KR20230109634A - Method for producing barium titanyl oxalate and method for producing barium titanate - Google Patents

Abstract

A method for producing barium titanyl oxalate in which a solution containing oxalic acid (liquid A) and a solution containing a titanium source and a barium source (liquid B) are mixed and reacted to produce barium titanyl oxalate. The A liquid and the B liquid are separately supplied to one end side of the A, the A liquid and the B liquid are mixed in the reaction flow passage, and the reaction liquid is discharged from the other end side of the reaction liquid flow passage, Subsequently, solid-liquid separation of the reaction liquid is performed, the retention time of the reaction liquid in the reaction liquid flow passage is 30 seconds or less, or the liquid A and the liquid B are separately placed on one end side of the reaction liquid flow passage. separately supplied, the A liquid and the B liquid are mixed at one end side of the reaction liquid flow passage, the reaction liquid is moved to the other end side of the reaction liquid flow passage while generating a vortex in the reaction liquid, and the reaction liquid flow passage A method for producing barium titanyl oxalate characterized in that the reaction liquid is discharged from the other end side of the reaction liquid, and then solid-liquid separation of the reaction liquid is performed.

Description

Method for producing barium titanyl oxalate and method for producing barium titanate

The present invention relates to a method for producing barium titanyl oxalate useful as a raw material for functional ceramics such as dielectrics, piezoelectric materials, optoelectronics materials, semiconductors and sensors.

Conventionally, barium titanate is produced by a solid phase method, a hydrothermal synthesis method, an alkoxide method, an oxalate method, or the like.

In the solid phase method, constituent raw powders are mixed and the mixture is produced by a dry method of heating the mixture at a high temperature. Therefore, the resulting powder forms an irregularly shaped agglomerate, and high-temperature firing is required to achieve desired properties. . In addition, the hydrothermal synthesis method is not industrially advantageous because the synthesis process is complicated, the productivity is low because the autoclave is used, and the price of the manufactured powder is high, despite the advantage of good powder characteristics. Also, similarly, the alkoxide method is not industrially advantageous because handling of the starting material is difficult and the price is high.

Barium titanate obtained by the oxalate method is characterized in that it can produce a product with a uniform composition at low cost compared to the hydrothermal synthesis method or the alkoxide method, and has a more uniform composition than barium titanate produced by the solid phase method. As a conventional oxalate method, a method in which a titanium source such as titanium tetrachloride, a barium source such as barium chloride, and oxalic acid are reacted in a solvent such as water to obtain barium titanyl oxalate, and then the barium titanyl oxalate is calcined ( For example, see Patent Documents 1 to 3).

Japanese Patent Publication No. 2005-500239 Japanese Unexamined Patent Publication No. 2010-202610 Japanese Unexamined Patent Publication No. 2013-63867

However, since the barium titanyl oxalate obtained in the patent literature produces barium titanate at a firing temperature of 700° C. or higher, at the time of generation of barium titanate, the crystallinity is low, but grain growth is caused to some extent. . When such barium titanyl oxalate is calcined at a high temperature, even high crystals become large particles, and there is a problem that properties as a raw material for functional ceramics cannot be satisfied.

Accordingly, an object of the present invention is to provide a production method for producing barium titanyl oxalate from which barium titanate having a small particle size and high crystallinity can be obtained.

The inventors of the present invention have conducted extensive research in view of the situation described above and, as a result, found that a solution (liquid A) containing oxalic acid, a titanium compound, and a barium compound are contained at one end side of a reaction liquid passage formed in an inline mixer, a microreactor, or the like. The mixing time of A liquid and B liquid is shortened by separately supplying a solution (liquid B), mixing liquid A and liquid B in the reaction passage, and discharging the reaction liquid from the other end of the reaction passage. By doing this, fine barium titanyl oxalate is obtained, when such fine barium titanyl oxalate is fired, carbon dioxide gas is easily released during thermal decomposition, and the temperature at which barium titanate is generated can be lowered, and barium titanate at a low temperature. It was found that barium titanate can be highly crystallized at a lower temperature than before, and grain growth of barium titanate can be suppressed, so that fine grained and highly crystalline barium titanate can be obtained compared to the prior art. and came to complete the present invention.

In view of the above situation, the inventors of the present invention conducted extensive research and found that a solution (liquid A) containing oxalic acid and a solution (liquid B) containing a titanium compound and a barium compound (liquid B) were prepared at one end of the reaction liquid passage. The reaction raw materials in Liquid A and Liquid B can be quickly contacted by supplying them separately, mixing Liquid A and Liquid B while generating a vortex in the reaction passage, and discharging the reaction liquid from the other end side of the reaction liquid passage. Therefore, fine barium titanyl oxalate is obtained, when such fine barium titanyl oxalate is fired, carbon dioxide gas is easily released during thermal decomposition, and the temperature at which barium titanate is generated can be lowered, and titanic acid at a low temperature. By generating barium, barium titanate can be highly crystallized at a lower temperature than before, and grain growth of barium titanate can be suppressed, so that barium titanate of fine grain and high crystallinity can be obtained compared to the past. found out and came to complete the present invention.

That is, according to the present invention (1), barium titanyl oxalate is produced by mixing and reacting a solution containing oxalic acid (liquid A) with a solution containing a titanium source and a barium source (liquid B). A method for producing tanyl,

The liquid A and the liquid B are separately supplied to one end side of the reaction liquid passage, the liquid A and the liquid B are mixed in the reaction passage, and the reaction liquid is discharged from the other end side of the reaction liquid passage. discharging, and then performing solid-liquid separation of the reaction liquid;

The retention time of the reaction liquid in the reaction liquid passage is 30 seconds or less

It is to provide a method for producing barium titanyl oxalate characterized by.

Further, the present invention (2) is of (1) characterized by forming the reaction liquid passage in the static mixer by separately supplying the liquid A and the liquid B to one end side of the static mixer. It is to provide a method for producing barium titanyl oxalate.

