JP4684657B2 - Method for producing barium titanyl oxalate powder and method for producing titanium-based perovskite ceramic raw material powder - Google Patents

Description

  The present invention particularly relates to a barium titanyl oxalate powder in which a part of barium element useful as a raw material for functional ceramics such as a piezoelectric material, an optoelectronic material, a dielectric material, a semiconductor, and a sensor is replaced with another alkaline earth metal element. The present invention relates to a production method and a production method of a titanium-based perovskite ceramic raw material powder using the production method.

  The dielectric layer of a multilayer ceramic chip capacitor (MLCC) generally takes the form of a multi-component system composed of main raw material barium titanate and a small amount of additives. For example, calcium is a component that is often used as an additive, but by replacing and dissolving in barium sites in barium titanate, the effect as a depressor that smoothes the temperature characteristics of the dielectric constant of the dielectric, or It is known that it is used as a component of glass serving as a sintering aid.

Recently, in B-characteristic capacitors, there has been a new movement to the shell core structure that has been generally used so far, and fine particle Ba _1-x Ca _x TiO ₃ -based materials have been reported as dielectric materials, and have attracted attention. ing.
However, alkaline earth metals such as calcium are difficult components to be combined, and the solid-phase method and partly the sol-gel method have proven results.

  The oxalate precursor method (hereinafter referred to as “oxalate method”) is one of the main production methods of barium titanate. This is a process for synthesizing barium titanate by heat-treating and de-acidifying a wet-synthesized oxalate precursor. The greatest feature of the oxalate method is the stability of the composition ratio (Ba / Ti ratio) of barium and titanium in the precursor crystal. Several processes have been reported for the oxalate method, but industrially, a method in which a reaction is carried out by adding a mixture of titanium chloride and barium chloride to an aqueous oxalic acid solution. A method for producing barium titanyl oxalate in which a part of barium element is substituted with another metal element using the oxalate method has also been proposed. For example, a method in which a mixed liquid of titanium chloride and barium chloride is mixed with another alkaline earth metal compound to be substituted and added to an aqueous oxalic acid solution (for example, see Patent Documents 1 and 2). However, there is a drawback that it is not industrially advantageous because the reaction is difficult to proceed quantitatively.

JP-A-60-185303, page 3 JP 2003-212543 A

  Accordingly, an object of the present invention is to provide a method capable of industrially advantageously producing barium titanyl oxalate powder having a high substitution rate of other alkaline earth metal elements substituted for Ba at the Ba site, and the barium titanyl oxalate powder. An object of the present invention is to provide an industrially advantageous method for producing the titanium-based perovskite ceramic raw material powder used.

  As a result of intensive studies to solve such problems, the inventors of the present invention have changed a solution (solution a) containing titanium tetrachloride and oxalic acid to a solution (solution b) containing a compound containing a barium compound and Me. It is found that the reactivity is improved when added and the reaction is improved, and barium titanyl oxalate powder having a high substitution rate of other alkaline earth metal elements substituted for Ba at the Ba site can be produced industrially advantageously. The invention has been completed.

（式中、ＭｅはＣａ、Ｓｒ及びＭｇから選ばれる少なくとも１種以上の金属元素を示す。ｘは０＜ｘ≦０．２の値をとる。）で表わされるバリウム元素の一部を他のアルカリ土類金属元素で置換した蓚酸バリウムチタニルの製造方法であって、四塩化チタンと蓚酸を含有する溶液（ａ液）を、バリウム化合物とＭｅを含む化合物を含有する溶液（ｂ液）に添加し反応を行うことを特徴とする蓚酸バリウムチタニル粉末の製造方法である。 That is, the first invention to be provided by the present invention is the following general formula (1).

(In the formula, Me represents at least one metal element selected from Ca, Sr, and Mg. X has a value of 0 <x ≦ 0.2.) A method for producing barium titanyl oxalate substituted with an alkaline earth metal element, wherein a solution (solution a) containing titanium tetrachloride and oxalic acid is added to a solution (solution b) containing a barium compound and a compound containing Me It is a manufacturing method of the barium titanyl oxalate powder characterized by performing reaction.

