Process for producing barium titanyl oxalate and process for producing barium titanate

Abstract

A method for producing barium titanyl oxalate, characterized by a method for producing barium titanyl oxalate by mixing a solution (A liquid) containing oxalic acid and a solution (B liquid) containing a titanium source and a barium source, allowing them to react, and thereby producing barium titanyl oxalate, wherein the A liquid and the B liquid are supplied to one end side of a reaction liquid flow path, respectively, the A liquid and the B liquid are mixed within the reaction flow path, and the reaction liquid is discharged from the other end side of the reaction liquid flow path, after which solid-liquid separation of the reaction liquid is performed; the residence time of the reaction liquid within the reaction liquid flow path is within 30 seconds; or the A liquid and the B liquid are supplied to one end side of a reaction liquid flow path, respectively, the A liquid and the B liquid are mixed at one end side of the reaction liquid flow path, the reaction liquid is allowed to generate a vortex while moving toward the other end side of the reaction liquid flow path, and the reaction liquid is discharged from the other end side of the reaction liquid flow path, after which solid-liquid separation of the reaction liquid is performed.

Description

Technical Field

[0001] This invention relates to a method for manufacturing barium titanium oxalate, which is useful as a raw material for functional ceramics such as dielectrics, piezoelectrics, optoelectronic materials, semiconductors, and sensors. Background Technology

[0002] Currently, barium titanate is typically manufactured using solid-state methods, hydrothermal synthesis methods, alkoxide methods, oxalate methods, and other methods.

[0003] In solid-state synthesis, a dry method is used to manufacture powders by mixing the constituent raw material powders and heating the mixture at high temperatures. The resulting powder forms irregularly shaped aggregates, and high-temperature calcination is required to achieve the desired properties. While hydrothermal synthesis offers the advantage of good powder properties, the synthesis process is complex and requires autoclaves, resulting in poor productivity and high powder production costs, making it industrially disadvantageous. Similarly, the alkoxide method also suffers from difficult and expensive starting material processing, making it industrially unfavorable.

[0004] Compared to hydrothermal synthesis and alkoxide methods, barium titanate obtained by the oxalate method can be produced inexpensively with a uniform composition. Furthermore, it exhibits a more uniform composition compared to barium titanate produced by solid-state methods. The existing oxalate method typically 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 oxalate oxytitanium, followed by calcination of the barium oxalate oxytitanium (see, for example, Patent Documents 1-3).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Publication No. 2005-500239

[0008] Patent Document 2: Japanese Patent Application Publication No. 2010-202610

[0009] Patent Document 3: Japanese Patent Application Publication No. 2013-63867 Summary of the Invention

[0010] The technical problem that the invention aims to solve

[0011] However, the barium titanate oxalate obtained in the aforementioned patent literature is generated by firing at temperatures above 700°C. Therefore, at the moment of barium titanate formation, the crystallinity is low, but some degree of grain growth occurs. When such barium titanate oxalate is fired at high temperatures, even with high crystallinity, the particles are large, which fails to meet the requirements for use as a functional ceramic raw material.

[0012] Therefore, the object of the present invention is to provide a method for manufacturing barium oxalate oxytannin for producing barium titanate with small particle size and high crystallinity.

[0013] Technical solutions for solving technical problems

[0014] The inventors of this invention, through repeated and meticulous research considering the aforementioned practical situation, discovered that by supplying a solution containing oxalic acid (solution A) and a solution containing titanium and barium compounds (solution B) to one end of a reaction liquid flow path forming an online mixer or microreactor, respectively, mixing solutions A and B within the reaction flow path, and discharging the reaction liquid from the other end of the reaction liquid flow path, the mixing time of solutions A and B is shortened, thereby obtaining fine barium oxalate. When such fine barium oxalate is calcined, the carbon dioxide from thermal decomposition easily escapes, lowering the temperature at which barium titanate is generated. Furthermore, by generating barium titanate at a low temperature, compared to existing technologies, barium titanate can be highly crystallized at low temperatures, thus suppressing barium titanate grain growth. Therefore, compared to existing technologies, microparticle and highly crystalline barium titanate can be obtained, thus completing this invention.

[0015] Furthermore, the inventors of this invention, through repeated and meticulous research considering the aforementioned actual conditions, discovered that by supplying a solution containing oxalic acid (solution A) and a solution containing titanium and barium compounds (solution B) to one end of the reaction liquid flow path, eddies are generated within the reaction flow path, mixing solutions A and B, and the reaction liquid is discharged from the other end of the reaction liquid flow path. This allows the reactants in solutions A and B to come into rapid contact, thereby obtaining fine barium oxalate oxide. When such fine barium oxalate oxide is calcined, the carbon dioxide from thermal decomposition easily escapes, lowering the temperature at which barium titanate is generated. Moreover, by generating barium titanate at a low temperature, compared to existing technologies, barium titanate can be highly crystallized at low temperatures, thus suppressing barium titanate grain growth. Therefore, compared to existing technologies, microparticle and highly crystalline barium titanate can be obtained, thus completing this invention.

[0016] That is, the present invention (1) provides a method for manufacturing barium titanium oxalate, characterized in that: barium titanium oxalate is manufactured by mixing a solution containing oxalic acid (solution A) and a solution containing a titanium source and a barium source (solution B) to react. In this method for manufacturing barium titanium oxalate, solution A and solution B are supplied to one end of the reaction liquid flow path, and solution A and solution B are mixed in the reaction liquid flow path. The reaction liquid is discharged from the other end of the reaction liquid flow path, and then solid-liquid separation of the reaction liquid is performed. The residence time of the reaction liquid in the reaction liquid flow path is less than 30 seconds.

[0017] In addition, the present invention (2) provides a method for manufacturing barium titanium oxalate as described in (1), characterized in that:

[0018] By supplying liquid A and liquid B to one end of the static mixer, the reaction liquid flow path is formed within the static mixer.

