JP3923159B2 - Method for producing alumina sol and alumina hydrate powder and recording medium - Google Patents
Method for producing alumina sol and alumina hydrate powder and recording medium Download PDFInfo
- Publication number
- JP3923159B2 JP3923159B2 JP35150997A JP35150997A JP3923159B2 JP 3923159 B2 JP3923159 B2 JP 3923159B2 JP 35150997 A JP35150997 A JP 35150997A JP 35150997 A JP35150997 A JP 35150997A JP 3923159 B2 JP3923159 B2 JP 3923159B2
- Authority
- JP
- Japan
- Prior art keywords
- alumina
- alumina hydrate
- slurry
- sol
- stirring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Description
【０００１】
【発明の属する技術分野】
本発明は、アルミナゾル及びアルミナ水和物粉末、特には記録媒体用アルミナゾル及びアルミナ水和物粉末の製造方法に関する。
【０００２】
【従来の技術】
基材上に擬ベーマイトを含有するインク受容層を形成した記録媒体が知られている（特開平２−２７６６７０、特開平４−３７５７６等）。このインク受容層は、アルミナゾルを基材上に塗布し、ゲル化することにより形成される多孔質層である。このような記録媒体において品質の高い記録をするためには、インク受容層の多孔質粒子の細孔径と細孔容積が大きく、かつ透明性が高いことが要求される。
【０００３】
印字後のインクの色濃度を高めるには印字するインク量を多くするが、インク受容層の細孔径と細孔容積が充分に大きくないとインク吸収時間が長く、インクのあふれやにじみ等の問題を生じ、さらには印字ドットの真円度も悪くなり、高品質の記録ができない。
【０００４】
また、インク受容層の透明性が低いと、透明な基材を使用してもオーバーヘッドプロジェクタ（以下、ＯＨＰという）用のシートに使用できる透明性の良好な記録媒体は得られない。そして、基材の透明性にかかわらず、インク受容層の透明性が低いと印字後のインクの色濃度が低下し、高品質の記録ができない。
【０００５】
アルミナゾルの製造方法としては、アルミニウムイソプロポキシドを加水分解した後、酸を添加して解膠する方法が知られている（Ｂ．Ｅ．Ｙｏｌｄａｓ，Ａｍｅｒ．Ｃｅｒａｍ．Ｓｏｃ．Ｂｕｌｌ．，５４，２８９（１９７５）等）。この方法により得られるアルミナゾルは透明なゾルであって、種々の用途に好ましく使用できる。
【０００６】
また、アルミン酸アルカリ金属塩に必要に応じてアルカリ金属水酸化物を添加し、酸又は塩化アルミニウム、硫酸アルミニウム、硝酸アルミニウム等と混合したり、アルミン酸アルカリ金属塩又はアルミニウム塩を、イオン交換樹脂でイオン交換して得られるアルミナの水和ゲルを熟成した後、解膠して製造する方法も知られている。
【０００７】
また、アルミニウムドデキシドを加水分解して得たアルミナスラリを熟成してゾル化する方法も知られている（特開平７−２３２４７３等）。
【０００８】
しかし、前記の３つの方法で得られるアルミナゾルを乾燥した固形物は、平均細孔半径や細孔容積が小さく、インク吸収性が不充分であった。
【０００９】
細孔容積の大きいアルミナの製造方法としては、水酸化アルミニウムのスラリにアルミニウム塩とｐＨ制御剤とを連続的に添加してｐＨ６〜１１に保ちつつ得たアルミナゲルを焼成したり（特開昭５８−１９０８２３）、水酸化アルミニウムのスラリにアルミニウムを含有する中和剤を加えてｐＨ６〜１１に調節する操作を複数回繰り返して得たアルミナゲルを焼成する方法（特開昭５８−２１３６３２）が知られている。しかし、いずれも５００℃で焼成した無水アルミナ粒子であり、これらのアルミナ粒子で形成したインク受容層は透明性が悪かった。
【００１０】
アルミニウム塩、アルミン酸アルカリ金属塩の中和又はイオン交換で得たアルミナゲルを乾燥、粉砕して細孔容積の大きいキセロゲルとし、適宜バインダと混合してインク受容層を形成する方法も知られているが（特公平３−２４９０６）、前記キセロゲルはアルミナ水和物の二次粒子径が大きく、バインダと混合した分散液においてもキセロゲルが解膠されず、インク受容層を形成しても透明性が悪いという欠点があった。
【００１１】
すなわち、細孔径と細孔容積が大きく、かつ透明性の高いアルミナ水和物粉末、及びそのようなアルミナ水和物粉末が得られるアルミナゾルは得られていなかった。
【００１２】
【発明が解決しようとする課題】
本発明は、インクの吸収性が高く透明性が良好な記録媒体用のインク受容層を得るために、細孔径と細孔容積が大きいアルミナ水和物粉末をゾル粒子とし、かつ透明性が高いアルミナゾル、及び細孔径と細孔容積の大きいアルミナ水和物粉末を容易に製造する方法を提供することを目的とする。
【００１３】
【課題を解決するための手段】
本発明は、固形分濃度１〜４０重量％のアルミナ水和物のスラリを、ｐＨ７〜１２にて実効消費動力０．５ｋＷ／ｍ3 以上で撹拌することにより凝集化処理し、次いで酸を添加して解膠処理することを特徴とするアルミナゾルの製造方法を提供する。
