JP4091147B2 - Production method of barium sulfate - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は分散性に優れた沈降性硫酸バリウムおよびその製造方法に関する。
【０００２】
【従来の技術】
硫酸バリウムには水簸（水ヒ）性硫酸バリウムと沈降性硫酸バリウムの二つがあり、工業的には前者は重晶石（ＢａＳＯ4 ）を選別して粗砕後、湿式で微粉砕し、水簸として微粉を集め、硫酸を少量加えて鉄分を除き水洗乾燥して粉砕したものである。後者の沈降性硫酸バリウムは重晶石の還元焙焼でつくった硫化バリウムの浸出溶液に過マンガン酸カリウムで脱鉄精製したボウ硝（硫酸ナトリウム）溶液を反応させ、できた沈殿を濾過、水洗、乾燥して製品とする。また硫酸塩水溶液のかわりに硫酸を加え、得られる白色沈殿を濾過水洗してもよい。
【０００３】
沈降性硫酸バリウムは空気や熱に安定で変色しないので、パーマネントホワイトと呼ばれ白色顔料として重要であり、ゴム、紙、絶縁テープの充填剤として使用されている。また、Ｘ線吸収力が大きく溶解度が小さく無害であるためＸ線造影剤として消化管の検査に用いられるほか、特に光沢を必要とするアート紙、バライト紙には最上質の沈降性硫酸バリウムが用いられる。
【０００４】
【発明が解決しようとする課題】
しかしながら、従来の沈降性硫酸バリウムは製品中に残存するナトリウムの存在量が多く、分散性および透明度が必ずしも満足できるものではなかった。また工業的に硫化バリウムとボウ硝あるいは硫酸との反応で生じた沈殿から得られる従来法の沈降性硫酸バリウムはその粉体ｐＨが６．５よりも低く白色度が低下し、塗料樹脂との混合性が劣っていた。さらに原料としての硫化バリウム溶液の硫化バリウム濃度や反応時の液温によって、得られる白色沈殿粉末の粒子径および粒度分布が影響を受け、これら特性が安定した微細な沈降性硫酸バリウムが得られないという課題があった。すなわち、本発明者らは、硫化バリウムにボウ硝あるいは硫酸を反応させる従来方法における問題点を改善して粒子径が小さく、かつ粒度分布の幅が狭い分散性に優れた沈降性硫酸バリウム粉末を得ることを発明の目的とした。
【０００５】
【課題を解決するための手段】
本発明者らは上記目的を達成すべく鋭意研究を進め、重晶石の還元焙焼でつくった硫化バリウムにボウ硝溶液を反応させる従来の方法では製品中のナトリウムが高いため分散性が改善されず、また硫酸を反応させる硫酸法では粉体ｐＨが６．５未満となって塗料との混合性に問題が残ることに鑑み、これらの欠点の改善に取り組んだ結果、硫化バリウムに反応させる溶液としてボウ硝または硫酸溶液のかわりに硫酸アンモニウム溶液を用いるとともに、硫化バリウムの濃度、硫酸アンモニウムの添加量および液温等の反応条件を調整することにより分散性に有害な影響を与えるナトリウムを１０ｐｐｍ以下に抑制でき、分散性に優れた沈降性硫酸バリウムが得られることを見いだし本発明に到達した。
【０００６】
すなわち本発明は第１に、硫化バリウム溶液に該硫化バリウムに対して０ . ８〜２ . ５反応当量の硫酸アンモニウムを添加して硫酸バリウムの沈殿を生成させた後、得られた硫酸バリウムの沈殿を含むスラリーに水酸化ナトリウムを添加し、ｐＨを１１〜１３に調整して熟成することを特徴とする硫酸バリウムの製造方法；第２に、前記硫化バリウム溶液のバリウム濃度を５０ｇ／ｌ以上とすることを特徴とする第１に記載の硫酸バリウムの製造方法；第３に、前記硫酸アンモニウム添加時の硫化バリウム溶液の温度を３０〜６０℃とすることを特徴とする第１または２に記載の硫酸バリウムの製造方法；第４に、前記熟成時のスラリーの温度を６０〜９０℃とすることを特徴とする第１〜３のいずれかに記載の硫酸バリウムの製造方法を提供するものである。
【０００７】
【発明の実施の形態】
