KR20120025431A - Barium titanyl oxalate particle, method for preparing the same and method for preparing barium titanate - Google Patents

Abstract

PURPOSE: A barium titanium oxalate particle, a manufacturing method thereof, a manufacturing method of barium titanate are provided to increase yielding rate by proceeding consecutive reactions within specific temperature range. CONSTITUTION: A manufacturing method of A barium titanium oxalate particle comprises the following steps: supplying aqueous solution which can be obtained by mixing oxalic acid and (TiSl4) titanium tetrachloride with water and barium chloride aqueous solution to a reactor(1); discharging the reacting solution(3) from the reactor; and proceeding manufacturing reaction of barium titanium oxalate at 50deg.C. The barium titanium oxalate stays in the reactor for 1-60 minutes. The barium titanium oxalate particle has average particle diameter of 0.1-50micro meters.

Description

BARUM TITANYL OXALATE PARTICLE, METHOD FOR PREPARING THE SAME AND METHOD FOR PREPARING BARIUM TITANATE}

The present invention relates in particular to barium titanyl oxalate particles useful as a raw material for functional ceramics such as piezoelectric materials, optoelectronic materials, dielectrics, semiconductors, sensors, and the like, and methods for producing barium titanate using the same.

Conventionally, barium titanate has been produced by a solid phase method, hydrothermal synthesis method, alkoxide method, oxalate method and the like.

In the solid phase method, since the raw material powder is produced by a dry method of mixing the raw material powder and the like and heating the mixture at a high temperature, the obtained powder forms an aggregate having an irregular shape, and high temperature firing is required to achieve desired characteristics. In addition, the hydrothermal synthesis method is not industrially advantageous because the synthesis process is complicated, the productivity is low because the use of the autoclave, and the production powder is expensive despite the advantages of good powder properties. In addition, the alkoxide method is also difficult to handle starting materials and is expensive and is not industrially advantageous.

The barium titanate obtained by the oxalate method can be produced at a lower cost than a hydrothermal synthesis method or an alkoxide method and has a uniform composition compared to barium titanate produced by the solid phase method. As a conventional oxalate method, an aqueous solution of TiCl ₄ and BaCl ₂ is added dropwise to an aqueous solution of H ₂ C ₂ O ₄ under stirring to obtain barium titanyl oxalate, and the method of calcining the barium titanyl oxalate is common (for example, , Non-Patent Document 1 and Patent Document 1).

Japanese Patent Laid-Open No. 2005-500239

 In W. S. Clabaugh et al., J. Res. Nat. Bur. Stand., 56 (5), 289-291 (1956)

Barium titanate obtained by the oxalate method exhibits excellent performance as a material for dielectric ceramics, but further performance improvement is required due to the recent increase in required performance. It is known that barium titanate as a dielectric ceramic generally has high crystallinity and good dielectric properties (for example, see Japanese Patent Laid-Open No. 2006-117446). In addition, the oxalate method has a problem that a small particle size is difficult to be obtained, and a high crystallinity is hard to be obtained even if it is obtained.

Conventionally, the barium titanyl oxalate particles obtained by the oxalate method are known in most cases to have an average particle diameter of 100 to 200 m and a particle shape of star candy.

The inventors of the present invention have found that when the reaction is performed by the continuous method instead of the conventional batch method in the oxalate method, the particle shape is spherical while the average particle size is smaller than that of the conventional method. In addition, it has been found that by using the spherical barium oxalate particles, barium titanate having excellent crystallinity and excellent performance can be produced. Further, the present inventors have found that the desired spherical barium titanyl oxalate can be obtained in a good yield by carrying out a continuous reaction in a specific temperature range, thereby completing the present invention.

It is therefore an object of the present invention to provide a barium titanyl oxalate particle having a fine and spherical particle shape, and also to provide a method for industrially advantageously producing the fine and spherical barium titanyl particles. An object of the present invention is to provide barium titanate excellent in crystallinity.

The first invention to be provided by the present invention is barium titanyl oxalate particles having an average particle diameter of 0.1 to 50 µm and a spherical particle shape.

Moreover, the 2nd invention which this invention intends to provide provides the reaction liquid from the said reaction container, supplying the aqueous solution (A1 liquid) and barium chloride aqueous solution (B1 liquid) obtained by mixing oxalic acid and titanium tetrachloride in water. It is providing the manufacturing method of the barium titanyl particle | grains which carry out the production | generation reaction of barium titanyl oxalate below 50 degreeC, discharging.

Moreover, the 3rd invention which this invention intends to provide provides the said reaction container, supplying the reaction liquid, supplying the aqueous solution (B2 liquid) obtained by mixing oxalic acid aqueous solution (A2 liquid), titanium tetrachloride, and barium chloride to water. It is providing the manufacturing method of the barium titanyl particle | grains which carry out the production | generation reaction of barium titanyl oxalate at less than 50 degreeC, discharge | emitting from this.

