing method for thermosetting resin compositions such as epoxy resin compositions may be followed. 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 may be selected as appropriate depending on the type of curing agent to be combined and the intended use. It may be heated within a temperature range of approximately ℃. In the case of active energy ray-curable resins, they can be cured and molded by irradiation with active energy rays such as ultraviolet rays and infrared rays.

Furthermore, even when the resin of the embodiment is a thermoplastic resin, it can be made into a molded article 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, blow molding method such as gas assist, molding method using insulation mold, molding method using rapid heating mold, foaming Examples include molding (including supercritical fluid), insert molding, IMC (in-mold coating molding), extrusion molding, sheet molding, rotary molding, lamination molding, press molding, and the like. Further, a molding method using a hot runner method can also be used. There are no restrictions on the shape, pattern, color, size, etc. of the molded product, and they may be set arbitrarily depending on the purpose of the molded product.

When the molded article of the resin composition is in the form of a sheet or layer, its thickness may be from 10 to 100 μm, or from 10 to 80 μm.

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

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples.

<Analysis/Evaluation>
The following measurements were performed using the powders of each example as samples.

[XRF (X-ray fluorescence) analysis]
Using an X-ray fluorescence analyzer Primus IV (manufactured by Rigaku Co., Ltd.), about 70 mg of sample powder was placed on a filter paper, covered with a PP film, and subjected to XRF (X-ray fluorescence) analysis under the following conditions. Measurement conditions EZ scan mode Measuring elements: F to U
Measurement time: Standard measurement diameter: 10mm
Residue (balance component): None

The sample powder was subjected to XRF analysis to determine the tantalum content in the sample powder, and the tantalum content was calculated as the content (mass%) in terms of Ta ₂ O ₅ based on 100 mass% of the total mass of the sample powder.
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 %) in terms of MoO ₃ based on the total mass 100 mass % of the sample powder.
The sample powder was subjected to XRF analysis to determine the potassium content in the sample powder, and calculated as a content rate (mass%) in terms of K ₂ O with respect to 100 mass% of the total mass of the sample powder. The sample powder was subjected to XRF analysis to determine the sodium content in the sample powder, and calculated as the content (mass%) in terms of Na ₂ O with respect to the total mass of the sample powder (100% by mass).

[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 it was set in a wide-angle X-ray diffraction (XRD) device (Ultima IV, manufactured by Rigaku Co., Ltd.), using Cu/Kα radiation, 40 kV/40 mA, and scanning speed. The measurement was carried out under the conditions of 2°/min and a scanning range of 10 to 70° or a scanning range of 10 to 90°.

[Measurement of particle size]
(For particles with cubic shape)
The sample powder was photographed using a scanning electron microscope (SEM). When the smallest unit particle (i.e., primary particle) observed on a two-dimensional image is recognized to have a cubic shape, the length of one side of the hexahedron determined from the particle image of the primary particle is calculated as the particle size. It was measured as
A similar operation was performed on 50 primary particles, and each average value was determined.

[Measurement of crystallite size]
Measurements were performed using SmartLab (manufactured by Rigaku Co., Ltd.) as an X-ray diffractometer, a high-intensity, high-resolution crystal analyzer (CALSA) as a detector, and PDXL as analysis software. The measurement method is the 2θ/θ method, with a peak appearing at 2θ = 23.0 ± 1.0°, a peak appearing at 2θ = 32.0 ± 1.2°, and 2θ = 57.0 ± 1.0. The average crystallite size was calculated from the half-width of the peak appearing at ° using the Scherrer equation. The measurement conditions were: scan speed was 0.05 degrees/min, scan range was 20 to 70 degrees, step was 0.002 degrees, and device standard width was 0.028 degrees (Si). .

