JP7200797B2 - Method for producing alkaline earth metal carbonate - Google Patents

Description

The present invention relates to a method for producing alkaline earth metal carbonates.

In recent years, in order to reduce the thickness and increase the number of dielectric layers in multilayer ceramic capacitors (MLCCs) with smaller sizes and higher capacities, barium titanate, which is a dielectric material, and titanium oxide and barium carbonate, which are raw materials for barium titanate, have been developed. It is important how to atomize the It is known that barium carbonate undergoes particle growth during the heating process during firing in the solid-phase synthesis method. As a result, there occurs a problem that the properties such as the particle size of the barium titanate powder to be produced are varied. Therefore, in order to obtain uniform and fine barium titanate, it is necessary to suppress the thermal grain growth of barium carbonate. In the past, a technique for suppressing particle growth due to heat was developed by subjecting barium carbonate to surface treatment by neutralization with a titanium compound (see Patent Documents 1 and 2).

JP 2013-28509 A Japanese Patent Publication No. 2008-508170

As described above, a technique for suppressing particle growth due to heat has been developed by treating the surface of barium carbonate with a titanium compound for neutralization. surface treatment, there is a problem that the process becomes redundant. Moreover, if barium titanate is synthesized using barium carbonate that has undergone a conventional surface treatment, there is a risk that the formed surface treatment layer will be destroyed due to shear in mixing with titanium oxide during synthesis.

In view of the above-mentioned current situation, the present invention aims to easily produce an alkaline earth metal carbonate in which grain growth is suppressed during heat treatment, which can be suitably used for producing barium carbonate as a raw material for synthesis of barium titanate. It aims at providing the manufacturing method which can do.

The inventors of the present invention have investigated a method for easily producing an alkaline earth metal carbonate in which particle growth is suppressed during heat treatment, and found that inorganic acids other than alkaline earth metal hydroxides, chlorides, and carbonates A mixing step of mixing at least one alkaline earth metal compound selected from the group consisting of salts, organic acid salts, and oxides with carbon dioxide and/or a water-soluble carbonate compound, and before the mixing step, and/or adding a water-soluble Group 4 transition metal compound to at least one of carbon dioxide and/or a water-soluble carbonate compound or a mixture thereof in the mixing step. The inventors have found that an alkaline earth metal carbonate in which particle growth is suppressed during heat treatment can be easily produced by producing an alkaline earth metal carbonate by a production method including the following, and have completed the present invention.

That is, the present invention provides at least one alkaline earth metal compound selected from the group consisting of inorganic acid salts other than alkaline earth metal hydroxides, chlorides, and carbonates, organic acid salts, and oxides, and carbon dioxide. and / or a mixing step of mixing with a water-soluble carbonate compound, and before the mixing step and / or in the mixing step, an alkaline earth metal compound, carbon dioxide and / or a water-soluble carbonate compound and adding a water-soluble Group 4 transition metal compound to at least one of or a mixture thereof.

The alkaline earth metal compound is preferably a barium compound or a strontium compound.

The water-soluble Group 4 transition metal compound is preferably a water-soluble titanium compound.

In the above production method, before the mixing step and/or in the mixing step, at least one of an alkaline earth metal compound and carbon dioxide and/or a water-soluble carbonate compound or a mixture thereof, citric acid and/or Or it is preferable to further include a step of adding a salt thereof.

The present invention also provides at least one barium compound selected from the group consisting of barium hydroxides, chlorides, inorganic acid salts other than carbonates, organic acid salts, and oxides, carbon dioxide and / or water-soluble In a mixing step of mixing with a carbonate compound, and before the mixing step and/or in the mixing step, at least one of a barium compound and carbon dioxide and/or a water-soluble carbonate compound or a mixture thereof a step of adding a water-soluble Group 4 transition metal compound to obtain barium carbonate; a mixing step of mixing the barium carbonate and a titanium compound; and a step of firing the mixture obtained in the mixing step. It is also a method for producing barium titanate characterized by:

INDUSTRIAL APPLICABILITY The method for producing an alkaline earth metal carbonate of the present invention can easily produce an alkaline earth metal carbonate in which particle growth is suppressed during heat treatment. It can be suitably used as a method for producing barium carbonate, etc., which is a raw material for synthesizing fine particles such as electronic materials such as certain ceramic capacitors, air electrode materials for solid oxide fuel cells, and oxide superconductor materials. It can be suitably used as a method for producing barium carbonate used as a raw material for synthesizing materials.