また、本発明は、固形分濃度１〜４０重量％のアルミナ水和物のスラリを、ｐＨ７〜１２にて実効消費動力０．５ｋＷ／ｍ3 以上で撹拌することにより凝集化処理し、次いで乾燥することを特徴とするアルミナ水和物粉末の製造方法を提供する。
【００１４】
本発明において、固形分濃度１〜４０重量％のアルミナ水和物のスラリをｐＨ７〜１２にて実効消費動力０．５ｋＷ／ｍ3 以上で強力に撹拌する凝集化処理を行うことが重要である。従来より、アルミナ水和物の製造において、ｐＨ７〜１２で熟成することは知られている。本発明者らは、研究を重ねた結果、熟成時に強力な撹拌を行うと、アルミナ水和物粒子の結晶成長と凝集化が効率的に起こり、細孔径と細孔容積が著しく増大することを見出した。
【００１５】
本発明で撹拌の実効消費動力とは、撹拌の全消費動力から無負荷状態の空転時の消費動力を差し引いた消費動力を意味し、本発明ではかかる実効消費動力として、アルミナ水和物のスラリの単位体積あたり０．５ｋＷ／ｍ3 以上の強力な撹拌を行う。０．５ｋＷ／ｍ3 未満であると、アルミナ水和物粒子の結晶成長と凝集化が充分進行せず、細孔径と細孔容積が大きくならないので不適当である。より好ましくは１．５ｋＷ／ｍ3 以上である。
【００１６】
撹拌の実効消費動力は、大きいほどより短時間でアルミナ水和物粒子の結晶成長と凝集化が充分進行し、細孔径と細孔容積の大きなアルミナキセロゲルを形成できるアルミナゾル及び細孔径と細孔容積の大きなアルミナ水和物粉末が得られるので、工業生産上きわめて有利である。しかし、撹拌が強力すぎる場合は設備の振動が激しくなり、操作が困難となるので、好ましくは１０ｋＷ／ｍ3 以下で行う。
【００１７】
該スラリにこのような強力な撹拌力を与えるためには、撹拌翼の構造は多段パドル翼、多段タービン翼、アンカー翼等が好ましく、かつこれらの形状の撹拌翼を高速で回転させることによって実現できる。ファウドラー翼等も使用できる。また、邪魔板等を設置することも有効である。
【００１８】
凝集化処理におけるｐＨは７〜１２である。ｐＨが７未満の場合は、アルミナ水和物粒子の結晶成長と凝集化が充分進行せず、細孔径と細孔容積が大きくならない。ｐＨが１２超であると、アルミナ水和物が溶解する。より好ましいｐＨは８〜１１である。
【００１９】
アルミナ水和物のスラリを上記のｐＨに調整するには、アルカリを添加することが好ましい。添加するアルカリは特に限定されないが、アルカリ金属水酸化物、アルカリ土類金属水酸化物、アンモニア、アミン、第４級アンモニウムヒドロキシド等が使用できる。また、アルミン酸アルカリ金属塩のようにアルミニウムを含有するアルカリでもよい。具体的には、水酸化ナトリウム、水酸化カルシウム、水酸化マグネシウム、アンモニア、トリエチルアミン、水酸化テトラメチルアンモニウム、アルミン酸ナトリウム、アルミン酸カリウム等を単独又は適宜混合して使用することが好ましい。なかでも水酸化ナトリウム、水酸化カリウム等のアルカリ金属水酸化物、アルミン酸ナトリウム、アルミン酸カリウムが好ましい。
【００２０】
凝集化処理を行う温度は５０〜１５０℃が好ましい。高温であるほどより短時間にアルミナ水和物粒子の結晶成長と凝集化が充分進行し、細孔径と細孔容積は大きくなるが、１５０℃超では操作が困難となる。より好ましくは、７０〜１１０℃である。
【００２１】
凝集化処理に要する時間は、他の要因によっても異なるが、１時間以上であることが好ましい。１時間未満の場合はアルミナ水和物粒子の結晶成長と凝集化が充分進行せず、細孔径と細孔容積が充分大きくならない。
【００２２】
凝集化処理において、アルミナ水和物のスラリの溶媒としては水が好適に使用される。溶媒中には水と相溶性のある有機溶媒、例えばエタノール、イソプロパノール等が５０モル％以下含まれていてもよい。
【００２３】
凝集化処理におけるアルミナ水和物のスラリの固形分濃度は１〜４０重量％である。１重量％未満であると、アルミナ水和物粒子の結晶成長と凝集化が充分進行せず、細孔径と細孔容積が大きくならない。４０重量％超であるとスラリがきわめて高粘度となり撹拌が難しくなる。より好ましくは３〜２０重量％である。ここでの固形分濃度としては、アルミナ水和物のスラリを１４０℃で乾燥し、恒量となった固形物を基に算出した濃度をいう。
【００２４】
本発明では、原料となるアルミナ水和物としては市販のアルミナ水和物粉末、アルミニウムアルコキシドやアルミニウムの無機塩の加水分解によって得られるアルミナ水和物等が使用できる。アルミニウムアルコキシドとしては、例えばアルミニウムイソプロポキシドが好ましく、これを加水分解してアルミナ水和物を得る。アルミニウムの無機塩としては、アルミン酸アルカリ金属塩などが挙げられる。
【００２５】
無機塩を用いる場合は、例えば、アルミン酸アルカリ金属塩に必要に応じてアルカリ金属水酸化物を添加し、酸又は塩化アルミニウム、硫酸アルミニウム、硝酸アルミニウム等の水に溶解したときに液性が酸性を示すアルミニウム塩を混合して加水分解してアルミナ水和物を得る。このとき、液性が酸性を示すアルミニウム塩としてポリ塩化アルミニウムなども好適に使用できる。ポリ塩化アルミニウムとは、組成式［Ａｌ2 （ＯＨ）n Ｃｌ6-n ］m （１＜ｎ＜５、ｍ＜１０）で示される化合物である。ポリ塩化アルミニウムとしては、ＪＩＳ−Ｋ４１７５に規定される塩基度が５〜９５％であるものが好ましい。
【００２６】
