JP3240643B2 - Manufacturing method of ceramic raw material fine powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a ceramic raw material, and more particularly, to a method for producing fine powder (ceramic raw material powder) for an electronic ceramic raw material which is fine, has a large specific surface area, and has a narrow particle size distribution. .

[0002]

2. Description of the Related Art As a conventional method for producing a raw material fine powder for an electronic ceramic, for example, there is a wet synthesis method proposed by the inventors of the present invention (JP-A-59-128263). In the method for producing a ceramic raw material, at least Ba, Sr, Ca,
Carbon dioxide or an aqueous solution of a soluble carbonate such as sodium carbonate or ammonium carbonate is added to an aqueous solution of nitrate or chloride containing one kind of Mg, the pH is adjusted to 7 to 10, and the constituent elements are precipitated as carbonates, In the second tank, at least Ti, Zr, Sn, P
b) in an aqueous solution of nitrate or chloride containing at least one of
PH is adjusted to 7 to 7 by adding caustic alkali such as H, NH ₄ OH.
A first step of adjusting to 10 and precipitating the constituent elements as a hydroxide, and a second step of mixing the slurry containing each precipitate obtained in the first step, filtering, washing with water, and drying;
And a third step of calcining and pulverizing the obtained mixed precipitated powder.

[0003] In addition, other conventional wet synthesis methods are disclosed in Japanese Patent Application Laid-Open Nos.
There is a wet synthesis method described in US Pat. Then, both of these two methods, for example, when looking at Ba, adjust the pH to 7 to 10 by adding a solution containing a precipitant such as sodium carbonate to a solution of Ba chloride,
A step of precipitating the constituent elements as carbonates.

[0004]

All of the above-mentioned conventional wet synthesis methods include a step of adding a solution containing a precipitant to a solution containing the components of the ceramic raw material. The volume is small relative to the volume of the solution containing the constituents of the ceramic raw material, and when the solution containing the precipitant is added to the solution containing the constituents of the ceramic raw material, it is difficult to quickly and uniformly mix the two. Yes, there is some bias in the state of dispersion. As a result, there are portions where the pH value of the solution containing the constituent components of the ceramic raw material is high and portions where the pH value is not so high, and the generation state of the precipitate varies.

In the conventional method, since the solution containing the precipitant is gradually added to the solution containing a large amount of the constituents of the ceramic raw material, the pH value gradually increases as the solution containing the precipitant is added. Changes to Accordingly, in the reaction process, the precursor-intermediate product-ceramic compound and the respective products are sequentially generated in a time series, and the ceramic compound at the initial stage where the solution containing the precipitant has begun to be added. However, there is a problem that powder characteristics are different from that of a ceramic compound in a stage after a solution containing a precipitant is considerably added, so that uniform ceramic raw material fine powder cannot be obtained.

Further, at the stage where the solution containing the precipitant is added to the solution containing the constituents of the ceramic raw material, the mixing state becomes non-uniform and the pH at which each product (precipitate) is stably present is obtained.
When the ratio is out of the range, the re-dissolution of the precipitate or the deviation of the composition ratio (becoming a composition ratio different from the intended composition ratio (composition)) occurs, and it is not possible to obtain fine ceramic raw material powder. is there.

The present invention solves the problems of the above-described conventional method for producing a ceramic raw material fine powder, and does not cause re-dissolution of a product (precipitate) or a deviation in a composition ratio in a reaction step. An object of the present invention is to provide a method for producing ceramic raw material fine powder capable of obtaining ceramic raw material fine powder having a target composition ratio.