1 is a conceptual diagram showing an apparatus for producing barium carbonate in Examples. FIG. 2 shows electron micrographs of barium carbonate produced in Example 1 before heat treatment and after heat treatment at 600° C. for 30 minutes. 3 is electron micrographs of barium carbonate produced in Example 2 before heat treatment and after heat treatment at 600° C. for 30 minutes. 3 shows electron micrographs of barium carbonate produced in Example 3 before heat treatment and after heat treatment at 600° C. for 30 minutes. 4 shows electron micrographs of barium carbonate produced in Example 4 before heat treatment and after heat treatment at 600° C. for 30 minutes. FIG. 10 is electron micrographs of barium carbonate produced in Example 5 before heat treatment and after heat treatment at 600° C. for 30 minutes; Fig. 10 is electron micrographs of barium carbonate produced in Example 6 before heat treatment and after heat treatment at 600°C for 30 minutes; 3 is electron micrographs of barium carbonate produced in Comparative Example 1 before heat treatment and after heat treatment at 600° C. for 30 minutes;

Preferred embodiments of the present invention will be specifically described below, but the present invention is not limited to the following description, and can be appropriately modified and applied without changing the gist of the present invention.

1. Method for Producing Alkaline Earth Metal Carbonate The method for producing an alkaline earth metal carbonate of the present invention comprises: A mixing step of mixing at least one alkaline earth metal compound selected from the group consisting of carbon dioxide and/or a water-soluble carbonate compound (hereinafter simply referred to as a mixing step), and before the mixing step, and/or adding a water-soluble Group 4 transition metal compound to at least one of carbon dioxide and/or a water-soluble carbonate compound or a mixture thereof in the mixing step. characterized by comprising
Thus, at least one alkaline earth metal compound selected from the group consisting of inorganic acid salts other than alkaline earth metal hydroxides, chlorides and carbonates, organic acid salts and oxides, and dioxide By adding a water-soluble group 4 transition metal compound to at least one of carbon and/or water-soluble carbonate compounds or a mixture thereof before and/or during mixing, grain growth during heat treatment The reason why the alkaline earth metal carbonate in which the is suppressed is obtained is considered as follows.
Particle growth of the alkaline earth metal carbonate during the heat treatment occurs when particles of the alkaline earth metal carbonate come into contact with each other during the heat treatment. On the other hand, when produced by the production method of the present invention, the presence of the Group 4 transition metal compound causes particles of the alkaline earth metal carbonate to grow during the heat treatment of the alkaline earth metal carbonate. It is believed that the Group 4 transition metal compound contacts the alkaline earth metal carbonate particles before contact with each other occurs, which inhibits the alkaline earth metal carbonate particle growth.
In the method for producing an alkaline earth metal carbonate of the present invention, in the step of producing an alkaline earth metal carbonate from a raw material, the alkaline earth metal carbonate is treated so that grain growth during heat treatment is suppressed at the same time. Therefore, compared with the conventional method in which surface treatment such as neutralization reaction is performed after synthesis of alkaline earth metal carbonate, it is easier to obtain alkaline earth metal carbonate with suppressed particle growth during heat treatment. Advantageous.
The alkaline earth metal carbonate obtained by such a production method of the present invention can also be called a group 4 transition metal element-containing alkaline earth metal carbonate, and the production method of the present invention is a group 4 transition metal element-containing alkaline earth metal carbonate. It can also be called a method for producing an alkaline earth metal carbonate.

The alkaline earth metal compound may be at least one selected from the group consisting of inorganic acid salts other than alkaline earth metal hydroxides, chlorides, and carbonates, organic acid salts, and oxides. It is preferably at least one selected from the group consisting of hydroxides and oxides. Hydroxides are more preferred because they have high solubility in water and high reaction efficiency in the conversion reaction to carbonates.
Examples of inorganic acid salts other than carbonates and organic acid salts include chlorates, acetates, and nitrates.