本発明では硫化バリウムの濃度がバリウムとして５０ｇ／ｌ以上の硫化バリウムの水溶液に、液温３０〜６０℃で、硫化バリウムに対して０．８反応当量以上の硫酸アンモニウムを添加する。次いで得られた硫酸バリウムの沈殿を含むスラリーにアルカリを添加しｐＨを１１〜１３に調整する。さらに６０〜９０℃で撹拌しながら熟成した後、濾過、水洗、乾燥、砕解して硫酸バリウム粉末を得る。ここで、熟成とは一定時間、一定温度で処理して、特に長時間液体、スラリーを攪拌して必要とする特性を、ここでは、Ｓ、Ｈ2 Ｓ等のＳ分をＮａ2 Ｓとして溶解させ、Ｓ分の少ない硫酸バリウムを得ることを言う。
【０００８】
反応溶液の硫化バリウムの濃度がバリウムとして５０ｇ／ｌ未満では、生成する硫酸バリウムの粒子径（Ｄ50）が１μｍを越え大きくなり好ましくなく、さらに粒度分布の幅がＤ90＞２μｍと広くなり硫酸バリウムの分散性が低下し好ましくない。
【０００９】
また硫化バリウムの水溶液の反応時の温度が３０℃よりも低いと硫化バリウムの溶解度が低下するため工業的には好ましくない。一方、６０℃を越える高温になると得られる硫酸バリウムの粒子径（Ｄ50）が１μｍを越え大きくなり好ましくなく、さらに粒度分布の幅がＤ90＞２μｍと広くなり硫酸バリウムの分散性が低下し好ましくない。
【００１０】
添加する硫酸アンモニウムの形態は固体でも水溶液でもどちらでもよい。添加する硫酸アンモニウムの量が硫化バリウムに対する反応当量で０．８当量未満では、未反応の硫化バリウムが存在し、硫酸バリウムの粒径が大きくなり過ぎて好ましくない。一方、添加する硫酸アンモニウムの量が硫化バリウムに対する反応当量で０．８当量以上であれば十分であり、特に上限はないが、２．５当量を越えても特に特性に変化はなく硫酸アンモニウムが過剰になるだけで、原材料費の面からは好ましくない。反応時に、逆に硫化バリウムの水溶液（または固体）を硫酸アンモニウム水溶液に添加しても構わない。
【００１１】
硫酸バリウムの沈殿を含むスラリーの熟成時のｐＨ調整剤は水酸化ナトリウム、硫化ナトリウム等のアルカリが使用できるが、Ｓ分をＮａ2 Ｓとして溶解させてＳ分を除去できるため、特に水酸化ナトリウムが好ましい。添加する水酸化ナトリウムの形態は固体でも水溶液でもどちらでもよい。
【００１２】
硫酸バリウムの沈殿を含むスラリーの熟成時の調整したｐＨが１１未満では、Ｓ分が残りやすく好ましくない。一方、ｐＨが１３を越えると、アルカリ除去のための水洗時間が長く必要になり好ましくない。
【００１３】
熟成時の液温は６０℃よりも低くても熟成の目的上は支障ないが、６０℃よりも低いとＳ分を除去するための熟成時間が延びるので好ましくない。一方、熟成時の温度は６０℃以上であれば十分であり特に上限はないが、装置の耐熱性、水溶液の沸点等を考慮すると９０℃までとするのが妥当である。
【００１４】
熟成後の沈殿の溶液からの分離および水洗方法は特に限定されず、一般的な方法が適用可能であり、デカンテーション、あるいはヌッチェ、ブフナー漏斗による自然濾過または吸引濾過、フィルタープレス、あるいは遠心分離法等が適用できるがその他の装置、方法等を適用してもよい。水洗時間は、付着したＮａＯＨ、Ｎ2 Ｓがなくなり、ｐＨが９以下となるように適宜行う。
【００１５】
乾燥方法は特に限定されず、一般的な方法が適用可能であり、大気圧乾燥、減圧乾燥、真空乾燥等が適用できるがその他の装置、方法等を適用してもよい。砕解方法は特に限定されず、一般的な方法が適用可能である。
【００１６】
得られた硫酸バリウムに対して種々の測定を行い、従来の硫酸バリウムと比較した。ナトリウム含有量は原子吸光法によって測定した。Ｓ分は硫化物として滴定法で分析した。次に、粉体ｐＨは、ＪＩＳＫ５１０１により測定した。粒度分布は、島津製作所製のレーザー回折式粒度分布測定装置により測定し、累積１０％径Ｄ１０、累積５０％径Ｄ５０、累積９０％径Ｄ９０を測定した。ＢＥＴは、湯浅アイオニクス製のＭＯＮＯＳＯＲＢにより測定した。塗布したときの表面状態、凹凸をみるための粒試験は、煮あまに油と混練し、ＪＩＳＫ５４００（Ａ法、Ｂ法）により測定した。白色度は、ミノルタ製の色彩色差計により測定した。