Further, the present invention (3) is to form the reaction liquid passage in the microreactor by separately supplying the liquid A and the liquid B to one end side of the reaction liquid passage of the continuous flow type microreactor. It is to provide the method for producing barium titanyl oxalate of (1) characterized by the above.

In the present invention (4), barium titanyl oxalate is produced by mixing a solution containing oxalic acid (liquid A) and a solution containing a titanium source and a barium source (liquid B) and reacting the mixture. A method for producing tanyl,

Liquid A and Liquid B are separately supplied to one end side of the reaction liquid flow passage, and Liquid A and Liquid B are mixed at one end side of the reaction liquid flow passage, generating a vortex in the reaction liquid. Moving the reaction liquid to the other end side of the reaction liquid flow passage, discharging the reaction liquid from the other end side of the reaction liquid flow passage, and then performing solid-liquid separation of the reaction liquid.

It is to provide a method for producing barium titanyl oxalate characterized by.

Furthermore, the present invention (5) provides the method for producing barium titanyl oxalate of (4) characterized in that the residence time of the reaction liquid in the reaction liquid passage is within 60 seconds.

Furthermore, the present invention (6) provides the method for producing barium titanyl oxalate according to (4), characterized in that the vortex is a Taylor vortex.

Furthermore, the present invention (7) provides the method for producing barium titanyl oxalate according to (1) or (4), characterized in that the solvent of the liquid A is an organic solvent.

In the present invention (8), the solvent of the liquid A is methanol, ethanol, propanol, butanol, diethyl ether, 1,3-butylene glycol, ethylene glycol, propylene glycol, dipropylene glycol, glycerol, N, It is to provide the method for producing barium titanyl oxalate of (1) or (4) characterized by using one or more selected from the group consisting of N-dimethylformamide and acetone.

Furthermore, the present invention (9) provides the method for producing barium titanyl oxalate according to (1) or (4), characterized in that the solvent of the liquid B is water.

Furthermore, the present invention (10) provides the method for producing barium titanyl oxalate according to (1) or (4), characterized in that the titanium compound in the Liquid B is titanium tetrachloride and the barium compound is barium chloride. will be.

Furthermore, the present invention (11) provides the method for producing barium titanyl oxalate according to (1) or (4), characterized in that the mixing temperature of the liquid A and the liquid B is 75°C or lower.

Further, the present invention (12) provides the method for producing barium titanyl oxalate according to (1) or (4), characterized in that the average particle diameter of the barium titanyl oxalate produced is 1.0 µm or less.

Furthermore, the present invention (13) provides a method for producing barium titanate characterized by calcining barium titanyl oxalate obtained by any of the production methods (1) to (6).

According to the present invention, it is possible to provide a production method for producing barium titanyl oxalate in which, when calcined at the same temperature, barium titanyl having a smaller particle size and high crystallinity is obtained as compared to conventional barium titanyl oxalate.

1 is a measurement result of thermogravimetric analysis of barium titanyl oxalate obtained in Example 1 and Comparative Example 1.
2 is a SEM photograph of barium titanyl oxalate obtained in Example 1.
3 is a SEM photograph of barium titanate obtained in Example 1.
4 is a SEM photograph of barium titanyl oxalate obtained in Comparative Example 1.
5 is a SEM photograph of a sintered product obtained in Comparative Example 1.
6 is a measurement result of thermogravimetric analysis of barium titanyl oxalate obtained in Example 6 and Comparative Example 5.
7 is a SEM photograph of barium titanyl oxalate obtained in Example 6.
8 is a SEM photograph of barium titanate obtained in Example 6.
9 is a SEM photograph of barium titanyl oxalate obtained in Comparative Example 5.
10 is a SEM photograph of a sintered product obtained in Comparative Example 5.

The first aspect of the present invention will be described.

<First Invention>

The method for producing barium titanyl oxalate of the present invention is to produce barium titanyl oxalate by mixing and reacting a solution containing oxalic acid (liquid A) with a solution containing a titanium source and a barium source (liquid B). A method for producing barium titanyl oxalate,

The liquid A and the liquid B are separately supplied to one end side of the reaction liquid passage, the liquid A and the liquid B are mixed in the reaction passage, and the reaction liquid is discharged from the other end side of the reaction liquid passage. discharging, and then performing solid-liquid separation of the reaction liquid;

The retention time of the reaction liquid in the reaction liquid passage is 30 seconds or less

It is a method for producing barium titanyl oxalate characterized by.

Liquid A according to the method for producing barium titanyl oxalate of the present invention is a solution containing oxalic acid. The concentration of oxalate ions in Liquid A is not particularly limited, but is preferably 0.1 to 7.0 mol/L, particularly preferably 0.6 to 5.0 mol/L.

The solvent of the liquid A includes an aqueous solvent, an organic solvent, or a mixed solvent thereof, and is preferably an organic solvent from the viewpoint of obtaining fine particle barium titanyl oxalate. The organic solvent is not particularly limited as long as it is hydrophilic and inert to raw materials, and methanol, ethanol, propanol, butanol, diethyl ether, 1,3-butylene glycol, ethylene glycol, propylene glycol, dipropylene glycol, glycerol, One or two or more selected from the group consisting of 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 a plurality of organic solvents, these mixing ratios are appropriately selected.

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

The titanium compound related to the production method of barium titanyl oxalate of the present invention is not particularly limited, and titanium tetrachloride, titanium lactate, and the like are exemplified. One type of titanium compound may be sufficient as it, and 2 or more types of combined use may be sufficient as it. As a titanium source, titanium tetrachloride is preferable.

The barium compound related to the method for producing barium titanyl oxalate of the present invention is not particularly limited, and examples thereof include barium chloride, barium carbonate, barium hydroxide, barium acetate, and barium nitrate. One type of barium compound may be sufficient as it, and 2 or more types of combined use may be sufficient as it. As the barium compound, one or two or more selected from the group consisting of barium chloride, barium acetate, barium nitrate and barium hydroxide is preferable, and barium chloride is particularly preferable.