Moreover, the 4th invention which this invention intends to provide provides, supplying the aqueous solution (C3 liquid) obtained by mixing oxalic acid aqueous solution (A3 liquid), barium chloride aqueous solution (B3 liquid), and titanium tetrachloride in water, It is an object of the present invention to provide a method for producing barium titanyl particles, wherein the reaction of barium titanyl is carried out at less than 50 ° C. while discharging the reaction solution from the reaction vessel.

In a fifth aspect of the present invention, there is provided a method for producing the barium titanyl particles of any one of the second to fourth inventions, wherein the barium titanate particles obtained are calcined. It is to provide a manufacturing method.

The barium titanyl oxalate particles of the present invention are fine and spherical in spherical shape, and according to the production method of the present invention, the barium oxalate titanyl can be produced in high yield by an industrially advantageous method. In addition, by using such spherical barium titanate particles, a dielectric ceramic material having high crystallinity and excellent performance can be provided.

1 is a schematic cross-sectional view of a reaction vessel of an overflow system.
2 is an electron micrograph (magnification; 500 times) showing the particle shape of barium titanyl oxalate particles obtained in Example 1. FIG.
3 is a SEM photograph (magnification; 500 times) showing the particle shape of barium titanyl oxalate particles obtained in Example 1. FIG.
4 is a SEM photograph (magnification; 2000 times) showing the particle shape of barium titanyl oxalate particles obtained in Example 1. FIG.
5 is an electron micrograph (magnification; 100 times) showing the particle shape of barium titanyl oxalate particles obtained in Comparative Example 1. FIG.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated based on the preferable embodiment.

The barium titanyl particles of the present invention are finer than conventional barium titanyl particles and are also characterized by their particle shape.

The barium titanyl particles of the present invention have a barium titanyl particle of the present invention, whereas the average barium titanyl particles obtained by a conventional batch type have a particle diameter of 100 μm or more, preferably 100 to 150 μm, which is determined by laser diffraction and scattering in most cases. The average particle diameter obtained by the laser diffraction scattering method is 0.1-50 micrometers, Preferably it is 5-40 micrometers, More preferably, it is 10-30 micrometers, and is very fine compared with the conventional thing.

Moreover, the barium titanyl particle which concerns on this invention is also one of the characteristics whose particle shape is spherical.

When the said particle shape is observed under the electron microscope at the magnification of 500 times, as long as the particle shape is a shape considered to be spherical, it does not necessarily need to be a true spherical shape.

Moreover, the barium titanyl particle which concerns on this invention is one of the characteristics that the particle | grain surface is smooth and substantially an angle | corner when it observes with a scanning electron microscope at the magnification of 2000 times.

In the method for producing barium titanyl particles of the present invention, an aqueous solution of oxalic acid (H ₂ C ₂ O ₄ ), barium chloride (BaCl ₂ ) and titanium tetrachloride (TiCl ₄ ), which are reaction raw materials for the production reaction of barium titanyl oxalate, is prepared. It is a manufacturing method of the barium oxalate titanyl particle | grains which produce | generates the reaction of barium titanyl oxalate below 50 degreeC, discharging a reaction liquid from a reaction container, supplying to a reaction container. And the manufacturing method of the barium titanyl particle of this invention has the following forms according to the kind of reaction raw material aqueous solution.

In addition, in this invention, a reaction liquid is a liquid in the reaction container to which the reaction raw material aqueous solution was supplied, the liquid which produces | generates the reaction which produces | generates barium titanyl, and is a liquid containing the produced | generated deposit of barium titanate oxalate.

In the method for producing barium titanate particles of the first embodiment of the present invention, the reaction solution is supplied while supplying an aqueous solution (A1 solution) and an aqueous barium chloride solution (B1 solution) obtained by mixing oxalic acid and titanium tetrachloride in water. It is the manufacturing method of the barium oxalate titanyl particle which performs the production | generation reaction of barium oxalate titanyl at less than 50 degreeC, discharging from a reaction container.

The manufacturing method of the barium titanate particle | grains of the 2nd aspect of this invention is supplying the reaction liquid, supplying the aqueous solution (B2 liquid) obtained by mixing oxalic acid aqueous solution (A2 liquid), titanium tetrachloride, and barium chloride to water to a reaction container. It is a manufacturing method of the barium oxalate titanyl particle which performs the production | generation reaction of barium oxalate titanyl at less than 50 degreeC, discharging from a reaction container.

In the method for producing barium oxalate titanyl particles according to the third aspect of the present invention, an aqueous solution (C3 solution) obtained by mixing an aqueous oxalic acid solution (A3 solution), an aqueous barium chloride solution (B3 solution), and titanium tetrachloride in water is a reaction vessel. It is a manufacturing method of the barium titanyl oxalate particle | grains which perform the reaction which produces | generates barium titanyl nil at less than 50 degreeC, discharging a reaction liquid from a reaction container, supplying to.