[0019] In addition, the present invention (3) provides a method for manufacturing barium oxalate titanium as described in (1), characterized in that: the above-mentioned liquid A and liquid B are supplied to one end of the reaction liquid flow path of a continuously flowing microreactor, thereby forming the above-mentioned reaction liquid flow path in the microreactor.

[0020] Furthermore, the present invention (4) provides a method for manufacturing barium titanium oxalate, characterized in that: barium titanium oxalate is manufactured by mixing a solution containing oxalic acid (solution A) and a solution containing a titanium source and a barium source (solution B) to react. In this method for manufacturing barium titanium oxalate, solution A and solution B are supplied to one end of the reaction liquid flow path, and solution A and solution B are mixed at one end of the reaction liquid flow path. While generating a vortex in the reaction liquid, the reaction liquid is moved to the other end of the reaction liquid flow path and discharged from the other end of the reaction liquid flow path. Then, solid-liquid separation of the reaction liquid is performed.

[0021] In addition, the present invention (5) provides a method for manufacturing barium oxalate titanium barium as described in (4), characterized in that the residence time of the reaction liquid in the reaction liquid flow path is less than 60 seconds.

[0022] In addition, the present invention (6) provides a method for manufacturing barium oxalate titanium barium as described in (4), characterized in that: the above-mentioned eddy current is a Taylor eddy current.

[0023] In addition, the present invention (7) provides a method for manufacturing barium oxalate titanium barium as described in (1) or (4), characterized in that: the solvent of the above-mentioned liquid A is an organic solvent.

[0024] In addition, the present invention (8) provides a method for manufacturing barium oxalate as described in (1) or (4), characterized in that: the solvent of the above-mentioned liquid A is one or more selected from methanol, ethanol, propanol, butanol, diethyl ether, 1,3-butanediol, ethylene glycol, propylene glycol, dipropylene glycol, glycerol, N,N-dimethylformamide and acetone.

[0025] In addition, the present invention (9) provides a method for manufacturing barium titanium oxalate as described in (1) or (4), characterized in that the solvent of the above-mentioned liquid B is water.

[0026] In addition, the present invention (10) provides a method for manufacturing barium oxalate as described in (1) or (4), characterized in that: the titanium compound in the above-mentioned liquid B is titanium tetrachloride, and the barium compound is barium chloride.

[0027] In addition, the present invention (11) provides a method for manufacturing barium oxalate titanium as described in (1) or (4), characterized in that the mixing temperature of the above-mentioned liquid A and the above-mentioned liquid B is below 75°C.

[0028] In addition, the present invention (12) provides a method for manufacturing barium oxalate oxytannin as described in (1) or (4), characterized in that the average particle size of the generated barium oxalate oxytannin is less than 1.0 μm.

[0029] In addition, the present invention (13) provides a method for manufacturing barium titanate, characterized in that: barium oxalate titanate obtained by any one of the manufacturing methods (1) to (6) is calcined.

[0030] The effects of the invention

[0031] According to the present invention, a method for manufacturing barium titanate oxalate can be provided, which, when calcined at the same temperature, yields barium titanate with smaller particle size and higher crystallinity compared to existing barium titanate oxalate. Attached Figure Description

[0032] Figure 1 The results are the thermogravimetric analysis results of barium oxalate obtained in Example 1 and Comparative Example 1.

[0033] Figure 2 This is a SEM image of barium titanium oxalate obtained in Example 1.

[0034] Figure 3 This is an SEM image of barium titanate obtained in Example 1.

[0035] Figure 4 This is a SEM image of barium titanium oxalate obtained in Comparative Example 1.

[0036] Figure 5 The image shown is a SEM image of the fired product obtained in Comparative Example 1.

[0037] Figure 6 The results are the thermogravimetric analysis results of barium titanium oxalate obtained in Example 6 and Comparative Example 5.

[0038] Figure 7 This is an SEM image of barium titanium oxalate obtained in Example 6.

[0039] Figure 8 This is an SEM image of barium titanate obtained in Example 6.

[0040] Figure 9 This is a SEM image of barium titanium oxalate obtained in Comparative Example 5.

[0041] Figure 10 This is a SEM image of the fired product obtained in Comparative Example 5. Detailed Implementation

[0042] The first invention of the present invention will be described.

[0043] <First Invention>

[0044] The method for manufacturing barium titanium oxalate of the present invention is as follows, characterized in that:

[0045] Barium titanium oxalate is produced by mixing a solution containing oxalic acid (solution A) and a solution containing titanium and barium sources (solution B) to allow them to react.

[0046] In this method for manufacturing barium titanium oxalate, solution A and solution B are supplied to one end of the reaction liquid flow path, respectively, and the solutions A and B are mixed within the flow path. The reaction liquid is then discharged from the other end of the flow path, followed by solid-liquid separation of the reaction liquid.

[0047] The residence time of the reaction solution in the flow path is less than 30 seconds.

[0048] The method for manufacturing barium titanium oxalate of the present invention involves a solution A containing oxalic acid. The concentration of oxalate ions in solution A is not particularly limited, but is preferably 0.1–7.0 mol / L, and particularly preferably 0.6–5.0 mol / L.

[0049] The solvent for solution A can be an aqueous solvent, an organic solvent, or a mixture thereof. From the viewpoint of obtaining barium titanium oxalate microparticles, an organic solvent is preferred. As an organic solvent, there are no particular limitations as long as it is hydrophilic and inert to the raw materials; one or more solvents selected from methanol, ethanol, propanol, butanol, diethyl ether, 1,3-butanediol, ethylene glycol, propylene glycol, dipropylene glycol, glycerol, N,N-dimethylformamide, and acetone can be used. When using a mixture of water and an organic solvent, or a mixture of multiple organic solvents, the mixing ratio can be appropriately selected.

[0050] The method for manufacturing barium titanium oxalate of the present invention involves a solution B containing a titanium compound and a barium compound. The concentration of titanium ions in solution B is not particularly limited, but is preferably 0.04–4.0 mol / L, and particularly preferably 0.2–3.0 mol / L. Similarly, the concentration of barium ions in solution B is not particularly limited, but is preferably 0.08–6.5 mol / L, and particularly preferably 0.4–3.0 mol / L.