[0008]

Means for Solving the Problems In order to achieve the above object, a method for producing a ceramic raw material fine powder according to the first invention of the present application uses a general formula ABO ₃ (where A is Ba, Sr, Mg, C
a is at least one member selected from the group consisting of divalent alkaline earth metals such as a, and B is at least one member selected from the group consisting of tetravalent metal elements such as Ti, Zr, and Sn). A method for producing a ceramic raw material fine powder comprising a compound, comprising: a hydroxide of a metal element constituting A;
A first solution having a liquid temperature of 60 to 95 ° C. containing 1 to 4 mol of one or more of a mixture selected from the group consisting of OH, KOH, LiOH, NH ₄ OH and an amine, and a metal element constituting B And a second solution containing the composite alkoxide of the formula (1), by a flow control member such as a twist blade provided in a cylindrical portion serving as a fluid passage so that the molar ratio of A and B becomes 1 to 1 from different routes. By feeding the fluid into a static line mixer that controls the flow of the fluid to mix the passing fluid, and uniformly mixing and reacting the two in the static line mixer, the ceramic raw material powder having a predetermined composition is precipitated. It is characterized by.

Further, the method for producing a ceramic raw material powder according to the second invention of the present application is based on the general formula ABO ₃ (where A is Ba, S
r is at least one selected from the group consisting of divalent alkaline earth metals such as Mg, Ca, etc., and B is Ti, Zr,
At least one member selected from the group consisting of tetravalent metal elements such as Sn), the first solution and the second solution of the first invention of the present application. Are sent to the first stage static line mixer from the different paths so that the molar ratio of A and B becomes 1: 1 and both are uniformly mixed in the first stage static line mixer. After the first reaction is performed, a slurry containing a precipitate of the complex perovskite compound generated by the first reaction and a component such as a complex alkoxide of a metal element necessary for improving the temperature coefficient are continuously contained. The third solution to be mixed is sent to the second-stage static line mixer, uniformly mixed and subjected to a secondary reaction, thereby precipitating ceramic raw material powder having a predetermined composition. It is characterized in that to.

[0010] Further, a semiconducting agent (such as a metal element) and other components can coexist in the second solution.

Further, as the stationary line mixer, a plurality of twist blades of a predetermined shape are arranged and fixed in an axial direction in the cylindrical portion, and the fluid passing through the cylindrical portion passes through the twist blades of each stage. It is possible to use a stationary line mixer that divides the passing fluid into 2 ⁿ pieces when the fluid is divided into two each time and passes through the n-stage twisting blade.

Hereinafter, the configuration of the present invention will be described in detail with reference to FIG. 1 and FIG.

FIG. 1 is a diagram showing an example of an apparatus used for carrying out the method for producing fine powder of ceramic raw material according to the first invention of the present application. This apparatus was produced by mixing a tank 1 for storing a first solution, a tank 2 for storing a second solution, a static line mixer 3 for mixing a first solution and a second solution, and a first solution and a second solution. A recovery tank 4 for recovering ceramic raw material powder (precipitate) is provided. Further, metering pumps 7 and 8 are provided in lines (pipe) 5 and 6 for supplying the first solution and the second solution from the tank 1 and the tank 2 to the stationary line mixer 3.

The stationary line mixer used in the present invention is, for example, a member (flow control) for controlling the flow of fluid or dividing the fluid, such as a twisting blade, in a cylindrical portion communicating with the lines 5 and 6. Component), which is a mixer that performs liquid / liquid mixing, solid / liquid mixing, etc. by using the flow of fluid passing therethrough. It has no moving parts and has high mixing efficiency. And the shape of the cylindrical portion and the flow control member is not particularly limited.

Further, among the static line mixers, stationary twist mixers in which a plurality of fixed twist blades for dividing a fluid into two (n stages) are arranged and fixed in the axial direction in the cylindrical portion (for example, Nippon Toki Co., Ltd.) Made by Noritake Reactor (trade name))
The slurry containing the generated ceramic raw material fine powder can be divided and mixed into 2 ⁿ pieces (for example, in the case of those having 27 stages of twisting blades, 2 ²⁷ = 1.4 × 10 ⁸ pieces). Performing sufficient stirring and mixing, which cannot be realized with a stirring mixer of the type in which a conventional stirring blade is rotated,
Since a uniform slurry can be obtained, it is particularly suitable for carrying out the method for producing a ceramic raw material powder of the present invention.