That is, the manufacturing method of the barium titanyl particle of the 1st form of this invention uses the aqueous solution (A1 liquid) and barium chloride aqueous solution (B1 liquid) obtained by mixing oxalic acid and titanium tetrachloride in water as reaction raw material aqueous solution. to be.

A1 liquid according to the method for producing barium titanyl particles of the first aspect of the present invention is an aqueous solution obtained by mixing oxalic acid and titanium tetrachloride in water, for example, firstly, titanium tetrachloride is mixed with water, and then oxalic acid in the aqueous solution obtained. Or by mixing titanium tetrachloride with an oxalic acid aqueous solution. The molar ratio of the oxalate ion to the Ti element in the A1 liquid (moles of oxalate ions / molar number of Ti elements) is 2.0 to 3.8, preferably 2.8 to 3.8, more preferably 3.0 to 3.3. When the molar ratio of the oxalate ion to the Ti element in the A1 liquid is in the above range, it is easy to obtain approximately 1 barium titanate having a Ba / Ti molar ratio of 0.998 to 1.002. The concentration of the Ti element in the A1 liquid is not particularly limited, but is preferably 0.04 to 3.0 mol / L, particularly preferably 0.2 to 0.6 mol / L. The concentration of oxalate ions in the A1 liquid is not particularly limited, but is preferably 0.1 to 7.0 mol / L, particularly preferably 0.6 to 1.4 mol / L.

The B1 liquid according to the method for producing barium titanyl particles of the first embodiment of the present invention is an aqueous solution of barium chloride. The concentration of Ba element in the B1 liquid is not particularly limited, but is preferably 0.1 to 6.5 mol / L, particularly preferably 0.5 to 1.3 mol / L.

In the method for producing barium oxalate titanyl particles of the first aspect of the present invention, the reaction of producing barium titanyl oxalate is performed at less than 50 ° C in the reaction vessel by supplying the A1 liquid and the B1 liquid to the reaction vessel.

At this time, the ratio of the supply rate of the Ba element to the supply rate of the Ti element to the reaction vessel (the supply rate of the Ba element / the supply rate of the Ti element) is 0.5 to 3.0, preferably 1.0 to 1.5. When the ratio of the feed rate of Ba element to the feed rate of Ti element to the reaction vessel is in the above range, approximately 1 barium titanate particles having a Ba / Ti molar ratio of 0.998 to 1.002 can be obtained.

In the method for producing barium titanyl particles of the first aspect of the present invention, the concentration of Ti element in A1 liquid, the concentration of Ba element in B1 liquid, the feeding rate of A1 liquid (L / hour) and the feeding rate of B1 liquid (L Per hour), the ratio of the feed rate of the Ba element to the feed rate of the Ti element to the reaction vessel can be adjusted.

In addition, in this invention, the supply rate of Ti element to a reaction container means the number-of-moles of supply of Ti element per unit time (mol / hour), and the supply rate of Ba element means the number-of-moles of supply of Ba element per unit time ( Mole / hour), and the supply rate of oxalate ions indicates the number of moles (mol / hour) of oxalate ions per unit time.

And in the manufacturing method of the barium oxalate titanyl particle of the 1st aspect of this invention, while supplying A1 liquid and B1 liquid to a reaction container, the reaction liquid containing the deposit of the barium titanate oxalate produced in the reaction container is carried out. Eject from. At this time, it is preferable that the total amount of the A1 liquid and the B1 liquid supplied to the reaction vessel and the amount of the reaction liquid discharged from the reaction vessel are the same in that stable reaction can be performed. For example, while supplying A1 liquid to the reaction vessel at a1 (L / hour) and B1 liquid at a feed rate of b1 (L / hour), simultaneously discharging the reaction liquid from the reaction vessel at a1 + b1 (L / hour). It is desirable to discharge at a speed.

Moreover, the manufacturing method of the barium oxalate titanyl particle of the 2nd aspect of this invention uses the aqueous solution obtained by mixing oxalic acid aqueous solution (A2 liquid), titanium tetrachloride, and barium chloride as water as a reaction raw material aqueous solution (B2 liquid). Form.

A2 liquid according to the manufacturing method of the barium oxalate titanyl particle of the 2nd aspect of this invention is an oxalic acid aqueous solution. The concentration of the oxalate ions in the A2 liquid is not particularly limited, but is preferably 0.1 to 7.0 mol / L, particularly preferably 0.6 to 1.4 mol / L.

The B2 liquid according to the method for producing the barium titanyl particles of the second aspect of the present invention is an aqueous solution obtained by mixing titanium tetrachloride and barium chloride with water. For example, first, titanium tetrachloride is mixed with water, and then to the obtained aqueous solution. It is produced by mixing barium chloride or by mixing titanium tetrachloride in an aqueous solution of barium chloride. The molar ratio of the Ba element (the number of moles of the Ba element / the number of moles of the Ti element) to the Ti element in the B 2 solution is 0.5 to 3.0, preferably 1.0 to 1.5. When the molar ratio of the Ba element to the Ti element in the B2 solution is in the above range, approximately 1 barium titanate having a Ba / Ti molar ratio of 0.998 to 1.002 can be obtained. The concentration of the Ti element in the B 2 liquid is not particularly limited, but is preferably 0.04 to 4.0 mol / L, particularly preferably 0.2 to 0.8 mol / L. The concentration of Ba element in the B 2 liquid is not particularly limited, but is preferably 0.08 to 6.5 mol / L, particularly preferably 0.4 to 1.3 mol / L.