【００１７】
本発明の方法で得られる沈降性硫酸バリウムは、ナトリウムの含有量がきわめて低く、常に１００重量ｐｐｍ以下であり、必要に応じ１０重量ｐｐｍ以下とすることも容易にできる。かつ粉体ｐＨが７．０〜９．０のほぼ中性から弱アルカリ性である。さらにレーザー回折法での粒度分布は累積５０％径（Ｄ50）が１μｍ以下、累積９０％径（Ｄ90）が２μｍ以下である。所望により累積１０％径（Ｄ10）が０．４μｍ以下であり、累積５０％径（Ｄ50）が０．６μｍ以下であり、かつ累積９０％径（Ｄ90）が１μｍ以下である製品も容易に製造できる。実施例にその製造の一例を示した。
【００１８】
ナトリウム含有率が高く、例えば１００ｐｐｍを越えると硫酸バリウムの分散性が低下し、粒度分布の幅が広くなり好ましくなく、また硫酸バリウムの透明度が低下し好ましくない。そのため、ナトリウム含有率が１００ｐｐｍ以下、より好ましくは１０ｐｐｍ以下となるように制御することが必要であるが、本発明の方法ではナトリウム含有率１００ｐｐｍ以下とすることが容易にでき、所望により１０ｐｐｍ以下とすることもできる。硫化物としてのＳ分は＜０．０１％が好ましい。≧０．０１％ではＳ分がＳＯ4 等まで酸化されて粉体ｐＨが下がる傾向があり好ましくない。
【００１９】
またボウ硝の代わりに硫酸を用いた場合のように粉体ｐＨが７．０未満では硫酸バリウムの白色度が低下し、樹脂塗料との混合性も劣り好ましくない。
【００２０】
一方、粉体ｐＨが９．０でも使用できるものの、９．０を越えると、混合後樹脂塗料が劣化し易くなり好ましくない。
【００２１】
レーザー回折法での粒度分布における累積５０％径が１μｍを越え、累積９０％径が２μｍを越えると、樹脂との混練に時間がかかったり、塗布後の表面が不均一になり好ましくない。
【００２２】
ＢＥＴは、高い方がよいが、高過ぎても二次凝集が進み、樹脂の分散時間がかかるため、５〜２５ｍ2 ／ｇが好ましい。
【００２３】
粒試験で得られる粒度は低い方がよく、Ａ法では３０μｍ以下、Ｂ法では２０μｍ以下が好ましい。
【００２４】
白色度は、Ｗ、Ｌは高い方がよく、ａ、ｂは０に近い方がよい。
【００２５】
本発明の硫酸バリウムは上記全ての要件を満たし、最上質の沈降性硫酸バリウムとして広範囲の用途に使用することができる。
【００２６】
上記本発明の硫酸バリウムを、アート紙およびバライト紙の充填剤として使用したところ、Ｄ50≦１μｍ、Ｄ90≦２μｍのため分散性が良く、粉体ｐＨが７．０〜９．０のため、白色度が高く、混練性が良く、劣化しにくく、Ｎａ≦１０重量ｐｐｍのため、分散性が良く透明度も高く、粒試験Ａ法≦３０μｍ、Ｂ法≦２０μｍであり、混合性、なじみが良く、表面の凹凸が少なく、均一な良好なアート紙、バライト紙を得た。さらに、塗料用の顔料として用いても同様の良好の結果を得た。
【００２７】
【実施例】
硫化バリウム（ＢａＳ）の濃度が１００ｇ／ｌ（Ｂａとして８１ｇ／ｌ）の４０℃の水溶液に２当量の硫酸アンモニウム［（ＮＨ4 ）2 ＳＯ4 ］水溶液を反応させた後、液温８０℃にて水酸化ナトリウムを加えｐＨを１２に調整して２時間攪拌しながら熟成してからＮｏ．５Ｃ濾紙を敷いたヌッチェで濾過、約１時間水洗した後乾燥および砕解の処理を行い硫酸バリウム粉末を得た。
【００２８】
得られた硫酸バリウムについて、実施の形態に示した方法でナトリウム含有量および各種の物性を測定した。
【００２９】
該硫酸バリウム中のナトリウム含有量を調べたところ、１０重量ｐｐｍ未満、Ｓ分含有量は０．０１重量％未満で、粉体ｐＨは８．１であった。レーザー回折法粒度分布は累積１０％径が０．３７μｍ、累積５０％径が０．５１μｍ、累積９０％径が０．７０μｍであった。粒度分布曲線１を図１に示す。
【００３０】
ＢＥＴは、５．７ｍ2 ／ｇであり、粒試験は、Ａ法で２５μｍ、Ｂ法で１４μｍであった。また白色度は、Ｗ ９８．５、Ｌ９９．０、ａ−０．４５、ｂ０．２２であった。
【００３１】