[0051] The titanium compound used in the method for manufacturing barium titanium oxalate of the present invention is not particularly limited, and examples include titanium tetrachloride and titanium lactate. One type of titanium compound may be used, or two or more may be used in combination. Titanium tetrachloride is preferred as the titanium source.

[0052] The barium compound used in the method for manufacturing barium titanium oxalate of the present invention is not particularly limited, and examples include barium chloride, barium carbonate, barium hydroxide, barium acetate, and barium nitrate. One barium compound may be used, or two or more may be used in combination. Preferably, the barium compound is selected from one or more of barium chloride, barium acetate, barium nitrate, and barium hydroxide, with barium chloride being particularly preferred.

[0053] In the method for manufacturing barium oxalate oxytannin of the present invention, liquid A and liquid B are supplied to one end of the reaction liquid flow path, and liquid A and liquid B are mixed in the reaction liquid flow path, thereby carrying out the formation reaction of barium oxalate oxytannin in the reaction liquid flow path.

[0054] As a method for supplying liquid A and liquid B separately to one end of the reaction flow path and mixing them within the reaction flow path, examples include supplying liquid A and liquid B separately to one end of an online mixer such as a static mixer, screw mixer, or dynamic mixer, and mixing them within the online mixer. When using an online mixer, a reaction flow path is formed within the online mixer. As an online mixer, a static mixer is preferred for easily obtaining finely ground barium titanium oxalate. There are no particular limitations on the static mixer; examples include the MC08-32 manufactured by Tomita Engineering Co., Ltd.

[0055] Furthermore, as a method for supplying liquid A and liquid B separately to one end of the reaction liquid flow path and mixing liquid A and liquid B within the reaction flow path, an example is a method for supplying liquid A and liquid B separately to one end of a continuous flow microreactor and mixing liquid A and liquid B within the flow path of the microreactor. Here, a microreactor refers to, for example, a reaction apparatus having: a flow path composed of a tube with a flow path of 0.1 to 10 mm and a length of 1 to 2000 mm; and a supply section for simultaneously supplying liquid A and liquid B to one end of this flow path. When using a continuous flow microreactor, the reaction liquid flow path is formed within the flow path of the continuous flow microreactor.

[0056] In the method for manufacturing barium titanium oxalate of the present invention, liquid A and liquid B are supplied to the reaction liquid flow path, where they are mixed. Liquid A reacts with the reactants in liquid B to generate particulate barium titanium oxalate. Furthermore, in the method for manufacturing barium titanium oxalate of the present invention, liquid A and liquid B are supplied from one end of the reaction liquid flow path while the generated reaction liquid is discharged from the other end of the reaction liquid flow path.

[0057] In the method for manufacturing barium titanium oxalate of the present invention, the residence time of the reaction liquid in the reaction liquid flow path is within 30 seconds, preferably within 10 seconds, and particularly preferably 0.1 to 5 seconds. By ensuring that the residence time of the reaction liquid in the reaction liquid flow path is within the above range, particulate barium titanium oxalate can be obtained. The residence time of the reaction liquid in the reaction liquid flow path refers to the time it takes for the mixture of liquid A and liquid B supplied to one end of the reaction liquid flow path to reach the other end of the reaction liquid flow path.

[0058] The mixing temperature of liquid A and liquid B, i.e. the temperature of the reaction liquid in the reaction liquid flow path, is preferably below 75°C, and more preferably 5 to 50°C.

[0059] The mixing ratio of solution A and solution B is such that the ratio of the number of moles of titanium and barium in solution B (in atomic conversion) to the number of moles of oxalic acid in solution A is preferably 0.01 to 20.0, and particularly preferably 0.10 to 10.0.

[0060] Next, in the method for manufacturing barium oxalate oxalate of the present invention, solid-liquid separation of the reaction liquid discharged from the reaction liquid flow path is carried out.

[0061] In addition, after solid-liquid separation, the solid components are washed with water. There are no particular limitations on the washing method, but methods such as re-pulping are preferred for high washing efficiency. After washing, the solid components are dried and pulverized as needed to obtain barium titanium oxalate.

[0062] Next, the second invention of the present invention will be described.

[0063] <Second Invention>

[0064] The method for manufacturing barium titanium oxalate of the present invention is characterized by the following steps: mixing a solution containing oxalic acid (solution A) and a solution containing a titanium source and a barium source (solution B) to allow them to react, thereby manufacturing barium titanium oxalate.

[0065] In the method for manufacturing barium titanium oxalate, liquid A and liquid B are supplied to one end of the reaction liquid flow path, respectively. Liquid A and liquid B are mixed at one end of the reaction liquid flow path, and while generating a vortex in the reaction liquid, the reaction liquid is moved to the other end of the reaction liquid flow path and discharged from the other end of the reaction liquid flow path. Then, solid-liquid separation of the reaction liquid is performed.

[0066] The method for manufacturing barium titanium oxalate of the present invention involves a solution A containing oxalic acid. The concentration of oxalate ions in solution A is not particularly limited, but is preferably 0.1–7.0 mol / L, and particularly preferably 0.6–5.0 mol / L.

[0067] The solvent for solution A can be an aqueous solvent, an organic solvent, or a mixture thereof. From the viewpoint of obtaining barium titanium oxalate microparticles, an organic solvent is preferred. As an organic solvent, there are no particular limitations as long as it is hydrophilic and inert to the raw materials; one or more solvents selected from methanol, ethanol, propanol, butanol, diethyl ether, 1,3-butanediol, ethylene glycol, propylene glycol, dipropylene glycol, glycerol, N,N-dimethylformamide, and acetone can be used. When using a mixture of water and an organic solvent, or a mixture of multiple organic solvents, the mixing ratio can be appropriately selected.