In the method for producing barium titanyl oxalate of the present invention, liquid A and liquid B are separately supplied to one end side of a reaction liquid flow passage, and liquid A and liquid B are mixed in the reaction liquid flow passage. In this, a reaction for producing barium titanyl oxalate is performed.

As a method of separately supplying Liquid A and Liquid B to one end side of the reaction liquid passage and mixing Liquid A and Liquid B in the reaction passage, for example, an inline mixer such as a static mixer, a screw mixer, or a dynamic mixer A method of separately supplying liquid A and liquid B to one end side of the mixer and mixing liquid A and liquid B in an in-line mixer is exemplified. When using an in-line mixer, a reaction liquid passage is formed in the in-line mixer. As an in-line mixer, a static mixer is preferable from the viewpoint of making it easier to obtain fine barium titanyl oxalate. The static mixer is not particularly limited, and examples thereof include MC08-32 manufactured by Tomita Engineering Co., Ltd.

Further, as a method of separately supplying Liquid A and Liquid B to one end side of the reaction liquid passage and mixing Liquid A and Liquid B in the reaction passage, for example, one end side of a microreactor of a continuous flow type. For example, a method in which liquid A and liquid B are supplied separately and liquid A and liquid B are mixed in the flow path of the microreactor is exemplified. In addition, a microreactor is a reaction having, for example, a flow path comprising a tube having a flow path diameter 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 side of the flow path. It is a device. In the case of using a continuous flow type microreactor, a reaction liquid flow path is formed within the flow path of the continuous flow type microreactor.

In the method for producing barium titanyl oxalate of the present invention, Liquid A and Liquid B are mixed in the reaction liquid passage by supplying Liquid A and Liquid B to the reaction liquid passage, and the reaction raw materials in Liquid A and Liquid B are mixed. As a result of the reaction, particulate barium titanyl oxalate is produced. Then, in the production method of barium titanyl oxalate of the present invention, the generated reaction liquid is discharged from the other end of the reaction liquid passage while supplying Liquid A and Liquid B from one end side of the reaction passage.

In the method for producing barium titanyl oxalate of the present invention, the residence time of the reaction liquid in the reaction liquid passage is within 30 seconds, preferably within 10 seconds, and particularly preferably within 0.1 to 5 seconds. When the residence time of the reaction liquid in the reaction liquid flow passage is within the above range, fine-grained barium titanyl oxalate is obtained. The residence time of the reaction liquid in the reaction liquid passage refers to the time until the mixture of Liquid A and Liquid B supplied to one end of the reaction liquid passage reaches the other end of the reaction liquid passage.

The mixing temperature of liquid A and liquid B, that is, the temperature of the reaction liquid in the reaction liquid passage, is preferably 75°C or less, particularly preferably 5 to 50°C.

The mixing ratio of liquid A and liquid B is such that the ratio of the number of moles of titanium and barium in liquid B to the number of moles of oxalic acid in liquid A is preferably 0.01 to 20.0, particularly preferably 0.10 to 10.0.

Next, in the method for producing barium titanyl oxalate of the present invention, the reaction liquid discharged from the reaction liquid passage is subjected to solid-liquid separation.

In addition, after performing solid-liquid separation, solid content is washed with water. The water washing method is not particularly limited, but washing by repulping or the like is preferable in terms of high washing efficiency. After washing, the solid content is dried and, if necessary, pulverized to obtain barium titanyl oxalate.

Next, the second aspect of the present invention will be described.

<Second Invention>

In the method for producing barium titanyl oxalate of the present invention, barium titanyl oxalate is produced by mixing and reacting a solution containing oxalic acid (liquid A) with a titanium source and a barium source (liquid B), thereby producing oxalic acid. A method for producing barium titanyl,

Liquid A and Liquid B are separately supplied to one end side of the reaction liquid flow path, and Liquid A and Liquid B are mixed at one end side of the reaction liquid flow path to generate a vortex in the reaction liquid. Moving the reaction liquid to the other end side of the reaction liquid flow passage, discharging the reaction liquid from the other end side of the reaction liquid flow passage, and then performing solid-liquid separation of the reaction liquid.

It is a method for producing barium titanyl oxalate characterized by.

Liquid A according to the method for producing barium titanyl oxalate of the present invention is a solution containing oxalic acid. The concentration of oxalate ions in Liquid A is not particularly limited, but is preferably 0.1 to 7.0 mol/L, particularly preferably 0.6 to 5.0 mol/L.

The solvent of the liquid A includes an aqueous solvent, an organic solvent, or a mixed solvent thereof, and is preferably an organic solvent from the viewpoint of obtaining fine particle barium titanyl oxalate. The organic solvent is not particularly limited as long as it is hydrophilic and inert to raw materials, and methanol, ethanol, propanol, butanol, diethyl ether, 1,3-butylene glycol, ethylene glycol, propylene glycol, dipropylene glycol, glycerol, One or two or more selected from the group consisting of 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 a plurality of organic solvents, these mixing ratios are appropriately selected.

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

The titanium compound related to the production method of barium titanyl oxalate of the present invention is not particularly limited, and titanium tetrachloride, titanium lactate, and the like are exemplified. One type of titanium compound may be sufficient as it, and 2 or more types of combined use may be sufficient as it. As a titanium source, titanium tetrachloride is preferable.

The barium compound related to the method for producing barium titanyl oxalate of the present invention is not particularly limited, and examples thereof include barium chloride, barium carbonate, barium hydroxide, barium acetate, and barium nitrate. One type of barium compound may be sufficient as it, and 2 or more types of combined use may be sufficient as it. As the barium compound, one or two or more selected from the group consisting of barium chloride, barium acetate, barium nitrate and barium hydroxide is preferable, and barium chloride is particularly preferable.