上記本発明の硫酸バリウムを、アート紙およびバライト紙の充填剤として使用したところ、Ｄ50≦１μｍ、Ｄ90≦２μｍのため分散性が良く、粉体ｐＨが７．０〜９．０のため、白色度が高く、混練性が良く、劣化しにくく、Ｎａ≦１０重量ｐｐｍのため、分散性が良く透明度も高く、粒試験Ａ法≦３０μｍ、Ｂ法≦２０μｍであり、混合性、なじみが良く、表面の凹凸が少なく、均一な良好なアート紙、バライト紙を得た。さらに、塗料用の顔料として用いても同様の良好の結果を得た。
【００３２】
【比較例１】
実施例と同様に濃度１００ｇ／ｌの硫化バリウムを用意し、これに硫酸を加えてｐＨ３で液温を４０℃に調整した後、実施例と同様に熟成を行い硫酸バリウムを得た。ナトリウム含有量は１０重量ｐｐｍ、Ｓ分含有量は０．０１重量％で、粉体ｐＨは６．５であった。レーザー回折法粒度分布は累積１０％径が０．５６μｍ、累積５０％径が０．８０μｍ、累積９０％径が４．３４μｍであった。粒度分布曲線２を図２に示す。
【００３３】
ＢＥＴは、６．５ｍ2 ／ｇであり、粒試験は、Ａ法で４０μｍ、Ｂ法で２５μｍであった。また白色度は、Ｗ ９７．４、Ｌ９８．０、ａ−０．２４、ｂ２．１１であった。
【００３４】
上記の硫酸バリウムを、アート紙およびバライト紙の充填剤および塗料用の顔料として用いたが、良好な結果は得られなかった。
【００３５】
【比較例２】
実施例と同様に濃度１００ｇ／ｌの硫化バリウムとボウ硝との反応により上記と同様にして粉末を得た。
【００３６】
ナトリウム含有量が１００重量ｐｐｍで、Ｓ分含有量は０．０１重量％未満、粉体ｐＨは９．５であった。レーザー回折法粒度分布は累積１０％径が０．７５μｍ、累積５０％径が２．６９μｍ、累積９０％径が３．８１μｍであった。粒度分布曲線３を図３に示す。
【００３７】
ＢＥＴは、３．５ｍ2 ／ｇであり、粒試験は、Ａ法で４０μｍ、Ｂ法で３０μｍであった。また白色度は、Ｗ ９７．４、Ｌ９７．８、ａ−０．５１、ｂ０．４０であった。
【００３８】
上記の硫酸バリウムを、アート紙およびバライト紙の充填剤および塗料用の顔料として用いたが、良好な結果は得られなかった。
【００３９】
【発明の効果】
以上説明したように、ボウ硝や硫酸を反応させる従来の方法に対して、本発明の方法によれば、硫化バリウムに対して０．８〜２．５当量の硫酸アンモニウムを添加反応させて沈殿を生成させるとともに、硫化バリウムの濃度、液温および沈殿発生後のスラリーのｐＨ等を調整するので、ナトリウム含量が１０重量ｐｐｍ以下と少なく、かつ粉末の粒度分布が適正であって分散性に優れた沈降性硫酸バリウムを得ることができる。本発明の硫酸バリウムは従来の硫酸バリウムに比し、粒度分布が極めてシャープであり、この特性を本発明品の同定のために用いることができる。図４に、実施例で得られた本発明品の粒度分布曲線１を比較例１および２で得られた従来品の粒度分布曲線２および３と同一座標上に対比して示した。また、各製品の物性値を表１に対比して示した。
【００４０】
【表１】
この表から明らかであるように、本発明の硫酸バリウムは、白色度も高く分散性に優れているため、アート紙、バライト紙等への充填剤や塗料用の顔料として好適に用いることができる。
【図面の簡単な説明】
【図１】実施例１に記載した方法で得られた本発明の硫酸バリウムについてレーザー回折法で得られ粒度分布曲線１を示す図である。
【図２】比較例１に記載した方法で得られた従来法の硫酸バリウムについてレーザー回折法で得られ粒度分布曲線２を示す図である。
【図３】比較例２に記載した方法で得られた従来法の硫酸バリウムについてレーザー回折法で得られ粒度分布曲線２を示す図である。
【図４】比較のため粒度分布曲線１、２、３を同一の座標上に対比して示したものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to precipitated barium sulfate excellent in dispersibility and a method for producing the same.