In the method for producing barium oxalate titanyl particles according to the second aspect of the present invention, the reaction of producing barium titanyl oxalate is performed at less than 50 ° C in the reaction vessel by supplying the A2 liquid and the B2 liquid to the reaction vessel.

At this time, the ratio of the supply rate of the oxalate ion to the supply rate of the Ti element to the reaction vessel (the supply rate of the oxalate ion / the feed rate of the Ti element) is 2.0 to 3.8, preferably 2.8 to 3.8, particularly preferably 3.0 to 3.3. When the ratio of the supply rate of the oxalate ion to the supply rate of the Ti element to the reaction vessel is in the above range, approximately 1 barium titanate having a Ba / Ti molar ratio of 0.998 to 1.002 can be obtained.

In the method for producing barium oxalate titanyl particles of the second aspect of the present invention, the concentration of oxalate ions in the A2 liquid, the concentration of the Ti element in the B2 liquid, the feed rate of the A2 liquid (L / hour), and the feed rate of the B2 liquid ( L / time) can be appropriately selected to adjust the ratio of the supply rate of oxalate ions to the supply rate of the Ti element to the reaction vessel.

And in the manufacturing method of the barium oxalate titanyl particle of the 2nd aspect of this invention, reacting the reaction liquid containing the precipitate of barium titanyl oxalate produced in the reaction container, supplying A2 liquid and B2 liquid to a reaction container. Drain from the container. Under the present circumstances, it is preferable at the point that the total amount of A2 liquid and B2 liquid supplied to a reaction container, and the quantity of the reaction liquid discharged | emitted from a reaction container can perform the stable reaction. For example, while supplying A2 liquid to the reaction vessel at a2 (L / hour) and B2 liquid at a feed rate of b2 (L / hour), simultaneously discharging the reaction liquid from the reaction vessel to a2 + b2 (L / hour). It is desirable to discharge at a speed.

Moreover, the manufacturing method of the barium oxalate titanyl particle of the 3rd form of this invention is an aqueous solution obtained by mixing oxalic acid aqueous solution (A3 liquid), barium chloride aqueous solution (B3 liquid), and titanium tetrachloride as water as a reaction raw material aqueous solution. (C3 liquid).

A3 liquid according to the manufacturing method of the barium oxalate titanyl particle of the 3rd aspect of this invention is an oxalic acid aqueous solution. The concentration of oxalic acid ions in the A3 liquid is not particularly limited, but is preferably 0.1 to 7.0 mol / L, particularly preferably 0.6 to 1.4 mol / L.

B3 liquid according to the method for producing barium titanyl particles of the third embodiment of the present invention is an aqueous solution of barium chloride. The concentration of Ba element in the B 3 solution is not particularly limited, but is preferably 0.1 to 6.5 mol / L, particularly preferably 0.5 to 1.3 mol / L.

C3 liquid which concerns on the manufacturing method of the barium titanyl particle of the 3rd aspect of this invention is an aqueous solution obtained by mixing titanium tetrachloride in water. The concentration of the Ti element in the C 3 solution is not particularly limited, but is preferably 0.04 to 6.0 mol / L, particularly preferably 0.2 to 3.0 mol / L.

In the method for producing barium oxalate titanyl particles of the third aspect of the present invention, the reaction reaction of barium titanyl oxalate is performed at less than 50 ° C in a reaction vessel by supplying A3 liquid, B3 liquid and C3 liquid to the reaction vessel.

At this time, the ratio of the supply rate of the Ba element to the supply rate of the Ti element to the reaction vessel (the supply rate of the Ba element / the supply rate of the Ti element) is 0.5 to 3.0, preferably 1.0 to 1.5. When the ratio of the feed rate of Ba element to the feed rate of Ti element to the reaction vessel is in the above range, approximately 1 barium titanate having a Ba / Ti molar ratio of 0.998 to 1.002 can be obtained. The ratio of the supply rate of the oxalate ions to the supply rate of the Ti element to the reaction vessel (the supply rate of the oxalate ion / the feed rate of the Ti element) is 2.0 to 3.8, preferably 2.8 to 3.8. When the ratio of the supply rate of the oxalate ion to the supply rate of the Ti element to the reaction vessel is in the above range, approximately 1 barium titanate having a Ba / Ti molar ratio of 0.998 to 1.002 can be obtained.

