JP3601759B2 - Composite oxide green pigment and method for producing the same - Google Patents
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【０００１】
【発明の属する技術分野】
本発明は複合酸化物グリーン顔料に関し、更に詳しくは発色性に優れ、無機顔料としては深みを有するとともに、冴えた緑色を呈し、更に透明性を有しかつ分散性も良好な複合酸化物グリーン顔料及びその製法に関するものである。発色を高めたため従来の樹脂用としては勿論、塗料やインキ用としてさらには微粒子化することにより、新たに現れる特性を利用し、例えばカラーフィルター用のグリーン顔料として、また基材の色調を生かしたメタリック塗料、カラークリヤー用グリーン顔料として、さらには蛍光体用付着顔料、薄膜、化粧品、紫外線吸収剤等にも有用な複合酸化物グリーン顔料に関する。
【０００２】
【従来の技術】
複合酸化物グリーン顔料は、耐熱性、耐候性等に優れた無機顔料として広く知られ、例えば、塗料や合成樹脂の着色剤、窯業用着色剤として幅広く使用されている。
なかでもコバルト、ニッケル、亜鉛、チタン系及びコバルト、アルミニウム、クロム、チタン系のスピネル型複合酸化物グリーン顔料がよく知られている。前者は冴えた黄みのグリーンであるが、各成分の割合は一定で、単一色のみしか得られない。即ち、Ｃｏ２ＴｉＯ４・２Ｎｉ２ＴｉＯ４・Ｚｎ２ＴｉＯ４の成分割合が最も良好な発色を示す。一方、後者は主にクロムの含有量によって青みのグリーンから青みと黄みの中間のグリーンまでかなりの範囲で連続的に変化させることが可能である。
【０００３】
また、これら一連のグリーン顔料の微粒子化の方法等については既に本出願人らによって公表されている（特開平４−５５３２２号公報、特開平４−５５３２３号公報、特開平３−８７２８号公報、特開平８−２１７４５７号公報）。
しかしながら、特開平３ー８７２８による方法ではコバルト、ニッケル、亜鉛、チタン系複合酸化物グリーン顔料はかなり黄みの緑色の単一色相しか得られないことが明示されている。また、コバルト、アルミニウム、クロム、チタン系複合酸化物グリーン顔料は前述のように、かなり幅広い色相が現れるかわりに構成成分にクロムを含むことが必須条件になっている。複合酸化物系顔料では、いずれの種類の顔料でもその有害性からクロムを使用しない顔料が熱望されているが、グリーン顔料にも同様の要望がある。
【０００４】
【発明が解決しようとする課題】
従って本発明の目的は、コバルトブルーからグリーンまでの色相をもつ彩度が高く、透明性にも優れたクロムを含有する複合酸化物系グリーン顔料の代替として、ほぼ同等の色相と特性を有し、かつクロムを含まない組成の複合酸化物系グリーン顔料及びその製造方法を提供することである。
本発明者等は上述の従来技術の問題点を解決すべく鋭意研究の結果、コバルト及びアルミニウムの酸化物が高温で固溶すると赤味の青色に発色する、いわゆるコバルトブルー顔料が８００〜１０００℃範囲の中間温度域で、青色への移行段階に緑色に発色することを発見した。この緑色はやや黄みぐすみで、顔料は青色顔料への遷移状態であるので表面積も大きいため、吸油量も高く、着色力も低く、色相も充分に強くない。
【０００５】
本発明者等は更に鋭意研究した結果、コバルトブルー顔料の成分組成であるコバルト及びアルミニウムの酸化物にチタン及びコバルト、チタンの酸化物を固溶させることにより青みの緑から深い緑まで幅広い色調が得られ、色相も強く、且つ適当な吸油量になると同時に種々の顔料適性も向上することを見いだした。また、上記コバルトの一部をニッケルや亜鉛で置換することによっても同様の顔料が得られることを見いだした。更にこの顔料は湿式合成法を用いることによって、透明性と彩度の高い複合酸化物グリーン顔料が得られることを見いだし、本発明を完成した。
【０００６】
【課題を解決するための手段】
上記の目的は以下の発明によって達成せられる。即ち、本発明は、コバルト、アルミニウム及びチタンの酸化物から成ることを特徴とする複合酸化物グリーン顔料及びアルミニウム及びチタンの混合塩水溶液とアルカリ水溶液でアルミニウム及びチタンの水酸化物又は炭酸塩を沈殿させた後、この沈殿スラリー中でコバルトの塩水溶液とアルカリ水溶液によってコバルトの水酸化物又は炭酸塩を沈殿、共存させた後、加熱、熟成し、その後濾過、水洗後、焼成することを特徴とする上記の複合酸化物グリーン顔料の製造方法である。
【０００７】
【発明の実施の形態】
次に好ましい実施形態を挙げて本発明を更に詳しく説明する。
本発明のコバルト、アルミニウム及びチタンの酸化物からなる複合酸化物顔料は、各金属塩の水溶液とアルカリ水溶液とを接触させて形成させた各金属の水酸化物又は炭酸塩の共沈澱を８００〜１０００℃の範囲の温度で焼成することによって得ることができる。同様に上記の各金属塩とともにニッケル塩及び亜鉛塩を用いることによっても上記同様の複合酸化物顔料を得ることができる。
【０００８】
本発明で使用するアルミニウム、コバルト及びチタンの塩としては硫酸塩、硝酸塩、塩化物、酢酸塩等の従来の複合酸化物系顔料の湿式合成に使用されている塩はいずれも使用することができる。又、上記の必須成分に加え、色調調整及び分散性の向上のためにマグネシウム塩及びリン酸塩を少量併用することも可能である。ニッケル塩及び亜鉛塩に関しても上記と同様である。