In the method for producing barium titanyl oxalate of the present invention, liquid A and liquid B are separately supplied to one end side of a reaction liquid flow passage, and then liquid A and liquid B are mixed at one end side of the reaction liquid flow passage. While generating a vortex in the obtained reaction liquid (liquid A and liquid mixture B), the reaction liquid is moved to the other end side of the reaction liquid flow passage, whereby a reaction for generating barium titanyl oxalate is performed in the reaction liquid flow passage, and then the reaction liquid The reaction liquid is discharged from the other end side of the flow path.

In the method for producing barium titanyl oxalate of the present invention, the reaction raw materials in Liquid A and Liquid B are reacted with each other while generating a vortex in the mixed liquid of Liquid A and Liquid B in the reaction liquid flow passage. can be contacted quickly. Therefore, in the method for producing barium titanyl oxalate of the present invention, after mixing liquid A and liquid B, since a large number of barium titanyl oxalate nuclei can be generated in the obtained reaction liquid (mixture), barium oxalate having a large particle size It is difficult to produce titanyl, and barium titanyl oxalate with a small particle size is produced. In addition, in the method for producing barium titanyl oxalate of the present invention, since the reaction raw materials in the obtained reaction liquid (mixture liquid) can be quickly brought into contact, the reaction time (residence time) can be shortened, so the reaction efficiency can be increased. .

Examples of the vortex generated in the reaction liquid passage include Taylor vortex. The Taylor vortex refers to a toroidal vortex generated when the inner cylinder is rotated in a state in which the gap between the double cylinder including the inner cylinder and the outer cylinder is filled with fluid.

As a device for supplying a supply liquid from one end side of the flow path and discharging the discharged liquid from the other end side of the flow path while generating a Taylor vortex in the flow path, for example, Japanese Patent Laid-Open No. 2011-83768 and Japanese Patent Laid-Open No. 2016 -10774, Japanese Unexamined Patent Publication No. 2017-209660, etc., and, for example, a Taylor vortex type stirring device such as TVF by Tipton Co., Ltd., small reactor riser by Toku Injection Co., Ltd. there is.

In the method for producing barium titanyl oxalate of the present invention, the produced reaction liquid is discharged from the other end of the reaction liquid flow path while supplying Liquid A and Liquid B to one end side of the reaction liquid flow path. Between this supply and discharge reaction liquid flow path, if the reaction liquid is within the residence time described later, as described in Japanese Patent Laid-Open No. 2011-83768, for example, a reaction device that generates a vortex such as a Taylor vortex You may use it combining multiple.

In the method for producing barium titanyl oxalate of the present invention, the residence time of the reaction liquid in the reaction liquid passage is preferably within 60 seconds, more preferably within 20 seconds, and particularly preferably 0.1 to 10 seconds. When the residence time of the reaction liquid in the reaction liquid passage is within the above range, it becomes easy to obtain fine-grained barium titanyl oxalate. In addition, the residence time of the reaction liquid in the reaction liquid passage means that the mixture of Liquid A and Liquid B (reaction liquid produced by mixing Liquid A and Liquid B) supplied to one end side of the reaction liquid passage is the reaction liquid It refers to the time from one end of the flow path to the other end of the reaction liquid flow path.

The mixing temperature of liquid A and liquid B, that is, the temperature of the reaction liquid in the reaction liquid passage, is preferably 75°C or less, particularly preferably 5 to 50°C.

The mixing ratio of liquid A and liquid B is such that the ratio of the number of moles of titanium and barium in liquid B to the number of moles of oxalic acid in liquid A is preferably 0.01 to 20.0, particularly preferably 0.10 to 10.0.

Next, in the method for producing barium titanyl oxalate of the present invention, the reaction liquid discharged from the reaction liquid passage is subjected to solid-liquid separation.

In addition, after performing solid-liquid separation, solid content is washed with water. The water washing method is not particularly limited, but washing by repulping or the like is preferable in terms of high washing efficiency. After washing, the solid content is dried and, if necessary, pulverized to obtain barium titanyl oxalate.

Next, barium titanyl oxalate obtained by carrying out the methods for producing barium titanyl oxalate according to the first and second inventions of the present invention will be described.

In this way, barium titanyl oxalate obtained by carrying out the method for producing barium titanyl oxalate of the present invention has a temperature at which the weight loss rate reaches 99% relative to the weight loss rate of 1000 ° C. in thermogravimetric analysis is 600 to 700 ° C. , It is barium titanyl oxalate characterized in that it is preferably 610 to 690 ° C, particularly preferably 615 to 685 ° C. In addition, the weight loss rate at 1000°C in thermogravimetric analysis refers to the weight loss rate at the time point when the analysis temperature in thermogravimetric analysis is 1000°C. The temperature at which the weight loss rate relative to the weight loss rate at 1000°C in thermogravimetric analysis reaches 99% means that the weight loss rate at the start of the analysis is 99% of the weight loss rate at the time point at which the analysis temperature is 1000°C. indicates the temperature at which

In thermogravimetric analysis, the temperature at which the weight loss rate relative to the weight loss rate at 1000 ° C. reaches 99% is the temperature at which thermal decomposition of barium titanyl oxalate occurs and the change to barium titanate ends, that is, barium titanyl oxalate. It indicates the temperature at which barium titanate is produced from Regarding the weight loss measured by thermogravimetric analysis of barium titanyl oxalate, when the sample to be measured was heated from room temperature at 10°C/min, some weight loss was confirmed, and then a weight loss was confirmed around 700°C. and finally, it can be confirmed that the thermal decomposition to barium titanate has occurred. It can be confirmed that the conventional barium titanyl oxalate loses weight loss at 700 to 720°C, and barium titanate can be obtained in this temperature range. However, barium titanyl oxalate obtained by carrying out the method for producing barium titanyl oxalate of the present invention cannot be confirmed to lose weight at 600 to 700°C, preferably at 610 to 690°C, particularly preferably at 615 to 685°C. Therefore, barium titanate can be obtained from barium titanyl oxalate at a lower temperature than in the prior art. For this reason, barium titanyl oxalate obtained by performing the method for producing barium titanyl oxalate of the present invention is fine, with an average particle diameter of preferably 1.0 μm or less, particularly preferably 0.01 to 0.5 μm. The present inventors believe that this is because carbon dioxide gas easily escapes and is changed to barium titanate at a lower temperature than in the prior art.