The alkaline earth metal compound is preferably a barium compound or a strontium compound. As described above, barium carbonate is used as a raw material for producing barium titanate by solid phase synthesis, and strontium carbonate is also used as a raw material for producing strontium titanate.
Therefore, it is one of preferred embodiments of the present invention that the method for producing alkaline earth metal carbonate of the present invention is used as a method for producing barium carbonate or strontium carbonate.

Examples of the water-soluble carbonate compounds include alkali metal or ammonium carbonates, hydrogencarbonates, and hydroxycarbonates. Examples of water-soluble carbonates include ammonium carbonate, sodium carbonate, potassium carbonate and the like, and one or more of these can be used. Examples of water-soluble hydrogencarbonates include sodium hydrogencarbonate and potassium hydrogencarbonate. Examples of water-soluble hydroxycarbonates include sodium hydroxide carbonate, potassium hydroxide carbonate, and the like.
In the present invention, "water-soluble" means dissolving 5 g or more in 100 g of water.

In the mixing step, the number of moles of carbon dioxide and water-soluble carbonate compound (the total number of moles when using both of them) per 1 mole of alkaline earth metal atoms contained in the alkaline earth metal compound. is preferably mixed so as to be 0.7 mol or more. More preferably, they are mixed so that the amount becomes 0.8 mol or more. From the point of view of economy, it is preferable to mix 3 mol or less with respect to 1 mol of alkaline earth metal atoms contained in the alkaline earth metal compound.
Among them, when carbon dioxide is used, it is more preferable to mix carbon dioxide in an amount of 1 mol or more with respect to 1 mol of alkaline earth metal atoms contained in the alkaline earth metal compound. Thereby, the yield of the alkaline earth metal carbonate to be obtained can be increased. Especially preferably, it is mixed so that the amount becomes 1.6 mol or more.
Further, when a water-soluble carbonate compound is used, from an economical point of view, the number of moles of the water-soluble carbonate compound per 1 mole of the alkaline earth metal atom contained in the alkaline earth metal compound is It is more preferable to mix so that the amount becomes 1.5 mol or less.

The water-soluble Group 4 transition metal compound may be a Group 4 transition metal compound, but is preferably a compound of titanium, zirconium, or hafnium, and more preferably titanium from the viewpoint of economy. is a compound of
In addition, the Group 4 transition metal compound may be any water-soluble compound, such as halides such as fluorides, chlorides, bromides, and iodides, lactates, ammonium lactates, sulfates, peroxates, alkoxides, and the like. 1 type or 2 types or more can be used. Among these, halides, lactates, and lactate ammonium salts are preferred. More preferably, it is a chloride, and an alkaline earth metal carbonate in which grain growth during heat treatment is more sufficiently suppressed can be obtained.

The amount of the water-soluble Group 4 transition metal compound to be added is determined in terms of sufficiently exhibiting the effect of suppressing grain growth during heat treatment of the alkaline earth metal carbonate to be produced and considering the production cost. The Group 4 transition metal element is preferably 0.5 to 10 parts by weight per 100 parts by weight of the alkaline earth metal carbonate converted from the alkaline earth metal compound. More preferably, it is 1 to 7 parts by weight, and still more preferably 2 to 5 parts by weight.

In the method for producing an alkaline earth metal carbonate of the present invention, at least one of an alkaline earth metal compound and carbon dioxide and/or a water-soluble carbonate compound is added before and/or in the mixing step. It is preferred to further include the step of adding citric acid and/or its salts to one or a mixture thereof.
By adding citric acid and/or a salt thereof, it becomes possible to sufficiently suppress grain growth during heat treatment of the obtained alkaline earth metal carbonate.

Examples of the citric acid salt include salts of Group 1 elements of the periodic table such as lithium, sodium and potassium, and salts of Group 2 elements of the periodic table such as magnesium, calcium and strontium. The above can be used.