[0002]
[Prior art]
There are two types of barium sulfate: hydrated barium sulfate and precipitated barium sulfate. Industrially, the former selects barite (BaSO 4 ), coarsely pulverizes, then wet pulverizes, Fine powder is collected as a water tank, a small amount of sulfuric acid is added, iron is removed, water is washed, dried and pulverized. The latter precipitated barium sulfate was reacted with barium sulfide leaching solution produced by reduction roasting of barite and reacted with boron nitrate (sodium sulfate) solution, which was deiron-purified with potassium permanganate, and the resulting precipitate was filtered and washed with water. Dry to make a product. Further, sulfuric acid may be added instead of the sulfate aqueous solution, and the resulting white precipitate may be washed with filtered water.
[0003]
Since precipitated barium sulfate is stable to air and heat and does not discolor, it is called permanent white and is important as a white pigment, and is used as a filler for rubber, paper, and insulating tape. In addition, it has a high X-ray absorption capacity, low solubility, and is harmless, so it is used as an X-ray contrast agent for the examination of the digestive tract. In addition, art paper and barite paper that require gloss have the highest quality precipitated barium sulfate. Used.
[0004]
[Problems to be solved by the invention]
However, conventional precipitated barium sulfate has a large amount of sodium remaining in the product, and dispersibility and transparency are not always satisfactory. In addition, the precipitated barium sulfate of the conventional method obtained from the precipitate produced by the reaction of barium sulfide with bow glass or sulfuric acid industrially has a powder pH lower than 6.5, and the whiteness is lowered. Mixability was inferior. Furthermore, the particle size and particle size distribution of the resulting white precipitated powder are affected by the concentration of barium sulfide in the barium sulfide solution as the raw material and the liquid temperature during the reaction, and fine precipitated barium sulfate with stable characteristics cannot be obtained. There was a problem. That is, the present inventors improved the problems in the conventional method in which barium sulfide or sulfuric acid was reacted with barium sulfide to obtain a precipitated barium sulfate powder having a small particle size and a narrow particle size distribution and excellent dispersibility. It was an object of the invention to obtain.
[0005]
[Means for Solving the Problems]
The inventors of the present invention have made extensive studies to achieve the above object, and the conventional method of reacting barium sulfide solution with barium sulfide produced by reduction roasting of barite improves the dispersibility due to high sodium in the product. In addition, in the sulfuric acid method in which sulfuric acid is reacted, the powder pH becomes less than 6.5, and there remains a problem in the mixing property with the paint. Use ammonium sulfate solution instead of bow nitrate or sulfuric acid solution, and adjust the reaction conditions such as the concentration of barium sulfide, the amount of ammonium sulfate added, and the liquid temperature, so that the sodium that adversely affects dispersibility is reduced to 10 ppm or less. The inventors have found that precipitated barium sulfate that can be suppressed and has excellent dispersibility is obtained, and the present invention has been achieved.
[0006]
That 0 in the present invention is first, with respect to sulfuric activated barium sulfide barium solution. 8 to 2.5 The reaction was allowed to produce a precipitate of equivalents of ammonium sulfate was added barium sulfate, precipitation of the resulting barium sulfate A method for producing barium sulfate, characterized in that sodium hydroxide is added to a slurry containing selenium and the pH is adjusted to 11 to 13 for aging; second, the barium sulfide solution has a barium concentration of 50 g / l or more. the method for producing barium sulfate according to the first, characterized by; the third, according to the temperature of the barium sulfide solution during the ammonium sulfate added to the first or 2, characterized in that a 30 to 60 ° C. method for producing a barium sulfate; fourth, Hisage a method for producing barium sulfate according to the first to third one of which is characterized in that the temperature of the slurry during the aging and 60 to 90 ° C. It is intended to.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, ammonium sulfate having a reaction temperature of not less than 0.8 reaction equivalent to barium sulfide is added to an aqueous solution of barium sulfide having a barium sulfide concentration of 50 g / l or more as barium at a liquid temperature of 30 to 60 ° C. Next, an alkali is added to the resulting slurry containing the barium sulfate precipitate to adjust the pH to 11-13. Further, the mixture is aged with stirring at 60 to 90 ° C., and then filtered, washed with water, dried and pulverized to obtain barium sulfate powder. Here, dissolution predetermined time and aging processes at a constant temperature, in particular long liquid, the stirring characteristics required in the slurry, where, S, the S content of such H 2 S as Na 2 S To obtain barium sulfate with low S content.
