JP3806790B2 - Process for producing spindle-shaped titanium dioxide - Google Patents
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【０００１】
【発明の属する技術分野】
本発明は長径が０．１５〜０．３０μｍであり、かつ長径／短径の比が２〜８である紡錘状二酸化チタンの製造方法に関する。
【０００２】
【従来の技術】
二酸化チタンは、塗料，化粧品の原料，トナーの電荷調整剤，プラスチック，ゴム，フィルムなどの充填剤として用いられており、紡錘状や針状といった形状を有するアスペクト比の大きな二酸化チタンも、その形状を生かした用途に用いられている。このような紡錘状二酸化チタンの製造方法には多くの方法が開示されている。
【０００３】
特開昭６２−２８１８１２号公報には紡錘状の二酸化チタンの簡単な製法が示されている。この方法によれば、四塩化チタン水溶液を湿式加水分解して水酸化チタンを生成させ、次いで、１５０〜６００℃の温度で焼成し、ルチル化を行ない、比表面積が６０〜２５０ｍ2 のルチル形結晶構造をもつ二酸化チタンが得られるとだけ記載されている。
【０００４】
特開昭６３−３０７１１９号公報には、四塩化チタンまたは硫酸法によって得られる二酸化チタン水和物を原料とし、最大寸法０．０１〜０．１５μｍ、最大寸法と最短寸法との比が８：１から２：１の範囲内である針状二酸化チタンおよびその製造方法が開示されている。
【０００５】
特公平６−７６２１５号公報には、結晶の大きさが１０〜１００ｎｍ、すなわち０．１〜０．０１μｍの微結晶二酸化チタンの製法が開示されている。そこには、おおよそ次のような製造工程が示されている。
チタン鉄鉱を硫酸と反応させて濃縮、不純物除去の後、加水分解による沈殿によって得られた二酸化チタン水和物を、水酸化ナトリウム水溶液を加えて強塩基性にして沸点付近で加熱処理する。次いで、この処理物に塩酸を加えてｐＨ２前後とし、温度を６０℃にして更に塩酸を添加し、ＨＣｌ濃度を８〜２５ｇ／ｌとする。更に温度を上げて９０℃とし、１２０分間熟成する。最後にアルカリで中和し、ろ過，洗浄，乾燥，粉砕する。
【０００６】
【発明が解決しょうとする課題】
一般的に”微粒子酸化チタン”と呼ばれる、平均粒子径０．１μｍ以下の酸化チタンは、可視光における透明性、ならびに紫外線遮蔽性を有するという物性を有してはいるものの、粒子が顔料用酸化チタンに比べて小さいだけに分散性が劣り、塗料，化粧品などの原料として使用する場合、分散時間がかかるなどの欠点を有していた。
本発明の目的は、上記分散性に関する欠点が解消され、しかも可視光における透明性ならびに紫外線遮蔽性という物性をも有する、結晶構造がルチル形であり、平均長径が０．１５〜０．３０μｍであり、長径／短径の比が２〜８であるような紡錘状二酸化チタンの製造方法を提供することにある。
本発明でいうところの”紡錘状”とは、その形状が両端のとがった円柱形に似た形をしており、とがった両端を結ぶ長さ（長径）と円柱部の最も太い部分（短径）との比が２〜８であるものをいう。
【０００７】
【課題を解決するための手段】
本発明者らは、製造条件を工夫することにより、上記二酸化チタンの製造方法を見出した。
すなわち本発明の要旨は、下記（ａ）〜（ｃ）の工程よりなる、粒子の平均の大きさが、長径０．１５〜０．３μｍ、短径０．０３〜０．１μｍ、長径／短径比２〜８の範囲内であり、その形状が紡錘状である、ルチル形二酸化チタンの製造方法に存する。
（ａ） 二酸化チタン水和物に塩基処理を行い、得られた二酸化チタン水和物スラリーを塩酸で中和し、ｐＨを６〜９にする：
（ｂ） 中和した二酸化チタン水和物スラリーを４０℃〜６０℃に加熱し、そこにスラリー中の塩酸濃度が１００％ＨＣｌ換算で３２〜４８ｇ／ｌとなる量の塩酸を、スラリー中に存在する二酸化チタン水和物のＴｉＯ2 換算１ｋｇに対し、１００％ＨＣｌ換算で０．０５〜０．２０ｋｇ／分の速度で添加する：
（ｃ） 塩酸添加後、更に加熱を行い、９０℃〜沸点で熟成した後に、塩基で中和し、ろ過、水洗、乾燥を行う。
【０００８】
本発明が従来の技術と異なる点は、工程（ａ）において塩基処理された二酸化チタン水和物スラリーを、塩酸で一旦ｐＨ６〜９に中和すること、および、工程（ｂ）において塩酸の添加速度をスラリー中に存在する二酸化チタン水和物の量に応じて特定値の範囲内に設定することにある。
【０００９】
以下、本発明を工程毎に説明する。
まず、原料として用いる二酸化チタン水和物は、四塩化チタン、チタンアルコキシド、硫酸チタニルなどから得られる。これらのうち、チタン鉄鉱を硫酸と反応させるいわゆる硫酸法によって得られる硫酸チタニルの加水分解から得られる二酸化チタン水和物が好ましい。
【００１０】
工程（ａ）における二酸化チタン水和物の塩基処理とは、硫酸チタニルの加水分解によって得られた二酸化チタン水和物ケーキに塩基を加え、９０〜１００℃の温度で約２時間加熱処理し、処理後の反応生成物をろ過，洗浄することである。塩基としては一般に水酸化ナトリウム、水酸化カリウムなどが用いられる。本工程自体は公知であり、例えば、特開昭５９−２２３２３１号公報、特公平６−７６２１５号公報などに記載されている。
