Production method of organic acid salt and production method of perovskite-type complex oxide

Abstract

To provide an industrially advantageous production method of an organic acid salt with which a highly crystalline perovskite type complex oxide with a small particle size can be obtained.SOLUTION: In a production method of an organic acid salt, a solution (solution A) containing any one of an organic acid, an A-site element compound, and a B-site element compound and a solution (solution B) containing two of the organic acid, the A-site element compound, and the B-site element compound that are not contained in the solution A are mixed and made to react with each other so as to obtain the organic acid salt, and in the production method of the organic acid salt, previously one of the solution A and the solution B and a granular medium of 5.0-95.0 vol.% based on the volume of the one solution are charged into a reaction vessel, and then while stirring the liquid and the granular medium in the reaction vessel, the other of the solution A and the solution B is mixed and made to react with the liquid in the reaction vessel.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing organic acid salts such as barium titanyl oxalate and barium titanyl citrate, which are useful as raw materials for functional ceramics such as dielectrics, piezoelectrics, optoelectronic materials, semiconductors, and sensors. [Background technology]

[0002] Conventionally, perovskite-type composite oxides, typified by barium titanate, have been produced by the solid phase method, hydrothermal synthesis method, alkoxide method, oxalate method, or the like.

[0003] In the solid-phase method, raw material powders are mixed and heated at high temperatures to produce a powder using a dry process. The resulting powder forms irregularly shaped aggregates, and high-temperature firing is required to achieve the desired properties. The hydrothermal synthesis method, despite its advantage of producing powders with good properties, is industrially unfavorable due to its complicated synthesis process, the use of an autoclave, poor productivity, and the high cost of the resulting powder. Similarly, the alkoxide method is industrially unfavorable due to the difficulty in handling the starting materials and the high cost.

[0004] Barium titanate obtained by the oxalate method can be produced at low cost with a uniform composition compared to the hydrothermal synthesis method or the alkoxide method, and is characterized by its uniform composition compared to barium titanate produced by a solid-phase method. A typical conventional oxalate method involves reacting a titanium source such as titanium tetrachloride, a barium source such as barium chloride, and oxalic acid in a solvent such as water to obtain barium titanyl oxalate, and then calcining the barium titanyl oxalate (see, for example, Patent Documents 1 to 3).

[0005] Barium titanate can be obtained by firing the barium titanyl oxalate obtained by this method, but firing at high temperatures to increase crystallinity causes grain growth of the barium titanate, making it difficult to obtain fine barium titanate particles. To solve this problem, Patent Document 4 describes making the obtained barium titanyl oxalate into a slurry, then grinding it in a wet grinding device such as a ball mill or a bead mill to obtain fine barium titanate particles, which are then fired, thereby obtaining barium titanate particles finer than conventional ones. Patent Document 5 also describes similarly wet-grinding barium titanyl oxalate in a bead mill and firing it. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2005-500239 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-202610 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-63867 [Patent Document 4] Japanese Patent Application Laid-Open No. 2004-123431 [Patent Document 5] International Publication No. WO2003-016219 Pamphlet Summary of the Invention [Problem to be solved by the invention]

[0007] As in Patent Documents 4 and 5, it is possible to obtain fine, highly crystalline barium titanate to a certain extent by pulverizing the obtained barium titanyl oxalate and firing it to grow particles, but further improvements are required to obtain barium titanate with the properties required as a raw material for recent functional ceramics.

[0008] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an industrially advantageous method for producing an organic acid salt which can yield a perovskite-type composite oxide having a small particle size and high crystallinity. [Means for solving the problem]

[0009] As a result of extensive research, the present inventors have discovered that when a solution (liquid A) containing one of an organic acid, an A-site element compound, and a B-site element compound is mixed with a solution (liquid B) containing two of the organic acid, the A-site element compound, and the B-site element compound that are not contained in liquid A to cause a reaction, one of liquids A and B and a granular medium in a predetermined amount relative to the volume of the one solution are charged into a reaction vessel, and the other of liquids A and B is mixed into the reaction vessel while stirring the liquid and the granular medium in the reaction vessel. In this way, the granular medium, which flows with the reaction liquid, causes the product to precipitate on minute crystal nuclei generated in the reaction liquid, preventing the crystals from growing large. As a result, the product crystals do not grow in the reaction liquid, and an organic acid salt with a small particle size is obtained. By calcining the resulting organic acid salt, a perovskite-type composite oxide with a small particle size and high crystallinity can be obtained, which led to the completion of the present invention.

[0010] That is, the present invention (1) is a method for producing an organic salt by mixing and reacting a solution (liquid A) containing any one of an organic acid, an A-site element compound, and a B-site element compound with a solution (liquid B) containing two of the organic acid, the A-site element compound, and the B-site element compound that are not contained in liquid A, First, a reaction vessel is charged with one of the solutions A and B and a granular medium in an amount of 5.0 to 95.0% by volume relative to the volume of the one of the solutions, and then, while stirring the liquid and the granular medium in the reaction vessel, the other of the solutions A and B is mixed with the liquid in the reaction vessel to cause a reaction; The present invention provides a method for producing an organic acid salt, characterized by the above.

[0011] The present invention (2) also provides the method for producing an organic acid salt according to (1), wherein the solution A is a solution containing the organic acid, and the solution B is a solution containing the A-site element compound and the B-site element compound.

[0012] The present invention (3) also provides the method for producing an organic acid salt according to (1), wherein the solution A is a solution containing the A-site element compound, and the solution B is a solution containing the organic acid and the B-site element compound.

[0013] The present invention (4) also provides the method for producing an organic acid salt according to (1), wherein the solution A is a solution containing the B-site element compound, and the solution B is a solution containing the organic acid and the A-site element compound.

[0014] The present invention (5) also provides the method for producing an organic acid salt according to any one of (1) to (4), wherein the granular medium is beads having a particle size of 0.005 to 10.0 mm.

