JP4235409B2 - Method for producing fine barium carbonate and method for producing barium titanate - Google Patents

Description

【００７０】
表１の結果、本発明に係る製造方法で得られたものは、ＢＥＴ比表面積が増加し、微細で不純物量が低く、強熱減量の低い炭酸バリウムを得ることができることが分かる。
【００７１】
実施例２
アスコルビン酸の添加量を５０gとして、上記式（８）から計算される炭酸バリウム量に対する添加率を５．０％に相当する量とした以外は実施例１と同様にして炭酸バリウム（炭酸バリウムＣ）を得た。この炭酸バリウムについて、実施例１と同様にしてＢＥＴ比表面積、平均粒子径、酸化性硫黄含有量及び強熱減量を測定した。この結果を表２に示す。
【００７２】
比較例２
ジルコニアビーズを添加しなかったこと以外は実施例２と同様にして炭酸バリウム（炭酸バリウムＤ）を得た。この炭酸バリウムについて、実施例１と同様にしてＢＥＴ比表面積、平均粒子径、酸化性硫黄含有量及び強熱減量を測定した。この結果を表２に示す。
【００７３】
【表２】

【００７４】
実施例３
塩化バリウムの二水塩１２２．２g/L を含有する水溶液１０Lを原料貯蔵槽２に投入し、この水溶液にアスコルビン酸２５gを粉末で添加溶解して、バリウム塩反応液（バリウム塩反応液Ｃ）を調製した。なお、アスコルビン酸の添加量は、下記化学反応式（９）
ＢａＣｌ_２＋ＣＯ_２＋２ＮａＯＨ→ＢａＣＯ_３＋２ＮａＣｌ＋Ｈ_２Ｏ（９）
から計算される炭酸バリウム量に対する添加率が２．５％に相当する量である。次いで、水酸化ナトリウム３００gを蒸留水に溶解したものをバリウム塩反応液Ｃに添加して攪拌し、アルカリ反応液（アルカリ反応液Ｃ）を調製した。なお、水酸化ナトリウムの添加量は生成する炭酸バリウムの当量以上に相当する量である。
【００７５】
その後、ジルコニアビーズを投入しなかったこと、及びアルカリ反応液Ａに代えてアルカリ反応液Ｃを用いたこと以外は実施例１と同様にして、ビーズミル装置１を用いてアルカリ反応液Ｃと二酸化炭素とを回転筒１ａ内の滞留時間が９０秒となるように回転筒１ａ内で反応させ、反応後のスラリーを排出口１ｈから生成物貯蔵槽４に排出した。この時の回転筒１ａ内の反応温度は３０℃であり、また排出口１ｈから生成物貯蔵槽４に供給されるスラリーのｐＨが１３．２まで低下した時点で反応を終了させた。なお、ジルコニアビーズはメディア分離装置１ｄを通過せず、生成物貯蔵槽４に移動することはなかった。
【００７６】
次いで、予め生成物貯蔵槽４と導入口１ｇとの間を図示しないポンプを介して接続してある戻り配管を用いて、生成物貯蔵槽４中のスラリー（スラリーＥ）を導入口１ｇに返送し、生成物貯蔵槽４と回転筒１ａとの間でスラリーＥを循環させた。
【００７７】
次いで、流動媒体として径が０．４mmのジルコニアビーズを回転筒１ａ内の充填率が８５％になるように導入口１ｇから投入し、ジルコニアビーズが周速度１０m/sで攪拌されるように回転筒１ａ及び攪拌羽根部１ｂを駆動してスラリーＥの滞留時間が９０秒となるようにして湿式粉砕処理を行い、粉砕処理後のスラリーを排出口１ｈから生成物貯蔵槽４に排出した。なお、ジルコニアビーズはメディア分離装置１ｄを通過せず、生成物貯蔵槽４に移動することはなかった。
【００７８】
次いで、生成物貯蔵槽４内のスラリー（スラリーＦ）を濾過、洗浄、乾燥して炭酸バリウム（炭酸バリウムＥ）を得た。この炭酸バリウムについて、実施例１と同様にしてＢＥＴ比表面積、平均粒子径及び強熱減量を測定し、また、塩素イオン含有量を下記の方法により測定した。この結果を表３に示す。
【００７９】
・塩素イオン含有量
炭酸バリウム試料を硝酸に溶かし、この溶液に硝酸銀水溶液を加え塩素イオンを塩化銀とした。塩化銀の白濁の程度を塩化物の標準液と比濁して溶液中の塩化銀の濃度を求め、該濃度と炭酸バリウム試料の重量とから炭酸バリウム試料中の塩化物の含有量を定量した。
【００８０】
比較例３
スラリーＥをスラリーＦにする処理を行わず、スラリーＥを直接に濾過、洗浄、乾燥したこと以外は実施例３と同様にして炭酸バリウム（炭酸バリウムＦ）を得た。この炭酸バリウムについて、実施例１と同様にしてＢＥＴ比表面積、平均粒子径、強熱減量及び塩素イオン含有量を測定した。この結果を表３に示す。
【００８１】
【表３】

【００８２】
表３の結果より、流動媒体を作用させることにより微細で不純物が低く、強熱減量が低い炭酸バリウムを得ることができることが分かる。
【００８３】
実施例４
生成物貯蔵槽４内のスラリーＡをそのまま濾過することに代えて、スラリーＡ中に含まれる炭酸バリウム量に対して２３．３重量％となる量のエチレングリコールをスラリーＡに添加し、攪拌してスラリー（スラリーＧ）を調製した後に、スラリーＧを濾過した以外は、実施例１と同様にして炭酸バリウム（炭酸バリウムＧ）を得た。この炭酸バリウムについて、実施例１と同様にしてＢＥＴ比表面積、平均粒子径、酸化性硫黄含有量及び強熱減量を測定した。この結果を表４に示す。
【００８４】
【表４】

【００８５】
＜チタン酸バリウムの製造法＞
実施例５
実施例３で得られた微粒炭酸バリウム（炭酸バリウムＥ）と高純度酸化チタン（チタン工業株式会社製、品名；クロルス酸化チタンKA-10C、ＢＥＴ比表面積；９．２m²/g、平均粒子径０．３７μm）とをＴｉ／Ｂａのモル比で１．００６となるように湿式混合機としてボールミル（三井三池化工機株式会社製、型式；アトライタMA−015C）を用いて充分混合し、１３０℃で２４時間乾燥後、粉砕した。次いで、９００℃で２時間焼成を行ってチタン酸バリウムを得た。
【００８６】
得られたチタン酸バリウムは、走査型電子顕微鏡（SEM）写真から求めた平均粒子径が０．７μmであり、また、このチタン酸バリウムについてＣｕＫα線を線源としてＸ線回折を行ったところ、未反応原料の炭酸バリウムと二酸化チタンのピークは確認できなかった。この結果を表５に示す。
【００８７】
実施例６
実施例４で得られた微粒炭酸バリウム（炭酸バリウムＧ）と高純度酸化チタン（チタン工業株式会社製、品名；クロルス酸化チタンKA-10C、ＢＥＴ比表面積；９．２m²/g、平均粒子径０．３７μm）とをＴｉ／Ｂａのモル比で１．００６となるように湿式混合機としてボールミル（三井三池化工機株式会社製、型式；アトライタMA−015C）を用いて充分混合し、１３０℃で２４時間乾燥後、粉砕した。
【００８８】
この粉砕物の一部０．０８gを示差熱分析器（マックスサイエンス株式会社製、型式；TG−DTA2000）中で炭酸バリウムと二酸化チタンとの固相反応を行って、反応中のＤＴＡ曲線を図２に示す。また、この粉砕物４gを坩堝中で８３０℃で２時間焼成を行った際に得られたチタン酸バリウムは走査型電子顕微鏡（SEM）写真により求めた平均粒子径が０．５μmであった。更に、このチタン酸バリウムについてＣｕＫα線を線源としてＸ線回折を行ったところ、未反応原料の炭酸バリウムと二酸化チタンのピークは確認できなかった。この結果を表５に示す。
【００８９】
比較例５
市販の炭酸バリウム（平均粒子径１．４μm、比表面積２．５m²/g）、高純度酸化チタン（チタン工業株式会社製、品名；クロルス酸化チタンKA-10C、ＢＥＴ比表面積；９．２m²/g、平均粒子径０．３７μm）とをＴｉ／Ｂａのモル比で１．００６となるように湿式混合機としてボールミル（三井三池化工機株式会社製、型式；アトライタMA−015C）を用いて充分混合し、１３０℃で２４時間乾燥後、粉砕した。次いで、この粉砕物の一部０．０８gを示差熱分析器（マックスサイエンス株式会社製、型式；TG−DTA2000）中で炭酸バリウムと二酸化チタンとの固相反応を行って、反応中のＤＴＡ曲線を図２に示す。
【００９０】
また、この粉砕物４gを坩堝中で８３０℃で２時間焼成を行った際に得られたチタン酸バリウムは電子顕微鏡観察による平均粒子径が０.６μmであった。更に、このチタン酸バリウムについてＣｕＫα線を線源としてＸ線回折を行ったところ、未反応原料の炭酸バリウムと二酸化チタンのピークが確認できた。この結果を表５に示す。
【００９１】
【表５】