塩基処理された二酸化チタン水和物は、撹拌しながら、ＴｉＯ2 換算で１７０ｇ／ｌ以下となるように水を加えてスラリー化する。１７０ｇ／ｌを超えると、後の塩酸添加工程において増粘し、作業がしにくくなる。
次いで塩酸を加えてｐＨ６〜９に中和する。この時ｐＨが６より低いと、得られる二酸化チタンは、長径がせいぜい０．１μｍ以下の大きさにしかならず好ましくない。また、ｐＨが９を超えてしまうと、後の工程で加える塩酸の添加後の塩酸濃度の安定化が保たれなくなってしまい、結果的に二酸化チタンの長径が大きくならず好ましくない。
【００１１】
工程（ａ）によって塩酸で中和された状態にあるｐＨ６〜９のスラリーは、工程（ｂ）により撹拌しながら加熱され、４０〜６０℃の温度に調整される。この際、温度が６０℃を超えると、得られる二酸化チタンの長径は０．１μｍ以下となってしまうので好ましくない。また、４０℃より低い温度では、紡錘状の形状が形成されない。
上記温度に設定されたスラリーに塩酸を加え、スラリー中の塩酸濃度を１００％ＨＣｌ換算で３２〜４８ｇ／ｌにする。塩酸を添加する際には、スラリー中の二酸化チタン水和物ＴｉＯ2 換算１ｋｇに対し、１００％ＨＣｌ換算で０．０５〜０．２ｋｇ／分、好ましくは０．０８〜０．１３ｋｇ／分、の速度で塩酸を加えなければならない。
塩酸添加後の塩酸濃度が３２ｇ／ｌよりも低いと、形成される二酸化チタンの粒径が小さくなるので好ましくない。また逆に塩酸濃度が４８ｇ／ｌよりも高いと、得られる二酸化チタンの長径が大きくならず好ましくない。
また、塩酸の添加速度が０．０５ｋｇ／分よりも小さいと、形成される二酸化チタンの長径が小さくなるので好ましくない。また逆に、添加速度が０．２ｋｇ／分を越えてしまうと得られる二酸化チタンは凝集体となってしまう。
従って、本添加工程においては、上記添加量、添加速度を適正に行なえるようにするために、事前の準備や添加設備を充分に検討しておく必要がある。
【００１２】
工程（ｃ）では、工程（ｂ）の塩酸添加後、４０〜６０℃の温度範囲にある系に対し加熱を行い、温度を９０℃〜沸点とし、３０分以上の熟成を行なう。
熟成温度が９０℃より低いと紡錘状とはならず、球状に近い形状のものが形成されるので好ましくない。
熟成時間は長いほど二酸化チタンの粒径分布が狭くなり均一なものが得られるが、余り長くなりすぎると経済的ではない。好ましくは１時間ないし３時間が適切である。
熟成後のスラリーは、例えば、アンモニア水，苛性ソーダ水溶液，炭酸ソーダ水溶液などの塩基により中和し、公知の方法でろ過，洗浄，乾燥する。
必要に応じ、５００℃以下好ましくは２００〜４００℃の範囲内の任意の温度で３０分以上焙焼しても構わない。焙焼温度が５００℃を超えてしまうと粒子形状が丸味を帯びてしまうので、もはや紡錘状二酸化チタンとは呼べなくなってしまう。
【００１３】
このようにして得られた紡錘状二酸化チタンは、引き続きその表面を公知の方法により、無機化合物、有機化合物、あるいはそれらの複合体などで被覆しても構わない。
たとえば、上記紡錘状二酸化チタンを、エックアトマイザーなどの乾式粉砕機やサンドグラインダーなどの湿式粉砕機に通した後、スラリー化し無機化合物，有機化合物あるいはそれらの複合体で二酸化チタン表面を被覆処理する。
無機化合物としてはケイ素，アルミニウム，ジルコニウム，亜鉛，アンチモン，マグネシウム，鉄，ニッケル，コバルトなどの酸化物や水酸化物などがあげられる。
有機化合物としてはラウリン酸，イソステアリン酸，ステアリン酸，パルミチン酸などの脂肪酸、環状あるいは直鎖のシリコーンオイルに代表される有機ケイ素化合物，チタニウムアルコキシドに代表される有機チタン化合物などがあげられる。
無機，有機複合体としては、例えばアルミニウムの水和酸化物とステアリン酸などの複合体や、亜鉛、アルミニウム、カルシウム、バリウムなどの脂肪酸金属石鹸などがある。
これらの無機化合物や有機化合物、複合体は各々単独でも、いずれか二種以上を組み合わせて用いることも可能である。
【００１４】
本発明の製造方法によって得られる紡錘状二酸化チタンは、その大きさからすると、もはやいわゆる”微粒子酸化チタン”の範中には入らないが、それにもかかわらず、物性的には可視光における透明性や紫外線遮蔽性を有し、しかも分散に係る問題をも解消するものである。
【００１５】
【発明の実施の形態】
次に本発明を実施例によって詳しく説明する。
【００１６】
【実施例１】
工程（ａ）
常法により硫酸チタニル溶液を加水分解し、ろ過洗浄した含水二酸化チタンケーキ（二酸化チタン水和物）３５ｋｇ（ＴｉＯ2 換算で１０ｋｇ）に、４８％水酸化ナトリウム水溶液４０ｋｇを攪拌しながら投入し、その後加熱して９５〜１０５℃の温度範囲で２時間攪拌した。次いで、このスラリーをろ過し、充分洗浄することにより塩基処理された二酸化チタン水和物を得た。この水和物ケーキに水を加えてスラリー化し、ＴｉＯ2 換算濃度で１１０ｇ／ｌに調整した。
このスラリーを攪拌しながら、３５％塩酸を添加して、ｐＨ７．０とした。
工程（ｂ）
上記スラリーを５０℃に加熱し、この温度で３５％塩酸１２．５ｋｇを、攪拌しながら４分間で添加し、塩酸添加後のスラリー中における塩酸濃度が、１００％ＨＣｌ換算で４０ｇ／ｌとなるようにした。
塩酸添加速度は、ＴｉＯ2 換算１ｋｇ当たり０．１１ｋｇ／分である。
工程（ｃ）
塩酸添加に引き続き、スラリーの加熱を行い、１００℃で２時間熟成した。