  A second invention to be provided by the present invention is a method for producing a titanium-based perovskite ceramic raw material powder, characterized by calcining the barium titanyl oxalate powder of the first invention.

  According to the production method of the present invention, barium titanyl oxalate powder having a high substitution rate of another alkaline earth metal element substituted for Ba at the Ba site can be advantageously produced industrially. Further, by using the barium titanyl oxalate powder as a raw material, a titanium-based perovskite ceramic raw material powder having a high substitution rate of other alkaline earth metal elements substituted with Ba at the Ba site can be produced industrially advantageously. .

（式中、ＭｅはＣａ、Ｓｒ及びＭｇから選ばれる少なくとも１種以上の金属元素を示す。ｘは０＜ｘ≦０．２の値をとる。）で表わされるバリウム元素の一部を他のアルカリ土類金属元素で置換した蓚酸バリウムチタニルの製造方法であり、その製造方法は、四塩化チタンと蓚酸を含有する溶液（ａ液）を、バリウム化合物とＭｅを含む化合物を含有する溶液（ｂ液）に添加し反応を行うことを特徴とし、特に本発明の製法において前記一般式（１）の式中のＭｅがＣａであると誘電体セラミックのベース材料としての温度特性をフラットにする効果を有する点で特に好ましい。 Hereinafter, the present invention will be described based on preferred embodiments thereof.
The barium titanyl oxalate powder targeted by the production method of the present invention has the following general formula (1):

(In the formula, Me represents at least one metal element selected from Ca, Sr, and Mg. X has a value of 0 <x ≦ 0.2.) A method for producing barium titanyl oxalate substituted with an alkaline earth metal element, which comprises a solution containing titanium tetrachloride and oxalic acid (solution a), and a solution containing a compound containing barium compound and Me (b) In the production method of the present invention, when Me in the formula of the general formula (1) is Ca, the temperature characteristic as a base material of the dielectric ceramic is flattened. It is particularly preferable in that it has

  The solution containing titanium tetrachloride and oxalic acid (liquid a) used in the present invention is an aqueous solution in which titanium tetrachloride and oxalic acid are dissolved in water. The molar ratio of Ti and oxalic acid in the liquid a (Ti / oxalic acid) is 0.45 to 0.55, preferably 0.49 to 0.51, and the specific composition of the liquid a is titanium chloride to Ti. 0.1 to 1 mol / L, preferably 0.6 to 0.7 mol / L, and oxalic acid to 0.2 to 2 mol / L, preferably 1.2 to 1.4 mol / L. This is particularly preferable in that a stable product can be obtained in a high yield.

  On the other hand, the solution (liquid b) containing a barium compound and a compound containing Me dissolves or disperses a compound containing a barium compound and a metal element (Me) corresponding to Me in the general formula (1) in water. Solution.

  Examples of barium compounds that can be used include barium carbonate, barium hydroxide, barium chloride, barium acetate, and barium nitrate. These can be used alone or in combination of two or more.

  On the other hand, examples of the compound containing Me that can be used include hydroxides, carbonates, acetates, nitrates or chlorides containing at least one metal element selected from the group of Ca, Sr, and Mg. These can be used alone or in combination of two or more.

  In the method for producing barium titanyl oxalate of the present invention, the compound containing barium compound and Me, when using these carbonates or hydroxides, can increase the reactivity and obtain a stable product with high yield. It is particularly preferable in that

  In addition, since the carbonate or hydroxide of the compound containing barium compound and Me is usually insoluble in water, the liquid b becomes a slurry containing these compounds, and the reaction itself becomes a solid-liquid reaction. In order to increase the reactivity, it is particularly preferable to use those raw material compounds having an average particle size of 5 μm or less, preferably 0.01 to 0.5 μm, as determined from the laser particle size distribution measurement method.

  The blending amount of the barium compound and Me-containing compound in the liquid b is 0.1 to 0.4 in terms of the molar ratio (Me / Ba) between Ba in the barium compound and the metal element (Me) in the compound containing Me. , Preferably 0.2 to 0.35, and the concentration is 0.4 to 1 mol / L, preferably 0.5 to 0.8 mol / L in terms of the total amount of Ba and Me of the compound containing barium compound and Me. L is particularly preferable in that a stable quality can be obtained in a high yield.