【００９２】
実施例６と比較例５の結果より、比較例５の市販の微粒炭酸バリウムと二酸化チタンとを反応させたものは、図２において、下記反応式（１０）
ＢａＣＯ_３＋ＴｉＯ_２→ＢａＴｉＯ_３＋ＣＯ_２↑ （１０）
に基づく、炭酸バリウムの相転移（β→α）に伴う吸熱ピークが９８０℃付近に見られるのに対して、実施例６の本発明の微粒炭酸バリウムと二酸化チタンとの反応は、この９８０℃付近の相転移に伴う吸熱ピークがないことから、この相転移に達する前に脱ＣＯ_２が完了し、微粒炭酸バリウムと二酸化チタンとの反応によるチタン酸バリウムの生成反応が完了したことが解る。また、本発明の微粒炭酸バリウムと二酸化チタンとの反応は８３０℃という低温域でも、未反応炭酸バリウムが残存することなく高純度のチタン酸バリウムが得られることが解る。なお、実施例、比較例においてバリウム塩反応液、アルカリ反応液、スラリー及び炭酸バリウムに用いた符号の一覧を表６に示す。
【００９３】
【表６】

【００９４】
【発明の効果】
本発明に係る微粒炭酸バリウムの製造方法によれば、微細で、不純物含有量が低く、強熱減量が少ない微粒炭酸バリウムを低コストで製造することができる。また、上記方法で得られた微粒炭酸バリウムと二酸化チタンとを反応させることにより、電子部品用として好適なチタン酸バリウムが安価に得られる。
【図面の簡単な説明】
【図１】ビーズミル装置の一例を模式的に示した図である。
【図２】ＤＴＡ曲線を示すグラフである。
【符号の説明】
１ ビーズミル装置
１ａ 回転筒
１ｂ 攪拌羽根部
１ｃ ジルコニアビーズ
１ｄ メディア分離装置
１ｅ 攪拌羽根駆動部
１ｆ、１ｇ 導入口
１ｈ 排出口
２ 原料貯蔵槽
３ 炭酸ガスボンベ
４ 生成物貯蔵槽
Ｐ ポンプ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing fine-grained barium carbonate and a method for producing barium titanate. More specifically, the present invention is excellent in reactivity with titanium dioxide and produces barium titanate by firing in a lower temperature region than in the past. The present invention relates to a method for producing fine barium carbonate that can be produced and a method for producing barium titanate using the same as a raw material.
[0002]
[Prior art]
Barium carbonate is known as a raw material for ceramics and optical glass as well as a barium salt raw material such as barium titanate. Further, barium titanate, which is a reaction product of barium carbonate and titanium dioxide, is important as a material for ceramic capacitors because it has a high dielectric constant. Further, fine particles of barium carbonate are particularly preferably used as a raw material for producing barium titanate because they are highly reactive. For this reason, the manufacturing method which can obtain a granular barium carbonate at low cost is desired.
[0003]
As a general industrial production method of barium carbonate which is not fine, a method of reacting a soluble barium salt with a soluble carbonate or carbon dioxide by the reaction formulas shown in the following formulas (1) to (7) is known.
[0004]
BaS + Na ₂ CO ₃ → BaCO ₃ + Na ₂ S (1)
BaS + (NH ₄ ) ₂ CO ₃ → BaCO ₃ + (NH ₄ ) ₂ S (2)
BaS + CO ₂ + H ₂ O → BaCO ₃ + H ₂ S (3)
BaCl ₂ + Na ₂ CO ₃ → BaCO ₃ + 2NaCl (4)
BaCl ₂ + (NH ₄ ) ₂ CO ₃ → BaCO ₃ + 2NH ₄ Cl (5)
BaCl ₂ + NH ₄ HCO ₃ + NH ₃ → BaCO ₃ + (NH ₄ ) ₂ S (6)
Ba (OH) ₂ + CO ₂ → BaCO ₃ + H ₂ O (7)
[0005]
On the other hand, as an industrial production method of fine-grained barium carbonate, for example, as a method utilizing the reaction of the above formula (7), a mixture of a barium hydroxide solution and carbon dioxide is disclosed in JP-T-11-514916. Introduce into a stirring reactor (homogenizer) whose rotor rotates at a high rotational speed of 2000 to 8000 rpm, add a crystal growth inhibitor, apply shearing force and frictional force to the precipitated barium carbonate, and fine particles within a residence time of 5 seconds A method for producing barium carbonate is disclosed.
[0006]
As for the above formula (3), JP-A-49-90300 discloses that the temperature of a BaS reaction solution having a concentration of 30% by weight or less is 50 ° C. or less and carbon dioxide is blown in an oxygen-free state. After producing barium, a method for producing fine, highly reactive, high-purity barium carbonate is disclosed in which the produced barium carbonate is further heated in an alkaline aqueous solution in order to reduce the sulfur of impurities incorporated into the particles. .
[0007]
[Problems to be solved by the invention]
However, in the barium carbonate obtained by the production method described in the above-mentioned Japanese translation of PCT publication No. 11-514961, impurities such as a crystal growth inhibitor, oxidizing sulfur, sodium and chlorine remain in the barium carbonate, and the ignition loss (700 There is a problem that the amount of impurities due to reduction of impurities, chemically adsorbed water, etc. when roasted at 0 ° C.) increases, resulting in an expensive product.
[0008]
Further, in the method described in JP-A-49-90300, since the amount of impurities is reduced while heating in an alkaline solution for a long time to grow particles, the BET specific surface area is 5 m. ² There is a problem that fine barium carbonate with a high specific surface area of at least 10g / g cannot be obtained.
[0009]
Therefore, the object of the present invention is to produce fine barium carbonate that is fine, has a low impurity content, and has a low loss on ignition, and can produce barium titanate at a low cost. It is providing the manufacturing method and the manufacturing method of barium titanate.
[0010]
[Means for Solving the Problems]
In such a situation, the present inventor, when or after the production of barium carbonate, brings the barium carbonate reaction raw material or the produced barium carbonate and the granular medium into contact with each other in a state where the granular medium flows at high speed. The resulting barium carbonate is fine due to the shearing force and frictional force generated between the reaction raw material and the granular medium, the impurity content is low, the ignition loss is reduced, and the fine barium carbonate and dioxide It has been found that when titanium is reacted, barium titanate can be produced even if the firing temperature is lower than before, and the present invention has been completed.
[0011]
That is, the present invention relates to a soluble barium salt-containing solution (a), a carbon dioxide or soluble carbonate-containing solution (b), and a granular medium (c). Maximum peripheral speed 0.1-25m / s In a state of flowing in 15 seconds or more The present invention provides a method for producing fine-grained barium carbonate, which is characterized in that they are brought into contact.
[0012]
The present invention also provides a mixture of the barium carbonate slurry (d) and the granular medium (c), wherein the granular medium (c) Maximum peripheral speed 0.1-25m / s In a state of flowing in 15 seconds or more The present invention provides a method for producing fine-grained barium carbonate, which is fluidized.
[0013]
Moreover, this invention provides the manufacturing method of the barium titanate characterized by mixing and baking the fine barium carbonate obtained by the said manufacturing method, and titanium dioxide.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
A first method for producing fine barium carbonate according to the present invention comprises a soluble barium salt-containing solution (a), carbon dioxide or a soluble carbonate-containing solution (b), and a granular medium (c). ) Is contacted in a state of flowing at high speed. The carbon dioxide or soluble carbonate-containing solution (b) is an embodiment including only one of carbon dioxide and a soluble carbonate-containing solution, and an embodiment including both carbon dioxide and a soluble carbonate-containing solution. It is the meaning which shows 3 aspects. That is, in the present invention, carbon dioxide and a soluble carbonate-containing solution can be used in combination.
[0015]
The soluble barium salt-containing solution (a) used in the present invention is an aqueous solution of a soluble barium salt. Examples of the soluble barium salt used in the present invention include barium sulfide, barium chloride, barium hydroxide, barium nitrate and the like. In the present invention, one or more of these can be used in combination. The aqueous solution concentration of the soluble barium salt-containing solution (a) is not particularly limited as long as it is within the solubility of the soluble barium salt.
[0016]
In the present invention, carbon dioxide is used in a gaseous state upon contact with the soluble barium salt-containing solution (a) or the granular medium (c). Moreover, the soluble carbonate containing solution used by this invention is the aqueous solution of soluble carbonate. Examples of the soluble carbonate used in the present invention include ammonium bicarbonate, sodium carbonate, ammonium carbonate and the like. In the present invention, one or more of these can be used in combination. In addition, the aqueous solution density | concentration of a soluble carbonate containing solution should just be less than the solubility of soluble carbonate, and is not restrict | limited in particular.
[0017]
As the granular medium (c) in the present invention, a granular material capable of high-speed flow having chemical resistance such as acid resistance and alkali resistance, water resistance, non-reactivity, ductility, and non-destructiveness is used. Here, non-reactive means that there is no reactivity between the soluble barium salt-containing solution (a), carbon dioxide, soluble carbonate-containing solution and barium carbonate slurry (d). Examples of such granular medium (c) include ceramic beads and resin beads. Examples of the ceramic beads include zirconia beads, alumina beads, silica beads, zeolite beads, silicon carbide, and silicon nitride.
[0018]
Examples of the shape of the granular medium (c) include a spherical shape, a spindle shape, a cylindrical shape, and an indefinite shape. Among these, the spherical shape is preferable because a substantially constant shearing force and frictional force can be applied to the generated barium carbonate during high-speed flow, and there are few variations in the particle size and quality of barium carbonate.
[0019]
The particle size of the granular medium (c) is usually 0.05 to 10 mm, preferably 0.1 to 3 mm. If the diameter of the granular medium (c) is less than 0.05 mm, it is not preferable because mechanical separation by a filter or the like with the granular medium (c) and the barium carbonate slurry (d) in the same system tends to be difficult. On the other hand, when the diameter of the granular medium (c) exceeds 10 mm, the BET specific surface area is 5 m. ² It is not preferable because it is difficult to obtain fine barium carbonate of more than / g, and a process of flowing at a high speed is required for a long time and energy efficiency is likely to be lowered. In the present invention, the granular medium (c) can be used alone or in combination of two or more thereof.
[0020]
The first method for producing fine barium carbonate comprises the above-mentioned soluble barium salt-containing solution (a), carbon dioxide or a soluble carbonate-containing solution (b), and a granular medium (c). It contacts in the state which flows at high speed. In the first method for producing fine-grained barium carbonate, the contact means that in the presence of the soluble barium salt-containing solution (a) and carbon dioxide or the soluble carbonate-containing solution (b), and the granular medium (c). Means a state where the three come into contact, that is, a state where (a), (b) and (c) contact.
[0021]
The mixing order of the soluble barium salt-containing solution (a) and the like at the time of contacting is not particularly limited.For example, (a) and (c) are mixed and the granular medium (c) flows at a high speed. The order in which (b) is added to the mixture, soluble carbonate-containing solutions (b) and (c) are mixed, and the mixture is kept in a state where the granular medium (c) flows at a high speed. Examples include the order in which (a) is added to the mixture, and the order in which (a), (b) and (c) are mixed at the same time so that the granular medium (c) flows at a high speed.
[0022]
Further, the contact method may be a treatment method in which the soluble barium salt-containing solution (a) or the like is continuously supplied into the reactor and continuously contacted so as to sequentially discharge the barium carbonate slurry or the like, A treatment method in which the barium carbonate slurry or the like in the reaction vessel is exchanged every time the barium carbonate is produced may be contacted intermittently by so-called batch treatment.
[0023]