Barium titanyl oxalate obtained by carrying out the method for producing barium titanyl oxalate of the present invention has, in thermogravimetric analysis, a temperature at which the weight loss rate relative to the weight loss rate of 1000°C reaches 99% is 600 to 700°C, preferably. By being 610 to 690 ° C, particularly preferably 615 to 685 ° C, barium titanate can be produced in the temperature range of 600 to 700 ° C, preferably 610 to 690 ° C, particularly preferably 615 to 685 ° C there is. Therefore, since barium titanyl oxalate obtained by performing the method for producing barium titanyl oxalate of the present invention can generate barium titanate at a low temperature, high crystallization of barium titanate can be achieved at a lower temperature than before. In addition, since barium titanyl oxalate obtained by performing the method for producing barium titanyl oxalate of the present invention can achieve high crystallization of barium titanate at a lower temperature than before, grain growth of barium titanate can be suppressed. In comparison, barium titanate that is fine and highly crystalline is obtained. Therefore, when the barium titanyl oxalate obtained by performing the method for producing barium titanyl oxalate of the present invention is calcined at the same temperature, finer and highly crystalline barium titanate can be obtained than conventional barium titanyl oxalate. there is. On the other hand, if the temperature at which the weight reduction rate relative to the weight loss rate of 1000°C reaches 99% exceeds 700°C, the temperature at which barium titanate is produced from barium titanyl oxalate increases, so the heating temperature for subsequent high crystallization also increases. becomes high, and as a result, the particle diameter of barium titanate becomes large.

The thermogravimetric analyzer used for thermogravimetric analysis of barium titanyl oxalate is not particularly limited, and examples thereof include TGA/DSC 1 manufactured by Mettler-Toledo Co., Ltd.

Barium titanyl oxalate obtained by performing the method for producing barium titanyl oxalate of the present invention has a specific surface area of 15 to 20 m 2 /g and a c/a of 1.0030 in a heating test at 700 ± 10 ° C. in the air for 2 hours. to 1.0055 barium titanyl oxalate converted to barium titanate. The specific surface area of barium titanate obtained by heating barium titanyl oxalate obtained by the method for producing barium titanyl oxalate of the present invention in air at 700 ± 10 ° C. for 2 hours is particularly preferably 16 to 19 m 2 /g. am. Further, c/a of barium titanate obtained by subjecting barium titanyl oxalate obtained by performing the method for producing barium titanyl oxalate of the present invention in air at 700±10° C. for 2 hours is particularly preferably 1.0035 to 1.0050. am. When the specific surface area of barium titanate generated by the heating test at 700±10°C in the air for 2 hours is within the above range and c/a is within the above range, barium titanate is generated during the firing process. Even if grain growth occurs during heating for high crystallization after it has been formed, finer and highly crystalline barium titanate can be obtained compared to conventional barium titanyl oxalate. For the heating test of barium titanyl oxalate, the sample to be measured was held for 2 hours in a heating device temperature-controlled at 700 ± 10 ° C., and the sample to be measured was subjected to a heating test. Surface area analysis and X-ray diffraction analysis are performed to determine the specific surface area and c/a of the sample to be measured after the heating test.

The average particle diameter of barium titanyl oxalate obtained by performing the method for producing barium titanyl oxalate 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. When the average particle diameter of barium titanyl oxalate is within the above range, barium titanate can be produced at a low temperature. In the present invention, the average particle diameter of barium titanyl oxalate is determined by randomly measuring 200 particles using a scanning electron microscope (SEM) photograph, and taking the average value as the average particle diameter.

Further, when the barium titanyl oxalate obtained by performing the method for producing barium titanyl oxalate of the present invention is heated in a temperature range of 600 to 700°C, preferably 610 to 690°C, particularly preferably 615 to 685°C, It is barium titanyl oxalate that can produce barium titanate.

Barium titanyl oxalate obtained by the method for producing barium titanyl oxalate of the present invention is suitably used as a raw material for producing barium titanate-based ceramics as dielectric ceramic materials. The production method of barium titanate of the present invention is as follows.

The method for producing barium titanate of the present invention is characterized by calcining barium titanyl oxalate obtained by the method for producing barium titanyl oxalate of the present invention.

An organic substance derived from oxalic acid contained in the final product is undesirable because it impairs the dielectric properties of the material and becomes a factor in instability of behavior in the thermal process for ceramicization. Therefore, in the present invention, it is necessary to thermally decompose barium titanyl oxalate by firing to obtain the target barium titanate and to sufficiently remove organic substances derived from oxalic acid. As for the firing conditions, the firing temperature is preferably 600 to 1200°C, more preferably 620 to 1100°C. When the firing temperature is less than 600°C, only a part of barium titanate is generated, or it is difficult to obtain single-phase barium titanate. On the other hand, when the firing temperature exceeds 1200°C, the variation in particle size increases. The firing time is preferably 0.5 to 30 hours, more preferably 1 to 20 hours. The firing atmosphere is not particularly limited, and may be any of an inert gas atmosphere, a vacuum atmosphere, an oxidizing gas atmosphere, or air, or firing may be performed in the above atmosphere while introducing water vapor.

Firing may be performed as many times as desired. Alternatively, for the purpose of making the powder properties uniform, the fired material may be pulverized and then fired again.