[0068] The method for manufacturing barium titanium oxalate of the present invention involves a solution B containing a titanium compound and a barium compound. The concentration of titanium ions in solution B is not particularly limited, but is preferably 0.04 to 4.0 mol / L, and particularly preferably 0.2 to 3.0 mol / L. Similarly, the concentration of barium ions in solution B is not particularly limited, but is preferably 0.08 to 6.5 mol / L, and particularly preferably 0.4 to 3.0 mol / L.

[0069] The titanium compound used in the method for manufacturing barium titanium oxalate of the present invention is not particularly limited, and examples include titanium tetrachloride and titanium lactate. One type of titanium compound may be used, or two or more may be used in combination. Titanium tetrachloride is preferred as the titanium source.

[0070] The barium compound used in the method for manufacturing barium titanium oxalate of the present invention is not particularly limited, and examples include barium chloride, barium carbonate, barium hydroxide, barium acetate, and barium nitrate. One barium compound may be used, or two or more may be used in combination. Preferably, the barium compound is selected from one or more of barium chloride, barium acetate, barium nitrate, and barium hydroxide, with barium chloride being particularly preferred.

[0071] In the method for manufacturing barium titanium oxalate of the present invention, liquid A and liquid B are supplied to one end of the reaction liquid flow path. Next, at one end of the reaction liquid flow path, while generating a vortex in the reaction liquid (the mixture of liquid A and liquid B), the reaction liquid is moved to the other end of the reaction liquid flow path, thereby carrying out the barium titanium oxalate formation reaction in the reaction liquid flow path. Next, the reaction liquid is discharged from the other end of the reaction liquid flow path.

[0072] In the method for manufacturing barium titanium oxalate of the present invention, a vortex is generated in the mixture of liquid A and liquid B within the reaction liquid flow path, while the reactants in liquid A and liquid B react simultaneously, thereby enabling rapid contact between the reactants in liquid A and liquid B. Therefore, in the method for manufacturing barium titanium oxalate of the present invention, after mixing liquid A and liquid B, a large number of barium titanium oxalate nuclei are generated in the obtained reaction liquid (mixture), making it difficult to generate large-particle-size barium titanium oxalate, and instead generating small-particle-size barium titanium oxalate. Furthermore, in the method for manufacturing barium titanium oxalate of the present invention, since the reactants in the obtained reaction liquid (mixture) can be rapidly contacted, the reaction time (residence time) can be shortened, thereby improving reaction efficiency.

[0073] Examples of eddies generated within the flow path of a reaction liquid include Taylor eddies. Taylor eddies refer to annular eddies generated when the inner cylinder is rotated in a state where the gap between two cylinders, consisting of an inner and an outer cylinder, is filled with fluid.

[0074] As an apparatus that supplies feed liquid from one end of the flow path, generates Taylor vortexes within the flow path, and discharges discharge liquid from the other end of the flow path, examples include apparatuses disclosed in Japanese Patent Application Publication Nos. 2011-83768, 2016-10774, and 2017-209660. Other examples include Taylor vortex stirring apparatuses such as the TVF manufactured by Tipton Corporation and the small reactor (Jingduo) manufactured by Tokusatsu Corporation.

[0075] In the method for manufacturing barium titanium oxalate of the present invention, liquid A and liquid B are supplied to one end of the reaction liquid flow path while the generated reaction liquid is discharged from the other end of the reaction liquid flow path. If the reaction liquid is within the residence time described later between the supply and discharge of the reaction liquid flow path, multiple reaction devices that generate Taylor vortices or the like can be used in combination, as described in, for example, Japanese Patent Application Publication No. 2011-83768.

[0076] In the method for manufacturing barium titanium oxalate of the present invention, the residence time of the reaction liquid in the reaction liquid flow path is preferably within 60 seconds, more preferably within 20 seconds, and particularly preferably 0.1 to 10 seconds. By keeping the residence time of the reaction liquid in the reaction liquid flow path within the above range, particulate barium titanium oxalate is easily obtained. The residence time of the reaction liquid in the reaction liquid flow path refers to the time it takes for the mixture of liquid A and liquid B (the reaction liquid generated by mixing liquid A and liquid B) supplied to one end of the reaction liquid flow path to reach the other end of the reaction liquid flow path.

[0077] The mixing temperature of liquid A and liquid B, i.e. the temperature of the reaction liquid in the reaction liquid flow path, is preferably below 75°C, and particularly preferably 5 to 50°C.

[0078] The mixing ratio of solution A and solution B is such that the ratio of the number of moles of titanium and barium in solution B (in atomic conversion) to the number of moles of oxalic acid in solution A is preferably 0.01 to 20.0, and particularly preferably 0.10 to 10.0.

[0079] Next, in the method for manufacturing barium oxalate oxalate of the present invention, solid-liquid separation of the reaction liquid discharged from the reaction liquid flow path is carried out.

[0080] In addition, after solid-liquid separation, the solid components are washed with water. There are no particular limitations on the washing method, but methods such as re-pulping are preferred for high washing efficiency. After washing, the solid components are dried and pulverized as needed to obtain barium titanium oxalate.

[0081] Next, barium oxalate oxalate obtained by the manufacturing methods of barium oxalate oxalate according to the first and second inventions of this invention will be described.

[0082] The barium oxalate obtained by the method for manufacturing barium titanium oxalate according to the present invention is characterized in that, in thermogravimetric analysis, the temperature at which the weight reduction rate reaches 99% relative to the weight reduction rate at 1000°C is 600–700°C, preferably 610–690°C, and particularly preferably 615–685°C. Here, the weight reduction rate at 1000°C in the thermogravimetric analysis refers to the weight reduction rate at an analysis temperature of 1000°C in the thermogravimetric analysis. Furthermore, the temperature at which the weight reduction rate reaches 99% relative to 1000°C in the thermogravimetric analysis refers to the temperature at which the weight reduction rate reaches 99% of the weight reduction rate at the analysis temperature of 1000°C, relative to the weight reduction rate at the start of the analysis.