これら金属塩水溶液から金属塩をそれら金属の水酸化物又は炭酸塩として沈殿させるためのアルカリとしては、例えば、炭酸ソーダ、苛性ソーダ、セスキカーボネイト等の金属塩を沈殿させるアルカリ能のあるアルカリであればいずれも使用可能であるが、得られる沈殿物（顔料の前駆体）及び焼成後の顔料の取り扱い易さ及び分散性を考えると炭酸ソーダが最も適している。アルミニウム、チタン及びコバルトの配合割合によって得られる前駆体及び顔料の適性がアルカリの種類に依存して異なるため、一概に最適アルカリの種類を選定できないが、コバルト、ニッケル量の多い場合は苛性ソーダを用いても分散性の割合良好な顔料を得ることもできる。
【０００９】
以上の混合金属塩水溶液からそれぞれの金属の水酸化物又は炭酸塩を沈殿させる方法には、混合水溶液をこれら金属の水酸化物または炭酸塩の沈殿開始ｐＨ以上のｐＨにてアルカリにより一度に共沈させる方法が一般的であり、この方法でもほどほどの分散性を有する顔料が得られるが、アルミニウム及びチタンは、又ニッケル及び亜鉛も、コバルトとは沈殿開始ｐＨが大幅に違うため、得られる水酸化物または炭酸塩の性状が大きく異なり、得られる顔料の組成上の不均一が表面に表れ、高い透明性を要求される分野への適応は難しい。従って、本発明においては本発明者等が既に公開しているようにアルミニウム及びチタン、場合によってはこれらとニッケルと亜鉛は、コバルトとは別々のｐＨにて２段階に分けて水酸化物または炭酸塩の沈殿物を生成させる方法が最も適している。
【００１０】
以下ではニッケル塩と亜鉛塩を使用しない場合について説明するが、これらも使用する場合の沈澱形成のための溶液調製条件や沈澱条件等はアルミニウム塩及びチタン塩の場合と同じである。
２段階に分けて沈殿を形成させるには、先ず、以上の如きアルミニウム塩、チタン塩、コバルト塩及び炭酸ソーダをそれぞれ水に溶解して、別々の塩水溶液及びアルカリ水溶液を作製する。その際の各金属塩の濃度は最終顔料換算濃度として２〜１０重量％とするのがよい。尚、アルミニウム塩とチタン塩は同時に水に溶解して混合塩水溶液を作製してもよい。
次に、アルミニウム塩とチタン塩の混合水溶液は炭酸ソーダ水溶液を用い、予め用意した沈殿媒体中に同時滴下し、アルミニウム及びチタンの水酸化物又は炭酸塩の沈澱を生成させる。その後これらの沈澱を含むスラリー中に、上記同様にコバルト水溶液を滴下してコバルトの水酸化物又は炭酸塩の沈澱を生成させる。
【００１１】
その際、アルミニウム、チタン及びコバルトの各金属塩水溶液の濃度は、混合濃度で０．５〜２．０モル／リットルとするのがよい。混合濃度が上記範囲未満であると、得られる顔料の前駆体及び顔料が微細になりすぎて凝集力が大きく、分散性の悪いものになり、生産効率も低下する。一方、上記範囲を超えると、前駆体及び得られる顔料の嵩が大きくなりすぎ取り扱いが困難になるだけでなく、顔料の吸油量、吸水量も増加し、分散性が悪くなり、透明性が不足する傾向にある。
【００１２】
又、合成（沈澱生成）温度は、アルミニウム及びチタンの混合水酸化物又は炭酸塩の沈殿を生成させる時は４０〜６０℃の範囲が望ましく、この範囲未満の温度では沈殿物がゲル化し、顔料適性がなくなる。又、この範囲を超える温度では沈澱生成や顔料適性等にそれほど大きな影響を及ぼさないが、顔料の分散性がやや悪くなる傾向にある。又、上記温度における沈殿ｐＨは３．５〜４．５の範囲が適当である。ｐＨが３．５未満では沈澱が非常に微細な粒子になってゲル化し、得られる顔料は顔料適性がなくなり、分散性が極めて悪くなる。又、ｐＨが４．５を超えると顔料前駆体及び得られる顔料の嵩が大きくなりすぎ、顔料の吸油量、吸水量の増大を招き、分散不良を起こし好ましくない。
【００１３】
一方、コバルトの水酸化物又は炭酸塩の沈殿時の合成温度は、６０〜８０℃の範囲であれば、満足すべき顔料前駆体及び顔料を得ることができる（その効果を充分発揮できる）。合成温度が６０℃未満ではアルミニウム及びチタンの混合水酸化物又は炭酸塩との場所による組成上の均一性に欠ける傾向にあり、得られる顔料の発色が悪くなる傾向にある。又、８０℃を超えると沈澱時のｐＨ制御が難しいだけでなく、エネルギーの無駄である。望ましくは６０〜７０℃である。
又、上記合成温度における沈殿ｐＨは５．５〜７．５の範囲が望ましい。更に望ましいｐＨは６．０〜７．０である。ｐＨが５．５未満ではコバルトの水酸化物又は炭酸塩が非常に微細な粒子になり、ゲル化し易く、得られる顔料は顔料適性がなくなり、分散性が悪くなる。又、ｐＨが７．５を超えると顔料の前駆体及び顔料自体の嵩が大きくなりすぎ、吸油量、吸水量の増大を招き、分散性にあまりよい結果を生じない。
【００１４】
この様にしてアルミニウム、チタン及びコバルトの水酸化物又は炭酸塩の沈殿物を２段階に分けて生成させる。アルミニウム、チタン及びコバルトの水酸化物又は炭酸塩を同一温度、且つ同一ｐＨで同時に１段階で沈殿させる方法も当然ながら考えられるが、（イ）アルミニウム及びチタンと、（ロ）コバルトでは、お互いの性状が大幅に異なるため、この方法ではどのような条件下でも顔料適性のあまり良い顔料は得られない。