In the present invention, the state in which the granular medium (c) flows at a high speed means that the granular medium (c) has a maximum peripheral speed of 0.1 to 25 m / s, preferably 1 to 20 m / s. When the maximum peripheral speed is less than 0.1 m / s, the shearing force on the barium carbonate crystal is insufficient and it is difficult to obtain fine barium carbonate. On the other hand, when the maximum peripheral speed exceeds 25 m / s, the granular medium (c) It is not preferable because the barium carbonate slurry (d) is easily contaminated by its own wear and the energy efficiency of shearing force and frictional heat is likely to decrease.
[0024]
In the present invention, the filling rate of the granular medium (c) in the reactor is usually 40 to 95%, preferably 60 to 95%, more preferably 70 to 90%. Here, the filling rate is the volume of a substantial space excluding high-speed flow means such as a stirrer among the spaces in the reactor in an empty state in which no water or granular medium (c) is charged. It means the ratio of the apparent volume of the granular medium (c). Here, the apparent volume refers to a volume occupied by the outer shape of the entire granular medium (c) including a space generated between the granular mediums (c). The apparent volume is, for example, the product of the height of the granular medium (c) and the bottom area of the cylindrical container when the granular medium (c) is naturally dropped and filled in the cylindrical container and the upper surface is leveled flat. Desired. It is preferable that the filling rate of the granular medium (c) is within this range because the shearing force and frictional force of the granular medium (c) against the precipitated barium carbonate can be appropriately managed. On the other hand, if the filling rate exceeds 95%, a medium locking phenomenon occurs, resulting in an overload of the driving device. If the filling rate is less than 40%, the collision probability of the granular medium (c) is remarkably reduced, and barium carbonate is formed. Since it becomes difficult to miniaturize, each is not preferable.
[0025]
The contact time is usually 15 seconds or longer, preferably 1 to 10 minutes. When the contact time is less than 15 seconds, the generated barium carbonate is not sufficiently refined and impurities are not sufficiently removed. In order to sufficiently remove impurities in the generated barium carbonate, the contact time is preferably as long as possible within the above range.
[0026]
Moreover, contact temperature is 100 degrees C or less normally, Preferably it is 0-40 degreeC, More preferably, it is 0-30 degreeC. Here, the contact temperature means the average temperature of the entire mixture existing at the time of contacting the soluble barium salt-containing solution (a) with the carbon dioxide or soluble carbonate-containing solution (b). When the contact temperature is within this range, the lower the contact treatment temperature, the smaller the particle size of the barium carbonate obtained, which is preferable. However, when the temperature is lower than 0 ° C., the reaction efficiency is deteriorated, which is not preferable.
[0027]
In addition, when there is a possibility that the soluble barium salt-containing solution (a) reacts with carbon dioxide or the soluble carbonate-containing solution (b) to produce by-products such as hydrochloric acid or hydrogen sulfide, if necessary, An alkaline agent may be added to the soluble barium salt-containing solution (a) or the soluble carbonate-containing solution (b). Examples of the alkali agent include sodium hydroxide and ammonia. The amount of the alkali agent added is preferably equal to or greater than the amount of barium carbonate produced. Here, an equivalent means the quantity from which the normality of the produced | generated barium carbonate and an alkali agent becomes equal. It is preferable to add an alkali agent in an equivalent amount or more because the pH of the solution becomes 7 or more when barium carbonate is generated, and barium carbonate that is easily dissolved in the acidic region is difficult to dissolve. Examples of the method for adding the alkali agent include, for example, an embodiment in which an alkali agent is added to the soluble barium salt-containing solution (a), an embodiment in which an alkali agent is added to the soluble carbonate-containing solution (b), and a soluble barium salt-containing solution ( Examples include an embodiment in which an alkali agent is added to the mixture of a) and the granular medium (c), an embodiment in which an alkali agent is added to the mixture of the soluble carbonate-containing solution (b) and the granular medium (c).
[0028]
In the first method for producing fine-grained barium carbonate, a soluble barium salt-containing solution (a), carbon dioxide or a soluble carbonate-containing solution (b), a granular medium (c), and an alkaline agent as necessary are granular. As a specific embodiment in which the medium (c) is contacted in a state where it flows at a high speed, for example, the following method may be mentioned.
[0029]
(1) A soluble barium salt-containing solution (a) is supplied into the reaction apparatus charged with the granular medium (c), and the reaction apparatus is stirred at high speed to cause the granular medium (c) to flow at a high speed together with the solution (a). A method of bringing carbon dioxide or a soluble carbonate-containing solution (b) into contact with the apparatus.
(2) A soluble barium salt-containing solution (a) is supplied into the reaction apparatus charged with the granular medium (c), and the reaction apparatus is stirred at high speed to cause the granular medium (c) to flow at a high speed together with the solution (a). A method in which an alkali agent is added to the apparatus, and then carbon dioxide or a soluble carbonate-containing solution (b) is introduced and contacted.
(3) A soluble barium salt-containing solution (a) to which an alkaline agent has been added is fed into the reaction apparatus charged with the granular medium (c), and the reaction apparatus is stirred at a high speed to obtain the granular medium (c) in the solution (a ), And the carbon dioxide or soluble carbonate-containing solution (b) is introduced into and contacted with the apparatus.
(4) A soluble barium salt-containing solution (a) is supplied into the reaction apparatus charged with the granular medium (c), and the reaction apparatus is stirred at high speed to cause the granular medium (c) to flow at a high speed together with the solution (a). A method of introducing and contacting a soluble carbonate-containing solution (b) to which carbon dioxide or an alkaline agent is added in this apparatus.
(5) A soluble carbonate-containing solution (b) is supplied into the reaction apparatus charged with the granular medium (c), and the reaction apparatus is stirred at high speed to cause the granular medium (c) to flow at a high speed together with the solution (b). A method of introducing and contacting the soluble barium salt-containing solution (a) into the apparatus.
(6) A soluble carbonate-containing solution (b) is supplied into the reaction apparatus charged with the granular medium (c), and the reaction medium is stirred at high speed to cause the granular medium (c) to flow at a high speed together with the solution (b). A method of introducing a soluble barium salt-containing solution (a) and bringing it into contact after adding an alkali agent to the apparatus.
(7) A soluble carbonate-containing solution (b) to which an alkaline agent has been added is fed into the reaction apparatus charged with the granular medium (c), and the reaction apparatus is stirred at a high speed to obtain the granular medium (c) in the solution (b ), And a solution containing the soluble barium salt (a) is introduced into and contacted with the apparatus.
(8) The soluble carbonate-containing solution (b) is supplied into the reaction apparatus charged with the granular medium (c), and the reaction apparatus is stirred at high speed to cause the granular medium (c) to flow at a high speed together with the solution (b). A method of introducing and contacting the soluble barium salt-containing solution (a) to which an alkaline agent has been added, into the apparatus.
[0030]
In a state where the granular medium (c) flows at a high speed, when the soluble barium salt-containing solution (a), the carbon dioxide or soluble carbonate-containing solution (b), and the granular medium (c) are brought into contact with each other, Since the generated barium carbonate is refined by applying a shearing force and a frictional force by the granular medium (c), a slurry containing fine barium carbonate is obtained. The slurry is appropriately filtered and washed to separate fine barium carbonate filter cake, and when the filter cake is dried, fine barium carbonate is obtained. The resulting fine barium carbonate has a BET specific surface area of 5 to 50 m. ² / g, preferably 5-40m ² / g, the average particle size determined by the laser diffraction method is 0.01 to 1.0 μm, preferably 0.05 to 0.5 μm, and the content of impurities such as oxidizing sulfur, sodium, chlorine, soluble salts, etc. 0.02% by weight or less, preferably 0.01% by weight or less, loss of ignition at 700 ° C. is 1.5% by weight or less, preferably 0.3% by weight or less, extremely high purity and fine specific surface area Barium carbonate. Further, the obtained fine barium carbonate is de-CO 2 at a temperature lower than the β to α phase transition temperature 980 ° C. of barium carbonate. ₂ Is easily done.
[0031]
Examples of the reaction apparatus used in the present invention include an apparatus capable of bringing the granular medium (c) into contact with the granular medium (c) in a state where the granular medium (c) flows at a high speed.For example, the reaction vessel and the inside of the reaction vessel are stirred. A mixing stirrer having a stirrer (hereinafter also referred to as “first reaction device”), a reaction vessel having an inlet and an outlet, a stirrer for stirring the reaction vessel, and the reaction vessel And a mixing and stirring device (hereinafter, also referred to as “second reaction device”) having a filter that is provided and retains the granular medium (c) in the reaction vessel. The first reactor is suitable when the contact treatment is intermittently performed by batch processing, and the second reactor is suitable when the contact treatment is continuously processed. Examples of the second reaction apparatus include a wet dispersion pulverization apparatus, and specifically a bead mill apparatus. In addition, when using a bead mill apparatus, the said granular medium (c) is used as a bead used for this apparatus.
[0032]
The bead mill apparatus will be specifically described with reference to FIG. FIG. 1 is a diagram schematically illustrating an example of a bead mill apparatus. The reaction apparatus 1 includes a stirring blade portion 1b having a structure in which a large number of screw type impellers are coaxially fitted to a stirring main shaft, a stirring blade drive portion 1e that drives the stirring blade portion 1b, and the stirring blade portion 1b as an outer periphery of the impeller. A rotating cylinder 1a that converges with a small gap between them and rotates at a lower speed than the impeller in the opposite direction to the stirring blade 1b, inlets 1g and 1f provided on the inlet side of the rotating cylinder 1a, and a rotating cylinder A discharge port 1h provided on the outlet side of 1a and a media separating device 1d disposed in the vicinity of the discharge port 1h in the rotary cylinder 1a are provided. The media separator 1d functions as a filter, and as the media separator 1d, for example, a filter cloth, a gap separator, a screen separator, a centrifugal separator, or the like is used.
[0033]