  Next, the a liquid is added to the b liquid. The added amount of solution a is such that the molar ratio of the total amount of Ba and Me of the compound containing barium compound and Me to oxalic acid ({Ba + Me} / oxalic acid) is 0.3 to 0.8, preferably 0.6 to 0.7. It is particularly preferable that a stable quality can be obtained in a high yield.

  In addition, in the method for producing barium titanyl oxalate powder of the present invention, when solution a is added to solution b, the pH of the reaction solution is strongly inclined to the acidic range, but when the pH of the reaction solution is less than 0.1, Me represented by calcium. The solubility of the components is high and disadvantageous in terms of yield. On the other hand, if the pH exceeds 4, it tends to be difficult to obtain uniform single-phase coprecipitation precipitation. It is particularly preferable to add the liquid a to the liquid b so as to be 0.1 to 4, preferably 1.5 to 2.5. Further, in order to obtain a pH within the above range, an alkaline agent such as ammonia water, ammonia gas, alkali hydroxide or the like may be added to the liquid b to carry out the reaction while adjusting the pH.

  The addition of the liquid a to the liquid b is preferably performed with stirring, and the stirring speed may be any as long as the slurry containing barium titanyl oxalate produced between the start of addition and the end of the reaction always exhibits fluidity. There is no particular limitation.

  The addition of the liquid a to the liquid b is normally performed at a constant rate at an addition temperature of usually 10 ° C. or higher, preferably 20 to 30 ° C., an addition time of 0.5 hours or longer, preferably 1 hour or longer. It is particularly preferable in that a product having a high quality can be obtained. The temperature of the liquid b is not particularly limited, but is preferably in the same range as the addition temperature because the reaction operation becomes easy.

  After completion of the addition of solution a, the reaction is continued (hereinafter referred to as “ripening reaction”). When this ripening reaction is carried out, the desired barium titanyl oxalate powder can be obtained in which the reaction is completed and there is little variation in the composition of Ti, Ba and Me.

  In the present invention, the pH during the ripening reaction is preferably 0.1 to 4, and more preferably 1.5 to 2.5. This is because, as described above, when the pH is less than 0.1, the solubility of the Me component represented by calcium is high, which is disadvantageous in terms of yield. On the other hand, when the pH exceeds 4, uniform single-phase coprecipitation precipitation occurs. This is because it becomes difficult to obtain. In the present invention, the pH may be further adjusted with a commonly used acid or the alkali exemplified above so that the pH in this range is reached during this aging reaction.

  As other aging reaction conditions, the aging temperature is usually 10 ° C. or higher, preferably 20 to 30 ° C., and the aging reaction is performed for 0.5 hour or longer, preferably 1 hour or longer. The aging temperature refers to the temperature of the entire reaction solution after the addition of solution a. After completion of the aging, the solid and liquid are separated by a conventional method and then washed with water. Although it does not restrict | limit especially as a washing | cleaning method, since washing | cleaning efficiency is high when washing | cleaning by repulp etc. is preferable. Further, the washing is particularly preferred since a high-purity titanium-based perovskite ceramic raw material powder can be obtained by thoroughly washing until the chlorine concentration contained in the barium titanyl oxalate powder is 200 ppm or less, preferably 150 ppm or less. It is then dried and ground if necessary to obtain barium titanyl oxalate powder.

  As a preferable physical property of the barium titanyl oxalate powder thus obtained, the average particle size determined from a scanning electron micrograph (SEM) is 1 to 100 μm, preferably 5 to 20 μm. Furthermore, it is particularly preferable that the chlorine concentration contained in the barium titanyl oxalate powder is 200 ppm or less, preferably 150 ppm or less.

  The barium titanyl oxalate powder represented by the general formula (1) obtained by the production method of the present invention can be suitably used as a raw material for producing a titanium-based perovskite ceramic powder as a dielectric ceramic material.

Next, a method for producing the titanium-based perovskite ceramic raw material powder of the present invention will be described.
The method for producing a titanium-based perovskite ceramic raw material powder according to the present invention is characterized by calcining the barium titanyl oxalate powder obtained above.