また、アルミン酸アルカリ金属塩の陽イオン交換樹脂によるイオン交換や、アルミニウム塩の陰イオン交換樹脂によるイオン交換によって得られるアルミナ水和物も使用できる。
【００２７】
本発明において、上記アルミナ水和物のスラリとしては、既に一部が解膠し、ゾル化したアルミナゾルも使用でき、例えば市販のアルミナゾルも使用できる。
【００２８】
平均粒子径が大きいアルミナ水和物を原料とする場合は、凝集化処理の前に媒体撹拌ミル等によって粉砕して使用することが好ましい。媒体撹拌ミルによる粉砕によって平均二次粒子径を１μｍ以下、好ましくは０．７μｍ以下とすると、より効果的にアルミナ水和物の結晶成長と凝集化が起こり、細孔径と細孔容積が大きく、かつ透明性の高いアルミナゾルが得られる。
このときの媒体撹拌ミルのビーズ等の材質としては、耐摩耗性と不純物の混入防止の点から、アルミナ及び／又はジルコニアが好ましい。
【００２９】
本発明において凝集化処理が終了した段階では、アルミナ水和物はスラリ状であればよく、充分に解膠されたアルミナゾルである必要はない。本発明ではこの凝集化処理後のスラリを適宜洗浄、乾燥することにより、細孔径と細孔容積の大きいアルミナ水和物粉末が容易に得られる。しかし、このアルミナ水和物粉末は平均二次粒子径が１μｍ以上であり、また酸等の解膠剤を含有していないので、溶媒に分散させても充分に均一な分散液は得られず、透明性が不充分である。
【００３０】
そこで、細孔径と細孔容積が大きいだけでなく、透明性の良いアルミナゾル及びアルミナ水和物粉末を得るためには、凝集化処理後のスラリに酸等の解膠剤を添加し、解膠処理を行う。
【００３１】
凝集化処理後のスラリが、アルカリ金属イオン等の多量の不純物イオンを含有している場合には、解膠処理に先立って、この不純物イオンを除去し精製することが好ましい。不純物の除去の方法としては、限外濾過膜を用いると効率が良く好ましい。
【００３２】
本発明では精製により不純物イオンの総量がアルミニウム原子１モルに対して１０ミリ当量以下とすることが好ましい。簡易的には濾液の電気伝導度が好ましくは１００μＳ／ｃｍ以下となるまで行えばよい。不純物イオン量が１０ミリ当量より多いと、乾燥して得られるアルミナ水和物の細孔径と細孔容積が小さくなり、また解膠処理をしても分散性の良いアルミナゾルが得られないので好ましくない。
【００３３】
解膠処理で添加する酸としては特に限定されず、塩酸、硝酸、硫酸、アミド硫酸等の無機酸、又は酢酸等の有機酸等いずれも使用できる。このうち、特に酢酸又はアミド硫酸を使用するのが好ましい。
【００３４】
解膠処理での酸の添加量としては、アルミナゾル中のアルミニウム原子１モルに対して０．００５〜０．２当量が好ましい。０．００５当量未満の場合には、解膠に長時間を要するだけでなく、アルミナゾルの濃度が高い場合にゲル化しやすいので好ましくない。０．２当量超であると、アルミナ水和物が溶解する可能性があるので好ましくない。より好ましくは０．０１〜０．１当量である。
【００３５】
本発明では、解膠処理は好ましくは７０℃以上、特には８０℃以上で撹拌下で１時間以上行うことが好ましい。７０℃未満の場合は解膠に長時間を要したり、解膠が不充分になるおそれがあるので好ましくない。また、温度が高いと溶媒の蒸気圧が高くなり、沸騰する等して操作が困難になるので、１２０℃以下の温度が好ましい。解膠に要する時間は、解膠剤としての酸の含有量が多いほど短縮できる傾向があるが、通常１〜７２時間程度が適当である。
【００３６】
本発明では、解膠の方法として上記の加熱処理に加えて、又はこれに代えて、アルミナ水和物のスラリの超音波処理も使用できる。超音波処理は、加熱処理した後に行うと特に好ましい。
【００３７】
上記の解膠処理により、アルミナゾル粒子の二次粒子径は容易に調節できる。平均二次粒子径を５０〜１０００ｎｍとすると、ゾルを乾燥して得られるアルミナ水和物粉末の細孔径と細孔容積が大きく、かつ透明性の高いアルミナゾルを製造できるので好ましい。また、アルミナゾルを乾燥して得られるアルミナ水和物粉末は、解膠剤である酸を含有しているためバインダと混合すると容易に再解膠されるので、このアルミナ水和物粉末を用いても透明性の高いインク受容層を形成できる塗工液を提供できる。このときのアルミナゾルの乾燥温度としては、低すぎると長時間を要するので、５０℃以上であることが好ましい。
【００３８】
本発明の方法によれば、細孔径と細孔容積の大きいアルミナ水和物粉末、及びゾルを乾燥して得られるアルミナ水和物粉末の細孔径と細孔容積が大きく、かつ透明性の高いアルミナゾルが容易に製造できる。そして、本発明の方法により得られたアルミナゾル及びアルミナ水和物粉末をバインダと適宜混合して基材上に塗布、乾燥してインク受容層を形成すると、インク吸収性の良好な記録媒体が得られる。また、透明な基材を用いれば透明な記録媒体を得ることもできる。
【００３９】
具体的に本発明により得られるアルミナゾルの特性を挙げると、ゾル濃度０．５重量％に調整したアルミナゾルの波長５３０ｎｍの光の透過率が光路長１０ｍｍで測定したときに５〜７０％であり、かつアルミナ水和物粉末の平均細孔半径が５ｎｍ以上で細孔半径１〜１００ｎｍの全細孔容積が０．５０〜２．００ｃｃ／ｇである。ここにおけるアルミナ水和物粉末は、アルミナゾルを１４０℃で恒量になるまで乾燥して得られたキセロゲルをいい、ゾル濃度とは、アルミナゾル中の前記キセロゲルを基に算出した固形分濃度をいう。
【００４０】