本発明によれば（イ）アルミニウム及びチタンと、（ロ）コバルトの水酸化物又は炭酸塩を別々の条件下で沈殿させる方法を提案しているが、両者の性状の違いを詳細に検討した結果、本発明の沈殿条件下で行えば顔料適性の最も優れた前駆体が得られ、通常の共沈法と全く遜色のない顔料を得ることができる。
アルミニウム、チタン及びコバルトの水酸化物又は炭酸塩の沈殿を生成させた後、更に加熱、熟成して沈殿反応を完了させる。
【００１５】
最後に、得られた生成物を水洗、濾過し、１００〜１２０℃程度の温度で乾燥し、得られた乾燥物を酸化性雰囲気下で約８００〜１０００℃の温度で３０〜９０分焼成することにより、本発明の微粒子型複合酸化物グリーン顔料が得られる。
上記方法により、酸化アルミニウム、酸化チタン及び酸化コバルトからなるＢＥＴ法による比表面積が５０〜９０ｍ２ ／ｇである微粒子型複合酸化物グリーン系顔料が得られる。本発明の顔料における各金属の好ましいモル組成比は、コバルト１に対してアルミニウム１．５〜３．０、チタン０．１〜１．０である。又、該顔料が上記の金属の酸化物と共にニッケル及び亜鉛の酸化物からなる場合には、ニッケルと亜鉛のモル組成はコバルト１モルに対してそれぞれ３．０モル以下であり、他の金属のモル組成は上記と同じである。
【００１６】
以上の発明の特徴は、酸化アルミニウム、酸化コバルト、酸化チタン及び必要に応じて酸化ニッケル、酸化亜鉛からなる複合酸化物グリーン顔料でクロムを全く含まず、クロムを含んだとほぼ同様な色相を有することである。又沈殿剤として一般的なアルカリである炭酸ソーダを使用する単純な製造方法を提供することにある。
更にはアルミニウム及びコバルトの水酸化物又は炭酸塩の反応濃度、沈殿温度、沈殿ｐＨ等の合成条件をそれぞれ精密に制御することで反応性の良好な前駆体を得ることにある。又従来本発明者らの提供している鉱化剤であるモリブデン酸塩又はタングステン酸塩などを共存させ粒子の大きさを制御することも、勿論可能である。
【００１７】
【実施例】
以下に実施例及び比較例を挙げて本発明を具体的に説明する。尚、本文中の部及び％は特に断りのない限り重量基準である。
実施例１
塩化アルミニウム６水塩３１７部及びチタン分１６．５％の四塩化チタン水溶液２８．８部を計り水を加えてこれを完全に溶かして８００部とする。又、沈殿剤（１）を無水炭酸ソーダ２２８部及びリン酸２水素ナトリウム２水塩５部を計りとり、水を加えて７００部とし、約４０℃位に加熱して完全に溶解して作製する。
次に、塩化コバルト６水塩１６２部を計りとり水を加えてこれを完全に溶かして３５０部とする。又、塩化コバルト用沈殿剤（２）を無水炭酸ソーダ８４部及びモリブデン酸ソーダ２水塩４部を計りとり、水を加えて３００部とし、約４０℃に加熱して完全に溶解して作製する。
【００１８】
予め用意しておいた沈殿媒体である水約２０００部をガスバーナーや電熱器等で約５０℃に加熱し、これに塩化アルミニウム及び塩化チタンの混合水溶液とリン酸塩を含んだ炭酸ソーダ水溶液（沈澱剤（１））とを同時に滴下し、約３０分から１時間かけて沈殿反応を完了させる。
沈澱剤滴下時には系のｐＨが４．０前後になるように注意し、塩化アルミニウム及び塩化チタン混合水溶液の滴下が終了した後に、リン酸塩を含む過剰の炭酸ソーダ水溶液を続けて加えｐＨを約６．７とした後、７０℃まで徐々に加熱しながら６０分間程度熟成する。
【００１９】
次に、この媒体スラリー中に塩化コバルト水溶液と別途用意したモリブデン酸ソーダを含んだ炭酸ソーダ水溶液（沈澱剤（２））を同時に滴下し、２０〜２５分かけて沈殿反応を完了させる。
沈澱剤滴下時には系のｐＨが６．５〜６．７位になるように注意し、沈澱剤の滴下が終了した後に、残りの塩化コバルトの水溶液を全量加えてｐＨが６．３〜６．４位にする。その後９０℃まで加熱し、２時間程度熟成する。
次に生成物を取り出しデカンテーションにより充分に水洗し、残塩を洗い流し、濾過を行う。次いで１００〜１２０℃の温度にて１２時間以上乾燥させる。この乾燥物を９００℃で１時間酸化雰囲気にて焼成後冷却した。この様にして本発明の複合酸化物グリーン顔料を得た。この顔料の比表面積をＢＥＴ法で測定した。
【００２０】
得られた顔料（３０部）をペイントシェイカーにてメラミンアルキッド樹脂ワニス（１００部）中に分散させて塗料化し、従来のクロム含有複合酸化物グリーン顔料を用いたものとの対比で色調を観察した。その結果、本発明の顔料は透明性、分散性は従来のものと同等に良好で、色調がやや黄みのグリーンであり、明るさがやや低くかった。以上の結果を表１に示す。
【００２１】
実施例２
塩化アルミニウム６水塩３１７部及びチタン分１６．５重量％の四塩化チタン水溶液５７．６部を計り水を加えてこれを完全に溶かして８００部とする。又、沈殿剤（１）を無水炭酸ソーダ２５０部及びリン酸２水素ナトリウム２水塩５部を計りとり、水を加えて７００部とし、約４０℃位に加熱して完全に溶解して作製する。
次に、塩化コバルト６水塩２３４部を計りとり水を加えてこれを完全に溶かして４００部とする。又、これとは別に塩化コバルト用沈殿剤（２）を無水炭酸ソーダ１１６部及びモリブデン酸ソーダ２水塩４部を計りとり、水を加えて３００部とし、約４０℃に加熱して完全に溶解して作製する。
以下実施例１と同様にして顔料の合成を行った。
この様にして得られた顔料は、明るさはやや低いが、分散性、透明性の良好な深い緑色であった。
ＢＥＴによる比表面積と共に結果を表１に示す。
【００２２】
実施例３