[0015] The present invention (6) also provides the method for producing an organic acid salt according to (5), wherein the beads are resin beads made of at least one material selected from the group consisting of polyethylene, polypropylene, polyamide, polyvinyl chloride, polyvinylidene fluoride, polyimide, polyethylene terephthalate, and polystyrene.

[0016] The present invention (7) also provides the method for producing an organic acid salt according to (5), wherein the beads are resin beads made of at least one material selected from the group consisting of zirconia, alumina, silica, silicon carbide, and silicon nitride.

[0017] The present invention (8) also provides a method for producing an organic acid salt according to any one of (1) to (7), wherein the organic acid is at least one selected from the group consisting of oxalic acid, citric acid, malonic acid, and succinic acid.

[0018] The present invention (9) also provides a method for producing an organic acid salt according to any one of (1) to (8), wherein the A-site element compound in the solution B is a compound containing at least one element selected from the group consisting of Ba, Ca, Mg, and Sr, and the B-site element compound is a compound containing at least one element selected from the group consisting of Ti, Zr, V, Nb, Cr, B, Al, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Sb, Sc, Ta, Ru, Ir, Ga, In, and Sn.

[0019] The present invention (10) also provides the method for producing an organic acid salt according to any one of (1) to (9), wherein the mixing temperature of the solution A and the solution B is 75° C. or lower.

[0020] The present invention (11) also provides a method for producing an organic acid salt according to any one of (1) to (10), characterized in that the organic acid salt produced has an average particle size of 50 μm or less.

[0021] The present invention (12) also provides a method for producing a perovskite-type composite oxide, characterized in that the organic acid salt obtained by any one of the production methods (1) to (11) is calcined to obtain the perovskite-type composite oxide. [Effects of the Invention]

[0022] According to the present invention, an organic acid salt that can give a perovskite-type composite oxide having a small particle size and high crystallinity can be produced industrially and advantageously. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a scanning electron microscope (SEM) photograph of barium titanate obtained in Example 1 at a firing temperature of 750°C. [Figure 2] 1 is a scanning electron microscope (SEM) photograph of barium titanate obtained in Comparative Example 1 at a firing temperature of 750° C. DETAILED DESCRIPTION OF THE INVENTION

[0024] The method for producing an organic salt of the present invention is a method for producing an organic salt by mixing and reacting a solution (Solution A) containing any one of an organic acid, an A-site element compound, and a B-site element compound with a solution (Solution B) containing two of the organic acid, the A-site element compound, and the B-site element compound that are not contained in Solution A, to obtain an organic salt; First, a reaction vessel is charged with one of the solutions A and B and a granular medium in an amount of 5.0 to 95.0% by volume relative to the volume of the one of the solutions, and then, while stirring the liquid and the granular medium in the reaction vessel, the other of the solutions A and B is mixed with the liquid in the reaction vessel to cause a reaction; The method for producing an organic acid salt is characterized by the following.

[0025] Among the methods for producing an organic salt of the present invention, a first embodiment of the present invention is a method for producing an organic salt by mixing and reacting a solution containing an organic acid (liquid A) with a solution containing an A-site element compound and a B-site element compound (liquid B), thereby obtaining an organic salt, First, a reaction vessel is charged with one of the solutions A and B and a granular medium in an amount of 5.0 to 95.0 times the volume of the one of the solutions, and then, while stirring the liquid and the granular medium in the reaction vessel, the other of the solutions A and B is mixed with the liquid in the reaction vessel to cause a reaction; The method for producing an organic acid salt is characterized by the following.

[0026] Furthermore, among the methods for producing an organic salt of the present invention, a second embodiment of the method for producing an organic salt of the present invention is a method for producing an organic salt by mixing and reacting a solution containing an A-site element compound (liquid A) with a solution containing an organic acid and a B-site element compound (liquid B), First, a reaction vessel is charged with one of the solutions A and B and a granular medium in an amount of 5.0 to 95.0 times the volume of the one of the solutions, and then, while stirring the liquid and the granular medium in the reaction vessel, the other of the solutions A and B is mixed with the liquid in the reaction vessel to cause a reaction; The method for producing an organic acid salt is characterized by the following.

[0027] Furthermore, among the methods for producing an organic salt of the present invention, a third embodiment of the present invention is a method for producing an organic salt by mixing and reacting a solution containing a B-site element compound (liquid A) with a solution containing an organic acid and an A-site element compound (liquid B), to obtain an organic salt, First, a reaction vessel is charged with one of the solutions A and B and a granular medium in an amount of 5.0 to 95.0 times the volume of the one of the solutions, and then, while stirring the liquid and the granular medium in the reaction vessel, the other of the solutions A and B is mixed with the liquid in the reaction vessel to cause a reaction; The method for producing an organic acid salt is characterized by the following.

[0028] The methods for producing an organic salt of the first, second, and third aspects of the present invention have some points in common, although they differ in which of the organic acid, the A-site element compound, and the B-site element compound is contained in Solution A and Solution B. Therefore, with regard to the points common to the methods for producing an organic salt of the first, second, and third aspects of the present invention, the methods for producing an organic salt of the first, second, and third aspects of the present invention will be collectively referred to and explained as the methods for producing an organic salt of the present invention.

[0029] The method for producing an organic salt of the present invention uses two types of solutions, Liquid A and Liquid B, as reaction raw material solutions, and mixes and reacts these two solutions to obtain an organic salt. In a first embodiment of the method for producing an organic salt of the present invention, Liquid A is a solution containing an organic acid, and Liquid B is a solution containing an A-site element compound and a B-site element compound. In a second embodiment of the method for producing an organic salt of the present invention, Liquid A is a solution containing an A-site element compound, and Liquid B is a solution containing an organic acid and a B-site element compound. In a third embodiment of the method for producing an organic salt of the present invention, Liquid A is a solution containing a B-site element compound, and Liquid B is a solution containing an organic acid and an A-site element compound.