The amount of citric acid and/or its salt to be added should be sufficient to exhibit the effect of suppressing particle growth during heat treatment of the alkaline earth metal carbonate to be produced, and considering the production cost, the alkaline earth metal It is preferably 0.1 to 10 mol per 100 mol of alkaline earth metal atoms contained in the compound. It is more preferably 0.5 to 5 mol, still more preferably 1 to 3 mol.

The method for producing an alkaline earth metal carbonate of the present invention further comprises at least an alkaline earth metal compound and carbon dioxide and/or a water-soluble carbonate compound before and/or in the mixing step. A step of adding at least one polybasic carboxylic acid other than citric acid and/or a salt thereof, an acid anhydride thereof, or a salt thereof (hereinafter referred to as polybasic carboxylic acid, etc.) to one or a mixture thereof You can
By using citric acid and/or its salt together with a polybasic carboxylic acid or the like, a finer alkaline earth metal carbonate can be produced.

The above polybasic carboxylic acid is preferably any one of tartaric acid, succinic acid, malic acid, maleic acid, malonic acid and trimellitic acid. Among these, tartaric acid, trimellitic acid, malic acid, and maleic acid are more preferred, and tartaric acid and trimellitic acid are even more preferred.

The amount of the polybasic carboxylic acid or the like added is preferably 1.10 to 9.90 mol % with respect to 100 mol % of the alkaline earth metal atoms in the alkaline earth metal compound. More preferably 1.25 to 8.00 mol%, still more preferably 2.00 to 6.5 mol%.

In the method for producing an alkaline earth metal carbonate of the present invention, the water-soluble Group 4 transition metal compound may be added to any of the alkaline earth metal compound, carbon dioxide and/or the water-soluble carbonate compound. , It may be added to both, or it may be added to the mixture after mixing them, and the time of addition may be the above-mentioned mixing step, before that, or both. However, when carbon dioxide is used, it is preferable to add at least part of the water-soluble Group 4 transition metal compound to the alkaline earth metal compound before mixing with carbon dioxide. At least part of the Group 4 transition metal compound and the alkaline earth metal compound are sufficiently mixed in advance and then mixed with carbon dioxide, so that the Group 4 transition metal compound is uniformly and highly concentrated in the resulting alkaline earth metal carbonate. It can be present in the dispersion, and the effect of suppressing grain growth during heat treatment can be exhibited more fully.
The amount of the Group 4 transition metal compound premixed with the alkaline earth metal compound is preferably 0.5% by weight or more of the total Group 4 transition metal compound to be added. More preferably, it is 1.0% by weight or more.

In the method for producing an alkaline earth metal carbonate of the present invention, the timing of addition when citric acid and/or a salt thereof is added is the same as the addition of the water-soluble Group 4 transition metal compound. When used, it is preferred to add at least a portion of the citric acid and/or its salts to the alkaline earth metal compound prior to mixing with carbon dioxide.
The amount of citric acid and/or its salt premixed with the alkaline earth metal compound is preferably 0.1% by weight or more based on the total amount of citric acid and/or its salt to be added. More preferably, it is 1.0% by weight or more.

In the mixing step, when the alkaline earth metal compound and carbon dioxide are mixed, the alkaline earth metal compound may be brought into contact with carbon dioxide. It is preferable to mix the raw material solution and carbon dioxide.
In that case, the solvent is not particularly limited as long as it is an aqueous medium, and water and a mixture of water and a water-soluble organic solvent (methanol, ethanol, acetone, etc.) can be used, and water is preferable. That is, mixing and reacting an alkaline earth metal compound aqueous solution and carbon dioxide is one of the preferred embodiments of the present invention.
The concentration of the alkaline earth metal compound in the raw material solution is not particularly limited, but is preferably 0.03 to 1.58 mol/L, more preferably 0.16 to 1.27 mol/L as alkaline earth metal ion. and more preferably 0.16 to 0.32 mol/L.