塩化アルミニウム６水塩３１７部及びチタン分１６．５重量％の四塩化チタン水溶液５７．６部を計り水を加えてこれを完全に溶かして８００部とする。又、沈殿剤（１）を無水炭酸ソーダ２５０部及びリン酸２水素ナトリウム２水塩５部を計りとり、水を加えて７００部とし、約４０℃位に加熱して完全に溶解して作製する。
次に、塩化コバルト６水塩１８６部、硫酸亜鉛７水塩２８．７部、塩化ニッケル６水塩２３．７部を計りとり水を加えてこれを完全に溶かして４００部の混合水溶液とする。又、これとは別に塩化コバルト、塩化ニッケル硫酸亜鉛用沈殿剤（２）を無水炭酸ソーダ１１６部及びモリブデン酸ソーダ２水塩４部を計りとり、水を加えて３００部とし、約４０℃に加熱して完全に溶解して作製する。
以下実施例１と同様にして顔料の合成を行った。
この様にして得られた顔料は、明るさはやや低いが、分散性、透明性の良好な深い黄みの緑色であった。
ＢＥＴによる比表面積と共に結果を表１に示す。
【００２３】
比較例１
硝酸アルミニウム９水塩３７．５部、硝酸コバルト６水塩２９．１部、硝酸クロム９水塩８０．０部、及びチタン分１６．３重量％の四塩化チタン水溶液１１．７６部を計り、水を加えてこれを完全に溶かし全体を約５００部とする。次に沈殿剤（１）として苛性ソーダ５１．０部を計りとり水を加えて全体を５００部とする。
予め用意しておいた沈殿媒体である水１，２００部をガスバーナー等で約３０℃に加熱保持し、ここに混合塩水溶液と苛性ソーダ水溶液（沈澱剤（１））とを同時に滴下し、約３０分から１時間かけて沈殿反応を完了させる。この際のｐＨは９になる様に注意し、滴下が終了したら沈殿が完全に行われるようにｐＨを約１０にアップさせ、液温は３０℃を保つようにしながら１時間程度熟成させる。次に熟成を終了したならば、これを取り出してデカンテーションにより充分に水洗し残塩を洗い流し濾過を行う。次いで１００〜１２０℃の温度にて１２時間以上乾燥させる。この乾燥物を８００℃で１時間酸化雰囲気にて焼成する。
この様にして得られた顔料は、青みの深い緑色をした透明性の高いものであった。
ＢＥＴによる比表面積と共に結果を表１に示す。
【００２４】
比較例２
硝酸コバルト６水塩２９．１部、硝酸アルミニウム９水塩３．７５部、硝酸クロム９水塩７２．０３部及びチタン分１６．６％の四塩化チタン水溶液１１．５４部を計り、水を加えてこれを完全に溶かして全体を約４００部とする。次に沈殿剤として苛性ソーダ３７．０部を計りとり、水を加えて全体を約４００部とする。以下比較例１と同様の方法にて顔料の合成を行った。
この様にして得られた顔料は深い緑色をした透明性の高いものであった。
ＢＥＴによる比表面積と共に結果を表１に示す。
【００２５】
表１
【発明の効果】
以上の発明によれば、クロムを含まずに青みの緑から黄みの緑色までの色相を有する緑色顔料が提供される。また、湿式法によれば、高い透明性を有する微粒子型の緑色顔料を得ることもできる。
従って、本発明によるノンクロムグリーン顔料及び微粒子型複合酸化物グリーン顔料は、鮮明な発色と良好な分散性、高い着色力を合わせ持ち、塗料や合成樹脂の着色剤等に用いられる他、これらの特性を活かした光学的カラーフィルター用のグリーン顔料として、また、基材の色調を活かしたメタリック塗料やカラークリヤーへ、さらには蛍光体着色用顔料、紫外線吸収剤、薄膜、印刷インキ、化粧品、研磨剤等への応用が期待できる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a composite oxide green pigment, and more particularly, to a composite oxide green pigment which is excellent in color developability, has a deep green color as an inorganic pigment, exhibits a clear green color, and has good transparency and good dispersibility. And its manufacturing method. Utilizing the newly emerging properties by increasing the color development, not only for conventional resins, but also for paints and inks and by further reducing the particle size, for example, as a green pigment for color filters, and taking advantage of the color tone of the base material The present invention relates to a composite oxide green pigment which is useful as a metallic paint, a green pigment for color clear, an adhesion pigment for a phosphor, a thin film, cosmetics, an ultraviolet absorber and the like.