熟成後のスラリーに、アンモニア水を添加してｐＨ＝６．５に中和した。充分にろ過、水洗を行い、乾燥後、流体エネルギーミルで粉砕した。
得られた粉体は平均長径０．２５μｍ、平均短径０．０６μｍの紡錘状の形をした二酸化チタンであった。Ｘ線回折装置による測定の結果、結晶形はルチル形であった。
【００１７】
【実施例２】
工程（ａ）における３５％塩酸添加後のｐＨを６．２とした以外は、実施例１と同じ処理を行った。
【００１８】
【実施例３】
工程（ａ）における３５％塩酸添加後のｐＨを８．８とした以外は、実施例１と同じ処理を行った。
【００１９】
【実施例４】
工程（ｂ）におけるスラリー温度を５０℃から５５℃とした以外は、実施例１と同じ処理を行った。
【００２０】
【実施例５】
工程（ｂ）におけるスラリー温度を５０℃から４５℃にした以外は、実施例１と同じ処理を行った。
【００２１】
【実施例６】
工程（ｂ）における３５％塩酸添加時間を２．５分間とした（塩酸添加速度：ＴｉＯ2 換算１ｋｇ当たり０．１７５ｋｇ／分）以外は、実施例１と同じ処理を行った。
【００２２】
【実施例７】
工程（ｂ）における３５％塩酸添加時間を８分間とした（塩酸添加速度：ＴｉＯ2 換算１ｋｇ当たり０．０５５ｋｇ／分）以外は、実施例１と同じ処理を行った。
【００２３】
【実施例８】
工程（ｂ）における塩酸添加後のスラリー中における塩酸濃度を３７ｇ／ｌとなるように、１１．５６ｋｇの３５％塩酸を４分間で添加した（塩酸添加速度：ＴｉＯ2 換算１ｋｇ当たり０．１ｋｇ／分）以外は、実施例１と同じ処理を行った。
【００２４】
【実施例９】
工程（ｂ）における塩酸添加後のスラリー中における塩酸濃度を４４ｇ／ｌとなるように、１３．７５ｋｇの３５％塩酸を４分間で添加した（塩酸添加速度：ＴｉＯ2 換算１ｋｇ当たり０．１２ｋｇ／分）以外は、実施例１と同じ処理を行った。
【００２５】
【実施例１０】
実施例１で得た粉体試料をさらに３３０℃で焙焼した。
【００２６】
【実施例１１】
実施例１で得た粉体試料を水に分散し、ＴｉＯ2 重量基準で２００ｇ／ｌのスラリー８００ｍｌを作成し、４０℃に加熱して、撹拌しながらアルミン酸ソーダ水溶液（Ａｌ2 Ｏ3 換算で２００ｇ／ｌ）４０ｍｌと３０％希硫酸を、ｐＨ５〜６に保ちながら１０分間で添加した。更に６０℃に加熱後、３０分間撹拌した。これらをろ過、洗浄し、１１０℃で２４時間乾燥した後、粉砕した。
【００２７】
【比較例１】
工程（ａ）における３５％塩酸添加後のｐＨを５．０とした以外は、実施例１と同じ処理を行った。得られた二酸化チタンの形状は紡錘状であったが、その長径はおおよそ１００ｎｍであり、後述の試験例で示すとおり、紫外線遮蔽能において優れた値を示さなかった。
【００２８】
【比較例２】
工程（ａ）における３５％塩酸添加後のｐＨを１０．０とした以外は、実施例１と同じ処理を行った。得られた二酸化チタンは、比較例１の場合と同様な形状・機能を示した。
【００２９】
【比較例３】
工程（ｂ）における３５％塩酸添加時間を１５分間とした（塩酸添加速度：ＴｉＯ2 換算１ｋｇ当たり０．０２９ｋｇ／分）以外は、実施例１と同じ処理を行った。得られた二酸化チタンは、比較例１の場合と同様な形状ならびに機能を示した。
【００３０】
【比較例４】
工程（ｂ）における３５％塩酸添加時間を１分間とした（塩酸添加速度：ＴｉＯ2 換算１ｋｇ当たり０．４４ｋｇ／分）以外は、実施例１と同じ処理を行った。結果として得られたのは二酸化チタンの凝集体であり、後述の試験例で示すとおり、可視光線における透明性について優れた値を示さなかった。
【００３１】
【比較例５】
工程（ｂ）における塩酸添加後のスラリー中における塩酸濃度を３０ｇ／ｌとなるように、９．１ｋｇの３５％塩酸を４分間で添加した（塩酸添加速度：ＴｉＯ2 換算１ｋｇ当たり０．０８ｋｇ／分）以外は、実施例１と同じ処理を行った。得られた二酸化チタンは、平均粒径が０．１μｍ以下のいわゆる”微粒子”二酸化チタンであり、結晶形はアナタース形であった。
【００３２】
【比較例６】
工程（ｂ）における塩酸添加後のスラリー中における塩酸濃度を５０ｇ／ｌとなるように、１５．７５ｋｇの３５％塩酸を４分間で添加した（塩酸添加速度：ＴｉＯ2 換算１ｋｇ当たり０．１３８ｋｇ／分）以外は実施例１と同じ処理を行った。得られた二酸化チタンは、比較例１の場合と同様な形状ならびに機能を示した。
【００３３】
【比較例７】
実施例１で得た粉体試料をさらに５５０℃で焙焼した。得られた二酸化チタンは、上記加熱処理により粒子形状がいわゆる楕円状に変化し、可視光線における透明性が低下した。
【００３４】
【比較例８】
工程（ａ）における３５％塩酸添加後のｐＨを２とし、工程（ｂ）における３５％塩酸添加時間を１５分間とした以外は実施例１と同じ処理を行った。得られた二酸化チタンの形状は針状に近い紡錘状であり、しかも長径はおおよそ５０ｎｍであり、後述の試験例で示すとおり、紫外線遮蔽能において優れた値を示さなかった。
【００３５】
【試験例】
〔粒子の形状、平均長径、平均短径の測定〕
各実施例、比較例で得られた二酸化チタンを電子顕微鏡で観察し、写真撮影を行った。この電子顕微鏡写真から粒子の形状、長径、短径を読みとり、平均長径、平均短径を計算した。長径／短径の比は、平均長径／平均短径の比である。
【００３６】
〔透明性、紫外線遮蔽能の測定〕
下記の配合で油分散体を作成した。