When the alkaline earth metal compound aqueous solution and carbon dioxide are mixed and reacted, the method of mixing is not particularly limited as long as they react. A method of inhaling, mixing, and reacting can be used. In this method, the alkaline earth metal compound aqueous solution and carbon dioxide are sufficiently stirred in the pump, so that the reaction can proceed sufficiently. In addition, by connecting a plurality of pumps in series and reacting in multiple stages, it is possible to proceed the reaction more sufficiently and efficiently produce a large amount of alkaline earth metal carbonate. Also suitable for production. Thus, at least one alkaline earth metal compound selected from the group consisting of inorganic acid salts other than alkaline earth metal hydroxides, chlorides and carbonates, organic acid salts and oxides of the present invention It is one of the preferred embodiments of the present invention that the mixing step of mixing with carbon dioxide is carried out by a pump reaction in which the alkaline earth metal compound aqueous solution and carbon dioxide are sucked into a pump, mixed in the pump, and reacted. is one.

In the above-mentioned mixing step, even when a water-soluble carbonate compound is used, the alkaline earth metal compound may be brought into contact with the water-soluble carbonate compound. It is preferable to add a solvent to either one or both of the salt compounds to obtain a raw material solution and then mix them. As the solvent in that case, the same ones as those mentioned above are preferable.
When a solvent is added to an alkaline earth metal compound to form a raw material solution, the concentration of the alkaline earth metal compound in the raw material solution is preferably the same as above.
When a solvent is added to a water-soluble carbonate compound to form a raw material solution, the concentration of the water-soluble carbonate compound in the raw material solution is not particularly limited, but is preferably 0.02 to 1.90 mol/mol as carbonate ion. L, more preferably 0.11 to 0.48 mol/L, still more preferably 0.11 to 0.35 mol/L.

In the mixing step, the aqueous alkaline earth metal compound solution, carbon dioxide and/or the water-soluble carbonate compound are mixed so that the pH of the mixed solution obtained by mixing the aqueous alkaline earth metal compound solution, carbon dioxide and/or the water-soluble carbonate compound is 12 or less. / Or mixing and reacting a water-soluble carbonate compound is preferable for obtaining fine alkaline earth metal carbonate particles. More preferably, the pH of the mixture is 8 or less, and more preferably 7 or less. Moreover, the pH of the mixed liquid is usually 5 or more.

Although the temperature at which the mixing step is performed is not particularly limited, it is preferably 10 to 70° C., for example. By carrying out the reaction at such a temperature, the reaction between the alkaline earth metal compound and carbon dioxide and/or the water-soluble carbonate compound can be sufficiently advanced. It is more preferably 15 to 50°C, still more preferably 20 to 40°C.

The method for producing an alkaline earth metal carbonate of the present invention may include other steps than the steps described above. Other steps include a purification step of the produced alkaline earth metal carbonate, a drying step, a pulverization step, and the like.
The step of purifying the alkaline earth metal carbonate can be carried out by filtration, washing with water, and the like.
The drying temperature in the step of drying the alkaline earth metal carbonate is preferably 60 to 200°C. More preferably, it is 80 to 130°C.

2. Method for Producing Barium Titanate As described above, the method for producing an alkaline earth metal carbonate of the present invention is a method capable of producing barium carbonate in which grain growth during heat treatment is sufficiently suppressed. Barium carbonate can be suitably used as a raw material for producing barium titanate.
A method for producing barium titanate including a step of producing barium carbonate by the method for producing alkaline earth metal carbonate of the present invention, that is, inorganic acid salts other than barium hydroxide, chloride and carbonate , an organic acid salt, a mixing step of mixing at least one barium compound selected from the group consisting of an organic acid salt and an oxide with carbon dioxide and/or a water-soluble carbonate compound, before the mixing step, and/or In the mixing step, a barium compound and a step of adding a water-soluble Group 4 transition metal compound to at least one of carbon dioxide and/or a water-soluble carbonate compound to obtain barium carbonate; A method for producing barium titanate, which includes a mixing step of mixing a titanium compound, and a step of firing the mixture obtained in the mixing step, is also one aspect of the present invention.

Examples of the titanium compound used in the mixing step of mixing the barium carbonate and the titanium compound include titanium oxide, metatitanic acid, orthotitanic acid, and titanium hydroxide, and one or more of these may be used. can be done.