[0030] Examples of organic acids used in the method for producing an organic acid salt of the present invention include oxalic acid, citric acid, malonic acid, tartaric acid, lactic acid, glycolic acid, malic acid, aspartic acid, and succinic acid. The organic acid may be used alone or in combination of two or more. Among these, oxalic acid is preferred as the organic acid.

[0031] The A-site element in the method for producing an organic salt of the present invention refers to an element occupying the A-site in an ABO-type perovskite complex oxide, and the B-site element refers to an element occupying the B-site in an ABO-type perovskite complex oxide. In other words, the organic salt obtained by the method for producing an organic salt of the present invention is a raw material for calcining an ABO-type perovskite complex oxide, and an ABO-type perovskite complex oxide can be obtained by calcining the organic salt obtained by the method for producing an organic salt of the present invention.

[0032] The A-site element in the method for producing an organic acid salt of the present invention includes at least one element selected from the group consisting of Ba, Ca, Mg, and Sr.

[0033] Examples of the A-site element compound used in the method for producing an organic acid salt of the present invention include chlorides, carbonates, hydroxides, acetates, nitrates, formates, and oxides of the A-site element. One type of A-site element compound may be used, or two or more types may be used in combination. Preferred A-site element compounds are one or more types selected from the group consisting of barium chloride, calcium chloride, magnesium chloride, strontium chloride, barium acetate, calcium acetate, magnesium acetate, strontium acetate, barium nitrate, calcium nitrate, magnesium nitrate, strontium nitrate, barium hydroxide, calcium hydroxide, magnesium hydroxide, and strontium hydroxide.

[0034] The B-site element in the method for producing an organic acid salt of the present invention includes at least one element selected from the group consisting of Ti, Zr, V, Nb, Cr, B, Al, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Sb, Sc, Ta, Ru, Ir, Ga, In, and Sn, and is preferably Ti or Zr.

[0035] Examples of the B-site element compound used in the method for producing an organic acid salt of the present invention include chlorides, lactates, alkoxides, acetates, and hydroxides of B-site elements. Examples of the B-site element compound include titanium tetrachloride, zirconium tetrachloride, titanium lactate, and zirconium lactate. The B-site element compound may be one type, or two or more types may be used in combination.

[0036] The solvent for Solution A in the method for producing an organic acid salt of the present invention may be an aqueous solvent, an organic solvent, or a mixed solvent thereof, and is preferably an aqueous solvent from the viewpoint of ease of handling and the production of fine particles of the organic acid salt. Examples of the aqueous solvent include highly purified water such as pure water and ion-exchanged water, and mixed solvents of such highly purified water with a hydrophilic organic solvent.

[0037] The solvent for Solution B in the method for producing an organic acid salt of the present invention may be an aqueous solvent, an organic solvent, or a mixed solvent thereof, and is preferably an aqueous solvent from the viewpoint of ease of handling and the production of fine particles of the organic acid salt. Examples of the aqueous solvent include highly purified water such as pure water and ion-exchanged water, and mixed solvents of such highly purified water with a hydrophilic organic solvent.

[0038] The organic solvents for solutions A and B are not particularly limited as long as they are hydrophilic and inert to the raw materials, and one or more selected from the group consisting of methanol, ethanol, propanol, butanol, diethyl ether, 1,3-butylene glycol, ethylene glycol, propylene glycol, dipropylene glycol, glycerol, N,N-dimethylformamide, and acetone can be used. In the case of a mixed solvent of water and an organic solvent or a mixed solvent of multiple organic solvents, the mixing ratio between these is selected appropriately.

[0039] The concentration of organic acid ions in Solution A or Solution B in the method for producing an organic salt of the present invention, i.e., the concentration of organic acid ions in Solution A in the method for producing an organic salt of the first embodiment of the present invention, the concentration of organic acid ions in Solution B in the method for producing an organic salt of the second embodiment of the present invention, and the concentration of organic acid ions in Solution B in the method for producing an organic salt of the third embodiment of the present invention, is not particularly limited, but is preferably 0.10 to 7.0 mol / L, and particularly preferably 0.60 to 5.0 mol / L.

[0040] The concentration of the A-site element ion in Solution A or Solution B in the method for producing an organic salt of the present invention, i.e., the concentration of the A-site element ion in Solution B in the method for producing an organic salt of the first aspect of the present invention, the concentration of the A-site element ion in Solution A in the method for producing an organic salt of the second aspect of the present invention, and the concentration of the A-site element ion in Solution B in the method for producing an organic salt of the third aspect of the present invention, is not particularly limited, but is preferably 0.010 to 6.5 mol / L, and particularly preferably 0.10 to 3.0 mol / L.

[0041] The concentration of B-site element ions in Solution A or Solution B in the method for producing an organic salt of the present invention, i.e., the concentration of B-site element ions in Solution B in the method for producing an organic salt of the first embodiment of the present invention, the concentration of B-site element ions in Solution B in the method for producing an organic salt of the second embodiment of the present invention, and the concentration of B-site element ions in Solution A in the method for producing an organic salt of the third embodiment of the present invention, is not particularly limited, but is preferably 0.010 to 4.0 mol / L, and particularly preferably 0.10 to 3.0 mol / L.