A preferred example of the continuous contact treatment using the bead mill apparatus shown in FIG. 1 and its operation will be specifically described. First, an alkali-adjusted barium solution (hereinafter also referred to as “solution A”) containing a soluble barium salt solution and an alkali agent is prepared in the raw material storage tank 2 connected to the introduction port 1 g. Here, the blending amount of the alkaline agent is set to an amount equal to or more than the equivalent amount of barium carbonate to be produced. On the other hand, the carbon dioxide gas cylinder 3 connected to the introduction port 1f is filled with carbon dioxide gas. Next, after the granular medium (c) is charged into the rotary cylinder 1a from the introduction port 1g, the liquid A is introduced from the introduction port 1g using the pump P provided between the raw material storage tank 2 and the introduction port 1g. It introduce | transduces in the rotation cylinder 1a, drives the rotation cylinder 1a and the stirring blade part 1b, and makes the mixture of A liquid and a granular medium (c) flow at high speed. At this time, the mixture takes a predetermined time in the rotating cylinder 1a and is separated into the granular medium (c) and the liquid A by the media separator 1d, and the granular medium (c) stays in the rotating cylinder 1a. The liquid A is discharged from the discharge port 1h so that the contact treatment can be continuously performed. However, A liquid discharged | emitted from the discharge port 1h is introduce | transduced into tanks other than the product storage tank 4 which is not shown in figure so that it may not mix with the fine barium carbonate slurry after contact. Next, after connecting the discharge port 1 h and the product storage tank 4 so that the discharge from the discharge port 1 h is introduced into the product storage tank 4, the carbon dioxide in the carbon dioxide gas cylinder 3 is introduced into the introduction port in this state. It is introduced into the rotating cylinder 1a from 1f, the soluble barium salt and carbon dioxide are brought into contact with each other in a state where the granular medium (c) flows at a high speed, and barium carbonate is deposited while passing through the rotating cylinder 1a. Since barium carbonate is refined by applying a shearing force and a frictional force by the granular medium (c) flowing at high speed from the moment of precipitation, a mixture containing the fine barium carbonate slurry and the granular medium (c) in the rotating cylinder 1a. Is obtained. The mixture is separated into the granular medium (c) and the fine barium carbonate slurry by the media separator 1d, the granular medium (c) stays in the rotating cylinder 1a, and the fine barium carbonate slurry is discharged from the discharge port 1h and formed. It introduces into the thing storage tank 4. The fine barium carbonate slurry in the product storage tank 4 is appropriately filtered, washed and dried to obtain fine barium carbonate.
[0034]
Next, the manufacturing method of the 2nd fine barium carbonate which concerns on this invention is demonstrated. In this method, the mixture of the barium carbonate slurry (d) and the granular medium (c) is fluidized while the granular medium (c) flows at a high speed.
[0035]
The barium carbonate slurry (d) used in the second method for producing finely divided barium carbonate is one in which barium carbonate is dispersed in water. Barium carbonate used for the barium carbonate slurry is not particularly limited, and any barium carbonate may be used as long as the slurry can be prepared. Further, the barium carbonate slurry (d) may be the same as the barium carbonate slurry in addition to the above barium carbonate dispersed in water. As such a barium carbonate slurry, for example, in the first method for producing finely divided barium carbonate, a soluble barium salt-containing solution (a) and carbon dioxide or a soluble carbonate-containing solution (b) are mixed with a granular medium (c ) Can be used without mixing them.
[0036]
The granular medium (c) used in the second method for producing finely divided barium carbonate is the same as the method for producing the first finely divided barium carbonate. The mixture of the barium carbonate slurry (d) and the granular medium (c) used in the second method for producing fine barium carbonate is a mixture of the barium carbonate slurry (d) and the granular medium (c). .
[0037]
In the second method for producing fine barium carbonate, the mixture of the barium carbonate slurry (d) and the granular medium (c) is fluidized while the granular medium (c) flows at a high speed. The conditions for the fluid treatment are the same as the contact conditions in the first method for producing fine barium carbonate except that the specific fluid treatment time is used in the present invention instead of the contact time, and the description thereof is omitted.
[0038]
The flow treatment time in the second method for producing finely divided barium carbonate is usually 1 minute or longer, preferably 2 to 10 minutes. If the flow treatment time is less than 1 minute, the barium carbonate is not sufficiently refined and impurities are not sufficiently removed. Further, in order to sufficiently remove impurities in barium carbonate, it is preferable that the flow treatment time be as long as possible within the above range.
[0039]
In the second method for producing fine barium carbonate, when the mixture of the barium carbonate slurry (d) and the granular medium (c) is fluidized in a state where the granular medium (c) flows at a high speed, the barium carbonate in the slurry is obtained. Since a shearing force and a frictional force are applied to the granular medium (c) to make it finer, a slurry containing fine barium carbonate is obtained. When finely divided barium carbonate is appropriately separated from the slurry by filtration or the like and dried, finely divided barium carbonate is obtained. The obtained fine barium carbonate is the same as that obtained by the first method for producing fine barium carbonate.
[0040]
Examples of the reactor used in the second method for producing finely divided barium carbonate include those similar to those used in the method for producing the first finely divided barium carbonate. A preferred example of the continuous contact treatment using the bead mill apparatus shown in FIG. 1 and its operation will be specifically described. First, the granular medium (c) is introduced into the rotary cylinder 1a from the introduction port 1g. Next, the barium carbonate slurry is introduced into the rotary cylinder 1a from the introduction port 1g, and the rotary cylinder 1a and the stirring blade portion 1b are driven to stir the mixture of the barium carbonate slurry and the granular medium (c). The medium (c) is fluidized while passing through the rotary cylinder 1a in a state of fluidizing at high speed. At this time, the fine-grained barium carbonate slurry after the flow treatment is continuously subjected to the flow treatment so that the residence time in the rotary cylinder 1a takes a predetermined value and is discharged from the discharge port 1h. The barium carbonate in the slurry is refined by applying a shearing force and a frictional force by the granular medium (c) flowing at high speed, and a mixture containing the fine barium carbonate slurry and the granular medium (c) is obtained in the rotating cylinder 1a. It is done. The mixture is separated into the granular medium (c) and the fine barium carbonate slurry by the media separator 1d, the granular medium (c) stays in the rotating cylinder 1a, and the fine barium carbonate slurry is discharged from the discharge port 1h and formed. The product storage tank 4 is introduced. The fine barium carbonate slurry in the product storage tank 4 is appropriately filtered, washed and dried to obtain fine barium carbonate.
[0041]
The barium carbonate slurry initially introduced into the rotating cylinder 1a can be prepared using the bead mill apparatus shown in FIG. 1 in advance without introducing the granular medium (c). For example, first, liquid A is prepared in the raw material storage tank 2 connected to the introduction port 1g. On the other hand, the carbon dioxide gas cylinder 3 connected to the introduction port 1f is filled with carbon dioxide gas. Next, using the pump P provided between the raw material storage tank 2 and the inlet 1g, the liquid A is introduced into the rotary cylinder 1a from the inlet 1g, and the rotary cylinder is introduced without introducing the granular medium (c). The liquid A is caused to flow by driving the la and the stirring blade 1b. At this time, the liquid A has a predetermined residence time in the rotary cylinder 1a and is discharged from the discharge port 1h so that the contact process can be continuously performed. However, A liquid discharged | emitted from the discharge port 1h is returned to the raw material storage tank 2 using the pump etc. which are not shown in figure. Next, after connecting the discharge port 1h and the intermediate product storage tank so that the discharge from the discharge port 1h is introduced into an intermediate product storage tank (not shown), the carbon dioxide in the carbon dioxide gas cylinder 3 is removed in this state. It introduce | transduces in the rotation cylinder 1a from the inlet 1f, and deposits barium carbonate in the rotation cylinder 1a. The obtained barium carbonate slurry passes through the media separator 1d and is then discharged from the discharge port 1h and introduced into the intermediate product storage tank.
[0042]
In the first or second method for producing fine barium carbonate, the soluble barium salt-containing solution (a), the soluble carbonate-containing solution (b), the barium carbonate slurry (d), the fine barium carbonate slurry, and the fine barium carbonate When a particle growth inhibitor is present in one or more of the slurry cleaning liquids, the growth of particles can be suppressed and the fine barium carbonate can be further finely divided. In order to make the particle growth inhibitor present, for example, a method of adding the particle growth inhibitor to the soluble barium salt-containing solution (a) and the like can be mentioned.
[0043]
As the particle growth inhibitor used in the present invention, for example, at least one selected from the group consisting of polyhydric alcohol, pyrophosphoric acid, ascorbic acid, carboxylic acid and carboxylate is used.
[0044]
Examples of the polyhydric alcohol used in the present invention include those having two or more OH groups, such as ethylene glycol, propylene glycol, glycerin, alcohol glycerin, erythritol, adnit, mannitol, and sorbit.
[0045]
The carboxylic acid or carboxylic acid salt used in the present invention is not particularly limited as long as it is a carboxylic acid or carboxylic acid salt. For example, citric acid, carboxymethyl cellulose, oxalic acid, malonic acid, succinic acid , Malic acid, maleic acid, tartaric acid, adipic acid, acrylic acid, polycarboxylic acid, polyacrylic acid, and sodium and ammonium salts thereof.
[0046]
Of the above particle growth inhibitors, polyhydric alcohol and ascorbic acid are preferable because they have a large crystal growth preventing effect. In addition, a polyhydric alcohol and ascorbic acid are used in combination, and ascorbic acid is added to one or both of the soluble barium salt-containing solution (a) and the soluble carbonate-containing solution (b), and barium carbonate is added in the presence of ascorbic acid. After the precipitation of barium carbonate slurry, polyhydric alcohol having a boiling point higher than that of water is added to the slurry, followed by filtration, washing, and drying, so that growth and aggregation due to drying can be prevented, and the particle size distribution is fine and sharp. Barium carbonate can be obtained.
[0047]
The addition amount of the particle growth inhibitor is 0.1% by weight or more, preferably 0.75 to 30% by weight, and more preferably 2 to 10% by weight with respect to the generated barium carbonate. The added particle growth inhibitor remains in the barium carbonate, but can be removed by firing. For this reason, barium carbonate can be used as a reaction raw material of, for example, barium titanate without particularly removing the particle growth inhibitor.