（１） 各実施例、比較例で得られた二酸化チタン ３ｇ
（２） ブチレングリコール ２７ｇ
成分（１）、（２）にガラスビーズ（直径１．５ｍｍ）７０ｇを加え、ペイントシェイカー（レッドデビル社製）にて１時間分散した。
試料油分散体をポリプロピレン製フィルム（厚み４０μｍ）へ１０μｍの膜厚になるように塗布し、分光光度計（日立自記分光光度計Ｕ−３４１０）にて２９０ｎｍ〜７００ｎｍの散乱光も含めた全透過率を測定した。紫外線領域である２９０ｎｍ〜４００ｎｍ、および可視光線領域である４００ｎｍ〜７００ｎｍにおける透過率積分値（ｎｍ・％）をそれぞれ以下の式により求め、各々紫外線遮蔽能、透明性として各表に記載した。
すなわち、ここでいう紫外線遮蔽能とは、２９０〜４００ｎｍにおける透過率積分値で表したＵＶ−Ａ、ＵＶ−Ｂ領域の遮蔽効果を示したものであり、その数値が小さいほど紫外線遮蔽効果が優れている。また、透明性とは、４００〜７００ｎｍにおける透過率積分値で表した可視光線に対する透明性を示したものであり、その数値が大きいほど透明性が優れている。
透過率積分値（ｎｍ・％）＝Σ設定された波長領域（ｎｍ）×透過率（％）
【００３７】
〔結晶形の測定〕
理学電機（株）Geigerflexにて試料の結晶形を測定した。測定条件は以下の通りである。
測定電圧：４０ｋＶ 測定角度：５°〜６０°
測定電流：３５ｍＡ 走査測度：５°／ｍｉｎ．
これらの測定の結果を表１および表２にまとめた。
【測定結果】
【００３８】
【表１】
【表２】
BACKGROUND OF THE INVENTION
The present invention relates to a process for producing spindle-shaped titanium dioxide having a major axis of 0.15 to 0.30 μm and a major axis / minor axis ratio of 2 to 8.
[0002]
[Prior art]
Titanium dioxide is used as a filler for paints, cosmetic raw materials, toner charge control agents, plastics, rubber, films, etc., and titanium dioxide with a large aspect ratio such as a spindle shape or a needle shape also has its shape. It is used for applications that take advantage of Many methods for producing such spindle-shaped titanium dioxide have been disclosed.
[0003]
Japanese Patent Application Laid-Open No. 62-281812 discloses a simple method for producing spindle-shaped titanium dioxide. According to this method, a titanium tetrachloride aqueous solution is hydrolyzed to form titanium hydroxide, and then calcined at a temperature of 150 to 600 ° C. to perform rutile formation, and a rutile form having a specific surface area of 60 to 250 m 2 . It is described only that titanium dioxide having a crystal structure is obtained.
[0004]
In JP-A-63-307119, titanium dioxide hydrate obtained by a titanium tetrachloride or sulfuric acid method is used as a raw material, the maximum dimension is 0.01 to 0.15 μm, and the ratio of the maximum dimension to the shortest dimension is 8: An acicular titanium dioxide within the range of 1 to 2: 1 and a method for its production are disclosed.
[0005]
Japanese Examined Patent Publication No. 6-76215 discloses a method for producing microcrystalline titanium dioxide having a crystal size of 10 to 100 nm, that is, 0.1 to 0.01 μm. There are roughly shown the following manufacturing steps.