[0042] The molar ratio of the A-site element to the B-site element in atomic terms in the method for producing an organic acid salt of the present invention is appropriately selected depending on the molar ratio of the ABO-type perovskite complex oxide to be obtained by calcining the organic acid salt. When two or more A-site elements are used, the number of moles of the A-site element in atomic terms refers to the total moles of those two or more A-site elements. When two or more B-site elements are used, the number of moles of the B-site element in atomic terms refers to the total moles of those two or more B-site elements. In the method for producing an organic acid salt of the present invention, the ratio of the total moles of the A-site element in atomic terms to the total moles of the B-site element in atomic terms (A-site element / B-site element) is, for example, 0.10 to 25.0, preferably 0.20 to 15.0. For example, in the method for producing an organic acid salt of the first aspect of the present invention, the ratio of the total moles of the A-site element in atomic terms to the total moles of the B-site element in solution B (A-site element / B-site element) is 0.10 to 25.0, preferably 0.20 to 15.0. The ratio of the total moles of A-site elements in solution A to the total moles of B-site elements in solution B (A-site element / B-site element) used in the second embodiment of the present invention is, for example, 0.10 to 25.0, preferably 0.20 to 15.0. The ratio of the total moles of A-site elements in solution B to the total moles of B-site elements in solution A (A-site element / B-site element) used in the third embodiment of the present invention is, for example, 0.10 to 25.0, preferably 0.20 to 15.0.

[0043] In the method for producing an organic salt of the present invention, the ratio of the total number of moles of the A-site element and the B-site element in atomic terms to the number of moles of the organic acid is preferably 0.01 to 20.0, particularly preferably 0.10 to 10.0. In the method for producing an organic salt of the first aspect of the present invention, the ratio of the total number of moles of the A-site element and the B-site element in atomic terms to the number of moles of the organic acid in Solution A used in the method for producing an organic salt of the first aspect of the present invention is preferably 0.01 to 20.0, particularly preferably 0.10 to 10.0. In the method for producing an organic salt of the second aspect of the present invention, the ratio of the total number of moles of the A-site element in Solution A and the B-site element in Solution B in atomic terms to the number of moles of the organic acid in Solution B used in the method for producing an organic salt of the third aspect of the present invention is preferably 0.01 to 20.0, particularly preferably 0.10 to 10.0.

[0044] In the method for producing an organic salt of the present invention, a reaction vessel is first charged with one of solutions A and B and a granular medium, and then the liquid in the reaction vessel and the granular medium are stirred in the reaction vessel while the other of solutions A and B is mixed with the liquid in the reaction vessel to cause a reaction. That is, in the method for producing an organic salt of the present invention, (I) the entire amount of solution A and the granular medium are first charged in the reaction vessel, and then the liquid in the reaction vessel and the granular medium are stirred in the reaction vessel while mixing solution B with the liquid in the reaction vessel to cause a reaction, or (II) the entire amount of solution B and the granular medium are first charged in the reaction vessel, and then the liquid in the reaction vessel and the granular medium are stirred in the reaction vessel while mixing solution A with the liquid in the reaction vessel to cause a reaction.

[0045] In the method for producing an organic acid salt of the present invention, a reaction vessel is first charged with one of Solutions A and B and a granular medium. The volumetric loading of the granular medium relative to the volume of one of Solutions A and B is 5.0 to 95.0% by volume, preferably 7.0 to 70.0% by volume, and more preferably 10.0 to 60.0% by volume. By controlling the loading of the granular medium within this range, the granular medium, which flows with the reaction solution, prevents the product from precipitating on minute crystal nuclei generated in the reaction solution, preventing the crystals from growing larger, resulting in the production of an organic acid salt with a small particle size. On the other hand, if the loading of the granular medium is below this range, the effect of the granular medium in preventing the product from precipitating on minute crystal nuclei is not fully achieved, making it difficult to produce an organic acid salt with a small particle size. On the other hand, if the loading of the granular medium is above this range, the amount of reaction solution charged is reduced, which hinders successful stirring and reduces contact between the reaction solution and the granular medium, making it difficult to achieve the effects of the present invention.

[0046] Examples of materials for the granular medium, such as beads or balls, used in the method for producing an organic acid salt of the present invention include resin, ceramic, zeolite, etc. Among these, from the viewpoints of chemical resistance, prevention of contamination due to wear of the granular medium, and ease of separation from the produced particles, it is preferable that the granular medium be resin. Furthermore, from the viewpoints of chemical resistance and the ability to efficiently refine the produced particles, it is preferable that the granular medium be ceramic.

[0047] The resin for the granular medium is preferably resin beads or resin balls that are at least one selected from the group consisting of polyethylene, polypropylene, polyamide, polyvinyl chloride, polyvinylidene fluoride, polyimide, polyethylene terephthalate, and polystyrene, and resin beads are particularly preferred from the viewpoint of being able to effectively break down the organic acid salts that are produced.

[0048] When resin beads are used as the granular medium, the diameter of the beads is preferably 0.005 to 10.0 mm, particularly preferably 0.01 to 6.0 mm.

[0049] The ceramic for the granular medium is preferably ceramic beads or ceramic balls made of at least one material selected from the group consisting of zirconia, alumina, silica, silicon carbide, and silicon nitride, and ceramic beads are particularly preferred from the viewpoint of effectively breaking down the organic acid salts produced.

[0050] When ceramic beads are used as the granular medium, the diameter of the beads is preferably 0.005 to 10.0 mm, particularly preferably 0.01 to 6.0 mm.

[0051] The reaction vessel used in the method for producing an organic acid salt of the present invention is not particularly limited as long as it can stir the liquid in the reaction vessel, i.e., one of the solutions A and B before the reaction or the reaction liquid and the granular medium during the reaction, and cause the granular medium to flow together with the reaction liquid. In the method for producing an organic acid salt of the present invention, examples of an apparatus for mixing the other of the solutions A and B into the liquid in the reaction vessel while stirring the liquid and the granular medium in the reaction vessel to cause the reaction include a reaction vessel equipped with a stirrer, a bead mill, a ball mill, etc.

[0052] In the method for producing an organic acid salt of the present invention, the liquid in the reaction vessel and the granular medium are then stirred in the reaction vessel, and the other of the liquids A and B is mixed with the liquid in the reaction vessel (either the liquid A or the liquid B before the reaction or the reaction liquid during the reaction) to cause a reaction.