本発明によるアルミナゾル中のゾル粒子及びアルミナ水和物粉末は、組成式ＡｌＯＯＨ・ｘＨ2 Ｏ（０≦ｘ＜２）で表されるベーマイト構造を有するアルミナ水和物であることが好ましい。本発明のアルミナゾル及びアルミナ水和物粉末中のベーマイト構造を有する結晶は、（０１０）面に垂直な方向の結晶の厚さ（以下、結晶サイズという）が６ｎｍ以上であることが好ましい。結晶サイズが６ｎｍ未満であると、吸収性に優れるインク受容層を形成できない。
【００４１】
この結晶サイズは、アルミナゾルを１４０℃で恒量になるまで乾燥して得られたアルミナ水和物粉末のＸ線回折分析から、（０２０）面のピークの回折角度２θ（°）と半値幅Ｂ（ｒａｄ）から、シェラーの式（ｔ＝０．９λ／Ｂｃｏｓθ）を使って求めた値をいう。この式において、ｔは結晶サイズ（ｎｍ）、λはＸ線の波長（ｎｍ）である。
【００４２】
【実施例】
以下、実施例（例１〜８、１２）及び比較例（例９〜１１）によって本発明の製造方法を詳しく説明する。諸物性の評価は、以下の（１）〜（４）によって行った。測定結果はまとめて表１に示す。なお、以下の例においてアルミナ水和物粉末とは、アルミナゾルを１４０℃で恒量になるまで乾燥して得られたキセロゲルをいい、ゾル濃度とは、前記キセロゲルを基に算出した、アルミナゾルの固形分濃度をいう。
【００４３】
（１）粒子径（単位はｎｍ）：大塚電子製レーザー散乱粒子径測定装置ＬＰＡ−３０００／３１００型によりアルミナゾルのゾル粒子の平均二次粒子径を測定した。
（２）光透過率（単位は％）：アルミナゾルのゾル濃度を０．５重量％に希釈して、島津製作所製の分光光度計ＵＶ−１２００型を用いて、光路長１０ｍｍで，波長５３０ｎｍの光の透過率を測定した。
【００４４】
（３）結晶サイズ（単位はｎｍ）：アルミナ水和物粉末について、Ｘ線回折により求めた。
（４）細孔容積（単位はｃｃ／ｇ）、細孔半径（単位はｎｍ）、比表面積（単位はｍ2 ／ｇ）：アルミナ水和物粉末を１２０℃で１×１０-2Ｔｏｒｒで２時間真空脱気した後、コールター製の窒素吸脱着装置オムニソープ１００型を用いて測定した。この実施例及び比較例では、細孔容積は細孔半径１〜１００ｎｍの全細孔容積を表し、細孔半径は平均細孔半径とする。
【００４５】
［例１］
容量２０００ｃｃのガラス製反応容器に、Ａｌ2 Ｏ3 換算で濃度５重量％の硝酸アルミニウム水溶液１４０ｃｃと１５００ｃｃのイオン交換水を仕込み、９５℃まで加温した。この溶液を９５℃に保ちつつ、撹拌しながら、Ａｌ2 Ｏ3 換算で濃度２０重量％のアルミン酸ナトリウム水溶液を、溶液のｐＨが９．５になるまで添加した。ｐＨが９．５の状態で５分間保持した後、濃度５重量％の硝酸アルミニウム水溶液を、溶液のｐＨが３．５になるまで添加した。ｐＨが３．５の状態で５分間保持した後、再度濃度２０重量％のアルミン酸ナトリウム水溶液を、溶液のｐＨが９．５になるまで添加し、ｐＨが９．５の状態で５分間保持した。以下同様にしてｐＨが３．５とｐＨ９．５との間を８回繰り返した後、室温まで冷却してアルミナの微細粒子が懸濁した液を得た。
【００４６】
この液を、限外濾過装置を用い、イオン交換水を添加しながら溶液の容量を一定に保ちつつ、濾液の電気伝導度が１０μＳ／ｃｍ以下に低下するまで限外濾過した。この後、水酸化ナトリウム水溶液を、溶液のｐＨが１０．０になるまで添加し、再度溶液を９５℃に加温し、強力に撹拌しながら９５〜９７℃に保って４８時間凝集化処理した。反応容器には４枚の邪魔板付きの容量２０００ｃｃの反応容器を使用し、撹拌翼としてアンカー翼を用いて６００ｒｐｍで撹拌した。このときの撹拌の実効消費動力は、１．５ｋＷ／ｍ3 であった。
【００４７】
この後、酢酸をアルミニウム原子１モルに対して０．０２５当量添加し、２４時間、９５〜９７℃に保持して解膠した後、ゾル濃度が１０重量％になるまで濃縮し、超音波処理してアルミナゾルを得た。
【００４８】
［例２］
限外濾過の後、撹拌の回転数を７００ｒｐｍとし、撹拌の実効消費動力を２．０ｋＷ／ｍ3 として３４時間凝集化処理した以外は例１と同様にしてアルミナゾルを製造した。
【００４９】
［例９］
限外濾過の後、凝集化処理をせず、昇温後直ちに酢酸を添加して解膠した以外は例１と同様にしてアルミナゾルを製造した。
【００５０】
［例３］
容量３．０ｍ3 のガラス製反応容器に、Ａｌ2 Ｏ3 換算１１．５重量％の塩化アルミニウム水溶液４５１ｋｇと２０５３ｋｇのイオン交換水を仕込み、撹拌しながら、Ａｌ2 Ｏ3 換算で２０．０重量％のアルミン酸ナトリウム水溶液を３３９ｋｇ添加してｐＨを５．０に調整し、アルミナ水和物のスラリを得た。このスラリに４８重量％の水酸化ナトリウム水溶液を添加し、スラリのｐＨを１１．０とし、９５℃に加温し、強力に撹拌しながら９５℃に保ちつつ２７時間凝集化処理した。このとき、撹拌翼としてはファウドラー翼を用い、撹拌の実効消費動力は０．７ｋＷ／ｍ3 であった。
【００５１】
凝集化処理後のスラリを限外濾過装置を用い、イオン交換水を添加しながら溶液の量を一定に保ちつつ、濾液の電気伝導度が１５μＳ／ｃｍ以下に低下するまで限外濾過した。このスラリに、酢酸をアルミニウム原子１モルに対して０．０５当量添加して、２４時間、９５〜９７℃に保持して解膠した後、ゾル濃度が１０重量％になるまで濃縮し、超音波処理してアルミナゾルを製造した。
【００５２】
［例４］
例３と同様にして得たｐＨ５．０のアルミナの水和物のスラリ１９３０ｇを容量２０００ｃｃで４枚の邪魔板付きのガラス製反応容器に入れ、４８重量％の水酸化ナトリウム水溶液を添加してスラリのｐＨを１１．０とし、９５℃に加温して強力に撹拌しながら、９５℃に保ちつつ２０時間凝集化処理した。撹拌翼としてはアンカー翼を用い、６００ｒｐｍで撹拌した。撹拌の実効消費動力は１．５ｋＷ／ｍ3 であった。次いで、例３と同様に精製と解膠を行い、アルミナゾルを製造した。