After reacting titanite with sulfuric acid to concentrate and remove impurities, titanium dioxide hydrate obtained by precipitation by hydrolysis is made strongly basic by adding aqueous sodium hydroxide solution and heat-treated near the boiling point. Next, hydrochloric acid is added to the treated product to obtain a pH of around 2, and the temperature is set to 60 ° C., and hydrochloric acid is further added to adjust the HCl concentration to 8 to 25 g / l. The temperature is further raised to 90 ° C. and aging is performed for 120 minutes. Finally, neutralize with alkali, filter, wash, dry and grind.
[0006]
[Problems to be solved by the invention]
Titanium oxide with an average particle diameter of 0.1 μm or less, generally called “fine-particle titanium oxide”, has the physical properties of transparency in visible light and ultraviolet shielding properties, but the particles are oxidized for pigments. Since it is small compared to titanium, it has poor dispersibility, and when used as a raw material for paints, cosmetics, etc., it has the disadvantage that it takes a long time for dispersion.
The object of the present invention is to solve the above-mentioned drawbacks related to dispersibility, and also to have the properties of transparency in visible light and ultraviolet shielding properties, the crystal structure is rutile, and the average major axis is 0.15 to 0.30 μm. Another object is to provide a process for producing spindle-shaped titanium dioxide having a major axis / minor axis ratio of 2 to 8.
The “spindle shape” as used in the present invention has a shape similar to a cylindrical shape with sharpened ends, and the length (major diameter) connecting the sharpened ends and the thickest portion (short) of the cylindrical portion. The ratio with respect to (diameter) is 2-8.
[0007]
[Means for Solving the Problems]
The present inventors have found a method for producing the above titanium dioxide by devising production conditions.
That is, the gist of the present invention consists of the following steps (a) to (c), in which the average particle size is: major axis 0.15-0.3 μm, minor axis 0.03-0.1 μm, major axis / short It exists in the manufacturing method of the rutile type titanium dioxide which is in the range of the diameter ratio 2-8, and the shape is a spindle shape.
(A) Titanium dioxide hydrate is treated with a base, and the resulting titanium dioxide hydrate slurry is neutralized with hydrochloric acid to adjust the pH to 6-9:
(B) The neutralized titanium dioxide hydrate slurry is heated to 40 ° C. to 60 ° C., and an amount of hydrochloric acid in which the hydrochloric acid concentration in the slurry is 32 to 48 g / l in terms of 100% HCl is added to the slurry. To 1 kg of TiO 2 equivalent of the existing titanium dioxide hydrate, it is added at a rate of 0.05 to 0.20 kg / min in terms of 100% HCl:
(C) After addition of hydrochloric acid, the mixture is further heated and aged at 90 ° C. to the boiling point, then neutralized with a base, filtered, washed with water, and dried.
[0008]
The present invention is different from the prior art in that the titanium dioxide hydrate slurry base-treated in step (a) is once neutralized with hydrochloric acid to pH 6-9, and hydrochloric acid is added in step (b). The speed is set within a specific value range depending on the amount of titanium dioxide hydrate present in the slurry.
[0009]
Hereinafter, this invention is demonstrated for every process.
First, titanium dioxide hydrate used as a raw material is obtained from titanium tetrachloride, titanium alkoxide, titanyl sulfate and the like. Of these, titanium dioxide hydrate obtained by hydrolysis of titanyl sulfate obtained by the so-called sulfuric acid method in which titanite is reacted with sulfuric acid is preferred.
[0010]
The base treatment of titanium dioxide hydrate in step (a) is to add a base to the titanium dioxide hydrate cake obtained by hydrolysis of titanyl sulfate, and heat-treat at a temperature of 90 to 100 ° C. for about 2 hours, The reaction product after the treatment is filtered and washed. As the base, sodium hydroxide, potassium hydroxide or the like is generally used. This process itself is known and is described in, for example, JP-A-59-223231 and JP-B-6-762215.
The base-treated titanium dioxide hydrate is slurried by adding water so as to be 170 g / l or less in terms of TiO 2 while stirring. If it exceeds 170 g / l, the viscosity increases in the subsequent hydrochloric acid addition step, and the operation becomes difficult.
Hydrochloric acid is then added to neutralize to pH 6-9. At this time, if the pH is lower than 6, the resulting titanium dioxide is not preferable because the major axis is at most 0.1 μm or less. On the other hand, if the pH exceeds 9, stabilization of the hydrochloric acid concentration after the addition of hydrochloric acid to be added in the subsequent step cannot be maintained, and as a result, the major axis of titanium dioxide is not increased, which is not preferable.
[0011]
The slurry having a pH of 6 to 9 in a state neutralized with hydrochloric acid in the step (a) is heated with stirring in the step (b) and adjusted to a temperature of 40 to 60 ° C. At this time, when the temperature exceeds 60 ° C., the major axis of the obtained titanium dioxide is not preferable because it becomes 0.1 μm or less. Further, at a temperature lower than 40 ° C., a spindle shape is not formed.
Hydrochloric acid is added to the slurry set at the above temperature so that the hydrochloric acid concentration in the slurry is 32 to 48 g / l in terms of 100% HCl. When adding hydrochloric acid, 0.05 kg to 0.2 kg / min, preferably 0.08 to 0.13 kg / min in terms of 100% HCl, with respect to 1 kg in terms of titanium dioxide hydrate TiO 2 in the slurry, Hydrochloric acid must be added at a rate of
If the concentration of hydrochloric acid after addition of hydrochloric acid is lower than 32 g / l, the particle size of the titanium dioxide formed is not preferable. Conversely, if the hydrochloric acid concentration is higher than 48 g / l, the major axis of the resulting titanium dioxide is not increased, which is not preferable.