[0053] The stirring speed when stirring the liquid and granular medium in the reaction vessel is preferably 1 to 15 m / min, particularly preferably 4 to 12 m / min, in terms of peripheral velocity, on a 0.5 L scale. Furthermore, on a 100 L scale, it is preferably 3 to 18 m / min, particularly preferably 6 to 15 m / min. Furthermore, on a 10,000 L scale, it is preferably 50 to 200 m / min, particularly preferably 80 to 180 m / min. Furthermore, on a 50,000 L scale, it is preferably 200 to 1,200 m / min, particularly preferably 500 to 900 m / min. By keeping the stirring speed when stirring the liquid and granular medium in the reaction vessel within the above range, the granular medium moving in the reaction liquid prevents the product from precipitating on minute crystal nuclei generated in the reaction liquid, preventing the crystals from growing large, thereby producing an organic acid salt with a small particle size. On the other hand, if the stirring speed when stirring the liquid and granular medium in the reaction vessel is less than the above range, the formation rate of fine crystal nuclei generated in the reaction vessel will increase, causing particle growth and resulting in an organic acid salt with a large particle size.If the stirring speed exceeds the above range, the granular medium will be more susceptible to wear or pulverization, leading to contamination and deviations in the composition of the organic acid salt, as well as the reaction liquid being scattered, which will likely worsen the working environment.

[0054] The stirring conditions for stirring the liquid and granular medium in the reaction vessel are, for example, when a reaction apparatus equipped with a stirrer is used as the reaction vessel, such that the filling rate (volume ratio) of the granular medium to one of the solutions A and B is 5.0 to 95.0 volume %, preferably 7.0 to 85.0 volume %, and more preferably 10.0 to 75.0 volume %, and the stirring speed is 50 to 1000 rpm, preferably 100 to 800 rpm, and more preferably 150 to 500 rpm.

[0055] The stirring conditions for stirring the liquid and granular medium in the reaction vessel are, for example, when a bead mill device is used as the reaction vessel, such that the filling rate (volume ratio) of the granular medium to one of the solutions A and B is 5.0 to 95.0 volume %, preferably 7.0 to 85.0 volume %, and more preferably 10.0 to 75.0 volume %, and the stirring speed is preferably a peripheral velocity of 1 to 15 m / sec, and particularly preferably 2 to 12 m / sec.

[0056] The rate of addition of the other solution, either Solution A or Solution B, to the liquid in the reaction vessel depends on the scale of the reaction. For example, on a 0.5 L scale, the rate is preferably 0.25 ml / min or more, and more preferably 0.5 ml / min or more. On a 100 L scale, the rate is preferably 0.03 L / min or more, and more preferably 0.05 L / min. On a 10,000 L scale, the rate is preferably 5 L / min or more, and more preferably 10 L / min or more. On a 50,000 L scale, the rate is preferably 10 L / min or more, and more preferably 20 L / min or more. By setting the rate of addition within the above range, it becomes easier to obtain a fine organic acid salt. There is no particular upper limit as long as the rate of addition is within the above range.

[0057] The mixing temperature when the other of Solution A and Solution B is mixed with the solution in the reaction vessel, i.e., the temperature of the solution in the reaction vessel, is preferably 75° C. or lower, more preferably 5 to 70° C., and particularly preferably 10 to 65° C. By keeping the mixing temperature within the above range, it becomes easier to obtain a fine organic acid salt.

[0058] The mixing ratio of liquid A to liquid B in the first embodiment of the present invention is such that the ratio of the total moles of the A-site elements and the B-site elements in liquid B, calculated on an atomic basis, to the moles of the organic acid in liquid A is preferably 0.01 to 20.0, particularly preferably 0.10 to 10.0. The mixing ratio of liquid A to liquid B in the second embodiment of the present invention is such that the ratio of the total moles of the A-site elements in liquid A and the B-site elements in liquid B, calculated on an atomic basis, to the moles of the organic acid in liquid B is preferably 0.01 to 20.0, particularly preferably 0.10 to 10.0. The mixing ratio of liquid A to liquid B in the third embodiment of the present invention is such that the ratio of the total moles of the A-site elements in liquid B and the B-site elements in liquid A, calculated on an atomic basis, to the moles of the organic acid in liquid B is preferably 0.01 to 20.0, particularly preferably 0.10 to 10.0.

[0059] The mixing ratio of solutions A and B in the method for producing an organic acid salt of the second embodiment of the present invention is such that the ratio of the total moles of A-site elements in solution A to the total moles of B-site elements in solution B in atomic terms (A-site elements / B-site elements) is preferably 0.10 to 25.0, particularly preferably 0.20 to 15.0. The mixing ratio of solutions A and B in the method for producing an organic acid salt of the third embodiment of the present invention is such that the ratio of the total moles of A-site elements in solution B to the total moles of B-site elements in solution A in atomic terms (A-site elements / B-site elements) is preferably 0.10 to 25.0, particularly preferably 0.20 to 15.0.

[0060] The reaction may be terminated by immediately cooling the reaction solution or removing the reaction solution by filtration or the like after mixing the entire amount of the other of Solution A and Solution B with the liquid in the reaction vessel, or by maintaining the reaction solution at a predetermined temperature for a certain period of time after mixing the entire amount of the other of Solution A and Solution B with the liquid in the reaction vessel. When aging is performed, the aging temperature is preferably 10°C or higher, more preferably 5 to 70°C, and particularly preferably 10 to 65°C, and the aging time is preferably 0.1 hour or longer, particularly preferably 0.2 hour or longer.