[0008]
When the concentration of barium sulfide in the reaction solution is less than 50 g / l as barium, the particle size (D50) of the generated barium sulfate exceeds 1 μm, which is not preferable, and the particle size distribution width becomes wide as D90> 2 μm. Dispersibility is lowered, which is not preferable.
[0009]
Further, when the reaction temperature of the aqueous solution of barium sulfide is lower than 30 ° C., the solubility of barium sulfide is lowered, which is not industrially preferable. On the other hand, when the temperature exceeds 60 ° C., the particle size (D50) of the obtained barium sulfate exceeds 1 μm, which is not preferable. Further, the particle size distribution width becomes wide as D90> 2 μm, and the dispersibility of barium sulfate is decreased. .
[0010]
The form of ammonium sulfate to be added may be either solid or aqueous solution. If the amount of ammonium sulfate to be added is less than 0.8 equivalent in terms of reaction equivalent to barium sulfide, unreacted barium sulfide is present, and the particle size of barium sulfate becomes too large. On the other hand, it is sufficient if the amount of ammonium sulfate to be added is 0.8 equivalent or more in terms of reaction equivalent to barium sulfide, and there is no particular upper limit. However, even if it exceeds 2.5 equivalents, there is no particular change in characteristics, and ammonium sulfate is excessive. This is not preferable from the viewpoint of raw material costs. Conversely, an aqueous solution (or solid) of barium sulfide may be added to the aqueous ammonium sulfate solution during the reaction.
[0011]
The pH adjusting agent for aging of the slurry containing the precipitation of barium sulfate can use alkali such as sodium hydroxide, sodium sulfide, etc. However, since S component can be dissolved as Na 2 S to remove S component, especially sodium hydroxide Is preferred. The form of sodium hydroxide to be added may be either a solid or an aqueous solution.
[0012]
If the adjusted pH at the time of aging of the slurry containing the precipitate of barium sulfate is less than 11, the S component is likely to remain, which is not preferable. On the other hand, when the pH exceeds 13, it is not preferable because a long washing time for alkali removal is required.
[0013]
Even if the liquid temperature at the time of aging is lower than 60 ° C., there is no problem for the purpose of aging. However, if the temperature is lower than 60 ° C., the aging time for removing the S component is unpreferable. On the other hand, it is sufficient that the temperature during the aging is 60 ° C. or higher, and there is no particular upper limit. However, considering the heat resistance of the apparatus, the boiling point of the aqueous solution, etc., it is appropriate that the temperature is 90 ° C.
[0014]
Separation of the precipitate after ripening from the solution and washing method are not particularly limited, and general methods can be applied. Decantation, natural filtration or suction filtration using Nutsche or Buchner funnel, filter press, or centrifugal separation method However, other devices and methods may be applied. The washing time is appropriately performed so that the attached NaOH and N 2 S disappear and the pH is 9 or less.
[0015]
The drying method is not particularly limited, and a general method can be applied. Atmospheric pressure drying, reduced pressure drying, vacuum drying, and the like can be applied, but other apparatuses, methods, and the like may be applied. The disintegration method is not particularly limited, and a general method can be applied.
[0016]
Various measurements were performed on the obtained barium sulfate and compared with conventional barium sulfate. The sodium content was measured by atomic absorption method. S content was analyzed by the titration method as sulfide. Next, the powder pH was measured according to JISK5101 . The particle size distribution was measured with a laser diffraction particle size distribution measuring device manufactured by Shimadzu Corporation, and a cumulative 10% diameter D10, a cumulative 50% diameter D50, and a cumulative 90% diameter D90 were measured. BET was measured by MONOSORB manufactured by Yuasa Ionics. The grain test for observing the surface condition and unevenness when applied was kneaded with oil and measured by JISK5400 (Method A, Method B). The whiteness was measured with a color difference meter manufactured by Minolta.