On the other hand, when the addition rate of hydrochloric acid is less than 0.05 kg / min, the major axis of the formed titanium dioxide becomes small, which is not preferable. Conversely, when the addition rate exceeds 0.2 kg / min, the resulting titanium dioxide becomes an aggregate.
Therefore, in this addition process, it is necessary to fully consider advance preparation and addition equipment so that the addition amount and the addition speed can be appropriately performed.
[0012]
In step (c), after addition of hydrochloric acid in step (b), the system in the temperature range of 40 to 60 ° C. is heated to a temperature of 90 ° C. to boiling point and aged for 30 minutes or longer.
When the aging temperature is lower than 90 ° C., it is not preferable because it does not have a spindle shape, and a nearly spherical shape is formed.
The longer the aging time, the narrower the titanium dioxide particle size distribution and the more uniform it can be obtained, but it is not economical if it is too long. Preferably 1 hour to 3 hours is appropriate.
The slurry after aging is neutralized with a base such as aqueous ammonia, aqueous caustic soda solution or aqueous sodium carbonate solution, and is filtered, washed and dried by a known method.
If necessary, it may be roasted at 500 ° C. or less, preferably 200 to 400 ° C. for 30 minutes or more at any temperature. If the roasting temperature exceeds 500 ° C., the particle shape becomes rounded, so it can no longer be called spindle-shaped titanium dioxide.
[0013]
The surface of the spindle-shaped titanium dioxide thus obtained may be subsequently coated with an inorganic compound, an organic compound, or a composite thereof by a known method.
For example, the spindle-shaped titanium dioxide is passed through a dry pulverizer such as an ectomizer or a wet pulverizer such as a sand grinder, and then slurried to coat the surface of the titanium dioxide with an inorganic compound, an organic compound or a composite thereof.
Inorganic compounds include oxides and hydroxides of silicon, aluminum, zirconium, zinc, antimony, magnesium, iron, nickel, cobalt, and the like.
Examples of the organic compound include fatty acids such as lauric acid, isostearic acid, stearic acid, and palmitic acid, organic silicon compounds typified by cyclic or linear silicone oil, and organic titanium compounds typified by titanium alkoxide.
Examples of inorganic and organic composites include composites such as aluminum hydrated oxide and stearic acid, and fatty acid metal soaps such as zinc, aluminum, calcium, and barium.
These inorganic compounds, organic compounds, and composites can be used alone or in combination of any two or more thereof.
[0014]
The spindle-shaped titanium dioxide obtained by the production method of the present invention is no longer in the category of so-called “fine-particle titanium oxide” due to its size, but nevertheless the physical properties are transparency in visible light. And has an ultraviolet shielding property, and solves the problem of dispersion.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in detail by examples.
[0016]
[Example 1]
Step (a)
The titanyl sulfate solution was hydrolyzed by a conventional method, and 40 kg of 48% sodium hydroxide aqueous solution was added to 35 kg (10 kg in terms of TiO 2 ) of hydrous titanium dioxide cake (filtered and washed) with stirring. The mixture was heated and stirred at a temperature range of 95 to 105 ° C. for 2 hours. The slurry was then filtered and washed thoroughly to obtain a base-treated titanium dioxide hydrate. Water was added to the hydrate cake to make a slurry, and the hydrated TiO 2 concentration was adjusted to 110 g / l.
While stirring the slurry, 35% hydrochloric acid was added to adjust the pH to 7.0.
Step (b)
The slurry is heated to 50 ° C., and 12.5 kg of 35% hydrochloric acid is added at this temperature over 4 minutes with stirring, and the hydrochloric acid concentration in the slurry after addition of hydrochloric acid is 40 g / l in terms of 100% HCl. I did it.
The hydrochloric acid addition rate is 0.11 kg / min per 1 kg of TiO 2 .
Step (c)
Following the addition of hydrochloric acid, the slurry was heated and aged at 100 ° C. for 2 hours.
Ammonia water was added to the slurry after aging to neutralize to pH = 6.5. After sufficiently filtering and washing with water, it was dried and then pulverized with a fluid energy mill.
The obtained powder was titanium dioxide having a spindle shape with an average major axis of 0.25 μm and an average minor axis of 0.06 μm. As a result of measurement by an X-ray diffractometer, the crystal form was a rutile form.
[0017]
[Example 2]
The same treatment as in Example 1 was performed, except that the pH after addition of 35% hydrochloric acid in step (a) was 6.2.
[0018]
[Example 3]
The same treatment as in Example 1 was performed except that the pH after addition of 35% hydrochloric acid in step (a) was 8.8.
[0019]
[Example 4]
The same treatment as in Example 1 was performed except that the slurry temperature in the step (b) was changed from 50 ° C to 55 ° C.
[0020]
[Example 5]
The same treatment as in Example 1 was performed except that the slurry temperature in the step (b) was changed from 50 ° C to 45 ° C.
[0021]
[Example 6]
The same treatment as in Example 1 was performed except that the 35% hydrochloric acid addition time in step (b) was 2.5 minutes (hydrochloric acid addition rate: 0.175 kg / min per kg of TiO 2 ).