[0061] In the method for producing an organic salt of the present invention, the reaction vessel, the filling rate of the granular medium, the rate of addition of liquid A or liquid B, the mixing temperature and mixing time of liquid A and liquid B, the aging temperature and aging time after mixing, etc. are appropriately selected so that the average particle size of the organic salt determined by laser diffraction scattering is preferably 50 μm or less, more preferably 0.01 to 40 μm. By obtaining an organic salt having an average particle size within the above range, the perovskite-type composite oxide obtained by calcining the organic salt is fine and has little variation in particle size.

[0062] Next, in the method for producing an organic acid salt of the present invention, after mixing the solution A and the solution B to carry out the reaction, the resulting reaction solution is subjected to solid-liquid separation.

[0063] After the solid-liquid separation, the solid is washed with water. The washing method is not particularly limited, but washing by redispersing the solid in water is preferred because it has high washing efficiency. After washing, the solid is dried and, if necessary, pulverized to obtain the organic acid salt.

[0064] The average particle size of the organic acid salt obtained by the method for producing an organic acid salt of the present invention is preferably 50 μm or less, more preferably 0.01 to 40 μm. In the present invention, the average particle size of the organic acid salt refers to the particle size of aggregates (secondary particles), and D50 measured by a laser diffraction scattering method is defined as the average particle size.

[0065] The organic acid salt obtained by the method for producing an organic acid salt of the present invention is suitably used as a raw material for producing a perovskite complex oxide ceramic, which is a dielectric ceramic material. The method for producing a perovskite complex oxide of the present invention is as follows.

[0066] The method for producing a perovskite complex oxide of the present invention is characterized by calcining the organic acid salt obtained by the method for producing an organic acid salt of the present invention.

[0067] Organic substances derived from the organic acid contained in the final product are undesirable because they impair the dielectric properties of the material and cause unstable behavior during the thermal process for ceramicization. Therefore, in the present invention, the organic acid salt is thermally decomposed by calcination to obtain the desired perovskite-type composite oxide, while the organic substances derived from the organic acid must be sufficiently removed. Regarding calcination conditions, the calcination temperature is preferably 600 to 1200°C, more preferably 620 to 1100°C. Calcination temperatures below 600°C result in only partial formation of the perovskite-type composite oxide, or it is difficult to obtain a single-phase perovskite-type composite oxide. On the other hand, calcination temperatures above 1200°C result in significant variation in particle size. The calcination time is preferably 0.5 to 30 hours, more preferably 1 to 20 hours. The calcination atmosphere is not particularly limited and may be in an inert gas atmosphere, a vacuum atmosphere, an oxidizing gas atmosphere, or air, or may be performed in the above atmosphere while introducing water vapor.

[0068] The calcination may be carried out any number of times as desired. Alternatively, in order to make the powder characteristics uniform, the calcined product may be pulverized and then calcined again.

[0069] After calcination, the mixture is cooled appropriately and pulverized as necessary to obtain a perovskite-type composite oxide powder. The pulverization, which is performed as needed, is performed appropriately when the perovskite-type composite oxide obtained by calcination is brittle and block-like. However, the perovskite-type composite oxide particles themselves have the following specific average particle size and BET specific surface area. Specifically, the perovskite-type composite oxide powder obtained above has an average particle size of secondary particles (aggregates) determined by laser diffraction scattering, preferably 30 μm or less, more preferably 1 to 20 μm. Furthermore, the average particle size of primary particles of the perovskite-type composite oxide obtained above is preferably 10 to 700 nm, more preferably 20 to 600 nm. The average particle size of primary particles of the perovskite-type composite oxide is determined by measuring 200 particles randomly from a scanning electron microscope (SEM) photograph and averaging the measurements. The BET specific surface area is preferably 2 to 100 m. 2 / g. Furthermore, the composition of the perovskite complex oxide obtained by the production method of the present invention preferably has a molar ratio (A-site element / B-site element) of A-site elements such as Ba, Ca, Mg, Sr, etc. to B-site elements such as Ti, Zr, etc. of 0.800 to 1.200, particularly 0.850 to 1.150. The c-axis / a-axis ratio, which is an index of crystallinity, is 0.800 to 1.200, particularly 0.850 to 1.15 ... 2 / g or more, 1.0030 to 1.0095 is preferable, and 1.0035 to 1.0090 is particularly preferable. 2 / g, and within this range, the c-axis / a-axis ratio is preferably more than 1.0040, and particularly preferably 1.0043 or more.

[0070] Furthermore, for the purpose of adjusting the dielectric properties and temperature characteristics, the perovskite complex oxide obtained by the method for producing a perovskite complex oxide of the present invention can be made to contain an auxiliary element by adding an auxiliary element-containing compound to the perovskite complex oxide obtained by the method for producing a perovskite complex oxide of the present invention. Examples of the auxiliary element-containing compound that can be used include compounds containing at least one element selected from the group consisting of rare earth elements Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, Ba, Li, Bi, Zn, Mn, Al, Si, Ca, Sr, Co, Ni, Cr, Fe, Mg, Ti, V, Nb, Mo, W, and Sn.

[0071] The auxiliary element-containing compound may be either inorganic or organic. Examples include oxides, hydroxides, chlorides, nitrates, oxalates, carboxylates, and alkoxides containing the aforementioned elements. When the auxiliary element-containing compound is a compound containing Si, silica sol, sodium silicate, and the like can also be used in addition to oxides. One or more auxiliary element-containing compounds can be used in appropriate combination. The amount of each compound added and the combination of the added compounds can be determined according to conventional methods.

[0072] To incorporate the minor component element into the perovskite composite oxide, for example, the perovskite composite oxide and the minor component element-containing compound may be uniformly mixed and then calcined, or the organic acid salt and the minor component element-containing compound may be uniformly mixed and then calcined.