【００５３】
［例５］
凝集化処理を行う時間を９６時間にする以外は例４と同様にしてアルミナゾルを製造した。
【００５４】
［例６］
容量３．０ｍ3 で４枚の邪魔板付きのガラス製反応容器を使用した以外は例３と同様にして、ｐＨ５．０のアルミナの水和物のスラリを得た。このスラリに４８重量％の水酸化ナトリウム水溶液を添加し、スラリのｐＨを１１．０とし、９５℃に加温して強力に撹拌しながら、９５℃に保ちつつ１１時間凝集化処理した。このとき、撹拌翼としては５段パドル翼を使用し８４ｒｐｍで撹拌した。このときの撹拌の実効消費動力は３．６ｋＷ／ｍ3 であった。次いで、例３と同様に精製と解膠を行い、アルミナゾルを製造した。
【００５５】
［例１０］
例３と同様にして得たｐＨ５．０のアルミナ水和物のスラリを凝集化処理しなかった以外は例３と同様にしてアルミナゾルを製造した。
【００５６】
［例７］
市販のベーマイト粒子７５ｇ（平均二次粒子径：６０μｍ）にイオン交換水６００ｃｃを加えたスラリを、直径０．３ｍｍのジルコニア製ビーズを使用し媒体撹拌ミルによって粉砕し、平均二次粒子径を２８５ｎｍとした。次いで、このスラリを容量２０００ｃｃで４枚の邪魔板付きのガラス製反応容器に入れ、イオン交換水８２５ｃｃを加え、さらにアルミニウム原子１モルに対して１ミリ当量の水酸化ナトリウム水溶液を添加してｐＨを９．４とし、９０℃に昇温して９時間の凝集化処理を行った。このとき、撹拌翼としてはアンカー翼を使用し、５７０ｒｐｍで撹拌した。撹拌の実効消費動力は１．７ｋＷ／ｍ3 であった。
【００５７】
このスラリを精製せずに、アルミニウム原子１モルに対して０．０２５当量の酢酸を添加し、１４時間、９０℃に保持して解膠した後、ゾル濃度が１０重量％になるまで濃縮し、超音波処理してアルミナゾルを製造した。
【００５８】
［例１１］
例７で用いた市販のベーマイト粒子を粉砕せずに、アルミナの濃度が１０重量％となるようにイオン交換水を添加してスラリとし、アルミニウム原子１モルに対して０．２当量の酢酸を添加して、９５℃で７２時間保持し、さらに超音波処理したが、二次粒子径は１μｍ以下にできなかった。
【００５９】
［例８］
例４と同様にして凝集化処理、精製を行った後、解膠処理は行わずに、光透過率を測定した後、１４０℃で乾燥し、アルミナ水和物粉末を得た。
【００６０】
［例１２］
容量３．０ｍ3 のガラス製反応容器に、塩基度８４％、Ａｌ2 Ｏ3 換算で２４重量％のポリ塩化アルミニウム水溶液（多木化学製、商品名：タキバイン＃１５００）４９１ｋｇと２０５３ｋｇのイオン交換水を仕込み、マントルヒーターにより液温を９５℃に加熱した。次いで、９５℃に保持したまま、Ａｌ2 Ｏ3 換算で２０．０重量％のアルミン酸ナトリウム水溶液を添加して、ｐＨを８．７に調整し、アルミナ水和物のスラリを得た。
【００６１】
このスラリに４８重量％の水酸化ナトリウム水溶液を添加し、スラリのｐＨを１１．０とし、９５℃に加温し、強力に撹拌しながら９５℃に保ちつつ１８時間凝集化処理した。このとき、撹拌翼としては５段パドル翼を用い９０ｒｐｍで撹拌した。このときの、撹拌の実効消費動力は４．２ｋＷ／ｍ3 であった。さらに、例３と同様にして濾過及び解膠してアルミナゾルを製造した。
【００６２】
【表１】
例１〜６と例９〜１０を比較すると、凝集化処理によってアルミナ水和物粒子の結晶成長と凝集化が充分進行し、細孔容積と細孔半径が大きくなることがわかる。
【００６４】
例１と例２、及び例３、４、６をそれぞれ比較すると、凝集化処理における撹拌の実効消費動力が大きいと短時間でアルミナ水和物粒子の結晶成長と凝集化が充分進行することがわかる。さらに、例４と例５を比較すると、凝集化処理の時間が長いほど、アルミナ水和物粉末の細孔容積と細孔半径が大きくなることがわかる。
【００６５】
例７と例１１を比較すると、細孔容積と細孔半径が小さく、かつ解膠し難いベーマイト粒子を原料としても、媒体撹拌ミル等による粉砕をし、かつ凝集化処理をすると、アルミナ水和物粉末の細孔容積と細孔半径が大きく、かつ透明性の高いアルミナゾルが得られることがわかる。
【００６６】
また、例８と例４を比較すると、解膠処理を行わずに乾燥して得たアルミナ水和物粉末は、透明性は低いものの、細孔容積と細孔半径がきわめて大きいことがわかる。
【００６７】
【発明の効果】
本発明の方法により、細孔径及び細孔容積が大きいアルミナ水和物粉末、及びゾルから溶媒を除去して得られるアルミナ水和物の細孔径と細孔容積が大きく、かつ透明性の高いアルミナゾルが容易に製造できる。前記アルミナ水和物粉末を適宜バインダと混合して塗工液とし、これを基材上に塗布、乾燥してインク受容層を形成すると、インク吸収性が良好な記録媒体が形成できる。
【００６８】
また、前記アルミナゾル、及び前記アルミナゾルから媒体を除去して得られるアルミナ水和物粉末を適宜バインダと混合し、必要に応じてさらに分散媒を加えて塗工液とし、これを基材上に塗布、乾燥してインク受容層を形成すると、透明性が良好なインク受容層を有する、インクの吸収性が良好な記録媒体となる。特に透明な基材上にインク受容層を形成すると、ＯＨＰシートとして好適な記録媒体が得られる。また不透明な基材上にインク受容層を形成しても、色濃度の高い鮮明な記録が可能である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an alumina sol and an alumina hydrate powder, and more particularly to a method for producing an alumina sol and an alumina hydrate powder for a recording medium.