[0002]
[Prior art]
Composite oxide green pigments are widely known as inorganic pigments having excellent heat resistance, weather resistance, and the like, and are widely used, for example, as colorants for paints and synthetic resins, and for ceramics.
Among them, cobalt, nickel, zinc, titanium-based and cobalt, aluminum, chromium, and titanium-based spinel-type composite oxide green pigments are well known. The former is a clear yellowish green, but the proportion of each component is constant, and only a single color can be obtained. That is, component ratio of Co 2 TiO 4 · 2Ni 2 TiO 4 · Zn 2 TiO 4 shows the best color. On the other hand, the latter can be changed continuously in a considerable range from a bluish green to a bluish-yellowish green mainly depending on the chromium content.
[0003]
In addition, a series of methods for forming fine particles of the green pigment and the like have already been published by the present applicants (JP-A-4-55322, JP-A-4-55323, JP-A-3-8728, JP-A-8-217457).
However, it is specified that the cobalt, nickel, zinc, and titanium-based composite oxide green pigments can obtain only a fairly yellowish green single hue by the method according to JP-A-3-8728. As described above, it is an essential condition that the cobalt, aluminum, chromium, and titanium-based composite oxide green pigments contain chromium as a component instead of exhibiting a fairly wide hue. Among composite oxide pigments, pigments that do not use chromium are eagerly desired due to their harmfulness in all types of pigments, but green pigments have similar demands.
[0004]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a highly saturated chromium-containing composite oxide-based green pigment having a hue from cobalt blue to green, which has excellent transparency, and has almost the same hues and characteristics. And a composite oxide green pigment having a composition not containing chromium and a method for producing the same.
The present inventors have conducted intensive studies to solve the above-mentioned problems of the prior art, and as a result, a so-called cobalt blue pigment which develops a reddish blue color when the oxides of cobalt and aluminum form a solid solution at a high temperature is 800 to 1000 ° C. In the middle temperature range of the range, it was found to develop a green color during the transition to blue. The green color is slightly yellowish and the pigment is in a transition state to a blue pigment, so that the surface area is large, so that the oil absorption is high, the coloring power is low, and the hue is not sufficiently strong.
[0005]
The present inventors have further studied diligently and found that a wide range of colors from bluish green to deep green can be obtained by dissolving titanium, cobalt, and titanium oxide in cobalt and aluminum oxide, which is the component composition of the cobalt blue pigment. It has been found that the resulting pigment has a strong hue and an appropriate oil absorption, while at the same time improving the suitability of various pigments. It has also been found that a similar pigment can be obtained by substituting part of the above cobalt with nickel or zinc. Further, the present inventors have found that a complex oxide green pigment having high transparency and high chroma can be obtained by using a wet synthesis method, and the present invention has been completed.
[0006]
[Means for Solving the Problems]
The above object is achieved by the following invention. That is, the present invention provides a composite oxide green pigment comprising an oxide of cobalt, aluminum and titanium, and a hydroxide or carbonate of aluminum and titanium precipitated with an aqueous solution of a mixed salt of aluminum and titanium and an aqueous alkaline solution. After that, the hydroxide or carbonate of cobalt is precipitated and coexisted with a cobalt salt aqueous solution and an alkaline aqueous solution in this precipitation slurry, heated, aged, then filtered, washed with water, and calcined. The method for producing a composite oxide green pigment described above.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described in more detail with reference to preferred embodiments.
The composite oxide pigment comprising an oxide of cobalt, aluminum and titanium according to the present invention has a coprecipitation of a hydroxide or carbonate of each metal formed by contacting an aqueous solution of each metal salt with an aqueous alkali solution to 800 to 800 μm. It can be obtained by firing at a temperature in the range of 1000 ° C. Similarly, a composite oxide pigment similar to the above can be obtained by using a nickel salt and a zinc salt together with each of the above metal salts.
[0008]
As the salts of aluminum, cobalt and titanium used in the present invention, any of the salts used for the wet synthesis of conventional complex oxide pigments such as sulfates, nitrates, chlorides and acetates can be used. . Further, in addition to the above essential components, it is also possible to use a small amount of a magnesium salt and a phosphate for adjusting the color tone and improving the dispersibility. The same applies to nickel salts and zinc salts.
Examples of the alkali for precipitating the metal salt from the aqueous solution of the metal salt as a hydroxide or a carbonate of the metal include, for example, sodium carbonate, caustic soda, and an alkali capable of precipitating a metal salt such as sesquicarbonate. Any of them can be used, but sodium carbonate is most suitable in consideration of the resulting precipitate (pigment precursor) and the ease of handling and dispersibility of the pigment after firing. Because the suitability of the precursor and pigment obtained by the mixing ratio of aluminum, titanium and cobalt differs depending on the type of alkali, it is not possible to select the optimum alkali type in general, but if the amount of cobalt or nickel is large, use caustic soda. However, a pigment having a good dispersibility can be obtained.