[0083] In thermogravimetric analysis, the temperature at which the weight loss rate reaches 99% relative to 1000°C refers to the temperature at which barium oxalate undergoes thermal decomposition and the transformation to barium titanate ends, i.e., the temperature at which barium oxalate is converted to barium titanate. Regarding the weight loss of barium oxalate measured by thermogravimetric analysis, if the sample is heated from room temperature at a rate of 10°C / min, after confirming some weight loss, no further weight loss is confirmed around 700°C, ultimately confirming thermal decomposition into barium titanate. Existing barium oxalate shows no weight loss at 700–720°C, within which barium titanate can be confirmed. However, the barium oxalate produced by the method of the present invention shows no weight loss at 600–700°C, preferably 610–690°C, and particularly preferably 615–685°C. Therefore, compared to existing technologies, barium titanate can be obtained from barium oxalate at a lower temperature. The inventors of this invention believe that the barium oxalate obtained by the method for manufacturing barium oxalate of this invention consists of particles with an average particle size preferably less than 1.0 μm, particularly preferably 0.01 to 0.5 μm. Therefore, carbon dioxide can easily escape during thermal decomposition, and compared with the prior art, it can be transformed into barium titanate at a lower temperature.

[0084] The barium oxalate oxytitanate obtained by the method of manufacturing barium oxalate according to the present invention can generate barium titanate within a temperature range of 600-700°C, preferably 610-690°C, and particularly preferably 615-685°C, by achieving a weight reduction rate of 99% relative to 1000°C in thermogravimetric analysis. Therefore, the barium oxalate oxytitanate obtained by the method of manufacturing barium oxalate according to the present invention can generate barium titanate at low temperatures, thus enabling high crystallinity of barium titanate at lower temperatures than in the prior art. Furthermore, since barium titanate can be highly crystallized at lower temperatures than in the prior art, barium titanate grain growth can be suppressed, resulting in microparticle and highly crystalline barium titanate compared to the prior art. Therefore, when barium titanate oxalate obtained by the method for manufacturing barium titanate according to the present invention is calcined at the same temperature, barium titanate with finer texture and higher crystallinity can be obtained compared to conventional barium titanate oxalate. On the other hand, if the temperature at which the weight reduction rate reaches 99% relative to a weight reduction rate of 1000°C exceeds 700°C, the temperature at which barium titanate is generated from barium titanate oxalate becomes higher, and therefore the heating temperature for subsequent high crystallinity also becomes higher, resulting in an increase in the particle size of barium titanate.

[0085] There are no particular limitations on the thermogravimetric analysis apparatus used in the thermogravimetric analysis of barium titanium oxalate; for example, the TGA / DSC 1 manufactured by METTLER TOLEDO Co., Ltd.

[0086] The barium oxalate obtained by the method for manufacturing barium titanium oxalate according to the present invention is preferably capable of being converted into a specific surface area of ​​15-20 m² by heating in air at 700±10°C for 2 hours. 2 Barium titanate oxalate, with a c / a ratio of 1.0030 to 1.0055, is a type of barium titanate. The barium titanate oxalate obtained by the method of manufacturing barium titanate oxalate according to the present invention is subjected to a heating test at 700 ± 10°C in atmosphere for 2 hours. The specific surface area of ​​the resulting barium titanate is particularly preferably 16 to 19 m². 2 / g. Furthermore, the c / a of barium titanate obtained by heating barium titanate obtained through the method for manufacturing barium titanate oxalate according to the present invention at 700±10°C for 2 hours in atmosphere is particularly preferably 1.0035 to 1.0050. Since the barium titanate produced by heating at 700±10°C for 2 hours in atmosphere has a specific surface area and c / a within the above range, even if grain growth occurs during the heating process for high crystallinity after barium titanate formation, a finer and more crystalline barium titanate can be obtained compared to conventional barium titanate oxalate. Regarding the heating test of barium titanate oxalate, the test sample is held for 2 hours in a heating apparatus with the temperature adjusted to 700±10°C. After cooling, the specific surface area and c / a of the test sample after the heating test are determined by specific surface area analysis using the BET method and X-ray diffraction analysis.

[0087] The average particle size of barium titanate oxalate obtained by the manufacturing method of the present invention is preferably 1.0 μm or less, more preferably 0.005 to 1.0 μm, and particularly preferably 0.01 to 0.5 μm. With the average particle size of barium titanate oxalate within the above range, barium titanate can be generated at low temperatures. Furthermore, in the present invention, the average particle size of barium titanate oxalate is determined by scanning electron microscopy (SEM) of arbitrarily measuring 200 particles and averaging them as the average particle size.

[0088] Furthermore, the barium oxalate oxytannin obtained by implementing the manufacturing method of the present invention is barium oxalate oxytannin that can generate barium titanate when heated in a temperature range of 600-700°C, preferably 610-690°C, and particularly preferably 615-685°C.

[0089] The barium titanate oxalate obtained by the method of the present invention is suitable for use as a raw material in the manufacture of barium titanate-based ceramics, which are dielectric ceramic materials. The method for manufacturing barium titanate of the present invention is as follows.

[0090] The method for manufacturing barium titanate of the present invention is characterized by calcining the barium titanate oxalate obtained by the method for manufacturing barium titanate oxalate of the present invention.

[0091] Organic matter from oxalic acid in the final product is undesirable because it impairs the dielectric properties of the material and is a major factor causing instability during the thermal process of ceramicization. Therefore, in this invention, it is necessary to obtain the target barium titanate by thermally decomposing barium titanate oxalate through firing, and to thoroughly remove organic matter from oxalic acid. Regarding firing conditions, the firing temperature is preferably 600–1200°C, more preferably 620–1100°C. When the firing temperature is below 600°C, only a portion of barium titanate is generated, or it is difficult to obtain a single-phase barium titanate. On the other hand, if the firing temperature exceeds 1200°C, the particle size deviation becomes larger. The firing time is preferably 0.5–30 hours, more preferably 1–20 hours. In addition, there are no particular limitations on the firing atmosphere; it can be carried out in an inert gas atmosphere, a vacuum atmosphere, an oxidizing gas atmosphere, or in the atmosphere, or firing can be carried out in the above atmospheres while introducing water vapor.