  In the present invention, if necessary, the barium titanyl oxalate powder is averaged so that a fine titanium-based perovskite ceramic raw material powder can be obtained even if calcined in a low temperature range before the calcining. You may grind | pulverize by wet processes, such as a ball mill and a bead mill, so that a particle size may be set to 1 micrometer or less, Preferably it is 0.05-0.5 micrometer. In this case, as the solvent used in the wet pulverization treatment, those inert to barium titanyl oxalate are used. For example, water, methanol, ethanol, propanol, butanol, toluene, xylene, acetone, methylene chloride, ethyl acetate , Dimethylformamide, diethyl ether and the like. Among these, when an organic solvent such as methanol, ethanol, propanol, butanol, toluene, xylene, acetone, methylene chloride, ethyl acetate, dimethylformamide, and diethyl ether is used, the crystallinity is reduced. High titanium-based perovskite ceramic raw material powder can be obtained, which is preferable.

  In the present invention, organic substances derived from oxalic acid contained in the final product are not preferable because they impair the dielectric properties of the material and cause unstable behavior in the thermal process for ceramization. Therefore, in the present invention, it is necessary to thermally decompose the barium titanyl oxalate by calcination to obtain a target titanium-based perovskite ceramic raw material powder and to sufficiently remove organic substances derived from oxalic acid. The calcination conditions are such that the calcination temperature is 700 to 1200 ° C, preferably 800 to 1100 ° C. The reason for setting the calcining temperature in the above range is that a single-phase titanium-based perovskite ceramic raw material powder is difficult to obtain when the temperature is lower than 700 ° C., whereas, when the temperature exceeds 1200 ° C., the variation in particle size increases. The calcination time is 2 to 30 hours, preferably 5 to 20 hours. The atmosphere of the calcination is not particularly limited, and may be either air or an inert gas atmosphere.

  In the present invention, this calcination may be performed as many times as desired. In order to make the powder characteristics uniform, the calcination once may be pulverized and then recalcined.

  After calcination, it is appropriately cooled and pulverized as necessary to obtain a titanium-based perovskite ceramic raw material powder.

The pulverization performed as necessary is appropriately performed when the titanium-based perovskite-type ceramic raw material powder obtained by calcination is in a brittlely bonded block shape, etc., but the particles of the titanium-based perovskite-type ceramic raw material powder As such, it has a specific average particle size and BET specific surface area. That is, the obtained titanium-based perovskite ceramic raw material powder has an average particle size of 0.1 to 4 μm, preferably 0.1 to 0.5 μm, and a BET specific surface area of 0.5, as determined from a scanning electron microscope (SEM). It is ˜20 m ² / g, preferably 4 to 10 m ² / g, and has little variation in composition. Further, in addition to the above physical properties, the chlorine content as an impurity is 500 ppm or less, preferably 250 ppm or less, and it is more preferable that the crystallinity is excellent.

  The titanium-based perovskite-type ceramic raw material powder obtained by the production method of the present invention may contain an auxiliary component element-containing compound added to the titanium-based perovskite-type ceramic raw material powder for the purpose of adjusting dielectric properties and temperature characteristics as necessary. Can do. Examples of the subcomponent element-containing compound that can be used include Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu rare earth elements. At least one selected from the group consisting of Ba, Li, Bi, Zn, Mn, Al, Si, Ca, Sr, Co, Ni, Cr, Fe, Mg, Ti, V, Nb, Mo, W and Sn Examples include compounds containing elements.

  The subcomponent element-containing compound may be either an inorganic substance or an organic substance, and examples thereof include oxides, hydroxides, chlorides, nitrates, oxalates, carboxylates and alkoxides containing the above elements. In addition, when a subcomponent element containing compound is a compound containing Si element, in addition to the said oxide etc., a silica sol, sodium silicate, etc. can be used. The subcomponent element-containing compounds can be used singly or in combination of two or more, and the addition amount and the combination of the additive compounds may be performed according to conventional methods according to the purpose.

  The method for adding the subcomponent element to the titanium-based perovskite ceramic raw material powder of the present invention is, for example, uniformly mixing the titanium-based perovskite-type ceramic raw material powder of the present invention after calcining and the subcomponent element-containing compound, followed by firing. Or, after the barium titanyl oxalate powder of the present invention and the subcomponent element-containing compound are uniformly mixed, calcining may be performed.