[0002]
[Prior art]
Recording media in which an ink receiving layer containing pseudoboehmite is formed on a substrate are known (JP-A-2-276670, JP-A-4-37576, etc.). This ink receiving layer is a porous layer formed by applying alumina sol on a substrate and gelling. In order to perform high-quality recording on such a recording medium, it is required that the pore diameter and pore volume of the porous particles of the ink receiving layer are large and the transparency is high.
[0003]
To increase the color density of the ink after printing, the amount of ink to be printed is increased. However, if the pore diameter and pore volume of the ink receiving layer are not sufficiently large, the ink absorption time will be long and problems such as ink overflow and bleeding will occur. In addition, the roundness of printed dots also deteriorates, and high quality recording cannot be performed.
[0004]
Also, if the transparency of the ink receiving layer is low, a recording medium with good transparency that can be used for a sheet for an overhead projector (hereinafter referred to as OHP) cannot be obtained even if a transparent substrate is used. Regardless of the transparency of the substrate, if the transparency of the ink receiving layer is low, the color density of the ink after printing is lowered, and high-quality recording cannot be performed.
[0005]
As a method for producing alumina sol, there is known a method in which aluminum isopropoxide is hydrolyzed and then peptized by adding an acid (BE Yoldas, Amer. Ceram. Soc. Bull., 54, 289). (1975) etc.). The alumina sol obtained by this method is a transparent sol and can be preferably used for various applications.
[0006]
In addition, an alkali metal hydroxide is added to the alkali metal aluminate as necessary, and acid, aluminum chloride, sulfuric acid Le Also known is a method in which it is mixed with minium, aluminum nitrate, etc., or hydrated alumina hydrated gel obtained by ion exchange of an alkali metal aluminate or aluminum salt with an ion exchange resin, followed by peptization. ing.
[0007]
Also known is a method of aging an alumina slurry obtained by hydrolyzing aluminum dodexide to form a sol (JP-A-7-232473, etc.).