[Particle size distribution measurement]
The particle size distribution of the sample powder was measured in a dry manner using a laser diffraction type dry particle size distribution meter (HELOS (H3355) & RODOS manufactured by Nippon Laser Co., Ltd.) under conditions of a dispersion pressure of 3 bar and a suction pressure of 90 mbar. The particle diameter at the point where the volume integration % distribution curve intersects the 50% horizontal axis was determined as _D50 . The particle diameter at the point where the volume integration % distribution curve intersects the horizontal axis of 10% from the small particle side was determined as _D10 . The particle diameter at the point where the volume integration % distribution curve intersects the 90% horizontal axis from the small particle side was determined as _D90 .

[Specific surface area measurement]
The specific surface area of the sample powder is measured using a specific surface area meter (BELSORP-mini, manufactured by Microtrac Bell Co., Ltd.), and the surface area per 1 g of the sample measured from the amount of nitrogen gas adsorbed by the BET method is calculated as the specific surface area ( m ² /g).

[Example 1]
Tantalum oxide (Kanto Kagaku Co., Ltd. reagent, Ta ₂ O ₅ ) 10.0 g, molybdenum oxide (Kanto Kagaku Co., Ltd. reagent, MoO ₃ ) 6.8 g, and sodium carbonate (Kanto Kagaku Co., Ltd. reagent, Na ₂ CO ₃ ) 11.5 g were mixed in a mortar to obtain a mixture. The obtained mixture was placed in a crucible and fired in a ceramic electric furnace at 1000° C. for 10 hours. After cooling, the crucible was taken out from the ceramic electric furnace.
Subsequently, the obtained fired product was ultrasonically cleaned with water five times, and then washed with water to remove the cleaning water by filtration, and dried to remove the remaining fluxing agent and prepare powder 9 of Example 1. .1g was obtained.

The above synthesis conditions are shown in Table 1.

[Examples 2 to 12]
Powders of Examples 2 to 12 were obtained in the same manner as in Example 1, except that the composition of the raw material compounds and the firing temperature were changed as shown in Table 1.
As the raw material K ₂ CO ₃ in Table 1, potassium carbonate (reagent manufactured by Kanto Kagaku Co., Ltd., K ₂ CO ₃ ) was used.

<Results>
SEM images of the powders of Examples 1 to 12 above are shown in FIGS. 1 to 12. (Figures 9 and 10 also show enlarged views of each.)

The results of each of the above evaluations are shown in Table 2. "-" indicates that the corresponding compound was not used. "N.D." is an abbreviation for "not detected" and represents non-detection.

Table 2 shows the shape and size of the particles of each example as determined from the SEM image.
When particles of different shapes are found to be mixed, the representative shape (the shape most often observed) is noted. Aggregates of cubic particles are also included in those having a cubic shape.

The results of the XRD analysis are shown in Figures 13-16.
In each of the samples of Examples 1 to 5, 2θ=23.0±1. derived from the (100) plane, (110) plane, and (221) plane of the perovskite structure of K _x Na _(1-x) TaO ₃ . Peaks at 0°, 2θ=32.0±1.2°, and 2θ=57.0±1.0° were observed.

From the results of the above SEM observation and XRD analysis, each of the powders obtained in Examples 1 to 12 has a cubic shape and consists of K _x Na _(1-x) TaO ₃ particles having a perovskite structure (Pe structure). It was confirmed that

Furthermore, the powder samples of Examples 1 to 12 were shown to contain tantalum, molybdenum, potassium, and sodium in the oxide equivalent amounts shown in Table 2 determined by XRF analysis.

Focusing on each particle size (SEM observation, D ₅₀ ) and crystallite size, the particles of Examples 1 to 12 had large primary particle sizes and large crystallite sizes. This is because most of the raw material compounds MoO ₃ , Na ₂ Co ₃ , and K ₂ CO ₃ (including their products and decomposition products) used in the production method of each example functioned as a fluxing agent. This is thought to be due to the fact that the crystal growth of the particles was able to progress well.

The larger the value of the K/Na blending ratio of the raw materials, the larger the particles tended to be obtained (Examples 3 to 6).
Furthermore, the higher the firing temperature, the larger the particles tended to be obtained (Examples 9 to 12).

It was confirmed that each particle of Examples 1 to 12 had a BET specific surface area shown in Table 2.