In the manufacturing method of the barium oxalate titanyl particle of the 3rd aspect of this invention, the concentration of the oxalate ion in A3 liquid, the concentration of Ba element in B3 liquid, the concentration of Ti element in C3 liquid, and the feed rate of A3 liquid (L / hour ), The feed rate (L / hour) of the B3 liquid and the feed rate (L / hour) of the C3 liquid are appropriately selected so that the ratio of the feed rate of the Ba element to the feed rate of the Ti element to the reaction vessel and the reaction vessel The ratio of the supply rate of the oxalate ion to the supply rate of the Ti element of can be adjusted.

And in the manufacturing method of the barium oxalate titanyl particle of the 3rd aspect of this invention, while supplying A3 liquid, B3 liquid, and C3 liquid to a reaction container, a reaction liquid is discharged | emitted from a reaction container. At this time, it is preferable to make the total amount of A3 liquid, B3 liquid, and C3 liquid supplied to a reaction container, and the quantity of the reaction liquid discharged | emitted from a reaction container into the same amount. For example, while supplying the A3 liquid to the reaction vessel at a3 (L / hour), the B3 liquid to b3 (L / hour), and the C3 liquid at a feed rate of c3 (L / hour), the reaction liquid was simultaneously supplied from the reaction vessel. It is preferable to discharge at a discharge rate of a3 + b3 + c3 (L / hour).

The manufacturing method of the barium titanyl particle of this invention can be performed using the reaction vessel of the overflow system shown in FIG. 1, for example. 1 is a schematic cross-sectional view of a reaction vessel of an overflow system. In FIG. 1, the overflow reaction vessel 1 has an overflow tube 2 attached to the upper side wall of the reaction vessel. In the reaction vessel 1 of the overflow system, since the overflow tube 2 serves as an outlet of the reaction liquid, the height of the liquid level 4 of the reaction liquid 3 is always at the attachment position of the overflow tube 2. It becomes height, the reaction liquid 3 overflows from the overflow pipe 2 only by the supply of the reaction raw material aqueous solution, and is discharged | emitted from the reaction container 1 of the overflow system. That is, in the reaction vessel 1 of the overflow system, the supply amount of the reaction raw material aqueous solution to the reaction vessel and the discharge amount of the reaction liquid from the reaction vessel can always be the same amount. Therefore, by using the overflow reaction vessel, the reaction liquid can be discharged from the reaction vessel while supplying the reaction raw material aqueous solution to the reaction vessel. In addition, although the reaction vessel 1 of the overflow system actually has other things, for example, a stirring apparatus, a heating apparatus, the supply pipe of reaction raw materials, etc. in FIG. The description is omitted.

The reaction vessel for carrying out the method for producing barium titanyl particles of the present invention is not limited to the reaction vessel of the overflow system. In addition, for example, a stirring device is provided inside, and the supply amount of the reaction raw material aqueous solution is adjusted. A sealed reaction vessel or agitation device, which is equipped with a supply pipe to which a pump can be installed, and a discharge pipe to which a valve for controlling the amount of reaction liquid is installed, is installed inside, and the supply amount of the reaction raw material aqueous solution can be adjusted. And a closed reaction vessel having a discharge pipe for discharging at a constant speed from the supply pipe and the reaction liquid in which a pump or the like is installed, and the pump.

In the method for producing barium titanyl particles of the present invention, the temperature of the reaction liquid, that is, the reaction temperature can be carried out in the range of 20 to 90 ° C, but when the reaction temperature is 50 ° C or higher, the desired barium titanyl oxalate Since a yield tends to fall, in this manufacturing method, reaction temperature is less than 50 degreeC, Preferably it is 25-40 degreeC. In the method for producing barium oxalate titanyl particles of the present invention, the desired barium oxalate titanyl particles can be obtained with good yield by setting the reaction temperature in the above range.

In the present production method, the size of the barium oxalate titanyl particles obtained is related to the residence time of the produced barium oxalate titanyl. That is, as the residence time becomes shorter, there is a tendency for a finer one to be easily obtained.

Therefore, in this manufacturing method, by adjusting the residence time of the produced | generated barium titanyl oxalate, it can produce by adjusting suitably an average particle diameter of 0.1-50 micrometers. For example, in order to obtain barium titanyl oxalate particles having an average particle diameter of 0.1 to 50 µm, preferably 5 to 40 µm, the residence time of the produced barium titanyl oxalate is 1 to 60 minutes, preferably 1 to 30 minutes. It is good to have a minute. In addition, in order to obtain the thing of 10-30 micrometers which is the range of the especially preferable average particle diameter in this invention, what is necessary is just to adjust the residence time of the produced barium titanyl oxalate to be 1 to 15 minutes.

In addition, when the residence time is less than 1 minute, it is difficult to control the molar ratio of Ba / Ti of the barium titanyl oxalate obtained, so that approximately 1 of which the molar ratio of Ba / Ti is 0.998 to 1.002 tends to be difficult to be obtained. When the time exceeds 60 minutes, the barium oxalate titanyl particles larger than the particle diameter in the above range tend to be produced, which is not preferable.