[0048]
The barium carbonate obtained when a particle growth inhibitor is added has a BET specific surface area of 5 to 50 m. ² / g, preferably 5-40m ² / g, the average particle size determined by the laser diffraction method is 0.01 to 1.0 μm, preferably 0.05 to 0.5 μm, and the content of impurities such as oxidizing sulfur, sodium, chlorine, soluble salts, etc. 0.02% by weight or less, preferably 0.01% by weight or less, loss of ignition at 700 ° C. is 1.5% by weight or less, preferably 0.3% by weight or less, extremely high purity and fine specific surface area Barium carbonate. Further, the obtained fine barium carbonate is de-CO 2 at a temperature lower than the β to α phase transition temperature 980 ° C. of barium carbonate. ₂ Is easily done.
[0049]
The fine barium carbonate obtained by the first or second production method according to the present invention can be suitably used as a raw material for ceramics and optical glass, particularly as a raw material for electronic materials such as barium titanate and superconducting materials.
[0050]
Next, a method for producing barium titanate according to the present invention will be described. In this method, fine barium carbonate obtained by the first or second fine barium carbonate production method and titanium dioxide are mixed and fired. A dried product is used as the fine barium carbonate mixed with titanium dioxide in the present invention.
[0051]
Titanium dioxide used in the present invention is not particularly limited in type and production history, but has a BET specific surface area of 5 m. ² / g or more, preferably 10 to 30 m ² / g, the average particle diameter determined by the laser diffraction method is 1 μm or less, preferably 0.1 to 0.5 μm. Moreover, it is preferable to use a high purity titanium dioxide in order to obtain high purity barium titanate.
[0052]
The mixing amount of titanium dioxide is usually 0.95 to 1.05, preferably 0.99 to 1.01, in terms of the molar ratio of Ti / Ba to Ba in fine barium carbonate.
[0053]
The mixing method of the fine barium carbonate and titanium dioxide may be either a dry method or a wet method. However, it is preferably carried out by a conventional wet mixing apparatus such as a bead mill or a ball mill in terms of easy uniform mixing.
[0054]
The mixture obtained by mixing fine barium carbonate and titanium dioxide is pulverized and fired as desired. When the mixture contains moisture for wet mixing or the like, the mixture is dried to remove moisture, and then pulverized and fired as desired. The drying conditions are not particularly limited, and examples thereof include a method of leaving it to dry naturally and a method of drying at 50 to 200 ° C.
[0055]
A calcination temperature is 700-1200 degreeC normally, Preferably it is 800-1000 degreeC, Preferably it is 800-900 degreeC. The finely divided barium carbonate used in the present invention is de-CO 2 at a temperature lower than 980 ° C. from the β to α phase transition temperature of barium carbonate. ₂ Is easily performed, so that barium titanate can be produced at a relatively low temperature. In the present invention, after the drying, the dried product is usually calcined at 700 to 1200 ° C., preferably 800 to 1000 ° C., then the calcined product is pulverized and granulated as desired, and further usually 700 to 1200. Firing may be carried out at a temperature of, preferably 800 to 1000 ° C.
[0056]
The barium titanate after baking can be made into a product by washing with an acid solution, washing with water and drying, for example. The drying method is not particularly limited as long as a conventional method is used, and examples thereof include a method using a spray dryer.
[0057]
The barium titanate obtained by the present invention has an average particle size of 0.05 to 2 μm determined by observation with an electron microscope, is extremely high purity, and is suitable for electronic parts.
[0058]
If necessary, before firing, that is, after mixing with titanium dioxide or after calcination, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, At least one element selected from rare earth elements such as Tm, Yb, and Lu, Ba, Li, Bi, Zn, Mn, Al, Si, Ca, Sr, Co, V, Nb, Ni, Cr, Fe, and Mg. When the subcomponent element-containing compound to be contained is mixed and then fired, a titanium-based perovskite ceramic raw material powder containing the subcomponent element oxide can be obtained. The combination and addition amount of these subcomponent element-containing compounds can be arbitrarily set in accordance with the dielectric characteristics required for the ceramic raw material powder to be produced. The specific addition amount of the subcomponent element-containing compound is usually 0.1 to 5 parts by weight as an element in the subcomponent element-containing compound with respect to 100 parts by weight of barium titanate.
[0059]
The barium titanate and titanium-based perovskite ceramic raw material powder obtained in the present invention can be used as a raw material for producing a multilayer capacitor. For example, first, the barium titanate or titanium-based perovskite ceramic raw material powder and a conventionally known compounding agent such as an additive, an organic binder, a plasticizer, and a dispersant are mixed and dispersed to form a slurry. A solid sheet is formed to obtain a ceramic sheet. Next, a conductive paste for forming an internal electrode is printed on one surface of the ceramic sheet, and after drying, a plurality of ceramic sheets are laminated and then pressed in the thickness direction to form a laminate. Further, the laminate is heat-treated to remove the binder, and is fired to obtain a fired body. Thereafter, an In—Ga paste, Ni paste, Ag paste, nickel alloy paste, copper paste, copper alloy paste or the like is applied to this sintered body and baked, whereby a multilayer capacitor can be obtained.
[0060]
Further, the barium titanate or titanium-based perovskite ceramic raw material powder obtained in the present invention is blended in a resin such as an epoxy resin, a polyester resin, or a polyimide resin, and is used as a resin sheet, a resin film, an adhesive, etc. And can be suitably used for materials such as multilayer printed wiring boards. The barium titanate or the ceramic raw material powder is a dielectric material for an EL element, a co-material for suppressing a shrinkage difference between an internal electrode and a dielectric layer, a base material for an electrode ceramic circuit board or a glass ceramic circuit board. In addition, it can be suitably used as a raw material for circuit peripheral materials, a catalyst used during reactions such as exhaust gas removal and chemical synthesis, and a surface modifier for printing toner that imparts an antistatic effect and a cleaning effect.
[0061]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.
[0062]
The bead mill apparatus used in the following examples and comparative examples will be described with reference to FIG. FIG. 1 is a schematic diagram of a bead mill apparatus. In FIG. 1, a bead mill device 1 is a model UVM-5 manufactured by Imex Co., Ltd., and drives a stirring blade portion 1b having a structure in which a large number of screw type impellers are coaxially fitted to a stirring main shaft, and a stirring blade portion 1b. A rotating cylinder 1a (capacity: 5L) that converges the stirring blade drive portion 1e and the stirring blade portion 1b with a small gap between the outer periphery of the impeller and rotates at a lower speed than the impeller in the opposite direction to the stirring blade portion 1b. ), Inlets 1g and 1f provided on the inlet side of the rotating cylinder 1a, an outlet 1h provided on the outlet side of the rotating cylinder 1a, and a media separating device 1d disposed near the outlet 1h in the rotating cylinder 1a. It comprises. A filter cloth was used as the media separating device 1d. Further, a carbon dioxide gas cylinder 3 was connected to the inlet 1f, a raw material storage tank 2 was connected to the inlet 1g, and a product storage tank 4 was connected to the outlet 1h.
[0063]
<Production method of fine barium carbonate>
Example 1
5 L of an aqueous solution containing 84.7 g / L of barium sulfide was added to the raw material storage tank 2, and 25 g of ascorbic acid was added and dissolved in this aqueous solution as a powder to prepare a barium salt reaction liquid (barium salt reaction liquid A). The amount of ascorbic acid added is the following chemical reaction formula (8)
BaS + CO ₂ + H ₂ O → BaCO ₃ + H ₂ S ↑ (8)
The amount of addition relative to the amount of barium carbonate calculated from is equivalent to 2.5%. Next, 300 g of sodium hydroxide dissolved in distilled water was added to the barium salt reaction solution A and stirred to prepare an alkali reaction solution (alkali reaction solution A). In addition, the addition amount of sodium hydroxide is an amount corresponding to the equivalent or more of the generated barium carbonate.
[0064]
Thereafter, using the bead mill apparatus 1, 0.4 mm-diameter zirconia beads as a granular medium (c) are introduced from the inlet 1 g so that the filling rate in the rotating cylinder 1 a is 85%, and the rotating cylinder 1 a and the stirring blade The part 1b is driven to stir the zirconia beads at a peripheral speed of 10 m / s, and the alkaline reaction liquid A is supplied from the inlet 1g so that the inside of the rotating cylinder 1a is filled and the residence time in the rotating cylinder 1a is 90 seconds. Then, carbon dioxide was blown from the inlet 1f at a rate of 1 L / min to react in the rotary cylinder 1a, and the slurry after the reaction was discharged from the outlet 1h to the product storage tank 4. The reaction temperature in the rotating cylinder 1a at this time is 30 ° C., and when the pH of the slurry supplied to the product storage tank 4 from the discharge port 1h is lowered to 12.5, the alkaline reaction liquid A and carbon dioxide The supply was stopped and the contact reaction was terminated. Note that the zirconia beads did not pass through the media separator 1d and did not move to the product storage tank 4.
[0065]
Next, the slurry (slurry A) in the product storage tank 4 was filtered, washed, and dried to obtain barium carbonate (barium carbonate A). About this barium carbonate, the BET specific surface area, the average particle diameter, the oxidizing sulfur content, and the ignition loss were measured. The results are shown in Table 1. The average particle size was determined by a laser diffraction method. Moreover, it shows below about the measuring method of oxidizing sulfur content and ignition loss.
[0066]
・ Oxidative sulfur content
Weight W ₀ After adding potassium permanganate aqueous solution as an oxidizer to the barium carbonate sample of, and then adding hydrochloric acid dropwise to completely oxidize the oxidizing sulfur content in the sample, the undissolved residue weight W ₁ Was measured. Weight W ₀ The barium carbonate sample was dissolved in hydrochloric acid and the undissolved residue weight W ₂ Was measured. Where W ₁ Than W ₂ Difference W minus ₃ W ₀ The value divided by the value was defined as the oxidizing sulfur content.
[0067]
・ Loss on ignition
Weight W ₀ Weight W decreased when a barium carbonate sample was heated in a heating furnace at 700 ° C. for 1 hour ₄ Seeking W ₄ W ₀ The value divided by was used as ignition loss.
[0068]
Comparative Example 1
Barium carbonate (barium carbonate B) was obtained in the same manner as in Example 1 except that zirconia beads were not added. About this barium carbonate, the BET specific surface area, the average particle diameter, the oxidizing sulfur content, and the ignition loss were measured in the same manner as in Example 1. The results are shown in Table 1.
[0069]
[Table 1]