Using an apparatus as shown in FIG.
When the ceramic raw material powder is produced by the method for producing ceramic raw material powder according to the invention of the invention, A
A first solution 1a at 60 to 95 ° C. containing at least one hydroxide of a metal element constituting ca. and a caustic alkali, and a second alkoxide solution of a metal element constituting B stored in a tank 2 2 solution 2a is supplied to metering pumps 7 and 8
Thus, the total equivalent of the metal element ions constituting A and B
From the separate lines 5 and 6 via the fluid mixer 9 at a ratio such that the total equivalents of the metal ion elements constituting
Sent to.

Then, in the static line mixer 3,
The first solution 1a and the second solution 2a come into contact with each other and are sufficiently mixed to produce a fine precipitate which becomes a ceramic raw material. In this step, the first solution 1
a, the second solution 2a is quantitatively supplied to the stationary line mixer 3 at an equivalent ratio of constituent metal elements of 1: 1 so that a uniform ceramic material fine powder precipitate is formed, and the composition and properties thereof are It does not change over time. Therefore, a precipitate generated at an initial stage when the first solution 1a and the second solution 2a are supplied to the stationary line mixer 3,
There is no variation in the powder characteristics between the precipitate and the precipitate formed in the subsequent stage, and a stable precipitate of the ceramic raw material fine powder can be generated. Then, the slurry 11 containing the precipitate generated in the stationary line mixer 3 is sent to the collection tank 4 through the line 10 and is separated into solid and liquid by a usual solid and liquid separating means (not shown), washed and dried. This produces a ceramic raw material fine powder.

By the way, a method according to the conventional wet synthesis method, that is, a solution (a first solution) at 60 to 95 ° C. containing a hydroxide of at least one metal element constituting A and a caustic alkali is used. , B, the solution (second solution) containing the complex alkoxide of at least one metal element is gradually added to cause the reaction, and the amount (volume) of the second solution added in the initial stage Is small with respect to the amount (volume) of the first solution, so that the generated ceramic raw material has a low sedimentation concentration, and the generated sediment repeats re-dissolution and sedimentation to become a sediment having a large particle size. On the other hand, at a stage after a certain amount of time has passed and a considerable amount of the second solution has been added, the concentration of the precipitate in the reaction tank increases, and the particle size of the insoluble precipitate formed decreases. As a result, the particle size of the precipitate generated in a time series changes, and it is not possible to obtain a ceramic raw material fine powder having a narrow particle size distribution (that is, a high degree of concentration of the particle size).

On the other hand, according to the method for producing fine powder of ceramic raw material of the present invention, the first solution and the second solution are quantitatively reacted while being sent to the static line mixer. Concentration, etc.) does not fluctuate in time series, and a fine powder of ceramic raw material having a narrow particle size distribution can be obtained.

Further, it is possible to add a metal element or the like (semiconductor agent) necessary for converting the raw material fine powder into a semiconductor into the second solution, whereby the characteristics of the obtained ceramic raw material fine powder can be improved. Can be improved. In addition, as a metal element necessary for semiconductor conversion, for example, La
And Zr, but other metal elements can also be used. Further, the second solution may contain components other than the semiconducting agent, for example, components necessary for improving other characteristics.

FIG. 2 is a view showing an example of an apparatus used to carry out the method for producing fine powder of ceramic raw material according to the second invention of the present application. This apparatus is an apparatus (FIG. 1) for implementing the method for producing ceramic raw material fine powder of the first invention of the present application.
After the static line mixer 3, another (second stage) static line mixer 13 is further connected,
The third solution 14a and the slurry solution containing the precipitate of the ceramic raw material powder obtained by performing the primary reaction in the stationary line mixer 3 at the stage and the third solution 14a are supplied to the fluid mixer 15, The configuration is such that both are mixed in the static line mixer 13 of the eye. The third solution 14a is stored in the tank 14, and the third pump 14a
Is supplied to the fluid mixer 15 via the line 16. The slurry 18 containing the final settled product is fed to a line 19
After that, the mixture is sent to the recovery tank 20, where it is subjected to solid-liquid separation by a usual solid-liquid separation means (not shown), washed with water and dried to produce ceramic raw material fine powder.