  The titanium-based perovskite-type ceramic raw material powder according to the present invention includes, for example, conventionally known additives, organic binders, plasticizers, dispersants and the like including the above-described subcomponent elements in manufacturing a multilayer ceramic capacitor. A ceramic sheet used for the production of a multilayer ceramic capacitor can be obtained by mixing and dispersing in an appropriate solvent to form a slurry, followed by sheet forming.

  In order to produce a multilayer ceramic capacitor from the ceramic sheet, first, a conductive paste for forming an internal electrode is printed on one surface of the ceramic sheet, and 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 heat treated to remove the binder, and fired to obtain a fired body. Furthermore, a multilayer capacitor can be obtained by applying Ni paste, Ag paste, nickel alloy paste, copper paste, copper alloy paste and the like to the sintered body and baking it.

  Further, for example, when the titanium-based perovskite ceramic raw material powder according to the present invention is blended with a resin such as an epoxy resin, a polyester resin, or a polyimide resin to form a resin sheet, a resin film, an adhesive, etc., a printed wiring board or a multilayer It can be suitably used as a material for printed wiring boards and the like, and is a co-material for suppressing the shrinkage difference between the internal electrode and the dielectric layer, electrode ceramic circuit board, glass ceramic circuit board, circuit peripheral material, and inorganic EL It can also be used as a dielectric material for use.

  The titanium-based perovskite ceramic raw material powder obtained in the present invention is also suitable as a catalyst for use in reactions such as exhaust gas removal and chemical synthesis, and as a surface modifier for printing toner that imparts antistatic and cleaning effects. Can be used.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.
Example 1
32.5 g of oxalic acid (0.258 mol as H ₂ C ₂ O ₄ ) and 64.1 g (0.123 mol as TiCl ₄ ) of 15.3 wt% titanium tetrachloride were dissolved in 140 ml of pure water. It was set as the liquid a.
A slurry was prepared by dispersing 18.2 g of barium carbonate (0.092 mol; average particle size of 0.24 μm) and 2.28 g of calcium hydroxide (0.031 mol; average particle size of 0.12 μm) in 150 ml of pure water, This was designated as solution b.
The solution a was added to the solution b over 120 minutes with stirring while maintaining the solution a at 25 ° C. (pH 0.2), and further aged with stirring at 25 ° C. for 30 minutes. After aging, filtration was performed to recover barium titanyl oxalate. The recovered barium titanyl oxalate was repulped twice with 300 ml of distilled water and carefully washed. Then, it was dried at 80 ° C. to obtain 40.9 g of barium titanyl oxalate. The physical property values of the obtained barium titanyl oxalate are shown in Table 1.
The chlorine content was measured by an ion chromatography method, and the molar ratio of Ba, Ti and Ca was calculated based on the measured value of the fluorescent X-ray analyzer. Moreover, the average particle diameter was calculated | required with the scanning electron microscope (SEM) photograph.

Example 2
As a liquid b, 21.8 g (0.110 mol; average particle size 0.24 μm) of barium carbonate and 2.7 g (0.037 mol; average particle size 0.12 μm) of calcium hydroxide were dispersed in 150 ml of pure water to prepare a slurry. A barium titanyl oxalate powder of 48.8 g was prepared by reacting in the same manner as in Example 1 except that this was prepared as b solution and the pH during aging was changed to 0.2. The obtained barium titanyl oxalate was measured in the same manner as in Example 1, and the physical properties are shown in Table 1.

Example 3
2.93 kg of oxalic acid (23.20 mol as H ₂ C ₂ O ₄ ) and 5.77 kg of 15.3 wt% titanium tetrachloride diluted solution (11.05 mol as TiCl ₄ ) were dissolved in 12.6 L of pure water. This was designated as solution a.
2.26 kg (11.44 mol; average particle size 0.24 μm) of barium carbonate and 0.28 kg (3.81 mol; average particle size 0.12 μm) of calcium hydroxide were dispersed in 27 L of pure water to prepare a slurry, This was designated as solution b.
The solution a was added to the solution b over 60 minutes with stirring while maintaining the solution at 25 ° C. (pH 0.2), and further aged with stirring at 25 ° C. for 30 minutes. After aging, filtration was performed to recover barium titanyl oxalate, and the recovered barium titanyl oxalate was repulped twice with 30 L of distilled water and carefully washed. Then, it was dried at 80 ° C. to obtain 4.72 kg of barium titanyl oxalate. The physical property values of the obtained barium titanyl oxalate are shown in Table 1.