Considering the yield and production cost of barium titanate, the amount of the titanium compound used in the mixing step of mixing the barium carbonate and the titanium compound should be It is preferable that the amount of titanium atoms contained in is 100.1 to 101 mol. More preferably, the amount is 100.3 to 100.6 mol.

The firing temperature in the step of firing the mixture obtained in the mixing step of mixing the barium carbonate and the titanium compound is preferably 900 to 1450°C. More preferably, it is 1000 to 1350°C.

The method for producing barium titanate of the present invention may include other steps than the steps described above. Other steps include a purification step of the produced barium titanate, a drying step, a pulverization step, and the like.

Specific examples are given below to describe the present invention in detail, but the present invention is not limited only to these examples. Unless otherwise specified, "%" and "wt%" mean "% by weight (% by mass)". In addition, the measuring method of each physical property is as follows.

(Example 1)
After dissolving 145 g of barium hydroxide octahydrate in pure water, 2.3 mol of citric acid/monohydrate aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) per 100 mol of barium ions in barium hydroxide. , 2 parts by weight of titanium tetrachloride aqueous solution (manufactured by Osaka Titanium Technologies, 150 g/L in terms of TiO ₂ ) was added as Ti to 100 parts by weight of barium hydroxide converted to barium carbonate.
Next, the barium hydroxide/citric acid aqueous solution ( Raw material A) was prepared. The liquid temperature at that time was adjusted to 32°C. In the reactor shown in FIG. 1, raw material A was introduced into the suction port of pump P1 at a flow rate of 400 ml/min. At the same time, the reaction was carried out by blowing carbon dioxide gas into the flow path of the raw material A to the pump P1 at 4.2 L/min so that the pH became 6.0 to 7.0. As shown in FIG. 1, the reaction apparatus used was one in which magnet pumps P1, P2 (manufactured by Iwaki Co., Ltd., MD-10K-N) and P3 (manufactured by Iwaki Co., Ltd., MD-15R-N) were connected in three stages. .
The initial distillation at the initial stage of the reaction was discarded for 1 minute, and the reaction slurry was recovered. This slurry was immediately filtered and washed with water, and the water-containing cake was dried at 100°C. After drying, the dried product was pulverized with a pulverizer to obtain powdery barium carbonate.

(Example 2)
Barium carbonate was produced in the same manner as in Example 1 except that titanium tetrachloride in Example 1 was changed to titanium lactate (Orgatics TC-315, manufactured by Matsumoto Fine Chemicals Co., Ltd.).

(Example 3)
Barium carbonate was produced in the same manner as in Example 1 except that titanium tetrachloride in Example 1 was changed to titanium ammonium lactate (Orgatics TC-335, manufactured by Matsumoto Fine Chemicals Co., Ltd.).

(Example 4)
The same procedure as in Example 1 was repeated except that the addition amount of titanium tetrachloride in Example 1 was changed to 0.5 parts by weight as Ti with respect to 100 parts by weight of barium hydroxide converted to barium carbonate. manufactured.

(Example 5)
The same procedure as in Example 1 was repeated except that the addition amount of titanium tetrachloride in Example 1 was changed to 1.0 parts by weight as Ti with respect to 100 parts by weight of barium hydroxide converted to barium carbonate. manufactured.

(Example 6)
The same procedure as in Example 1 was repeated except that the addition amount of titanium tetrachloride in Example 1 was changed to 5.0 parts by weight as Ti with respect to 100 parts by weight of barium hydroxide converted to barium carbonate. manufactured.

(Example 7)
Strontium carbonate was produced in the same manner as in Example 1, except that barium hydroxide octahydrate in Example 1 was changed to strontium hydroxide octahydrate.

(Comparative example 1)
Barium carbonate was produced in the same manner as in Example 1, except that the titanium tetrachloride in Example 1 was changed to non-additive.

(Comparative example 2)
Strontium carbonate was produced in the same manner as in Comparative Example 1, except that barium hydroxide octahydrate in Comparative Example 1 was changed to strontium hydroxide octahydrate.