[0009]
In the above-mentioned method of precipitating hydroxides or carbonates of the respective metals from the aqueous solution of the mixed metal salt, the aqueous solutions are mixed at once with an alkali at a pH not lower than the pH at which the precipitation of the hydroxides or carbonates of these metals is started. The method of precipitation is generally used, and a pigment having a moderate dispersibility can be obtained by this method.However, aluminum and titanium, nickel and zinc, and cobalt have significantly different precipitation starting pHs. The properties of the oxides or carbonates are greatly different, and the resulting pigment has non-uniform composition on the surface, making it difficult to adapt to fields requiring high transparency. Therefore, in the present invention, as already disclosed by the present inventors, aluminum and titanium, and in some cases nickel and zinc, are separated from cobalt and hydroxide or carbonate in two steps at a different pH from cobalt. Most suitable is a method that produces a salt precipitate.
[0010]
In the following, a case where no nickel salt and zinc salt are used will be described. However, when these are also used, solution preparation conditions and precipitation conditions for forming a precipitate are the same as those of the aluminum salt and the titanium salt.
In order to form a precipitate in two stages, first, the aluminum salt, titanium salt, cobalt salt and sodium carbonate as described above are dissolved in water to prepare separate salt aqueous solutions and alkaline aqueous solutions. At that time, the concentration of each metal salt is preferably 2 to 10% by weight in terms of the final pigment conversion concentration. The aluminum salt and the titanium salt may be simultaneously dissolved in water to prepare a mixed salt aqueous solution.
Next, a mixed aqueous solution of an aluminum salt and a titanium salt is simultaneously dropped into a previously prepared precipitation medium using an aqueous sodium carbonate solution to form a precipitate of a hydroxide or a carbonate of aluminum and titanium. Thereafter, a cobalt aqueous solution is dropped into the slurry containing these precipitates in the same manner as described above to form a precipitate of cobalt hydroxide or carbonate.
[0011]
At that time, the concentration of each of the aqueous solutions of the metal salts of aluminum, titanium and cobalt is preferably 0.5 to 2.0 mol / liter in a mixed concentration. When the mixing concentration is less than the above range, the obtained pigment precursor and pigment are too fine, resulting in large cohesive strength, poor dispersibility, and reduced production efficiency. On the other hand, if it exceeds the above range, not only the bulk of the precursor and the obtained pigment becomes too large and handling becomes difficult, but also the oil absorption and water absorption of the pigment increase, the dispersibility becomes poor, and the transparency is insufficient. Tend to.
[0012]
The temperature of the synthesis (precipitation) is preferably in the range of 40 to 60 ° C. when a mixed hydroxide or carbonate of aluminum and titanium is formed. You lose your aptitude. Further, at a temperature exceeding this range, precipitation formation and pigment suitability are not significantly affected, but the dispersibility of the pigment tends to be slightly deteriorated. The precipitation pH at the above temperature is suitably in the range of 3.5 to 4.5. If the pH is less than 3.5, the precipitate becomes very fine particles and gels, and the resulting pigment loses its suitability for pigment and has extremely poor dispersibility. On the other hand, when the pH exceeds 4.5, the bulk of the pigment precursor and the obtained pigment becomes too large, which leads to an increase in the oil absorption and water absorption of the pigment, resulting in poor dispersion, which is not preferable.
[0013]
On the other hand, if the synthesis temperature at the time of precipitation of cobalt hydroxide or carbonate is in the range of 60 to 80 ° C., satisfactory pigment precursors and pigments can be obtained (the effects can be sufficiently exhibited). If the synthesis temperature is lower than 60 ° C., the composition tends to lack uniformity depending on the location of the mixed hydroxide or carbonate of aluminum and titanium, and the resulting pigment tends to have poor coloring. On the other hand, when the temperature exceeds 80 ° C., not only is it difficult to control the pH during precipitation, but also energy is wasted. Desirably, it is 60 to 70 ° C.
Further, the precipitation pH at the above synthesis temperature is desirably in the range of 5.5 to 7.5. A more desirable pH is 6.0 to 7.0. If the pH is less than 5.5, the hydroxide or carbonate of cobalt becomes very fine particles, and the particles are easily gelled, and the resulting pigment has poor pigment suitability and poor dispersibility. On the other hand, when the pH exceeds 7.5, the bulks of the pigment precursor and the pigment itself become too large, which causes an increase in oil absorption and water absorption, and does not produce very good results in dispersibility.
[0014]
In this way, a precipitate of hydroxide or carbonate of aluminum, titanium and cobalt is formed in two stages. A method of simultaneously precipitating the hydroxide or carbonate of aluminum, titanium and cobalt in one step at the same temperature and the same pH can be naturally considered, but (a) aluminum and titanium and (b) cobalt each other Due to the vastly different properties, this method does not give pigments with good pigment suitability under any conditions.
According to the present invention, a method of precipitating (a) aluminum and titanium and (b) a hydroxide or carbonate of cobalt under different conditions has been proposed, but the difference in properties between the two has been examined in detail. As a result, under the precipitation conditions of the present invention, a precursor having the best pigment suitability can be obtained, and a pigment which is not inferior to the ordinary coprecipitation method can be obtained.
After the precipitation of hydroxides or carbonates of aluminum, titanium and cobalt, it is further heated and aged to complete the precipitation reaction.