In the present invention, the residence time of the produced barium titanyl oxalate is a value obtained by dividing the volume (L) of the reaction liquid in the reaction vessel by the discharge rate (L / hour) of the reaction liquid from the reaction vessel (volume of reaction liquid / Discharge rate of the reaction solution).

In the method for producing barium titanyl oxalate particles of the present invention, the reaction solution discharged from the reaction vessel is subjected to solid-liquid separation to obtain a precipitate, followed by washing and drying as necessary to obtain barium titanyl oxalate. Moreover, the obtained barium titanal oxalate can be grind | pulverized as needed.

Thus, the barium titanyl particle obtained by performing the manufacturing method of the barium oxalate titanyl particle of this invention is spherical in spherical shape, and the average particle diameter calculated | required by a laser diffraction scattering method is 0.1-50 micrometers, Preferably it is Is 5 to 40 µm, more preferably 10 to 30 µm.

Further, by firing the spherical barium oxalate particles, a barium titanate having high crystallinity is obtained in spite of a small particle size. Thus, a dielectric ceramic material having excellent performance is obtained.

The manufacturing method of the barium titanate of this invention is a manufacturing method of the barium titanate which obtains barium titanate by baking the barium oxalate titanyl particle obtained by performing the manufacturing method of the barium titanyl particle of this invention. In addition, the method of producing the barium titanyl particles of the present invention to obtain the barium titanyl particles is as described above.

That is, in the method for producing barium titanate of the present invention, the reaction solution is discharged from the reaction vessel while supplying an aqueous solution (A1 solution) and an aqueous barium chloride solution (B1 solution) obtained by mixing oxalic acid and titanium tetrachloride in water. It is a manufacturing method of the barium titanate which obtains barium titanate by baking the barium oxalate titanyl particle obtained by performing reaction which produces | generates barium titanyl nil at less than 50 degreeC.

Moreover, the manufacturing method of the barium titanate of this invention supplies the reaction liquid from the said reaction container, supplying the aqueous solution (B2 liquid) obtained by mixing oxalic acid aqueous solution (A2 liquid), titanium tetrachloride, and barium chloride to water. It is a manufacturing method of the barium titanate which obtains barium titanate by baking the barium oxalate titanyl particle obtained by performing reaction which produces | generates barium titanyl nil at less than 50 degreeC, discharging.

Moreover, the manufacturing method of the barium titanate of this invention reacts, supplying the aqueous solution (C3 liquid) obtained by mixing oxalic acid aqueous solution (A3 liquid), barium chloride aqueous solution (B3 liquid), and titanium tetrachloride in water, to a reaction container. It is a manufacturing method of the barium titanate which obtains barium titanate by baking the barium oxalate titanyl particle obtained by performing reaction which produces | generates barium titanyl reaction below 50 degreeC, discharging a liquid from the said reaction container.

The organic material derived from oxalic acid contained in the final product is not preferable because it impairs the dielectric properties of the material and at the same time becomes an instability factor in the thermal process for ceramicization. Therefore, in the present invention, it is necessary to thermally decompose the barium titanyl particles by firing to obtain the desired barium titanate and to sufficiently remove the organic substance derived from oxalic acid.

In the manufacturing method of the barium titanate of this invention, the baking temperature at the time of baking barium titanyl particle | grains is 600-1300 degreeC, Preferably it is 700-1200 degreeC. When the baking temperature at the time of baking barium titanyl oxalate exists in the said range, a fluctuation of a particle size is small and it becomes a single phase barium titanate in X-ray diffraction analysis which has high crystallinity. On the other hand, when baking temperature is less than the said range, a single phase barium titanate is hard to be obtained in X-ray-diffraction analysis, and when it exceeds the said range, the particle size of the obtained barium titanate will become large, and it is unpreferable.

In addition, the firing time is preferably 2 to 30 hours, particularly preferably 5 to 27 hours. In addition, the firing atmosphere is not particularly limited, and may be any of atmospheric air under an inert gas atmosphere, a vacuum atmosphere, an oxidizing gas atmosphere, or firing in the above atmosphere while introducing water vapor.

Moreover, in the manufacturing method of the barium titanate of this invention, baking of barium titanyl oxalate particle | grains can be performed by the multistep baking which changed the baking temperature. In addition, for the purpose of making the powder characteristics uniform, the one fired may be ground, followed by refiring or regrinding.

Barium titanate obtained by performing the method for producing barium titanate of the present invention can be ground or classified as necessary.

In this manner, the physical properties of the barium titanate obtained by performing the method for producing barium titanate of the present invention are approximately 1 in which the molar ratio of Ba / Ti is 0.998 to 1.002, and the crystallinity is high even when the particle size is small as described above.

Therefore, barium titanate obtained by performing the method for producing barium titanate of the present invention has excellent performance as a dielectric ceramic.