[evaluation]
The barium carbonate or strontium carbonate obtained in Examples 1 to 7 and Comparative Examples 1 and 2 were evaluated as follows.
<Evaluation of heat resistance>
1 g of a barium carbonate or strontium carbonate sample was placed in a magnetic crucible, heated to 600° C. at a heating rate of 200° C./hour in air, and held for 30 minutes. After that, it was allowed to cool to room temperature to obtain a heat-treated sample. The BET specific surface areas of the samples before and after the heat treatment were measured using a specific surface area measuring device, Macsorb manufactured by Mounttech. Table 1 shows the results.
<Analysis of Titanium Concentration>
Barium carbonate or strontium carbonate was subjected to elemental analysis by EZ scan, which is a contained element scanning function of a fluorescent X-ray analyzer (manufactured by Rigaku Corporation: model number ZSX PrimusII).
Specifically, the pressed sample is set on the measurement sample table, and the following conditions are selected (measurement range: FU, measurement diameter: 30 mm, sample form: oxide, measurement time: long, atmosphere: vacuum). Thus, the Ba or Sr content and the Ti content were measured, and the weight parts of Ti per 100 weight parts of barium carbonate or strontium carbonate were calculated using the following formula. Table 1 shows the results.
Parts by weight of Ti per 100 parts by weight of barium carbonate or strontium carbonate =
{Ti content [g]/[(Ba or Sr content [g]/Ba or Sr atomic weight [g/mol])×barium carbonate or strontium carbonate molecular weight [g/mol]]}×100
<Appearance evaluation>
Scanning electron microscope (SEM) (product name "JSM-6510A", manufactured by JEOL Ltd.) of barium carbonate or strontium carbonate samples subjected to heat treatment similar to the above heat resistance evaluation before and after heat treatment. observed using The results are shown in Figures 2-8. The SEM photographs of Figures 2-8 are at 30,000x magnification.

As shown in Table 1, the barium carbonates or strontium carbonates of Examples 1 to 7 produced by adding a titanium compound were superior to the barium carbonates or strontium carbonates of Comparative Examples 1 and 2 to which no titanium compound was added. In comparison, the rate of change in BET specific surface area after heat treatment is smaller than that before heat treatment. 2 to 8, it is confirmed that the barium carbonate particles after the heat treatment are larger in FIG. 8 than in FIGS. From these results, it was confirmed that grain growth during heat treatment was suppressed by adding a titanium compound during the production of alkaline earth metal carbonate. Furthermore, from a comparison of Examples 1 to 7, it was confirmed that grain growth during heat treatment can be more effectively suppressed by setting the addition ratio of the titanium compound within a predetermined range.

Claims (4)

At least one alkaline earth metal compound selected from the group consisting of inorganic acid salts other than alkaline earth metal hydroxides, chlorides and carbonates, organic acid salts and oxides, carbon dioxide and/or water solubility A mixing step of mixing with a carbonate compound of
Before the mixing step and/or in the mixing step, an alkaline earth metal compound and at least one of carbon dioxide and/or a water-soluble carbonate compound or a mixture thereof, and a water-soluble Group 4 transition metal compound and adding citric acid and/or a salt thereof. 2. The method for producing an alkaline earth metal carbonate according to claim 1, wherein the alkaline earth metal compound is a barium compound or a strontium compound. 3. The method for producing an alkaline earth metal carbonate according to claim 1, wherein the water-soluble Group 4 transition metal compound is a water-soluble titanium compound. At least one barium compound selected from the group consisting of inorganic acid salts other than barium hydroxides, chlorides, and carbonates, organic acid salts, and oxides, and carbon dioxide and/or a water-soluble carbonate compound In the mixing step of mixing, and before the mixing step and/or in the mixing step, a barium compound, and at least one of carbon dioxide and/or a water-soluble carbonate compound or a mixture thereof Water-soluble Group 4 obtaining barium carbonate by adding a transition metal compound and citric acid and/or a salt thereof ;
A mixing step of mixing the barium carbonate and a titanium compound;
and a step of firing the mixture obtained in the mixing step.

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