[0015]
Finally, the obtained product is washed with water, filtered, and dried at a temperature of about 100 to 120 ° C., and the obtained dried substance is calcined in an oxidizing atmosphere at a temperature of about 800 to 1000 ° C. for 30 to 90 minutes. Thereby, the fine particle type composite oxide green pigment of the present invention is obtained.
By the above method, a fine particle type composite oxide green pigment composed of aluminum oxide, titanium oxide, and cobalt oxide and having a specific surface area of 50 to 90 m 2 / g by a BET method is obtained. The preferred molar composition ratio of each metal in the pigment of the present invention is 1.5 to 3.0 aluminum and 0.1 to 1.0 titanium with respect to 1 cobalt. When the pigment is composed of nickel and zinc oxides together with the above-mentioned metal oxides, the molar composition of nickel and zinc is 3.0 mol or less with respect to 1 mol of cobalt, respectively. The molar composition is the same as above.
[0016]
The features of the invention described above are composite oxide green pigments composed of aluminum oxide, cobalt oxide, titanium oxide and, if necessary, nickel oxide and zinc oxide, containing no chromium at all, and having substantially the same hue as containing chromium. That is. Another object of the present invention is to provide a simple production method using sodium carbonate, which is a common alkali, as a precipitant.
Another object of the present invention is to obtain a precursor having good reactivity by precisely controlling synthesis conditions such as a reaction concentration of aluminum or cobalt hydroxide or carbonate, a precipitation temperature, and a precipitation pH. Further, it is of course possible to control the size of the particles by coexisting molybdate or tungstate which is a mineralizer provided by the present inventors.
[0017]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples. The parts and percentages in the text are based on weight unless otherwise specified.
Example 1
317 parts of aluminum chloride hexahydrate and 28.8 parts of an aqueous solution of titanium tetrachloride having a titanium content of 16.5% are weighed, and water is added thereto to completely dissolve it to 800 parts. In addition, 228 parts of anhydrous sodium carbonate and 5 parts of sodium dihydrogen phosphate dihydrate were weighed out to prepare a precipitant (1), and water was added to make 700 parts. I do.
Next, 162 parts of cobalt chloride hexahydrate are weighed out, water is added and the mixture is completely dissolved to 350 parts. In addition, a precipitant (2) for cobalt chloride was prepared by weighing 84 parts of anhydrous sodium carbonate and 4 parts of sodium molybdate dihydrate, adding water to 300 parts, and heating to about 40 ° C. to completely dissolve. I do.
[0018]
About 2000 parts of water, which is a precipitating medium prepared in advance, is heated to about 50 ° C. with a gas burner, an electric heater, or the like, and mixed with an aqueous solution of aluminum chloride and titanium chloride and an aqueous solution of sodium carbonate containing phosphate ( Precipitant (1)) is simultaneously added dropwise, and the precipitation reaction is completed in about 30 minutes to 1 hour.
When dropping the precipitant, be careful that the pH of the system is around 4.0. After the dropping of the mixed aqueous solution of aluminum chloride and titanium chloride is completed, excess sodium carbonate aqueous solution containing phosphate is continuously added to adjust the pH to about. After 6.7, it is aged for about 60 minutes while gradually heating to 70 ° C.
[0019]
Next, an aqueous solution of cobalt chloride and an aqueous solution of sodium carbonate (precipitant (2)) containing sodium molybdate separately prepared are simultaneously dropped into this medium slurry, and the precipitation reaction is completed in 20 to 25 minutes.
At the time of dropping the precipitant, care is taken that the pH of the system is about 6.5 to 6.7. After the dropping of the precipitant is completed, the whole amount of the remaining aqueous solution of cobalt chloride is added to adjust the pH to 6.3 to 6.7. Place fourth. Thereafter, the mixture is heated to 90 ° C. and aged for about 2 hours.
Next, the product is taken out and sufficiently washed by decantation to remove residual salts, followed by filtration. Next, it is dried at a temperature of 100 to 120 ° C. for 12 hours or more. The dried product was fired at 900 ° C. for 1 hour in an oxidizing atmosphere and then cooled. Thus, the composite oxide green pigment of the present invention was obtained. The specific surface area of this pigment was measured by the BET method.
[0020]
The obtained pigment (30 parts) was dispersed in a melamine alkyd resin varnish (100 parts) with a paint shaker to form a paint, and the color tone was observed in comparison with that using a conventional chromium-containing composite oxide green pigment. . As a result, the pigment of the present invention was as good in transparency and dispersibility as the conventional pigment, was a slightly yellowish green color, and was slightly low in brightness. Table 1 shows the above results.
[0021]
Example 2
317 parts of aluminum chloride hexahydrate and 57.6 parts of an aqueous solution of titanium tetrachloride having a titanium content of 16.5% by weight are weighed and completely dissolved to make 800 parts. In addition, 250 parts of anhydrous sodium carbonate and 5 parts of sodium dihydrogen phosphate dihydrate are weighed out to prepare a precipitant (1), and water is added to make 700 parts. I do.
Next, 234 parts of cobalt chloride hexahydrate are weighed, water is added thereto, and this is completely dissolved to 400 parts. Separately, 116 parts of anhydrous sodium carbonate and 4 parts of sodium molybdate dihydrate were weighed with a precipitating agent (2) for cobalt chloride, and water was added to make 300 parts. Prepare by dissolving.