[0070]
As a result of Table 1, it can be seen that the product obtained by the production method according to the present invention can obtain barium carbonate having a small BET specific surface area, a small amount of impurities and a low ignition loss.
[0071]
Example 2
Barium carbonate (barium carbonate C) was obtained in the same manner as in Example 1 except that the amount of ascorbic acid added was 50 g, and the addition rate relative to the amount of barium carbonate calculated from the above formula (8) was set to an amount corresponding to 5.0%. ) About this barium carbonate, the BET specific surface area, the average particle diameter, the oxidizing sulfur content, and the ignition loss were measured in the same manner as in Example 1. The results are shown in Table 2.
[0072]
Comparative Example 2
Barium carbonate (barium carbonate D) was obtained in the same manner as in Example 2 except that zirconia beads were not added. About this barium carbonate, the BET specific surface area, the average particle diameter, the oxidizing sulfur content, and the ignition loss were measured in the same manner as in Example 1. The results are shown in Table 2.
[0073]
[Table 2]

[0074]
Example 3
10 L of an aqueous solution containing 122.2 g / L of dihydrate of barium chloride is put into the raw material storage tank 2, and 25 g of ascorbic acid is added and dissolved in this aqueous solution as a powder to obtain a barium salt reaction liquid (barium salt reaction liquid C). Was prepared. The amount of ascorbic acid added is the following chemical reaction formula (9)
BaCl ₂ + CO ₂ + 2NaOH → BaCO ₃ + 2NaCl + H ₂ O (9)
The amount of addition relative to the amount of barium carbonate calculated from is equivalent to 2.5%. Next, 300 g of sodium hydroxide dissolved in distilled water was added to the barium salt reaction liquid C and stirred to prepare an alkali reaction liquid (alkali reaction liquid C). In addition, the addition amount of sodium hydroxide is an amount corresponding to the equivalent or more of the generated barium carbonate.
[0075]
Thereafter, the alkali reaction liquid C and carbon dioxide were used in the same manner as in Example 1 except that the zirconia beads were not added and the alkali reaction liquid C was used instead of the alkali reaction liquid A. Were reacted in the rotary cylinder 1a so that the residence time in the rotary cylinder 1a was 90 seconds, and the slurry after the reaction was discharged from the discharge port 1h to the product storage tank 4. The reaction temperature in the rotating cylinder 1a at this time was 30 ° C., and the reaction was terminated when the pH of the slurry supplied to the product storage tank 4 from the discharge port 1h dropped to 13.2. Note that the zirconia beads did not pass through the media separator 1d and did not move to the product storage tank 4.
[0076]
Next, the slurry (slurry E) in the product storage tank 4 is returned to the introduction port 1g using a return pipe in which the product storage tank 4 and the introduction port 1g are connected in advance via a pump (not shown). The slurry E was circulated between the product storage tank 4 and the rotating cylinder 1a.
[0077]
Next, zirconia beads having a diameter of 0.4 mm as a fluid medium are introduced from the introduction port 1g so that the filling rate in the rotary cylinder 1a is 85%, and rotated so that the zirconia beads are stirred at a peripheral speed of 10 m / s. The cylinder 1a and the stirring blade portion 1b were driven to perform a wet pulverization process so that the residence time of the slurry E was 90 seconds, and the slurry after the pulverization process was discharged from the discharge port 1h to the product storage tank 4. Note that the zirconia beads did not pass through the media separator 1d and did not move to the product storage tank 4.
[0078]
Next, the slurry (slurry F) in the product storage tank 4 was filtered, washed and dried to obtain barium carbonate (barium carbonate E). About this barium carbonate, the BET specific surface area, the average particle diameter and the ignition loss were measured in the same manner as in Example 1, and the chlorine ion content was measured by the following method. The results are shown in Table 3.
[0079]
・ Chlorine ion content
A barium carbonate sample was dissolved in nitric acid, and an aqueous silver nitrate solution was added to this solution to convert chloride ions into silver chloride. The concentration of silver chloride in the solution was determined by turbidity of the white turbidity of the silver chloride with the standard solution of chloride, and the chloride content in the barium carbonate sample was determined from the concentration and the weight of the barium carbonate sample.
[0080]
Comparative Example 3
Barium carbonate (barium carbonate F) was obtained in the same manner as in Example 3 except that the slurry E was not subjected to the treatment to make the slurry F, and the slurry E was directly filtered, washed and dried. About this barium carbonate, it carried out similarly to Example 1, and measured the BET specific surface area, the average particle diameter, the ignition loss, and chloride ion content. The results are shown in Table 3.
[0081]
[Table 3]