[0008]
However, the solid material obtained by drying the alumina sol obtained by the above three methods has a small average pore radius and pore volume, and has insufficient ink absorbability.
[0009]
As a method for producing alumina having a large pore volume, an alumina gel obtained by continuously adding an aluminum salt and a pH control agent to a slurry of aluminum hydroxide and maintaining the pH at 6 to 11 is calcined (Japanese Patent Application Laid-Open No. Sho A). 58-190823), and a method of calcining alumina gel obtained by repeating an operation of adjusting the pH to 6 to 11 by adding an aluminum-containing neutralizing agent to an aluminum hydroxide slurry (JP-A-58-213632) Are known. However, all were anhydrous alumina particles fired at 500 ° C., and the ink receiving layer formed with these alumina particles had poor transparency.
[0010]
Also known is a method in which an alumina gel obtained by neutralization or ion exchange of an aluminum salt or an alkali metal aluminate is dried and pulverized to form a xerogel having a large pore volume, and mixed with a binder as appropriate to form an ink receiving layer. However, the xerogel has a large secondary particle size of alumina hydrate, and the xerogel is not peptized even in a dispersion mixed with a binder, and is transparent even when an ink receiving layer is formed. There was a fault that it was bad.
[0011]
That is, an alumina hydrate powder having a large pore diameter and pore volume and high transparency, and an alumina sol from which such an alumina hydrate powder can be obtained have not been obtained.
[0012]
[Problems to be solved by the invention]
In order to obtain an ink receiving layer for a recording medium having high ink absorption and good transparency, the present invention uses alumina hydrate powder having a large pore diameter and pore volume as sol particles, and has high transparency. It is an object of the present invention to provide an alumina sol and a method for easily producing an alumina hydrate powder having a large pore diameter and pore volume.
[0013]
[Means for Solving the Problems]
In the present invention, a slurry of alumina hydrate having a solid content concentration of 1 to 40% by weight and an effective power consumption of 0.5 kW / m at pH 7 to 12 is used. Three There is provided a method for producing an alumina sol characterized in that the agglomeration treatment is carried out by stirring and then the acid is added to the peptization treatment.
The present invention also provides a slurry of alumina hydrate having a solid content concentration of 1 to 40% by weight and an effective power consumption of 0.5 kW / m at pH 7 to 12. Three There is provided a method for producing an alumina hydrate powder, characterized in that it is agglomerated by stirring and then dried.
[0014]
In the present invention, a slurry of alumina hydrate having a solid content concentration of 1 to 40% by weight and an effective power consumption of 0.5 kW / m at pH 7 to 12 is used. Three It is important to perform the agglomeration treatment with strong stirring. Conventionally, aging at pH 7 to 12 is known in the production of alumina hydrate. As a result of repeated research, the present inventors have found that if strong stirring is performed during aging, crystal growth and aggregation of alumina hydrate particles occur efficiently, and the pore diameter and pore volume increase significantly. I found it.
[0015]
In the present invention, the effective power consumption of stirring means the power consumed by subtracting the power consumption during idling in an unloaded state from the total power consumption of stirring, and in the present invention, as the effective power consumption, the slurry of alumina hydrate is used. Per unit volume of 0.5 kW / m Three Perform strong stirring above. 0.5kW / m Three If it is less than 1, the crystal growth and aggregation of the alumina hydrate particles do not proceed sufficiently, and the pore diameter and pore volume do not increase. More preferably, 1.5 kW / m Three That's it.
[0016]
The larger the effective consumption power of stirring, the larger the alumina hydrate particle crystal growth and agglomeration in a shorter time, and the alumina sol that can form an alumina xerogel with a large pore size and pore volume, and the pore size and pore volume. Large alumina hydrate powder is obtained, which is extremely advantageous for industrial production. However, if the stirring is too strong, the vibration of the equipment becomes intense and the operation becomes difficult, so preferably 10 kW / m Three Do the following:
[0017]
In order to give such a powerful stirring force to the slurry, the structure of the stirring blade is preferably a multistage paddle blade, a multistage turbine blade, an anchor blade, etc., and realized by rotating the stirring blade of these shapes at high speed it can. A Faudler wing can also be used. It is also effective to install a baffle plate or the like.
[0018]
The pH in the aggregation treatment is 7-12. When the pH is less than 7, crystal growth and aggregation of the alumina hydrate particles do not proceed sufficiently, and the pore diameter and pore volume do not increase. When the pH is more than 12, the alumina hydrate is dissolved. A more preferred pH is 8-11.
[0019]
In order to adjust the slurry of alumina hydrate to the above pH, it is preferable to add an alkali. The alkali to be added is not particularly limited, and alkali metal hydroxide, alkaline earth metal hydroxide, ammonia, amine, quaternary ammonium hydroxide and the like can be used. Further, an alkali containing aluminum such as an alkali metal aluminate may be used. Specifically, it is preferable to use sodium hydroxide, calcium hydroxide, magnesium hydroxide, ammonia, triethylamine, tetramethylammonium hydroxide, sodium aluminate, potassium aluminate, or the like alone or in an appropriate mixture. Of these, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, sodium aluminate, and potassium aluminate are preferable.
[0020]
The temperature at which the aggregation treatment is performed is preferably 50 to 150 ° C. The higher the temperature, the faster the crystal growth and aggregation of the alumina hydrate particles proceed in a shorter time, and the pore diameter and pore volume increase, but the operation becomes difficult at temperatures above 150 ° C. More preferably, it is 70-110 degreeC.