Thereafter, a pigment was synthesized in the same manner as in Example 1.
The pigment obtained in this way had a slightly low brightness, but was a deep green with good dispersibility and transparency.
The results are shown in Table 1 together with the specific surface area by BET.
[0022]
Example 3
317 parts of aluminum chloride hexahydrate and 57.6 parts of an aqueous solution of titanium tetrachloride having a titanium content of 16.5% by weight are weighed and completely dissolved to make 800 parts. In addition, 250 parts of anhydrous sodium carbonate and 5 parts of sodium dihydrogen phosphate dihydrate are weighed out to prepare a precipitant (1), and water is added to make 700 parts. I do.
Next, 186 parts of cobalt chloride hexahydrate, 28.7 parts of zinc sulfate heptahydrate, and 23.7 parts of nickel chloride hexahydrate are weighed, and water is added to completely dissolve the mixture to form a 400 part mixed aqueous solution. . Separately, 116 parts of anhydrous sodium carbonate and 4 parts of sodium molybdate dihydrate were weighed with a precipitant (2) for cobalt chloride and nickel chloride and zinc chloride, and water was added to make 300 parts. Heat to completely dissolve and make.
Thereafter, a pigment was synthesized in the same manner as in Example 1.
The pigment obtained in this way was a slightly yellowish green with good dispersibility and transparency, although the brightness was slightly low.
The results are shown in Table 1 together with the specific surface area by BET.
[0023]
Comparative Example 1
37.5 parts of aluminum nitrate nonahydrate, 29.1 parts of cobalt nitrate hexahydrate, 80.0 parts of chromium nitrate nonahydrate, and 11.76 parts of a titanium tetrachloride aqueous solution having a titanium content of 16.3% by weight were measured. Water is added to completely dissolve this to make about 500 parts in total. Next, 51.0 parts of caustic soda is measured as a precipitant (1), and water is added to make the whole 500 parts.
1,200 parts of water, which is a precipitating medium prepared in advance, is heated and maintained at about 30 ° C. by a gas burner or the like, and an aqueous solution of a mixed salt and an aqueous solution of caustic soda (precipitant (1)) are simultaneously added dropwise thereto. The precipitation reaction is completed in 30 minutes to 1 hour. At this time, care is taken so that the pH becomes 9, and when the dropping is completed, the pH is raised to about 10 so that precipitation is completely performed, and the solution is aged for about 1 hour while maintaining the liquid temperature at 30 ° C. Next, when the ripening is completed, the ripened product is taken out, washed sufficiently with decantation to remove residual salts, and filtered. Next, it is dried at a temperature of 100 to 120 ° C. for 12 hours or more. The dried product is fired at 800 ° C. for 1 hour in an oxidizing atmosphere.
The pigment obtained in this way had a deep blue green color and high transparency.
The results are shown in Table 1 together with the specific surface area by BET.
[0024]
Comparative Example 2
29.1 parts of cobalt nitrate hexahydrate, 3.75 parts of aluminum nitrate nonahydrate, 72.03 parts of chromium nitrate nonahydrate and 11.54 parts of an aqueous solution of titanium tetrachloride having a titanium content of 16.6% were measured. In addition, this is completely dissolved to make about 400 parts in total. Next, 37.0 parts of caustic soda is measured as a precipitant, and water is added to make the whole about 400 parts. Thereafter, a pigment was synthesized in the same manner as in Comparative Example 1.
The pigment thus obtained had a deep green color and high transparency.
The results are shown in Table 1 together with the specific surface area by BET.
[0025]
Table 1
【The invention's effect】
According to the above invention, a green pigment having a hue from bluish green to yellowish green without chromium is provided. Further, according to the wet method, a fine-particle type green pigment having high transparency can be obtained.
Therefore, the non-chromium green pigment and the fine particle type composite oxide green pigment according to the present invention have clear coloring, good dispersibility, high coloring power, and are used as a coloring agent for paints and synthetic resins, and have these properties. As a green pigment for optical color filters utilizing the color of the substrate, to metallic paints and color clears utilizing the color tone of the base material, as well as pigments for coloring phosphors, ultraviolet absorbers, thin films, printing inks, cosmetics, and abrasives It can be expected to be applied to such applications.
Claims (6)
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25800998A JP3601759B2 (en) | 1998-09-11 | 1998-09-11 | Composite oxide green pigment and method for producing the same |
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| JP25800998A JP3601759B2 (en) | 1998-09-11 | 1998-09-11 | Composite oxide green pigment and method for producing the same |
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| JP2000086246A JP2000086246A (en) | 2000-03-28 |
| JP3601759B2 true JP3601759B2 (en) | 2004-12-15 |
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| JP5266805B2 (en) * | 2008-03-07 | 2013-08-21 | 戸田工業株式会社 | Infrared reflective green pigment, paint and resin composition using the infrared reflective green pigment |
| US8961683B2 (en) | 2008-03-07 | 2015-02-24 | Toda Kogyo Corporation | Infrared reflecting blue pigment, infrared reflecting green pigment, paint and resin composition using the infrared reflecting blue pigment, and paint and resin composition using the infrared reflecting green pigment |
| KR101385721B1 (en) * | 2012-04-13 | 2014-04-15 | 롯데케미칼 주식회사 | Complex metal oxide, and method for preparing polyesters using the same |
| CN104477932A (en) * | 2014-12-18 | 2015-04-01 | 常熟市环虹化工颜料厂 | Preparation method of chrome oxide green pigment |
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1998
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