In addition, to the barium titanate obtained by performing the method for producing barium titanate of the present invention, a subcomponent element-containing compound is added to the barium titanate obtained by performing the method for producing barium titanate of the present invention, for the purpose of adjusting dielectric properties and temperature characteristics as necessary. It can contain a subcomponent element. As the subcomponent element-containing compound which can be used, for example, rare earth elements of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, 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; The compound to contain is mentioned.

The subcomponent element-containing compound may be either inorganic or organic. For example, oxides, hydroxides, chlorides, nitrates, oxalates, carboxylates and alkoxides containing the above elements may be mentioned. When the subcomponent element-containing compound is a compound containing Si element, silica sol, sodium silicate and the like can be used in addition to the oxide and the like. A subcomponent element containing compound can be used 1 type or in combination or 2 or more types as appropriate. The addition amount and combination of an addition compound can be performed according to a conventional method.

In order to contain a subsidiary element in barium titanate, baking can be performed, for example after mixing a barium titanate and a subsidiary element containing compound uniformly. Alternatively, the barium titanyl particles and the subcomponent element-containing compound may be uniformly mixed before firing.

When manufacturing a multilayer ceramic capacitor, for example using the barium titanate obtained by carrying out the manufacturing method of the barium titanate of this invention, the powder of barium titanate is first made into the powder of a barium titanate, including a subsidiary element, an additive conventionally known, an organic binder, and a plasticizer. And mixing and dispersing together with a compounding agent such as a dispersing agent in a suitable solvent to form a slurry. Thereby, the ceramic sheet used for manufacture of a multilayer ceramic capacitor is obtained. In order to manufacture a multilayer ceramic capacitor from the ceramic sheet, first, a conductive paste for forming internal electrodes is printed on one surface of the ceramic sheet. After drying, several ceramic sheets are laminated and pressed in the thickness direction to form a laminate. Next, this laminated body is heat-processed, a debonder process is performed, and it bakes, and a fired body is obtained. Further, a laminated ceramic capacitor is obtained by applying and baking Ni paste, Ag paste, nickel alloy paste, copper paste, copper alloy paste, and the like to the fired body.

Moreover, when the powder of the barium titanate obtained by performing the manufacturing method of the barium titanate of this invention is mix | blended with resin, such as an epoxy resin, a polyester resin, a polyimide resin, for example, it is set as a resin sheet, a resin film, an adhesive agent, etc., Materials such as printed wiring boards and multilayer printed wiring boards, materials for suppressing shrinkage differences between internal electrodes and dielectric layers, electrode ceramic circuit boards, glass ceramic circuit boards, circuit peripheral materials and inorganic EL dielectric materials can be used.

In addition, the barium titanate obtained by performing the method for producing barium titanate of the present invention is preferably used as a catalyst used in the reaction of exhaust gas removal, chemical synthesis, or the like, and as a surface modifier of a printing toner that provides an antistatic and cleaning effect. Is used.

<Examples>

Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples.

(Example 1)

To 2154 g of water, 250 g of oxalic acid dihydrate was mixed with 332 g of an aqueous titanium tetrachloride solution having a concentration of 2.56 mol / L, and oxalic acid and titanium tetrachloride having 0.79 mol / L and Ti of 0.26 mol / L. The aqueous solution (A1 liquid) obtained by mixing with water was manufactured. That is, the molar ratio of oxalate ion to Ti element in A1 liquid is 3.1. Further, 195 g of barium chloride was dissolved in 963 g of water to prepare an aqueous barium chloride solution (B1 solution) having Ba of 0.80 mol / L. Subsequently, pure water was put into the reaction vessel, and the A1 liquid and the B1 liquid were fed to the reaction vessel at a rate of 0.9 L / hour and 0.4 L / hour while stirring at 35 ° C. That is, the ratio of the feed rate of the Ba element to the feed rate of the Ti element to the reaction vessel was 1.3, and the residence time of the produced barium titanyl oxalate was 14 minutes, and the reaction was performed.

Solid precipitated from the reaction liquid discharged | emitted from the reaction container, the deposit was obtained, and it washed and dried, and obtained barium titanyl oxalate particle | grains.

Moreover, as a result of calculating the reaction rate of Ba and Ti, Ba was 80% and Ti was 99%.

In addition, reaction rate shows Ba and Ti eluted at the time of completion | finish of reaction by ICP, and shows the eluent as unreacted powder, and the amount which subtracted the unreacted powder from input amount as reaction content is shown as a percentage of addition. The higher the reaction rate, the less the remaining Ba and Ti components due to unreaction, indicating higher reaction efficiency and yield.

In order to measure the Ba / Ti molar ratio of the obtained barium oxalate, the barium titanyl was calcined, followed by fluorescence X-ray analysis. The bulk Ba / Ti mole ratio was 1.001.

In addition, the barium oxalate titanyl after drying had an average particle diameter of 20 µm determined by a laser diffraction scattering method (Horiba Seisakusho; laser diffraction / scattering particle size distribution analyzer (LA-920)).