After firing, it is cooled appropriately and, if necessary, pulverized to obtain a powder of barium titanate. Grinding, if necessary, is appropriately performed when the barium titanate obtained by firing is brittle and block-shaped, etc., but the barium titanate particles themselves have the following specific average particle diameter and BET specific surface area. That is, the average particle diameter of the barium titanate powder obtained above is preferably 0.5 µm or less, more preferably 0.02 to 0.5 µm, as determined from a scanning electron micrograph (SEM). The BET specific surface area is preferably 2 to 100 m 2 /g, more preferably 2.5 to 50 m 2 /g. Further, the composition of the barium titanate obtained by the production method of the present invention preferably has a molar ratio of Ba to Ti (Ba/Ti) of 0.998 to 1.004, particularly 0.999 to 1.003. The c-axis/a-axis ratio, which is an index of crystallinity, is preferably 1.0030 to 1.0055, particularly preferably 1.0035 to 1.0050, in a range where the specific surface area of barium titanate is 15 m 2 /g or more. Since grain growth occurs when the firing temperature increases, the specific surface area is in the range of less than 15 m 2 /g, but in that range, the c-axis / a-axis ratio preferably exceeds 1.0055, more preferably 1.0070 or more, more preferably 1.0075 or more. This is particularly preferred.

In addition, to the barium titanate obtained by performing the method for producing barium titanate of the present invention, a compound containing a subcomponent element is added to the barium titanate obtained by performing the method for producing barium titanate of the present invention for the purpose of adjusting the dielectric characteristics and temperature characteristics as necessary. It can be added to barium acid to contain subcomponent elements. Examples of compounds containing subcomponent elements that can be used include Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, rare earth elements of Lu, Ba At least one element selected from the group consisting of Li, Bi, Zn, Mn, Al, Si, Ca, Sr, Co, Ni, Cr, Fe, Mg, Ti, V, Nb, Mo, W, and Sn A compound containing it is mentioned.

The subcomponent element-containing compound may be either inorganic or organic. Examples include oxides, hydroxides, chlorides, nitrates, oxalates, carboxylates and alkoxides containing the above elements. In the case where the subcomponent element-containing compound is a compound containing Si element, silica sol, sodium silicate, or the like can be used in addition to an oxide or the like. The compounds containing subcomponent elements can be used alone or in appropriate combination of two or more. What is necessary is just to perform the combination of the addition amount and the addition compound in accordance with a conventional method.

In order to make the barium titanate contain the subcomponent element, for example, after uniformly mixing the barium titanate and the subconstituent element-containing compound, firing may be performed. Alternatively, firing may be performed after uniformly mixing the barium titanyl oxalate and the subcomponent element-containing compound.

In the case of manufacturing, for example, a multilayer ceramic capacitor using the barium titanate obtained by performing the method for producing barium titanate of the present invention, first, barium titanate powder is mixed with conventionally known additives including subcomponent elements; It is mixed and dispersed in an appropriate solvent together with a compounding agent such as an organic binder, a plasticizer, and a dispersing agent to form a slurry, and sheet molding is performed. In this way, a ceramic sheet used for manufacturing a multilayer ceramic capacitor is obtained. In order to manufacture a multilayer ceramic capacitor with the ceramic sheet, first, a conductive paste for forming internal electrodes is printed on one surface of the ceramic sheet. After drying, a plurality of the ceramic sheets are laminated and pressure-bonded in the thickness direction to obtain a laminate. Next, this laminate is subjected to a heat treatment, debinding agent treatment, and firing to obtain a fired body. Further, Ni paste, Ag paste, nickel alloy paste, copper paste, copper alloy paste or the like is applied to the fired body and baked to obtain a multilayer ceramic capacitor.

In addition, the barium titanate powder obtained by performing the method for producing barium titanate of the present invention is blended with a resin such as an epoxy resin, a polyester resin, or a polyimide resin to be used as a resin sheet, resin film, adhesive, or the like. In addition to being usable as a material for printed wiring boards and multi-layer printed wiring boards, it is also used as a common material for suppressing the difference in shrinkage between internal electrodes and dielectric layers, electrode ceramic circuit boards, glass ceramic circuit boards, circuit peripheral materials, and dielectrics for inorganic EL. It can also be used as a material.

In addition, the barium titanate obtained by carrying out the method for producing barium titanate of the present invention is used as a catalyst used in reactions such as exhaust gas removal and chemical synthesis, or as a surface modifier for printing toners that imparts antistatic and cleaning effects. used appropriately.

Example

Hereinafter, the present invention will be described in detail by examples, but the present invention is not limited to these examples.

(1) Thermogravimetric analysis of barium titanyl oxalate

A 30 mg sample was measured from 30°C to 1200°C at a temperature increase rate of 10°C/min in an air flow of 50 mL/min using a thermogravimetry device TGA/DSC 1 manufactured by Mettler-Toledo Co., Ltd.

(2) Average particle diameter of barium titanyl oxalate and barium titanate

Using a scanning electron microscope (SEM) photograph, 200 particles were arbitrarily measured, and the average value was taken as the average particle diameter.

(3) Specific surface area of barium titanate

obtained by the BET method.

(4) c/a value of barium titanate

The ratio c/a of the c-axis to the a-axis was measured using an X-ray diffractometer (D8 ADVANCE, manufactured by Bruker) using Cu-Kα rays as a light source.

(Example 1)

25.0 g of oxalic acid dihydrate was dissolved in 100 g of ethylene glycol to prepare 120 mL of a solution (liquid A) containing an oxalic acid component having an oxalic acid content of 2.21 mol/L. Apart from this, 64.4 g of titanium tetrachloride and 32.0 g of barium chloride are dissolved in 210 g of pure water, and a solution (liquid B) containing a titanium component and a barium component in which titanium tetrachloride is 0.59 mol/L and barium chloride is 0.63 mol/L. 270 mL was prepared.