In this method, the slurry containing the fine precipitate of the ceramic raw material generated by the first reaction is added to the slurry.
By adding and mixing a third solution containing a component such as a composite alkoxide of a metal element that improves the temperature characteristics (temperature coefficient), it is possible to produce a fine ceramic raw material powder having further excellent temperature characteristics. The metal element for the composite alkoxide for improving the temperature characteristics is M
Although n and the like are exemplified, other metal elements can be used. Further, the third solution may contain components necessary for improving other characteristics, other than the components required for improving the temperature characteristics.

The apparatus of FIG. 2 is an apparatus provided with two first-stage and second-stage static line mixers.
Further, it is also possible to provide a static line mixer at the third and subsequent stages to continuously perform a plurality of reactions.

Examples of the amine used in the method for producing a ceramic raw material fine powder of the present invention include aliphatic amines such as methylamine, dimethylamine, trimethylamine, and ethylamine; o-, m-, p-toluidine; N-dimethylbenzylamine and the like can be mentioned as typical examples.

Examples of the titanium alkoxide include titanium isopropoxide, titanium butoxide, titanium ethoxide, dibutoxy-ditriethanol-aminato titanium,
Dibutoxydi (2-hydroxyethylaminoethoxy)
Titanium and the like can be mentioned.

As a metal compound to be subjected to complex alkoxidation with titanium, it is more cost-effective to use an acetate salt such as zirconyl acetate or lanthanum acetate, which is liable to undergo a transesterification reaction. A metal alkoxide that can be converted into a metal alkoxide may be used.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The features of the present invention will be described in more detail with reference to examples of the present invention and comparative examples. Preparation of Raw Material Solutions (First, Second, and Third Solutions) The metal elements and NaOH constituting A are accurately weighed at the ratio shown in Table 1, and dissolved in 1 L of pure water at 90 ° C. to prepare the first solution. Is prepared.

[0028]

[Table 1]

For Experiment Nos. 1 and 2 in Table 1, the amount of titanium isopropoxide (Ti (O
C ₃ H ₇ ) ₄ ) is accurately weighed, isopropyl alcohol is added thereto, and the total volume is reduced to 1 liter to prepare a second solution.

In Experiment No. 3, according to Table 1, titanium isopropoxide (Ti (OC
₃ H ₇ ) ₄ ) and zirconyl acetate (ZrO (CH ₃ CO
O) ₂ ) was accurately weighed, placed in a round bottom flask and heated under reflux to produce a complex alkoxide of Ti—O—Zr by transesterification, and isopropyl alcohol was added thereto, and the total amount was 1 L. To prepare a second solution.

Further, for Experiment No. 4, according to Table 1, titanium isopropoxide (Ti (OC ₃ H ₇ ))
₄₎ and lanthanum acetate _{(La (CH 3 COO) 3} · 3 / 2H
The ₂ O) were weighed accurately, and heated to reflux placed in a round bottom flask, by transesterification, to produce a composite alkoxide of Ti-O-La, this was added isopropyl alcohol, and a total volume of 1L To prepare a second solution. Furthermore, in Experiment No. 4, the amine-modified manganese alkoxide was dissolved in isopropyl alcohol, and the total volume was 2 L to prepare a third solution.

[0032] Precipitation of the fine powder of the ceramic material produced by the reaction
For the recovery experiments No. 1 to No. 3 of the first solution and the second solution using a device as shown in FIG.
The mixture is fed at a rate of 1 L / min into a stationary line mixer provided with ten stages of twisting blades to cause a reaction. Then, the precipitate of the generated raw material fine powder is separated by a solid-liquid separation means such as a filter, washed with water and dried to obtain a ceramic raw material fine powder.

In Experiment No. 4, the first solution and the second solution were transferred to the first stationary type using an apparatus as shown in FIG. After being sent to the line mixer to perform the first reaction, the slurry containing the precipitate formed in the first reaction and the third solution are sent to the second stage stationary type line mixer to perform the first reaction. The slurry containing the precipitate generated by the above method and the third solution were each 2 L /
The mixture is fed at a ratio of min to a stationary line mixer provided with ten stages of twisting blades to cause a secondary reaction. then,
The precipitate of the generated fine powder of ceramic raw material is separated using a solid-liquid separation means such as a filter, washed with water and dried to obtain fine powder of ceramic raw material.