[0073] To manufacture a multilayer ceramic capacitor using the perovskite complex oxide obtained by the method for producing a perovskite complex oxide of the present invention, first, a powder of the perovskite complex oxide is mixed and dispersed in a suitable solvent together with conventional additives, including minor component elements, organic binders, plasticizers, dispersants, and other compounding agents to form a slurry, which is then formed into a sheet. This produces a ceramic sheet for use in manufacturing a multilayer ceramic capacitor. To fabricate a multilayer ceramic capacitor from the ceramic sheet, first, a conductive paste for forming internal electrodes is printed on one side of the ceramic sheet. After drying, multiple ceramic sheets are stacked and pressure-bonded in the thickness direction to form a laminate. Next, this laminate is heat-treated to remove the binder and fired to obtain a fired body. The fired body is then coated with a Ni paste, Ag paste, nickel alloy paste, copper paste, copper alloy paste, or the like and baked to obtain a multilayer ceramic capacitor.

[0074] Furthermore, when the perovskite complex oxide powder obtained by the method for producing a perovskite complex oxide of the present invention is blended with a resin such as an epoxy resin, a polyester resin, or a polyimide resin to form a resin sheet, a resin film, an adhesive, or the like, it can be used as a material for printed wiring boards and multilayer printed wiring boards, as well as a co-material for suppressing the difference in shrinkage between internal electrodes and dielectric layers, an electrode ceramic circuit board, a glass ceramic circuit board, a circuit peripheral material, and a dielectric material for inorganic EL.

[0075] Furthermore, the perovskite complex oxide obtained by the method for producing a perovskite complex oxide of the present invention is suitable for use as a catalyst used in reactions such as exhaust gas removal and chemical synthesis, or as a surface modifier for printing toner that imparts antistatic and cleaning effects. [Example]

[0076] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0077] (1) Average particle size (D50) of barium titanyl oxalate and barium titanate Measurements were made using the laser diffraction scattering method using a Microtrack Bell MT3000II. (2) c / a value of barium titanate The ratio c / a of the c-axis to the a-axis was measured by an X-ray diffractometer (D8 ADVANCE, manufactured by Bruker) using Cu-Kα radiation as a radiation source. (3) Specific surface area of ​​barium titanate It was determined by the BET method.

[0078] Example 1 40 g of oxalic acid dihydrate was dissolved in 150 g of pure water to prepare 160 ml of a solution containing an oxalic acid component (liquid A) with an oxalic acid concentration of 2 mol / L. Separately, 70 g of titanium tetrachloride and 45 g of barium chloride were dissolved in 200 g of pure water to prepare 250 ml of a solution containing a titanium component and a barium component (liquid B) with a titanium tetrachloride concentration of 0.3 mol / L and a barium chloride concentration of 0.9 mol / L. Next, 160 ml of Solution A was placed in a reaction vessel equipped with a stirrer (Three-One Motor, manufactured by Shinto Scientific Co., Ltd.) in which polypropylene beads (particle size 4 mm) had been charged at a bead filling rate of 10% relative to Solution A. Solution B was then fed into the reaction vessel at a flow rate of 1 ml / min, and the reaction was carried out at 60°C for 250 minutes. After the reaction, stirring was continued for 60 minutes and then cooled to 25°C. After stopping the stirring, the beads were separated using a sieve to obtain a slurry. The slurry was suction filtered, and the obtained solid was washed and dried to obtain a dry powder of barium titanyl oxalate. The physical properties of the obtained barium titanyl oxalate are shown in Table 1. The obtained barium titanyl oxalate was fired at the temperature and for the time shown in Table 1 to obtain barium titanate. The physical properties of the obtained barium titanate are shown in Table 1.

[0079] Example 2 Liquids A and B were prepared in the same manner as in Example 1. Next, 160 ml of Solution A was placed in a reaction vessel equipped with a stirrer (Three-One Motor, manufactured by Shinto Scientific Co., Ltd.) and polypropylene beads (particle size 4 mm) were charged at a bead filling rate of 20% relative to Solution A. Solution B was then fed into the reaction vessel at a flow rate of 1 ml / min, and the reaction was carried out at 60°C for 250 minutes. After the reaction, stirring was continued for 60 minutes and then cooled to 25°C. After stopping the stirring, the beads were separated using a sieve to obtain a slurry. The slurry was suction filtered, and the obtained solid was washed and dried to obtain a dry powder of barium titanyl oxalate. The physical properties of the obtained barium titanyl oxalate are shown in Table 1. The obtained barium titanyl oxalate was fired at the temperature and for the time shown in Table 1 to obtain barium titanate. The physical properties of the obtained barium titanate are shown in Table 1.

[0080] Example 3 Liquids A and B were prepared in the same manner as in Example 1. Next, 160 ml of Solution A was placed in a reaction vessel equipped with a stirrer (Three-One Motor, manufactured by Shinto Scientific Co., Ltd.) and polypropylene beads (particle size 4 mm) were charged at a bead filling rate of 30% relative to Solution A. Solution B was then fed into the reaction vessel at a flow rate of 0.6 ml / min, and the reaction was carried out at 60°C for 250 minutes. After the reaction, stirring was continued for 60 minutes and then cooled to 25°C. After stopping the stirring, the beads were separated using a sieve to obtain a slurry. The slurry was suction filtered, and the obtained solid was washed and dried to obtain a dry powder of barium titanyl oxalate. The physical properties of the obtained barium titanyl oxalate are shown in Table 1. The obtained barium titanyl oxalate was fired at the temperature and for the time shown in Table 1 to obtain barium titanate. The physical properties of the obtained barium titanate are shown in Table 1.

[0081] Example 4 Liquids A and B were prepared in the same manner as in Example 1. Next, 160 ml of Solution A was placed in a reaction vessel equipped with a stirrer (Three-One Motor, manufactured by Shinto Scientific Co., Ltd.) and polypropylene beads (particle size 4 mm) were charged at a bead filling rate of 10% relative to Solution A. Solution B was then fed into the reaction vessel at a flow rate of 1 ml / min, and the reaction was carried out at 50°C for 250 minutes. After the reaction, stirring was continued for 60 minutes and then cooled to 25°C. After stopping the stirring, the beads were separated using a sieve to obtain a slurry. The slurry was suction filtered, and the obtained solid was washed and dried to obtain a dry powder of barium titanyl oxalate. The physical properties of the obtained barium titanyl oxalate are shown in Table 1. The obtained barium titanyl oxalate was fired at the temperature and for the time shown in Table 1 to obtain barium titanate. The physical properties of the obtained barium titanate are shown in Table 1.