Moreover, the electron micrograph of the obtained barium titanyl particle is shown in FIG. 2, and the SEM photograph is shown in FIG. 3 and FIG.

Furthermore, the obtained barium oxalate titanyl particles were calcined at 900 ° C for 24 hours to obtain barium titanate. For the barium titanate obtained, the ratio of the c-axis to the a-axis length (c-axis / a-axis ratio), which is an index of crystallinity, was measured by XRD, and was 1.0093. The specific surface area of the barium titanate was 2.0 m ² / g. It was.

(Reference Example 1)

The reaction was carried out in the same manner and in the same manner as in Example 1, except that the production reaction of barium titanyl oxalate was 55 ° C, thereby obtaining barium titanyl particles. Further, as in Example 1, the reaction rates of Ba and Ti were determined, and as a result, Ba was 70% and Ti was 95%.

Therefore, compared with Example 1, it turns out that many components of Ba and Ti which remain unreacted remain and reaction efficiency and yield fell.

(Comparative Example 1)

A batch reaction vessel was prepared, and 325 g of oxalic acid dihydrate was dissolved in 1400 g of water at 55 ° C to prepare an aqueous oxalic acid solution (A11 solution) having an oxalic acid of 1.73 mol / L. 630 g of titanium tetrachloride solution having a concentration of 2.6 mol / L was mixed with an aqueous solution in which 325 g of barium chloride was added to 1830 g of water, and barium chloride and titanium tetrachloride having 0.55 mol / L of barium chloride and 0.52 mol / L of Ti were added. The aqueous solution (B11 liquid) obtained by mixing this with water was manufactured. That is, the molar ratio of Ba element to Ti element in B11 liquid is 1.1. Subsequently, B11 liquid was dripped at the speed | rate of 0.7 L / hour, and it supplied to the reaction container to A11 liquid made into 55 degreeC, stirring. That is, the ratio of the oxalate ion to the Ti element in the reaction vessel at the completion of dropping of B11 liquid is 2.1.

After aging for 0.5 hour, the reaction solution was solid-liquid separated to obtain a precipitate, which was washed and dried to obtain barium titanyl oxalate.

After calcining the obtained barium titanyl oxalate, fluorescence X-ray analysis was conducted and the bulk Ba / Ti molar ratio was 0.999.

In addition, the barium oxalate titanyl after drying had an average particle diameter of 145 µm determined by a laser diffraction scattering method (Horiba Seisakusho; laser diffraction / scattering particle size distribution analyzer (LA-920)).

In addition, the electron micrograph of the obtained barium titanate particle | grains is shown in FIG.

The obtained barium oxalate titanyl particles were calcined at 900 ° C for 24 hours to obtain barium titanate. The c-axis / a-axis ratio by XRD of obtained barium titanate was 1.0090, and the specific surface area by BET method was 1.5 m <^2> / g.

As is apparent from FIGS. 2 and 5, the barium titanyl particles of the present invention are substantially spherical in shape, whereas the barium titanyl particles obtained in Comparative Example 1 have a star-shaped particle shape. .

In addition, it can be seen from FIG. 4 that the barium titanyl oxalate particles of the present invention are particles having a smooth surface and substantially angleless particles.

1: overflow reaction vessel
2: overflow pipe
3: reaction liquid
4: face value

Claims (7)

Barium titanyl oxalate particles having an average particle diameter of 0.1 to 50 µm and a spherical particle shape. The reaction of producing barium titanyl oxalate was carried out while supplying an aqueous solution (A1 solution) obtained by mixing oxalic acid and titanium tetrachloride with water and a barium chloride aqueous solution (B1 solution) to the reaction vessel, while discharging the reaction solution from the reaction vessel. A method for producing barium titanyl oxalate particles, which is carried out at less than ° C. The reaction of producing the barium titanyl oxalate was carried out while supplying an aqueous solution of oxalic acid (A2 solution) and an aqueous solution (B2 solution) obtained by mixing titanium tetrachloride and barium chloride to water, while discharging the reaction solution from the reaction vessel. A method for producing barium titanyl oxalate particles, which is carried out at less than ° C. Barium tea oxalate while discharging the reaction solution from the reaction vessel while supplying an aqueous solution (C3 solution) obtained by mixing an aqueous oxalic acid solution (A3 solution), an aqueous barium chloride solution (B3 solution), and titanium tetrachloride to water. A method for producing barium titanyl particles, wherein the production reaction of tanyl is carried out at less than 50 ° C. The method for producing barium titanyl particles according to any one of claims 2 to 4, wherein the residence time of the resulting barium oxalate titanyl in the reaction vessel is 1 to 60 minutes. The barium titanate particle obtained by performing the manufacturing method of the barium titanyl particle of any one of Claims 2-5 is baked, The manufacturing method of the barium titanate characterized by the above-mentioned. The method for producing barium titanate according to claim 6, wherein the firing temperature is 600 to 1300 ° C.

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