[0092] The firing process can be repeated several times as needed. Alternatively, to ensure uniform powder properties, the product after one firing can be pulverized and then fired again.

[0093] After calcination, the material is appropriately cooled and then pulverized as needed to obtain barium titanate powder. The pulverization is suitable when the calcined barium titanate is brittle and in blocky form. The barium titanate particles themselves possess the following specific average particle size and BET specific surface area: Specifically, the average particle size of the obtained barium titanate powder, as determined by scanning electron microscopy (SEM), is preferably 0.5 μm or less, more preferably 0.02–0.5 μm. The BET specific surface area is preferably 2–100 m². 2 / g, more preferably 2.5 to 50 mg 2 / g. Furthermore, regarding the composition of barium titanate obtained by the manufacturing method of the present invention, the molar ratio of Ba to Ti (Ba / Ti) is preferably 0.998 to 1.004, particularly preferably 0.999 to 1.003. Additionally, the specific surface area of ​​barium titanate is 15 m² / g. 2 When the specific surface area is in the range of / g or higher, the c-axis / a-axis ratio, which is an indicator of crystallinity, is preferably 1.0030 to 1.0055, and particularly preferably 1.0035 to 1.0050. As the firing temperature increases, grain growth occurs, resulting in a specific surface area of ​​less than 15 m². 2 Within the range of / g, the c-axis / a-axis ratio is preferably greater than 1.0055, more preferably 1.0070 or more, and particularly preferably 1.0075 or more.

[0094] Furthermore, in the barium titanate obtained by the method for manufacturing barium titanate of the present invention, in order to adjust the dielectric and temperature characteristics as needed, a compound containing a secondary component element may be added to the barium titanate obtained by the method for manufacturing barium titanate of the present invention, thereby making it contain a secondary component element. Examples of compounds containing a secondary component element that can be used include, for example, compounds containing at least one element selected from rare earth elements selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, as well as Ba, Li, Bi, Zn, Mn, Al, Si, Ca, Sr, Co, Ni, Cr, Fe, Mg, Ti, V, Nb, Mo, W, and Sn.

[0095] Compounds containing secondary components can be any type of inorganic or organic compound. Examples include oxides, hydroxides, chlorides, nitrates, oxalates, carboxylates, and alkoxides containing the aforementioned elements. When the compound containing the secondary component is a Si compound, in addition to oxides, silica sol or sodium silicate can also be used. One type of compound containing the secondary component can be used, or two or more can be used in appropriate combinations. The amount added and the combination of compounds added can be determined according to standard methods.

[0096] To incorporate byproduct elements into barium titanate, it can be prepared by uniformly mixing barium titanate with a compound containing byproduct elements before firing. Alternatively, it can be prepared by uniformly mixing barium oxalate oxytitanium with a compound containing byproduct elements before firing.

[0097] When manufacturing a multilayer ceramic capacitor using barium titanate obtained by the method of manufacturing barium titanate according to the present invention, firstly, barium titanate powder is mixed and dispersed in a suitable solvent with conventionally known additives, organic binders, plasticizers, dispersants, and other compounding agents containing by-component elements, and then slurryed and sheet-formed. This yields a ceramic sheet for manufacturing a multilayer ceramic capacitor. In manufacturing the multilayer ceramic capacitor from this ceramic sheet, firstly, a conductive paste for forming internal electrodes is printed on one side of the ceramic sheet. After drying, multiple of the above-mentioned ceramic sheets are stacked and pressed together in the thickness direction, thereby forming a multilayer body. Next, the multilayer body is heat-treated, then subjected to a binder removal treatment, and fired to obtain a fired body. Then, Ni paste, Ag paste, nickel alloy paste, copper paste, copper alloy paste, etc., are coated onto the fired body and baked to obtain a multilayer ceramic capacitor.

[0098] Furthermore, when barium titanate powder obtained by the barium titanate manufacturing method of the present invention is incorporated into resins such as epoxy resin, polyester resin, and polyimide resin to form resin sheets, resin films, adhesives, etc., it can be used as a material for printed wiring boards or multilayer printed wiring boards. In addition, it can also be used as a common material for suppressing the shrinkage difference between internal electrodes and dielectric layers, electrode ceramic circuit boards, glass ceramic circuit boards, circuit peripheral materials, and dielectric materials for inorganic EL.

[0099] Furthermore, the barium titanate obtained by the method for manufacturing barium titanate of the present invention is suitable for use as a catalyst in reactions such as removing waste gas and chemical synthesis, and as a surface modifier for printing ink cartridges that impart antistatic and cleaning effects.

[0100] Example

[0101] The present invention will now be described in detail with reference to the embodiments, but the present invention is not limited to these embodiments.

[0102] (1) Thermogravimetric analysis of barium oxalate

[0103] Using a thermogravimetric analyzer TGA / DSC 1 from METTLER TOLEDO Corporation, a 30 mg sample was measured from 30 °C to 1200 °C in an air flow of 50 mL / min at a heating rate of 10 °C / min.

[0104] (2) Average particle size of barium oxalate and barium titanate

[0105] Using scanning electron microscope (SEM) images, 200 particles were randomly measured, and their average value was taken as the average particle size.

[0106] (3) Specific surface area of ​​barium titanate

[0107] It is obtained through the BET method.

[0108] (4) c / a value of barium titanate

[0109] Cu-Kα rays were used as the radiation source, and the ratio c / a of the c-axis to the a-axis was determined using an X-ray diffraction apparatus (Bruker, D8 ADVANCE).

[0110] (Example 1)

[0111] 25.0 g of oxalic acid dihydrate was dissolved in 100 g of ethylene glycol to prepare 120 mL of a solution containing oxalic acid (solution A) with a concentration of 2.21 mol / L. In addition, 64.4 g of titanium tetrachloride and 32.0 g of barium chloride were dissolved in 210 g of pure water to prepare 270 mL of a solution containing titanium and barium (solution B) with a titanium tetrachloride concentration of 0.59 mol / L and a barium chloride concentration of 0.63 mol / L.