Example 4
3.58 kg of oxalic acid (28.36 mol as H ₂ C ₂ O ₄ ), 7.05 kg of 15.3 wt% titanium tetrachloride diluted solution (13.50 mol as TiCl ₄ ) were dissolved in 15.4 L of pure water, This was designated as solution a.
A slurry was prepared by dispersing 2.53 kg of barium carbonate (12.83 mol; average particle size 0.24 μm) and 0.20 kg of calcium hydroxide (2.70 mol; average particle size 0.12 μm) in 15.4 L of pure water. This was designated as solution b.
The solution a was added to the solution b over 120 minutes with stirring while maintaining the solution at 25 ° C. (pH 0.2), and further aged with stirring at 25 ° C. for 30 minutes. After aging, filtration was performed to recover barium titanyl oxalate, and the recovered barium titanyl oxalate was repulped twice with 30 L of distilled water and carefully washed. Subsequently, it dried at 80 degreeC and obtained 5.64 kg of barium titanyl oxalate. The physical property values of the obtained barium titanyl oxalate are shown in Table 1.

Comparative Example 1
27.0 g of barium chloride dihydrate (0.110 mol as BaCl ₂ ), 5.4 g (0.037 mol) of calcium chloride dihydrate and 64.1 g of titanium tetrachloride (0.123 mol as TiCl ₄ ) were purified. A mixed solution dissolved in 180 ml of water was prepared, and this was designated as solution a.
Next, 32.5 g of oxalic acid (0.258 mol as H ₂ C ₂ O ₄ ) was dissolved in 140 ml of hot water at 55 ° C. to prepare an oxalic acid aqueous solution, which was designated as solution b.
The liquid a was added to the liquid b over 120 minutes with stirring while maintaining the liquid at 55 ° C. (pH 0.2), and further aged with stirring at 55 ° C. for 30 minutes. After cooling, it was filtered to recover barium titanyl oxalate, and the recovered barium titanyl oxalate was repulped twice with 300 ml of distilled water and carefully washed. Subsequently, it dried at 80 degreeC and 52g of barium titanyl oxalates were obtained. In this reaction, the setting is the same as the preparation composition of Example 2. The physical property values of the obtained barium titanyl oxalate were measured in the same manner as in Example 1, and the results are shown in Table 1.

  From the results in Table 1, it can be seen that when Example 2 and Comparative Example 1 having the same charging composition are compared, Example 2 has a higher calcium substitution rate and better reactivity than that obtained in Comparative Example 1. .

Examples 5-6
The barium titanyl oxalate samples obtained in Examples 3 and 4 were calcined for 14 hours in an air atmosphere at 850 ° C. and pulverized to prepare titanium-based perovskite ceramic raw material powder samples. Various physical properties of the obtained titanium-based perovskite ceramic raw material powder sample were measured in the same manner as in Example 1, and the results are shown in Table 2.

Claims (6)

The following general formula (1)

(In the formula, Me represents at least one metal element selected from Ca, Sr, and Mg. X has a value of 0 <x ≦ 0.2.) A method for producing barium titanyl oxalate substituted with an alkaline earth metal element, wherein a solution (solution a) containing titanium tetrachloride and oxalic acid is added to a solution (solution b) containing a barium compound and a compound containing Me And producing a barium titanyl oxalate powder, characterized in that the reaction is carried out.   The method for producing barium titanyl oxalate powder according to claim 1, wherein the Me is Ca.   The method for producing barium titanyl oxalate powder according to claim 1, wherein the barium compound is barium carbonate or barium hydroxide.   The method for producing barium titanyl oxalate powder according to claim 1, wherein the compound containing Me is a carbonate or hydroxide containing Me.   Barium titanyl oxalate powder produced by the method of claim 1.   A method for producing a titanium-based perovskite ceramic raw material powder, wherein the barium titanyl oxalate powder according to claim 5 is calcined.