[0082]
From the results shown in Table 3, it can be seen that by using a fluid medium, it is possible to obtain barium carbonate which is fine and has low impurities and low ignition loss.
[0083]
Example 4
Instead of filtering the slurry A in the product storage tank 4 as it is, an amount of 23.3% by weight of ethylene glycol with respect to the amount of barium carbonate contained in the slurry A is added to the slurry A and stirred. After preparing the slurry (slurry G), barium carbonate (barium carbonate G) was obtained in the same manner as in Example 1 except that the slurry G was filtered. About this barium carbonate, the BET specific surface area, the average particle diameter, the oxidizing sulfur content, and the ignition loss were measured in the same manner as in Example 1. The results are shown in Table 4.
[0084]
[Table 4]

[0085]
<Production method of barium titanate>
Example 5
Fine barium carbonate (barium carbonate E) obtained in Example 3 and high-purity titanium oxide (manufactured by Titanium Industry Co., Ltd., product name; chlorus titanium oxide KA-10C, BET specific surface area; 9.2 m ² / g, average particle size 0.37 μm) using a ball mill (Mitsui Miike Chemical Co., Ltd., model: Attritor MA-015C) as a wet mixer so that the molar ratio of Ti / Ba is 1.006 The mixture was thoroughly mixed, dried at 130 ° C. for 24 hours, and pulverized. Subsequently, it baked at 900 degreeC for 2 hours, and obtained the barium titanate.
[0086]
The obtained barium titanate has an average particle diameter of 0.7 μm determined from a scanning electron microscope (SEM) photograph, and when X-ray diffraction was performed on this barium titanate using CuKα rays as a radiation source, The peaks of unreacted raw materials barium carbonate and titanium dioxide could not be confirmed. The results are shown in Table 5.
[0087]
Example 6
Fine barium carbonate (barium carbonate G) obtained in Example 4 and high-purity titanium oxide (manufactured by Titanium Industry Co., Ltd., product name; chlorus titanium oxide KA-10C, BET specific surface area; 9.2 m ² / g, average particle size 0.37 μm) using a ball mill (Mitsui Miike Chemical Co., Ltd., model: Attritor MA-015C) as a wet mixer so that the molar ratio of Ti / Ba is 1.006 The mixture was thoroughly mixed, dried at 130 ° C. for 24 hours, and pulverized.
[0088]
A 0.08 g portion of this pulverized product was subjected to a solid phase reaction between barium carbonate and titanium dioxide in a differential thermal analyzer (manufactured by Max Science Co., Ltd., model: TG-DTA2000), and the DTA curve during the reaction was plotted. It is shown in 2. Further, barium titanate obtained when 4 g of this pulverized product was baked at 830 ° C. for 2 hours in a crucible had an average particle size of 0.5 μm determined by a scanning electron microscope (SEM) photograph. Further, when X-ray diffraction was performed on this barium titanate using CuKα rays as a radiation source, peaks of unreacted raw materials barium carbonate and titanium dioxide could not be confirmed. The results are shown in Table 5.
[0089]
Comparative Example 5
Commercially available barium carbonate (average particle size 1.4 μm, specific surface area 2.5 m ² / g), high purity titanium oxide (manufactured by Titanium Industry Co., Ltd., product name: chlorus titanium oxide KA-10C, BET specific surface area; 9.2 m ² / g, average particle size 0.37 μm) using a ball mill (Mitsui Miike Chemical Co., Ltd., model: Attritor MA-015C) as a wet mixer so that the molar ratio of Ti / Ba is 1.006 The mixture was thoroughly mixed, dried at 130 ° C. for 24 hours, and pulverized. Next, 0.08 g of this pulverized product was subjected to a solid phase reaction between barium carbonate and titanium dioxide in a differential thermal analyzer (manufactured by Max Science Co., Ltd., model: TG-DTA2000), and a DTA curve during the reaction. Is shown in FIG.
[0090]
Further, barium titanate obtained when 4 g of this pulverized product was calcined at 830 ° C. for 2 hours in a crucible had an average particle diameter of 0.6 μm as observed by an electron microscope. Further, when X-ray diffraction was performed on this barium titanate using CuKα rays as a radiation source, peaks of unreacted raw materials barium carbonate and titanium dioxide were confirmed. The results are shown in Table 5.
[0091]
[Table 5]