[0112] Next, in a static mixer (manufactured by Tomita Engineering Co., Ltd., MC08-32), solution A was supplied at a rate of 4.3 L / h, and solution B was supplied at a rate of 9.6 L / h. The reaction mixture was then discharged from the static mixer. The residence time of the reaction mixture in the static mixer was set to 2 seconds. The molar ratio of the oxalate ion supply rate to the Ba and Ti element supply rates in the static mixer was 1.91.

[0113] The reaction liquid discharged from the static mixer was subjected to solid-liquid separation to obtain a precipitate. This precipitate was washed and dried to obtain barium titanium oxalate. The physical properties of the obtained barium titanium oxalate are shown in Table 1. Furthermore, the results of the weight loss rate obtained from the thermal analysis of the obtained barium titanium oxalate are presented in... Figure 1 As a result, the weight reduction rate at 680°C was 45.42%, compared to 45.74% at 1000°C, for a total reduction of 99.30%.

[0114] The obtained barium oxalate was calcined at 700℃ for 2 hours to obtain barium titanate. The physical properties of the obtained barium titanate are shown in Table 1.

[0115] (Examples 2-4)

[0116] The barium oxalate barium titanate obtained in Example 1 was calcined at the temperatures shown in Table 1 to obtain barium titanate. The physical properties of the obtained barium titanate are shown in Table 1.

[0117] (Example 5)

[0118] 25.0 g of oxalic acid dihydrate was dissolved in 100 g of ethylene glycol to prepare 120 mL of a solution containing oxalic acid (solution A) with a concentration of 2.21 mol / L. In addition, 64.4 g of titanium tetrachloride and 32.0 g of barium chloride were dissolved in 210 g of pure water to prepare 270 mL of a solution containing titanium and barium (solution B) with a titanium tetrachloride concentration of 0.59 mol / L and a barium chloride concentration of 0.63 mol / L.

[0119] Next, in a microreactor (flow path diameter: 1.0 mm, flow path length: 1000 mm), solution A was supplied at a rate of 72 mL / min, and solution B was supplied at a rate of 160 mL / min. The reaction solution was then discharged from the microreactor. The residence time of the reaction solution within the microreactor was set to 2.6 seconds. The molar ratio of oxalate ion supply rate to Ba and Ti element supply rates in the microreactor was 1.91.

[0120] The reaction liquid discharged from the microreactor was subjected to solid-liquid separation to obtain a precipitate. This precipitate was washed and dried to obtain barium titanium oxalate. The physical properties of the obtained barium titanium oxalate are shown in Table 1. Furthermore, the results of the weight loss rate determined by the thermal analysis of the obtained barium titanium oxalate are presented in Table 1. Figure 1 As a result, the weight reduction rate at 680°C was 48.53%, compared to 45.28% at 1000°C, for a total reduction of 99.40%.

[0121] The obtained barium oxalate was calcined at 700℃ for 2 hours to obtain barium titanate. The physical properties of the obtained barium titanate are shown in Table 1.

[0122] (Comparative Example 1)

[0123] 35.0 g of barium chloride dihydrate and 35.0 g of oxalic acid dihydrate were dissolved in 120 g of pure water to prepare 120 mL of a solution (solution a) containing barium and oxalic acid with a barium concentration of 1.10 mol / L and an oxalic acid concentration of 2.20 mol / L. In addition, 54.0 g of titanium tetrachloride was dissolved in pure water to prepare 260 mL of a titanium solution (solution b) containing titanium with a titanium concentration of 0.40 mol / L.

[0124] Next, while stirring solution a, solution b was added over 90 seconds, and after maintaining the mixture for 1 hour, solid-liquid separation was performed to obtain a precipitate. This precipitate was washed and dried to obtain barium titanium oxalate. The physical properties of the obtained barium titanium oxalate are shown in Table 1. Furthermore, the results of the weight loss rate determined by the thermal analysis of the obtained barium titanium oxalate are presented in Table 1. Figure 1 As a result, the weight reduction rate at 680°C was 37.71%, compared to 84.15% at 1000°C (44.81%).

[0125] The obtained barium titanate oxalate was calcined at 700°C for 2 hours. However, the results of the weight loss determination by thermogravimetric analysis showed that barium titanate was not obtained.

[0126] (Comparative Examples 2-4)

[0127] The barium oxalate barium obtained in Comparative Example 1 was calcined at the temperatures shown in Table 1 to obtain barium titanate. The physical properties of the obtained barium titanate are shown in Table 1.

[0128] [Table 1]

[0129]

[0130] As shown in Table 1, a comparison of the average particle size, BET specific surface area, and c / a values ​​obtained when fired at the same temperature indicates that the barium titanate obtained in the examples is microparticles and highly crystalline compared to the barium titanate obtained in the comparative examples. Furthermore, as... Figure 1 As shown, it can be determined that the barium oxalate oxytannin obtained in Example 1 was converted to barium titanate at 700°C by thermogravimetric analysis, but the barium oxalate oxytannin obtained in Comparative Example 1 was not converted to barium titanate even at 700°C.

[0131] (Example 6)

[0132] 25.0 g of oxalic acid dihydrate was dissolved in 100 g of ethylene glycol to prepare 120 mL of a solution containing oxalic acid (solution A) with a concentration of 2.21 mol / L. In addition, 64.4 g of titanium tetrachloride and 32.0 g of barium chloride were dissolved in 210 g of pure water to prepare 270 mL of a solution containing titanium and barium (solution B) with a concentration of 0.59 mol / L titanium tetrachloride and 0.63 mol / L barium chloride.

[0133] Next, solution A was supplied to the Taylor vortex stirrer (Tipton, TVF-01) at a rate of 4.3 L / h, and solution B was supplied at a rate of 9.6 L / h. The reaction mixture was then discharged from the Taylor vortex stirrer. The residence time of the reaction mixture within the Taylor vortex stirrer was set to 5 seconds. The molar ratio of the oxalate ion supply rate to the Ba and Ti element supply rates in the Taylor vortex stirrer was 1.91.