[0022]
[Example 7]
The same treatment as in Example 1 was performed except that the 35% hydrochloric acid addition time in step (b) was 8 minutes (hydrochloric acid addition rate: 0.055 kg / min per kg of TiO 2 ).
[0023]
[Example 8]
11.56 kg of 35% hydrochloric acid was added over 4 minutes so that the hydrochloric acid concentration in the slurry after addition of hydrochloric acid in step (b) was 37 g / l (hydrochloric acid addition rate: 0.1 kg / kg of TiO 2 converted per kg) Except for (min), the same processing as in Example 1 was performed.
[0024]
[Example 9]
13.75 kg of 35% hydrochloric acid was added over 4 minutes so that the hydrochloric acid concentration in the slurry after the addition of hydrochloric acid in step (b) was 44 g / l (hydrochloric acid addition rate: 0.12 kg / kg of TiO 2 converted per kg) Except for (min), the same processing as in Example 1 was performed.
[0025]
[Example 10]
The powder sample obtained in Example 1 was further baked at 330 ° C.
[0026]
Example 11
The powder sample obtained in Example 1 was dispersed in water to prepare 800 ml of a slurry of 200 g / l based on the weight of TiO 2 , heated to 40 ° C. and stirred with sodium aluminate aqueous solution (in terms of Al 2 O 3). 200 g / l) 40 ml and 30% dilute sulfuric acid were added over 10 minutes while maintaining the pH at 5-6. Furthermore, after heating to 60 degreeC, it stirred for 30 minutes. These were filtered, washed, dried at 110 ° C. for 24 hours, and then pulverized.
[0027]
[Comparative Example 1]
The same treatment as in Example 1 was performed, except that the pH after addition of 35% hydrochloric acid in step (a) was 5.0. The shape of the obtained titanium dioxide was spindle-shaped, but its major axis was approximately 100 nm, and as shown in the test examples described later, it did not show an excellent value in ultraviolet shielding ability.
[0028]
[Comparative Example 2]
The same treatment as in Example 1 was performed except that the pH after addition of 35% hydrochloric acid in step (a) was 10.0. The obtained titanium dioxide exhibited the same shape and function as in Comparative Example 1.
[0029]
[Comparative Example 3]
The same treatment as in Example 1 was performed except that the 35% hydrochloric acid addition time in step (b) was 15 minutes (hydrochloric acid addition rate: 0.029 kg / min per kg of TiO 2 conversion). The obtained titanium dioxide exhibited the same shape and function as in Comparative Example 1.
[0030]
[Comparative Example 4]
The same treatment as in Example 1 was performed except that the 35% hydrochloric acid addition time in step (b) was 1 minute (hydrochloric acid addition rate: 0.44 kg / min per kg of TiO 2 ). As a result, an aggregate of titanium dioxide was obtained, and as shown in a test example described later, an excellent value for transparency in visible light was not shown.
[0031]
[Comparative Example 5]
9.1 kg of 35% hydrochloric acid was added over 4 minutes so that the hydrochloric acid concentration in the slurry after addition of hydrochloric acid in step (b) was 30 g / l (hydrochloric acid addition rate: 0.08 kg / kg of TiO 2 converted per kg) Except for (min), the same processing as in Example 1 was performed. The obtained titanium dioxide was so-called “fine particle” titanium dioxide having an average particle diameter of 0.1 μm or less, and the crystal form was anatase.
[0032]
[Comparative Example 6]
15.75 kg of 35% hydrochloric acid was added over 4 minutes so that the hydrochloric acid concentration in the slurry after the addition of hydrochloric acid in step (b) was 50 g / l (hydrochloric acid addition rate: 0.138 kg / kg of TiO 2 converted per kg) The same treatment as in Example 1 was performed except for (min). The obtained titanium dioxide exhibited the same shape and function as in Comparative Example 1.
[0033]
[Comparative Example 7]
The powder sample obtained in Example 1 was further baked at 550 ° C. The obtained titanium dioxide changed its particle shape into a so-called elliptical shape by the heat treatment, and the transparency in visible light was lowered.
[0034]
[Comparative Example 8]
The same treatment as in Example 1 was performed except that the pH after addition of 35% hydrochloric acid in step (a) was 2, and the 35% hydrochloric acid addition time in step (b) was 15 minutes. The obtained titanium dioxide had a spindle shape close to a needle shape, and the major axis was about 50 nm. As shown in the test examples described later, it did not show an excellent value in ultraviolet shielding ability.
[0035]
[Test example]
(Measurement of particle shape, average major axis, average minor axis)
The titanium dioxide obtained in each Example and Comparative Example was observed with an electron microscope and photographed. The shape, major axis and minor axis of the particles were read from this electron micrograph, and the average major axis and the average minor axis were calculated. The ratio of major axis / minor axis is the ratio of average major axis / average minor axis.
[0036]
[Measurement of transparency and UV shielding ability]
An oil dispersion was prepared with the following composition.
(1) 3 g of titanium dioxide obtained in each example and comparative example
(2) Butylene glycol 27g
70 g of glass beads (diameter 1.5 mm) were added to components (1) and (2), and the mixture was dispersed with a paint shaker (manufactured by Red Devil) for 1 hour.
The sample oil dispersion was applied to a polypropylene film (thickness 40 μm) so as to have a thickness of 10 μm, and totally transmitted including scattered light of 290 nm to 700 nm with a spectrophotometer (Hitachi's own spectrophotometer U-3410). The rate was measured. The transmittance integral values (nm ·%) in the ultraviolet region of 290 nm to 400 nm and the visible light region of 400 nm to 700 nm were determined by the following formulas, respectively, and described in the respective tables as the ultraviolet shielding ability and transparency, respectively.