[0082] Example 5 Liquids A and B were prepared in the same manner as in Example 1. Next, 160 ml of Solution A was placed in a reaction vessel equipped with a stirrer (Three-One Motor, manufactured by Shinto Scientific Co., Ltd.) and polypropylene beads (particle size 4 mm) were charged at a bead filling rate of 10% relative to Solution A. Solution B was then fed into the reaction vessel at a flow rate of 1 ml / min, and the reaction was carried out at 70°C for 250 minutes. After the reaction, stirring was continued for 60 minutes and then cooled to 25°C. After stopping the stirring, the beads were separated using a sieve to obtain a slurry. The slurry was suction filtered, and the obtained solid was washed and dried to obtain a dry powder of barium titanyl oxalate. The physical properties of the obtained barium titanyl oxalate are shown in Table 1. The obtained barium titanyl oxalate was fired at the temperature and for the time shown in Table 1 to obtain barium titanate. The physical properties of the obtained barium titanate are shown in Table 1.

[0083] (Comparative Example 1) Liquids A and B were prepared in the same manner as in Example 1. Next, 150 ml of Solution A was placed in a 500 ml beaker equipped with a stirrer (Three-One Motor, manufactured by Shinto Scientific Co., Ltd.), and stirring was started at 300 rpm. Solution B was then fed into the reaction vessel at a flow rate of 1 ml / min, and the reaction was carried out at 60°C for 250 minutes. After the reaction, stirring was continued for 60 minutes and then cooled to 25°C. After stirring was stopped, the resulting slurry was suction filtered to obtain a solid. The resulting solid was washed and dried to obtain a dry powder of barium titanyl oxalate. The physical properties of the resulting barium titanyl oxalate are shown in Table 1. The obtained barium titanyl oxalate was fired at the temperature and for the time shown in Table 1 to obtain barium titanate. The physical properties of the obtained barium titanate are shown in Table 1.

[0084] [Table 1]

[0085] In Table 1, BTO stands for barium titanyl oxalate, and BT stands for barium titanate.

[0086] As shown in Table 1, the barium titanyl oxalate obtained in Examples 1 to 5 has a smaller D50 and smaller secondary particles than the barium titanyl oxalate obtained in Comparative Example 1. Furthermore, the barium titanate obtained by firing the barium titanyl oxalate of Examples 1 to 5 has a smaller D50 than the barium titanate of Comparative Example 1 while having the same BET specific surface area and c / a ratio, and therefore it can be seen that highly crystalline secondary particles are obtained despite being small in size.

Claims

1. A method for producing an organic salt comprising mixing and reacting a solution (liquid A) containing any one of an organic acid, an A-site element compound, and a B-site element compound with a solution (liquid B) containing two of the organic acid, the A-site element compound, and the B-site element compound that are not contained in liquid A, to obtain an organic salt; first, a reaction vessel is charged with one of the solutions A and B and a granular medium in an amount of 5.0 to 95.0% by volume relative to the volume of the one of the solutions, and then, while stirring the liquid and the granular medium in the reaction vessel, the other of the solutions A and B is mixed with the liquid in the reaction vessel to cause a reaction; A method for producing an organic acid salt, comprising:

2. 2. The method for producing an organic acid salt according to claim 1, wherein the solution A is a solution containing the organic acid, and the solution B is a solution containing the A-site element compound and the B-site element compound.

3. 2. The method for producing an organic acid salt according to claim 1, wherein the solution A is a solution containing the A-site element compound, and the solution B is a solution containing the organic acid and the B-site element compound.

4. 2. The method for producing an organic acid salt according to claim 1, wherein the solution A is a solution containing the B-site element compound, and the solution B is a solution containing the organic acid and the A-site element compound.

5. 2. The method for producing an organic acid salt according to claim 1, wherein the granular medium is beads having a particle size of 0.005 to 10.0 mm.

6. 6. The method for producing an organic salt according to claim 5, wherein the beads are resin beads made of at least one material selected from the group consisting of polyethylene, polypropylene, polyamide, polyvinyl chloride, polyvinylidene fluoride, polyimide, polyethylene terephthalate, and polystyrene.

7. 6. The method for producing an organic acid salt according to claim 5, wherein the beads are ceramic beads made of at least one material selected from the group consisting of zirconia, alumina, silica, silicon carbide, and silicon nitride.

8. 2. The method for producing an organic salt according to claim 1, wherein the organic acid is at least one selected from the group consisting of oxalic acid, citric acid, malonic acid, tartaric acid, lactic acid, glycolic acid, malic acid, aspartic acid, and succinic acid.

9. 2. The method for producing an organic acid salt according to claim 1, wherein the A-site element compound is a compound containing at least one element selected from the group consisting of Ba, Ca, Mg, and Sr, and the B-site element compound is a compound containing at least one element selected from the group consisting of Ti, Zr, V, Nb, Cr, B, Al, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Sb, Sc, Ta, Ru, Ir, Ga, In, and Sn.

10. 2. The method for producing an organic acid salt according to claim 1, wherein the mixing temperature of the solution A and the solution B is 75° C. or lower.

11. 2. The method for producing an organic acid salt according to claim 1, wherein the organic acid salt produced has an average particle size of 50 μm or less.

12. 2. A method for producing a perovskite complex oxide, comprising calcining the organic acid salt obtained by the method of claim 1 to obtain a perovskite complex oxide.

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