From the results of Examples 1 to 12, high-quality K _x Na _{(1 -x)} It was shown that it is possible to sinter TaO ₃ particles.

In addition, in Examples 1 to 6 and 9 to 12 using molybdenum compounds, the yield calculated by the actual yield of K _x Na _(1-x) TaO ₃ particles/theoretical yield x 100 (mass%) was 76 mass However, in Examples 7 and 8 in which no molybdenum compound was used, the yields of K _x Na _(1-x) TaO ₃ particles were 45% by mass and 35% by mass, respectively.
This indicates that K _x Na _(1-x) TaO ₃ particles can be produced with high efficiency by using a molybdenum compound.

Since the K _x Na _(1-x) TaO ₃ particles obtained in Examples 1 to 12 are of high quality with a large crystallite size and few impurities, they are expected to exhibit excellent catalytic performance. .

The configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other changes to the configurations are possible without departing from the spirit of the present invention. Further, the present invention is not limited by each embodiment, but only by the scope of the claims.

Claims (16)

1. Contains the crystal structure of tantalate represented by K _x Na _(1-x) TaO ₃ (0≦x≦1),
   The crystal structure is a tantalate particle having an average crystallite size of 80 nm or more as determined from a peak at 2θ=23.0±1.0° of the tantalate obtained by X-ray diffraction measurement.
2. The tantalate particles according to claim 1, wherein the crystal structure includes a perovskite crystal structure.
3. The tantalate particles according to claim 1 or 2, which have a cubic shape.
4. 3. The crystal structure according to claim 1 or 2, wherein the average crystallite size determined from the peak of 2θ=32.0±1.2° of the tantalate salt obtained by X-ray diffraction measurement is 50 nm or more. of tantalate particles.
5. The tantalate particles according to claim 1 or 2, wherein the median diameter D ₅₀ calculated by a laser diffraction/scattering method is 0.1 to 100 μm.
6. The content of tantalum in the tantalate particles is determined by XRF analysis of the tantalate particles, and the content in terms of Ta ₂ O ₅ is 50 to 50% based on 100% by mass of the total mass of the tantalate particles. Tantalate particles according to claim 1 or 2, which are 99% by mass.
7. The potassium and/or sodium content in the tantalate particles is determined by XRF analysis of the tantalate particles, in terms of K ₂ O and Na ₂ O based on 100% by mass of the tantalate particles. The tantalate particles according to claim 1 or 2, wherein the total content of tantalate particles is 0.5 to 40% by mass.
8. The tantalate particles according to claim 1 or 2, containing molybdenum.
9. The molybdenum content in the tantalate particles is determined by XRF analysis of the tantalate particles, and the molybdenum content is 0.01 to 20 in terms of MoO ₃ based on 100% by mass of the total mass of the tantalate particles. 9. Tantalate particles according to claim 8, which are % by weight.
10. A method for producing tantalate particles according to claim 1, comprising:
    A method for producing tantalate particles, comprising firing a tantalum compound in the presence of a potassium compound and/or a sodium compound.
11. The method for producing tantalate particles according to claim 10, wherein the sodium compound is sodium carbonate and the potassium compound is potassium carbonate.
12. 11. A method for producing tantalate particles according to claim 8, which comprises firing a tantalum compound in the presence of a molybdenum compound and a potassium compound and/or a sodium compound. Method for producing acid salt particles.
13. The method for producing tantalate particles according to claim 12, wherein the molybdenum compound is at least one compound selected from the group consisting of molybdenum trioxide, potassium molybdate, and sodium molybdate.
14. A step of mixing a tantalum compound and a potassium compound and/or a sodium compound to form a mixture, and a step of firing the mixture,
    The method for producing tantalate particles according to claim 10 or 11, wherein the molar ratio (K+Na)/Ta of potassium atoms and sodium atoms to tantalum atoms in the mixture is 1.1 or more.
15. tantalate particles according to claim 1 or 2;
    A resin composition comprising a resin.
16. A molded article formed by molding the resin composition according to claim 15.

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