COMPARATIVE EXAMPLE An aqueous solution of ammonium carbonate was added dropwise to an aqueous solution of barium chloride to adjust the pH to 9 to 9.5 to precipitate barium carbonate, and an aqueous solution of hydrogen peroxide (30%) was added to an aqueous solution of titanium tetrachloride.
%) And aqueous ammonia were added to adjust the pH to 9 to 9.5 to precipitate the titanium compound. Then, the precipitate of barium carbonate and the titanium compound was filtered, washed with water, dried, and calcined at 900 ° C. to obtain barium titanate (BaTiO ₃ ) powder.

The powder obtained in evaluation experiment No. 1 was subjected to X-ray diffraction
As a result of the analysis, it was confirmed that the powder was cubic single-phase BaTiO ₃ .

As for the experiments No. 2, No. 3 and No. 4, as a result of analysis by X-ray diffraction method, the obtained powder (ceramic raw material fine powder) was a composite perovskite compound represented by the general formula ABO ₃ . Was confirmed.

Further, the powder (fine powder of ceramic raw material) obtained in Experimental Example 2 was analyzed by a transmission electron microscope.
The composition was randomly analyzed for the molar ratio at 10 points with a spot diameter of 3 μm. Table 2 shows the results.

[0038]

[Table 2]

The BaTiO obtained by the method of the comparative example
_{For the three} powders, the molar ratio analysis of the constituent components was performed in the same manner. Table 3 shows the results.

[0040]

[Table 3]

From Tables 2 and 3, the powder obtained by the method of the comparative example has a portion where the molar ratio largely deviates from the theoretical value when viewed microscopically. While ceramic powder having a composition ratio close to the theoretical value cannot be obtained, the ceramic raw material powder obtained by the method of the present invention has individual particles each having a composition ratio (molar ratio) close to the theoretical value. You can see that it is.

Although not particularly shown in Table 2, the experiment
The same molar ratio analysis was performed on the ceramic raw material powders obtained in No. 1, No. 3 and No.
For each of the samples No. 1, No. 3 and No. 4, the general formula ABO _{3 in} which the individual particles have a composition ratio close to the theoretical value
It has been confirmed that the compound is a composite perovskite compound represented by

[0043]

As described above, according to the method for producing a ceramic raw material fine powder of the first invention of the present application, the ratio of the total equivalent of the metal element in the first solution to the total equivalent of the metal element in the second solution is one. Since the first solution and the second solution are quantitatively sent to the static line mixer at a ratio of 1 to cause the contact reaction, the conditions for forming the precipitate (such as the concentration of the precipitate) are set.
Is not changed in time series and is stable, so that it is possible to obtain a fine ceramic raw material powder composed of the composite perovskite compound represented by the general formula ABO ₃ having a narrow particle size distribution and a large specific surface area.

In the method for producing a ceramic raw material powder according to the second invention of the present application, the first solution and the second solution are reacted (primary reaction), and subsequently, the composite perovskite compound produced by the first reaction is produced. And a third solution containing components other than A and B, such as a complex alkoxide of a metal element required to improve the temperature coefficient, into a stationary line mixer of the second stage, By mixing uniformly and allowing the secondary reaction to take place,
It is possible to obtain a ceramic raw material fine powder composed of the composite perovskite compound represented by the general formula ABO ₃ having not only a narrow particle size distribution but also excellent temperature characteristics.

Further, the stationary line mixer used in the method for producing a ceramic raw material powder of the present invention is much smaller than a conventional mixing stirrer in which a stirring blade is rotated, and the mounting space for the reactor is reduced. It is possible.