That is, the ultraviolet shielding ability here indicates the shielding effect in the UV-A and UV-B regions expressed by the integral value of transmittance at 290 to 400 nm, and the smaller the value, the better the ultraviolet shielding effect. ing. Transparency refers to transparency with respect to visible light expressed as an integral value of transmittance at 400 to 700 nm. The larger the value, the better the transparency.
Transmittance integral value (nm ·%) = Σ set wavelength region (nm) × transmittance (%)
[0037]
(Measurement of crystal form)
The crystal form of the sample was measured with Geigerflex, Rigaku Corporation. The measurement conditions are as follows.
Measurement voltage: 40 kV Measurement angle: 5 ° -60 °
Measurement current: 35 mA Scanning measure: 5 ° / min.
The results of these measurements are summarized in Tables 1 and 2.
【Measurement result】
[0038]
[Table 1]
[Table 2]
Claims (5)
（ａ） 二酸化チタン水和物に塩基処理を行い、得られた二酸化チタン水和物スラリーを塩酸で中和し、ｐＨを６〜９にする：
（ｂ） 中和した二酸化チタン水和物スラリーを４０℃〜６０℃に加熱し、そこにスラリー中の塩酸濃度が１００％ＨＣｌ換算で３２〜４８ｇ／ｌとなる量の塩酸を、スラリー中に存在する二酸化チタン水和物のＴｉＯ2 換算１ｋｇに対し、１００％ＨＣｌ換算で０．０５〜０．２０ｋｇ／分の速度で添加する：
（ｃ） 塩酸添加後、更に加熱を行い、９０℃〜沸点で熟成した後に、塩基で中和し、ろ過、水洗、乾燥を行う。The average size of the particles is in the range of a major axis of 0.15 to 0.3 μm, a minor axis of 0.03 to 0.1 μm, and a major axis / minor axis ratio of 2 to 8, and the shape thereof is a spindle shape. A method for producing rutile titanium dioxide comprising steps (a) to (c):
(A) Titanium dioxide hydrate is treated with a base, and the resulting titanium dioxide hydrate slurry is neutralized with hydrochloric acid to adjust the pH to 6-9:
(B) The neutralized titanium dioxide hydrate slurry is heated to 40 ° C. to 60 ° C., and an amount of hydrochloric acid in which the hydrochloric acid concentration in the slurry is 32 to 48 g / l in terms of 100% HCl is added to the slurry. To 1 kg of TiO 2 equivalent of the existing titanium dioxide hydrate, it is added at a rate of 0.05 to 0.20 kg / min in terms of 100% HCl:
(C) After addition of hydrochloric acid, the mixture is further heated and aged at 90 ° C. to the boiling point, then neutralized with a base, filtered, washed with water, and dried.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31886996A JP3806790B2 (en) | 1996-11-13 | 1996-11-13 | Process for producing spindle-shaped titanium dioxide |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31886996A JP3806790B2 (en) | 1996-11-13 | 1996-11-13 | Process for producing spindle-shaped titanium dioxide |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10139434A JPH10139434A (en) | 1998-05-26 |
| JP3806790B2 true JP3806790B2 (en) | 2006-08-09 |
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| JP31886996A Expired - Lifetime JP3806790B2 (en) | 1996-11-13 | 1996-11-13 | Process for producing spindle-shaped titanium dioxide |
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| JP (1) | JP3806790B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| KR102027404B1 (en) * | 2018-06-29 | 2019-10-02 | (주)쓰리에이씨 | Manufacturing method of Titanium dioxide nanoparticles dispersed solution, Titanium dioxide nanoparticles dispersed solution manufactured by the same, and preparing method of Titanium dioxide film using the Titanium dioxide nanoparticles dispersed solution having excellent deodorization effect for removing formaldehyde, ammonia, acetaldehyde, acetic acid and toluene |
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|---|---|---|---|---|
| JP2002338245A (en) * | 2001-05-16 | 2002-11-27 | Tayca Corp | Dispersion with high concentration of particulate titanium oxide |
| US7371275B2 (en) | 2004-07-02 | 2008-05-13 | E.I. Du Pont De Nemours And Company | Titanium dioxide pigment and polymer compositions |
| WO2017159286A1 (en) * | 2016-03-15 | 2017-09-21 | 大塚化学株式会社 | Inorganic filler for rubber, rubber composition and tire |
| JP6939785B2 (en) | 2016-06-29 | 2021-09-22 | 住友大阪セメント株式会社 | Titanium oxide particles, and titanium oxide particle dispersions and cosmetics using them. |
| JP7247792B2 (en) | 2019-07-03 | 2023-03-29 | 住友大阪セメント株式会社 | Titanium oxide powder, dispersion and cosmetics using the same |
-
1996
- 1996-11-13 JP JP31886996A patent/JP3806790B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR102027404B1 (en) * | 2018-06-29 | 2019-10-02 | (주)쓰리에이씨 | Manufacturing method of Titanium dioxide nanoparticles dispersed solution, Titanium dioxide nanoparticles dispersed solution manufactured by the same, and preparing method of Titanium dioxide film using the Titanium dioxide nanoparticles dispersed solution having excellent deodorization effect for removing formaldehyde, ammonia, acetaldehyde, acetic acid and toluene |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH10139434A (en) | 1998-05-26 |
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