[0017]
The precipitated barium sulfate obtained by the method of the present invention has a very low content of sodium and is always 100 ppm by weight or less, and can easily be 10 ppm by weight or less as required. The powder has a pH of 7.0 to 9.0 and is almost neutral to weakly alkaline. Further, the particle size distribution in the laser diffraction method has a cumulative 50% diameter (D50) of 1 μm or less and a cumulative 90% diameter (D90) of 2 μm or less. If desired, products with a cumulative 10% diameter (D10) of 0.4 μm or less, a cumulative 50% diameter (D50) of 0.6 μm or less, and a cumulative 90% diameter (D90) of 1 μm or less are easily manufactured. it can. An example of its manufacture is shown in the examples.
[0018]
When the sodium content is high, for example, it exceeds 100 ppm, the dispersibility of barium sulfate is lowered, the width of the particle size distribution is widened, and the transparency of barium sulfate is lowered. Therefore, it is necessary to control the sodium content to be 100 ppm or less, and more preferably 10 ppm or less. However, in the method of the present invention, the sodium content can be easily set to 100 ppm or less. You can also The S content as sulfide is preferably <0.01%. If ≧ 0.01%, the S content is oxidized to SO 4 or the like and the powder pH tends to decrease, which is not preferable.
[0019]
Further, when the pH of the powder is less than 7.0 as in the case of using sulfuric acid instead of bow glass, the whiteness of barium sulfate is lowered and the mixing property with the resin paint is inferior.
[0020]
On the other hand, although it can be used even if the powder pH is 9.0, if it exceeds 9.0, the resin coating tends to deteriorate after mixing, which is not preferable.
[0021]
If the cumulative 50% diameter in the particle size distribution by the laser diffraction method exceeds 1 μm and the cumulative 90% diameter exceeds 2 μm, kneading with the resin takes time, and the surface after coating becomes unfavorable.
[0022]
The BET is preferably high, but if it is too high, secondary aggregation proceeds and it takes a dispersion time of the resin, so 5 to 25 m 2 / g is preferable.
[0023]
The particle size obtained by the grain test should be low, and is preferably 30 μm or less in the A method and 20 μm or less in the B method.
[0024]
As for whiteness, W and L should be high, and a and b should be close to 0.
[0025]
The barium sulfate of the present invention satisfies all the above requirements, and can be used in a wide range of applications as the highest quality precipitated barium sulfate.
[0026]
When the barium sulfate of the present invention is used as a filler for art paper and barite paper, it has good dispersibility due to D50 ≦ 1 μm and D90 ≦ 2 μm, and since the powder pH is 7.0 to 9.0, it is white. High degree, good kneadability, hardly deteriorated, Na ≦ 10 ppm by weight, dispersibility and high transparency, grain test A method ≦ 30 μm, B method ≦ 20 μm, good mixing and familiarity, Uniform and good art paper and barite paper with few surface irregularities were obtained. Furthermore, the same good results were obtained even when used as a pigment for paints.
[0027]
【Example】
After reacting an aqueous solution of ammonium sulfate [(NH 4 ) 2 SO 4 ] with 2 equivalents to an aqueous solution of 40 ° C. having a barium sulfide (BaS) concentration of 100 g / l (81 g / l as Ba), the liquid temperature was 80 ° C. Sodium hydroxide was added to adjust the pH to 12, and the mixture was aged with stirring for 2 hours. The mixture was filtered with a Nutsche with 5C filter paper, washed with water for about 1 hour, dried and disintegrated to obtain barium sulfate powder.
[0028]
About the obtained barium sulfate, sodium content and various physical properties were measured by the method shown in the embodiment.
[0029]
When the sodium content in the barium sulfate was examined, it was less than 10 ppm by weight, the S content was less than 0.01% by weight, and the powder pH was 8.1. In the laser diffraction particle size distribution, the 10% cumulative diameter was 0.37 μm, the 50% cumulative diameter was 0.51 μm, and the 90% cumulative diameter was 0.70 μm. The particle
[0030]
The BET was 5.7 m 2 / g, and the grain test was 25 μm by the A method and 14 μm by the B method. Moreover, the whiteness was W 98.5, L99.0, a-0.45, b0.22.
[0031]
When the barium sulfate of the present invention is used as a filler for art paper and barite paper, it has good dispersibility due to D50 ≦ 1 μm and D90 ≦ 2 μm, and since the powder pH is 7.0 to 9.0, it is white. High degree, good kneadability, hardly deteriorated, Na ≦ 10 ppm by weight, dispersibility and high transparency, grain test A method ≦ 30 μm, B method ≦ 20 μm, good mixing and familiarity, Uniform and good art paper and barite paper with few surface irregularities were obtained. Furthermore, the same good results were obtained even when used as a pigment for paints.