Further, regarding the method of the second invention of the present application,
By connecting a stationary line mixer, multiple reactions can be performed continuously, which not only simplifies the reaction operation, but also makes it possible to reduce the size of the manufacturing equipment and is economical. ing. Further, the slurry containing the precipitate of the ceramic raw material fine powder generated by the primary reaction can be continuously guided to the second-stage static line mixer to be brought into contact with the third solution, so that the slurry formed in the previous step can be formed. This makes it possible to uniformly mix the precipitate formed and the precipitate formed in a later step, and it is possible to easily and reliably produce a ceramic raw material fine powder having excellent characteristics such as temperature characteristics.

[Brief description of the drawings]

FIG. 1 is a view showing an apparatus used for carrying out a method for producing a ceramic raw material fine powder of the first invention of the present application.

FIG. 2 is a view showing an apparatus used for carrying out the method for producing a ceramic raw material powder of the second invention of the present application.

[Explanation of symbols]

1a First solution 2a Second solution 3 Stationary line mixer 13 Second stage stationary line mixer 14a Third solution

Continued on the front page (72) Inventor Yukio Hamachi 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto, Japan Inside Murata Manufacturing Co., Ltd. (72) Inventor Yukio Sakabe 2-26-10, Tenjin, Nagaokakyo-shi, Kyoto Murata, Ltd. (56) References JP-A-1-286923 (JP, A) JP-A-2-31315 (JP, A) JP-A-3-103323 (JP, A) JP-A-64-3019 (JP, A) JP-A-59-128263 (JP, A) JP-A-59-195574 (JP, A) JP-A-59-195576 (JP, A) JP-A-63-117914 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C01G 23/00 C01G 1/00 C01G 25/00 C04B 35/626

Claims (4)

(57) [Claims] 1. A general formula ABO ₃ (where A is Ba, S
r is at least one selected from the group consisting of divalent alkaline earth metals such as Mg, Ca, etc., and B is Ti, Zr,
At least one selected from the group consisting of tetravalent metal elements such as Sn), and a fine powder of ceramic raw material comprising a composite perovskite compound represented by the formula: A first solution having a liquid temperature of 60 to 95 ° C. containing 1 to 4 mol of one or more of a mixture of two or more selected from the group consisting of NaOH, KOH, LiOH, NH ₄ OH and an amine with respect to 1 mol of the oxide; And a second solution containing a composite alkoxide of a metal element constituting B were provided on a cylindrical portion serving as a fluid passage so that the molar ratio of A and B was 1: 1 from different routes. Sending the fluid to a stationary line mixer that controls the flow of the fluid with a flow control member such as a twisting blade to mix the passing fluid, and uniformly mix and react the two in the stationary line mixer; More, the manufacturing method of the ceramic material fine powder, characterized in that to precipitate out the ceramic material fine powder having a predetermined composition. 2. The general formula ABO ₃ (where A is Ba, S
r is at least one selected from the group consisting of divalent alkaline earth metals such as Mg, Ca, etc., and B is Ti, Zr,
(2) at least one member selected from the group consisting of tetravalent metal elements such as Sn), wherein the first solution according to claim 1 and the first solution according to claim 1; And the second solution is sent to the static line mixer according to claim 1 from different paths such that the molar ratio of A and B is 1: 1 and both are uniformly mixed in the static line mixer. After the first reaction is performed, a slurry containing a precipitate of the complex perovskite compound generated by the first reaction and a component such as a complex alkoxide of a metal element necessary for improving the temperature coefficient are contained. With the third solution
A method for producing a fine ceramic raw material powder, wherein the fine raw material ceramic powder having a predetermined composition is precipitated by being sent to a stationary line mixer at the stage, uniformly mixed and subjected to a secondary reaction. 3. The method for producing fine powder of ceramic raw material according to claim 1, wherein a semiconducting agent and other components are further co-present in the second solution. 4. A stationary line mixer in which a plurality of twist blades having a predetermined shape are arranged and fixed in an axial direction in a cylindrical portion, and a fluid passing through the cylindrical portion passes through each of the twist blades in each stage. The ceramic raw material powder according to any one of claims 1, 2 and 3, wherein the stationary line mixer divides the passing fluid into 2 ⁿ pieces when passing through n stages of twisting blades. Production method.