[0134] The reaction liquid discharged from the Taylor vortex stirrer was subjected to solid-liquid separation to obtain a precipitate. This precipitate was washed and dried to obtain barium titanium oxalate. The physical properties of the obtained barium titanium oxalate are shown in Table 2. Furthermore, the results of the weight loss rate obtained from the thermal analysis of the obtained barium titanium oxalate are presented in Table 2. Figure 6 As a result, the weight reduction rate at 680°C was 48.53%, compared to 48.82% at 1000°C, for a total reduction of 99.40%.

[0135] The obtained barium oxalate was calcined at 700℃ for 2 hours to obtain barium titanate. The physical properties of the obtained barium titanate are shown in Table 2.

[0136] (Examples 7-9)

[0137] The barium oxalate barium titanate obtained in Example 7 was calcined at the temperatures shown in Table 2 to obtain barium titanate. The physical properties of the obtained barium titanate are shown in Table 2.

[0138] (Comparative Example 5)

[0139] 35.0 g of barium chloride dihydrate and 35.0 g of oxalic acid dihydrate were dissolved in 120 g of pure water to prepare 120 mL of a solution (solution a) containing barium and oxalic acid with a barium concentration of 1.10 mol / L and an oxalic acid concentration of 2.20 mol / L. In addition, 54.0 g of titanium tetrachloride was dissolved in pure water to prepare 260 mL of a titanium solution (solution b) containing titanium with a titanium concentration of 0.40 mol / L.

[0140] Next, while stirring solution a, solution b was added over 90 seconds. After maintaining the mixture for 1 hour, solid-liquid separation was performed to obtain a precipitate. This precipitate was washed and dried to obtain barium titanium oxalate. The physical properties of the obtained barium titanium oxalate are shown in Table 2. Furthermore, the results of the weight loss rate obtained from the thermal analysis of the obtained barium titanium oxalate are presented in Table 2. Figure 6 As a result, the weight reduction rate at 680°C was 37.71%, compared to 44.81% at 1000°C, for a total reduction of 84.15%.

[0141] The obtained barium titanate oxalate was calcined at 700°C for 2 hours. However, the results of the weight loss determination by thermogravimetric analysis showed that barium titanate was not obtained.

[0142] (Comparative Examples 6-8)

[0143] The barium oxalate barium obtained in Comparative Example 5 was calcined at the temperatures shown in Table 2 to obtain barium titanate. The physical properties of the obtained barium titanate are shown in Table 2.

[0144] [Table 2]

[0145]

[0146] As shown in Table 2, a comparison of the average particle size, BET specific surface area, and c / a values ​​obtained when fired at the same temperature indicates that the barium titanate obtained in the examples is microparticles and highly crystalline compared to the barium titanate obtained in the comparative examples. Furthermore, as... Figure 6 As shown, it can be determined that the barium oxalate oxytannin obtained in Example 6 was converted to barium titanate at 700°C by thermogravimetric analysis, but the barium oxalate oxytannin obtained in Comparative Example 5 was not converted to barium titanate even at 700°C.

Claims

1. A method for manufacturing barium titanium oxalate, characterized in that: This is a method for producing barium titanium oxalate by reacting a mixture of solution A and solution B, wherein... Solution A is a solution containing oxalic acid, and solution B is a solution containing a titanium source and a barium source. The manufacturing method involves supplying liquid A and liquid B to one end of the reaction liquid flow path, mixing liquid A and liquid B within the reaction flow path, discharging the reaction liquid from the other end of the reaction liquid flow path, and then performing solid-liquid separation of the reaction liquid. The residence time of the reaction solution within the flow path is less than 30 seconds. The reaction liquid flow route is formed by an online mixer or a continuous flow microreactor. The solvent of solution A is an aqueous solvent, an organic solvent, or a mixture of water and an organic solvent. The organic solvent is selected from one or more of the following: methanol, ethanol, propanol, butanol, diethyl ether, 1,3-butanediol, ethylene glycol, propylene glycol, dipropylene glycol, glycerol, N,N-dimethylformamide, and acetone. The solvent for liquid B is water.

2. The method for manufacturing barium titanium oxalate as described in claim 1, characterized in that: By supplying liquid A and liquid B to one end of the static mixer, a reaction liquid flow path is formed within the static mixer.

3. A method for manufacturing barium titanium oxalate, characterized in that: This is a method for producing barium titanium oxalate by reacting a mixture of solution A and solution B, wherein... Solution A is a solution containing oxalic acid, and solution B is a solution containing a titanium source and a barium source. The manufacturing method involves supplying liquid A and liquid B to one end of the reaction liquid flow path, mixing liquid A and liquid B at that end, generating Taylor vortices in the reaction liquid, and moving the reaction liquid to the other end of the reaction liquid flow path, from which the reaction liquid is discharged. Afterwards, solid-liquid separation of the reaction liquid is performed. The residence time of the reaction liquid within the reaction liquid flow path is less than 60 seconds. The solvent of solution A is an aqueous solvent, an organic solvent, or a mixture of water and an organic solvent. The organic solvent is selected from one or more of the following: methanol, ethanol, propanol, butanol, diethyl ether, 1,3-butanediol, ethylene glycol, propylene glycol, dipropylene glycol, glycerol, N,N-dimethylformamide, and acetone. The solvent for liquid B is water.

4. The method for manufacturing barium titanium oxalate as described in claim 1 or 3, characterized in that: The titanium source in solution B is titanium tetrachloride, and the barium source is barium chloride.

5. The method for manufacturing barium titanium oxalate as described in claim 1 or 3, characterized in that: The mixing temperature of liquid A and liquid B is below 75°C.

6. The method for manufacturing barium titanium oxalate as described in claim 1 or 3, characterized in that: The average particle size of the generated barium oxalate is less than 1.0 μm.

7. A method for manufacturing barium titanate, characterized in that: Barium oxalate oxytannin obtained by the manufacturing method according to any one of claims 1 to 3 is calcined.

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