[0092]
From the results of Example 6 and Comparative Example 5, the product obtained by reacting commercially available fine barium carbonate and titanium dioxide of Comparative Example 5 is shown in FIG.
BaCO ₃ + TiO ₂ → BaTiO ₃ + CO ₂ ↑ (10)
The endothermic peak accompanying the phase transition (β → α) of barium carbonate based on the above is seen at around 980 ° C., whereas the reaction between the fine barium carbonate of the invention of Example 6 and titanium dioxide is 980 ° C. Since there is no endothermic peak associated with the nearby phase transition, the de-CO2 ₂ Is completed, and the production reaction of barium titanate by the reaction of fine barium carbonate and titanium dioxide is completed. It can also be seen that the reaction between the finely divided barium carbonate and titanium dioxide of the present invention allows high-purity barium titanate to be obtained without remaining unreacted barium carbonate even in a low temperature range of 830 ° C. Table 6 shows a list of symbols used for the barium salt reaction solution, the alkali reaction solution, the slurry, and barium carbonate in the examples and comparative examples.
[0093]
[Table 6]

[0094]
【The invention's effect】
According to the method for producing fine barium carbonate according to the present invention, fine barium carbonate that is fine, has a low impurity content, and has a small loss on ignition can be produced at low cost. Moreover, the barium titanate suitable for electronic components can be obtained at low cost by reacting the finely divided barium carbonate obtained by the above method with titanium dioxide.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing an example of a bead mill apparatus.
FIG. 2 is a graph showing a DTA curve.
[Explanation of symbols]
1 Bead mill equipment
1a Rotating cylinder
1b Stir blade
1c Zirconia beads
1d media separator
1e Stirring blade drive
1f, 1g inlet
1h outlet
2 Raw material storage tank
3 Carbon dioxide cylinder
4 Product storage tank
P pump

Claims (11)

The granular medium (c) flows through the soluble barium salt-containing solution (a), the carbon dioxide or soluble carbonate-containing solution (b), and the granular medium (c) at a maximum peripheral speed of 0.1 to 25 m / s . A method for producing finely divided barium carbonate, wherein the contact is performed for 15 seconds or more in a state. To one or two of the soluble barium salt containing solution (a) and the soluble carbonate-containing solution (b), a polyhydric alcohol, pyrophosphoric acid, ascorbic acid, at least selected from the group consisting of carboxylic acids and carboxylic acid salts claim 1 Symbol placement of a method for manufacturing a fine barium carbonate, characterized in that the presence of one of the particle growth inhibitor. Fine particles characterized in that a mixture of barium carbonate slurry (d) and granular medium (c) is fluidized for 15 seconds or more in a state where granular medium (c) flows at a maximum peripheral speed of 0.1 to 25 m / s. A method for producing barium carbonate. 4. The barium carbonate slurry (d) contains at least one particle growth inhibitor selected from the group consisting of polyhydric alcohol, pyrophosphoric acid, ascorbic acid, carboxylic acid and carboxylate. The manufacturing method of the fine-grain barium carbonate of description. The granular medium (c) flows through the soluble barium salt-containing solution (a), the carbon dioxide or soluble carbonate-containing solution (b), and the granular medium (c) at a maximum peripheral speed of 0.1 to 25 m / s. For 15 seconds or more in a state to obtain a mixture containing the fine barium carbonate slurry and the granular medium (c), and then separating the granular medium (c) and the fine barium carbonate slurry. The fine barium carbonate slurry is characterized in that at least one particle growth inhibitor selected from the group consisting of polyhydric alcohol, pyrophosphoric acid, ascorbic acid, carboxylic acid and carboxylate is present in the fine barium carbonate slurry. Manufacturing method. A mixture of the barium carbonate slurry (d) and the granular medium (c) is fluidized for 15 seconds or more in a state where the granular medium (c) flows at a maximum peripheral speed of 0.1 to 25 m / s, It is a method for producing fine barium carbonate, wherein a mixture containing the granular medium (c) is obtained, and then separated into the granular medium (c) and the fine barium carbonate slurry. A polyhydric alcohol is added to the fine barium carbonate slurry. A method for producing fine barium carbonate, comprising the presence of at least one particle growth inhibitor selected from the group consisting of pyrophosphoric acid, ascorbic acid, carboxylic acid and carboxylate. The granular medium (c) flows through the soluble barium salt-containing solution (a), the carbon dioxide or soluble carbonate-containing solution (b), and the granular medium (c) at a maximum peripheral speed of 0.1 to 25 m / s. In a state for 15 seconds or more to obtain a mixture containing the fine barium carbonate slurry and the granular medium (c), then separated into the granular medium (c) and the fine barium carbonate slurry, and then the fine carbonic acid carbonate. A method for producing fine barium carbonate by filtering and cleaning a barium slurry, wherein the fine particle barium carbonate slurry is filtered and washed with at least one selected from the group consisting of polyhydric alcohol, pyrophosphoric acid, ascorbic acid, carboxylic acid and carboxylate. A method for producing fine-grained barium carbonate, characterized by including a seed grain growth inhibitor. The mixture of the barium carbonate slurry (d) and the granular medium (c) is fluidized for 15 seconds or more with the granular medium (c) flowing at a maximum peripheral speed of 0.1 to 25 m / s, A method for producing fine barium carbonate, comprising: obtaining a mixture containing the granular medium (c); then separating the granular medium (c) and the fine barium carbonate slurry; and then filtering and washing the mixture. Suppressing the growth of at least one particle selected from the group consisting of polyhydric alcohol, pyrophosphoric acid, ascorbic acid, carboxylic acid and carboxylate in the filtration and washing liquid of the slurry A method for producing fine barium carbonate, characterized by comprising an agent. A mixing and stirring apparatus having a reaction vessel having an inlet and an outlet, a stirrer for stirring the inside of the reaction vessel, and a filter provided in the reaction vessel and retaining the granular medium (c) in the reaction vessel. The method for producing fine barium carbonate according to any one of claims 1 to 8, wherein the method is used for continuous contact or intermittent contact by batch treatment. The method for producing fine-grained barium carbonate according to any one of claims 1 to 9 , wherein the granular medium (c) is ceramic beads or resin beads. A method for producing barium titanate, comprising mixing and firing fine barium carbonate obtained by the production method according to any one of claims 1 to 10 , and titanium dioxide.

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