Subsequently, Liquid A was supplied to a static mixer (MC08-32 manufactured by Tomita Engineering Co., Ltd.) at a rate of 4.3 L/hour and Liquid B was supplied at a rate of 9.6 L/hour, and the reaction liquid was discharged from the static mixer. At this time, the residence time of the reaction liquid in the static mixer was 2 seconds. The ratio of the supply rate of oxalate ion to the supply rate of element Ba and Ti element to the static mixer was 1.91 in terms of molar ratio.

The reaction liquid discharged from the static mixer was separated into solid and liquid to obtain a precipitate. After washing, this precipitate was dried to obtain barium titanyl oxalate. Table 1 shows the physical property values of the obtained barium titanyl oxalate. In addition, the result of measuring the weight loss rate of the obtained barium titanyl oxalate in thermal analysis is shown in FIG. As a result, the weight loss rate at 680°C was 45.42%, and the weight loss rate at 1000°C of 45.74% was 99.30%.

The obtained barium titanyl oxalate was calcined at 700°C for 2 hours to obtain barium titanate. The physical property values of the obtained barium titanate were shown in Table 1.

(Examples 2 to 4)

The barium titanyl oxalate obtained in Example 1 was calcined at the temperature shown in Table 1 to obtain barium titanate. Table 1 shows the physical property values of the obtained barium titanate.

(Example 5)

25.0 g of oxalic acid dihydrate was dissolved in 100 g of ethylene glycol to prepare 120 mL of a solution (liquid A) containing an oxalic acid component having an oxalic acid content of 2.21 mol/L. Apart from this, 64.4 g of titanium tetrachloride and 32.0 g of barium chloride are dissolved in 210 g of pure water, and a solution (liquid B) containing a titanium component and a barium component in which titanium tetrachloride is 0.59 mol/L and barium chloride is 0.63 mol/L. 270 mL was prepared.

Subsequently, Liquid A was supplied to a microreactor (flow path diameter: 1.0 mm, flow path length: 1000 mm) at a rate of 72 mL/min and Liquid B at a rate of 160 mL/min, and the reaction liquid was discharged from the microreactor. At this time, the residence time of the reaction liquid in the microreactor was 2.6 seconds. The ratio of the supply rate of oxalate ions to the supply rates of the Ba element and the Ti element to the microreactor was 1.91 in terms of molar ratio.

The reaction liquid discharged from the microreactor was separated into solid and liquid to obtain a precipitate. After washing, this precipitate was dried to obtain barium titanyl oxalate. Table 1 shows the physical property values of the obtained barium titanyl oxalate. In addition, the result of measuring the weight loss rate of the obtained barium titanyl oxalate in thermal analysis is shown in FIG. As a result, the weight loss rate at 680°C was 48.53%, and the weight loss rate at 1000°C of 45.28% was 99.40%.

The obtained barium titanyl oxalate was calcined at 700°C for 2 hours to obtain barium titanate. The physical property values of the obtained barium titanate were shown in Table 1.

(Comparative Example 1)

35.0 g of barium chloride dihydrate and 35.0 g of oxalic acid dihydrate were dissolved in 120 g of pure water, and 120 mL of a solution (liquid a) containing a barium component and an oxalic acid component having a barium concentration of 1.10 mol/L and an oxalic acid concentration of 2.20 mol/L was obtained. prepared Apart from this, 54.0 g of titanium tetrachloride was dissolved in pure water to prepare 260 mL of a solution (liquid b) containing a titanium component having a titanium concentration of 0.40 mol/L.

Subsequently, liquid b was added for 90 seconds while stirring liquid a, and after that, after holding|maintaining for 1 hour, it carried out solid-liquid separation and obtained the precipitate. After washing, this precipitate was dried to obtain barium titanyl oxalate. Table 1 shows the physical property values of the obtained barium titanyl oxalate. In addition, the result of measuring the weight loss rate of the obtained barium titanyl oxalate in thermal analysis is shown in FIG. As a result, the weight loss rate at 680°C was 37.71%, and the weight loss rate at 1000°C of 44.81% was 84.15%.

The obtained barium titanyl oxalate was calcined at 700°C for 2 hours. However, it was found that barium titanate could not be obtained from the measurement result of the weight loss rate by thermogravimetric analysis.

(Comparative Examples 2 to 4)

The barium titanyl oxalate obtained in Comparative Example 1 was calcined at the temperature shown in Table 1 to obtain barium titanate. Table 1 shows the physical property values of the obtained barium titanate.

As shown in Table 1, from the comparison of the average particle size, BET specific surface area and c/a values when fired at the same temperature, compared to the barium titanate obtained in the comparative example, the barium titanate obtained in the example was fine and It can also be seen that it is highly crystalline. 1, barium titanyl oxalate obtained in Example 1 was obtained by thermogravimetric analysis at 700°C, whereas barium titanyl oxalate obtained in Comparative Example 1 was obtained even at 700°C. It can be seen that barium titanate cannot be obtained.

(Example 6)

25.0 g of oxalic acid dihydrate was dissolved in 100 g of ethylene glycol to prepare 120 mL of a solution (liquid A) containing an oxalic acid component having an oxalic acid content of 2.21 mol/L. Apart from this, 64.4 g of titanium tetrachloride and 32.0 g of barium chloride were dissolved in 210 g of pure water, and a solution (liquid B) containing a titanium component and a barium component in which titanium tetrachloride was 0.59 mol/L and barium chloride was 0.63 mol/L. 270 mL was prepared.

Next, Liquid A was supplied to a Taylor vortex stirrer (TVF-01, manufactured by Tipton) at a rate of 4.3 L/hour and Liquid B was supplied at a rate of 9.6 L/hour, and the reaction liquid was discharged from the Taylor vortex stirrer. At this time, the residence time of the reaction liquid in the Taylor vortex type agitator was 5 seconds. The ratio of the supply rate of oxalate ion to the supply rate of element Ba and Ti element to the Taylor vortex type stirring device was 1.91 in terms of molar ratio.