[0032]
[Comparative Example 1]
Barium sulfide having a concentration of 100 g / l was prepared in the same manner as in the example, and sulfuric acid was added thereto to adjust the liquid temperature to 40 ° C. at
[0033]
The BET was 6.5 m 2 / g, and the grain test was 40 μm by the A method and 25 μm by the B method. Moreover, the whiteness was W 97.4, L98.0, a-0.24, b2.11.
[0034]
The above barium sulfate was used as a filler for art paper and barite paper and as a pigment for paints, but good results were not obtained.
[0035]
[Comparative Example 2]
Similarly to the example, powder was obtained in the same manner as described above by reaction of barium sulfide having a concentration of 100 g / l and bow nitrate.
[0036]
The sodium content was 100 ppm by weight, the S content was less than 0.01% by weight, and the powder pH was 9.5. In the laser diffraction particle size distribution, the cumulative 10% diameter was 0.75 μm, the cumulative 50% diameter was 2.69 μm, and the cumulative 90% diameter was 3.81 μm. The particle
[0037]
The BET was 3.5 m 2 / g, and the grain test was 40 μm by the A method and 30 μm by the B method. The whiteness was W 97.4, L97.8, a-0.51, and b0.40.
[0038]
The above barium sulfate was used as a filler for art paper and barite paper and as a pigment for paints, but good results were not obtained.
[0039]
【The invention's effect】
As described above, according to the method of the present invention compared to the conventional method of reacting bow glass or sulfuric acid, 0.8 to 2.5 equivalents of ammonium sulfate is added and reacted with barium sulfide to cause precipitation. As well as forming, the concentration of barium sulfide, the liquid temperature, the pH of the slurry after precipitation, etc. are adjusted, so the sodium content is as low as 10 ppm by weight or less, the powder particle size distribution is appropriate, and the dispersibility is excellent. Precipitated barium sulfate can be obtained. The barium sulfate of the present invention has an extremely sharp particle size distribution compared to conventional barium sulfate, and this characteristic can be used for identification of the product of the present invention. In FIG. 4, the particle
[0040]
[Table 1]
As is clear from this table, the barium sulfate of the present invention has high whiteness and excellent dispersibility, and therefore can be suitably used as a filler for art paper, barite paper and the like, and a pigment for paints. .
[Brief description of the drawings]
1 is a graph showing a particle
2 is a graph showing a particle
3 is a graph showing a particle
FIG. 4 shows a comparison of particle size distribution curves 1, 2, and 3 on the same coordinates for comparison.
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20380397A JP4091147B2 (en) | 1997-07-14 | 1997-07-14 | Production method of barium sulfate |
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| JP20380397A JP4091147B2 (en) | 1997-07-14 | 1997-07-14 | Production method of barium sulfate |
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| JP2007253090A Division JP2008050261A (en) | 2007-09-28 | 2007-09-28 | Barium sulfate and its producing method |
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| JP4454171B2 (en) | 2001-03-08 | 2010-04-21 | 株式会社資生堂 | Barium sulfate powder and cosmetics containing the same |
| DE102007033460A1 (en) * | 2007-07-18 | 2009-01-22 | Süd-Chemie AG | Circular process for the production of barium sulfate and lithium metal phosphate compounds |
| CN101475200B (en) * | 2009-01-06 | 2012-02-29 | 重庆科昌科技有限公司 | Preparation of subsphaeroidal barium sulfate by sulfuric acid process and use in copper foil substrate |
| EP3219673B1 (en) | 2014-11-10 | 2019-07-24 | Sakai Chemical Industry Co., Ltd. | Barium sulfate powder production method and barium sulfate powder |
| KR102571368B1 (en) * | 2015-12-25 | 2023-08-25 | 사까이가가꾸고오교가부시끼가이샤 | Low α-dose barium sulfate particles and their use and manufacturing method |
| JP6176421B1 (en) * | 2015-12-25 | 2017-08-09 | 堺化学工業株式会社 | Low α-dose barium sulfate particles, their use and production method |
| CN112850771A (en) * | 2021-01-23 | 2021-05-28 | 湖南华中矿业有限公司 | Purification and whitening processing technology and processing system for barite ore powder |
| CN114314631B (en) * | 2022-01-21 | 2023-09-01 | 贵州理工学院 | Barite purifying and whitening treatment method |
| CN115213197A (en) * | 2022-07-07 | 2022-10-21 | 四川君和环保股份有限公司 | Dry recovery method for low-grade barium sulfate in oil sludge dry slag of shale gas drilling well |
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