The reaction liquid discharged from the Taylor vortex type agitator was subjected to solid-liquid separation to obtain a precipitate. After washing, this precipitate was dried to obtain barium titanyl oxalate. The physical property values of the obtained barium titanyl oxalate are shown in Table 2. In addition, the result of measuring the weight loss rate of the barium titanyl oxalate obtained by thermal analysis is shown in FIG. 6 . As a result, the weight loss rate at 680°C was 48.53%, and the weight loss rate at 1000°C of 48.82% was 99.40%.

The obtained barium titanyl oxalate was calcined at 700°C for 2 hours to obtain barium titanate. The physical property values of the obtained barium titanate are shown in Table 2.

(Examples 7 to 9)

The barium titanyl oxalate obtained in Example 7 was calcined at the temperature shown in Table 2 to obtain barium titanate. Table 2 shows the physical property values of the obtained barium titanate.

(Comparative Example 5)

35.0 g of barium chloride dihydrate and 35.0 g of oxalic acid dihydrate were dissolved in 120 g of pure water, and 120 mL of a solution (liquid a) containing a barium component and an oxalic acid component having a barium concentration of 1.10 mol/L and an oxalic acid concentration of 2.20 mol/L was obtained. prepared Apart from this, 54.0 g of titanium tetrachloride was dissolved in pure water to prepare 260 mL of a solution (liquid b) containing a titanium component having a titanium concentration of 0.40 mol/L.

Subsequently, liquid b was added for 90 seconds while stirring liquid a, and after that, after holding|maintaining for 1 hour, it carried out solid-liquid separation and obtained the precipitate. After washing, this precipitate was dried to obtain barium titanyl oxalate. The physical property values of the obtained barium titanyl oxalate are shown in Table 2. In addition, the result of measuring the weight loss rate of the barium titanyl oxalate obtained by thermal analysis is shown in FIG. 6 . As a result, the weight loss rate at 680°C was 37.71%, and the weight loss rate at 1000°C of 44.81% was 84.15%.

The obtained barium titanyl oxalate was calcined at 700°C for 2 hours. However, it was found that barium titanate could not be obtained from the measurement result of the weight loss rate by thermogravimetric analysis.

(Comparative Examples 6 to 8)

The barium titanyl oxalate obtained in Comparative Example 5 was calcined at the temperature shown in Table 2 to obtain barium titanate. Table 2 shows the physical property values of the obtained barium titanate.

As shown in Table 2, from the comparison of the average particle size, BET specific surface area, and c/a values when fired at the same temperature, compared to the barium titanate obtained in the comparative example, the barium titanate obtained in the example was fine and It can also be seen that it is highly crystalline. As shown in Fig. 6, barium titanyl oxalate obtained in Example 6 was obtained by thermogravimetric analysis at 700°C, whereas barium titanyl oxalate obtained in Comparative Example 5 was obtained even at 700°C. It can be seen that barium titanate cannot be obtained.

Claims (13)

A method for producing barium titanyl oxalate in which a solution containing oxalic acid (liquid A) and a solution containing a titanium source and a barium source (liquid B) are mixed and reacted to produce barium titanyl oxalate,
The liquid A and the liquid B are separately supplied to one end side of the reaction liquid passage, the liquid A and the liquid B are mixed in the reaction passage, and the reaction liquid is discharged from the other end side of the reaction liquid passage. discharging, and then performing solid-liquid separation of the reaction liquid;
The retention time of the reaction liquid in the reaction liquid passage is 30 seconds or less
Method for producing barium titanyl oxalate, characterized in that. The method for producing barium titanyl oxalate according to claim 1, wherein the reaction liquid passage is formed in the static mixer by separately supplying the liquid A and the liquid B to one end side of the static mixer. . The reaction liquid passage according to claim 1, wherein the reaction liquid passage is formed in the microreactor by separately supplying the liquid A and the liquid B to one end side of the reaction liquid passage of the continuous flow type microreactor. Method for producing barium titanyl oxalate. A method for producing barium titanyl oxalate in which a solution containing oxalic acid (liquid A) and a solution containing a titanium source and a barium source (liquid B) are mixed and reacted to produce barium titanyl oxalate,
Liquid A and Liquid B are separately supplied to one end side of the reaction liquid flow path, and Liquid A and Liquid B are mixed at one end side of the reaction liquid flow path to generate a vortex in the reaction liquid. Moving the reaction liquid to the other end side of the reaction liquid flow passage, discharging the reaction liquid from the other end side of the reaction liquid flow passage, and then performing solid-liquid separation of the reaction liquid.
Method for producing barium titanyl oxalate, characterized in that. The method for producing barium titanyl oxalate according to claim 4, wherein the residence time of the reaction liquid in the reaction liquid passage is within 60 seconds. The method for producing barium titanyl oxalate according to claim 4, wherein the vortex is a Taylor vortex. The method for producing barium titanyl oxalate according to claim 1 or 4, wherein the solvent of the liquid A is an organic solvent. The solvent of the liquid A according to claim 1 or 4, wherein the solvent of the liquid A is methanol, ethanol, propanol, butanol, diethyl ether, 1,3-butylene glycol, ethylene glycol, propylene glycol, dipropylene glycol, glycerol, N , A method for producing barium titanyl oxalate, characterized in that it is one or two or more selected from the group consisting of N-dimethylformamide and acetone. The method for producing barium titanyl oxalate according to claim 1 or 4, wherein the solvent of the liquid B is water. The method for producing barium titanyl oxalate according to claim 1 or 4, wherein the titanium compound in the liquid B is titanium tetrachloride, and the barium compound is barium chloride. The method for producing barium titanyl oxalate according to claim 1 or 4, wherein the mixing temperature of the liquid A and the liquid B is 75°C or lower. The method for producing barium titanyl oxalate according to claim 1 or 4, wherein the barium titanyl oxalate produced has an average particle diameter of 1.0 µm or less. A method for producing barium titanate, characterized by calcining barium titanyl oxalate obtained by the method according to any one of claims 1 to 6.