[0021]
The time required for the agglomeration treatment varies depending on other factors, but is preferably 1 hour or more. If it is less than 1 hour, the crystal growth and aggregation of the alumina hydrate particles do not proceed sufficiently, and the pore diameter and pore volume do not increase sufficiently.
[0022]
In the agglomeration treatment, water is preferably used as a solvent for the alumina hydrate slurry. The solvent may contain 50 mol% or less of an organic solvent compatible with water, for example, ethanol, isopropanol and the like.
[0023]
The solid content concentration of the alumina hydrate slurry in the coagulation treatment is 1 to 40% by weight. If it is less than 1% by weight, crystal growth and agglomeration of the alumina hydrate particles do not proceed sufficiently, and the pore diameter and pore volume do not increase. If it exceeds 40% by weight, the slurry becomes very viscous and stirring becomes difficult. More preferably, it is 3 to 20% by weight. The solid content concentration herein refers to a concentration calculated based on a solid material obtained by drying a slurry of alumina hydrate at 140 ° C.
[0024]
In the present invention, as the alumina hydrate used as a raw material, commercially available alumina hydrate powder, alumina hydrate obtained by hydrolysis of aluminum alkoxide or aluminum inorganic salt, and the like can be used. As the aluminum alkoxide, for example, aluminum isopropoxide is preferable, and this is hydrolyzed to obtain an alumina hydrate. Examples of the inorganic salt of aluminum include alkali metal aluminates.
[0025]
When using an inorganic salt, for example, an alkali metal hydroxide is added to the alkali metal aluminate as necessary, and the liquidity becomes acidic when dissolved in acid or water such as aluminum chloride, aluminum sulfate, and aluminum nitrate. Alumina hydrate is obtained by mixing and hydrolyzing an aluminum salt having the following formula. At this time, polyaluminum chloride or the like can be suitably used as an aluminum salt whose liquidity is acidic. Polyaluminum chloride is the composition formula [Al 2 (OH) n Cl 6-n ] m (1 <n <5, m <10). As the polyaluminum chloride, those having a basicity defined by JIS-K4175 of 5 to 95% are preferable.
[0026]
Alumina hydrate obtained by ion exchange with a cation exchange resin of an alkali metal aluminate salt or ion exchange with an anion exchange resin of an aluminum salt can also be used.
[0027]
In the present invention, as the slurry of the above-mentioned alumina hydrate, an alumina sol that has already been partially peptized and formed into a sol can be used. For example, a commercially available alumina sol can also be used.
[0028]
When alumina hydrate having a large average particle size is used as a raw material, it is preferably used after being pulverized by a medium stirring mill or the like before the agglomeration treatment. When the average secondary particle size is 1 μm or less, preferably 0.7 μm or less by pulverization with a medium stirring mill, crystal growth and agglomeration of alumina hydrate occurs more effectively, and the pore diameter and pore volume are large. In addition, a highly transparent alumina sol can be obtained.
In this case, the material such as beads of the medium agitating mill is preferably alumina and / or zirconia from the viewpoint of wear resistance and prevention of impurities.
[0029]
In the present invention, at the stage where the agglomeration treatment is completed, the alumina hydrate may be in the form of a slurry, and need not be a fully peptized alumina sol. In the present invention, an alumina hydrate powder having a large pore diameter and a large pore volume can be easily obtained by appropriately washing and drying the slurry after the agglomeration treatment. However, since this alumina hydrate powder has an average secondary particle diameter of 1 μm or more and does not contain a peptizer such as an acid, a sufficiently uniform dispersion cannot be obtained even when dispersed in a solvent. Insufficient transparency.
[0030]
Therefore, in order to obtain not only a large pore diameter and pore volume, but also a highly transparent alumina sol and alumina hydrate powder, a peptizer such as an acid is added to the slurry after the agglomeration treatment to remove the peptizer. Process.
[0031]
When the slurry after the agglomeration treatment contains a large amount of impurity ions such as alkali metal ions, it is preferable to remove and purify the impurity ions prior to the peptization treatment. As a method for removing impurities, an ultrafiltration membrane is preferably used because of its high efficiency.
[0032]
In the present invention, the total amount of impurity ions is preferably 10 milliequivalents or less per mole of aluminum atoms by purification. For simplicity, it may be performed until the electric conductivity of the filtrate is preferably 100 μS / cm or less. When the amount of impurity ions is more than 10 milliequivalents, it is preferable because the pore diameter and pore volume of the alumina hydrate obtained by drying become small, and an alumina sol with good dispersibility cannot be obtained even after peptization treatment. Absent.
[0033]
The acid added in the peptization treatment is not particularly limited, and any of inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, and amidosulfuric acid, or organic acids such as acetic acid can be used. Among these, it is particularly preferable to use acetic acid or amidosulfuric acid.
[0034]
The amount of acid added in the peptization treatment is preferably 0.005 to 0.2 equivalents per mole of aluminum atoms in the alumina sol. When the amount is less than 0.005 equivalent, not only does it take a long time for peptization, but it is not preferable because it easily gels when the concentration of alumina sol is high. If it exceeds 0.2 equivalents, the alumina hydrate may dissolve, which is not preferable. More preferably, it is 0.01-0.1 equivalent.
[0035]
In the present invention, the peptization treatment is preferably performed at 70 ° C. or higher, particularly 80 ° C. or higher with stirring for 1 hour or longer. When the temperature is lower than 70 ° C., it is not preferable because it takes a long time for peptization or insufficient peptization. Further, when the temperature is high, the vapor pressure of the solvent becomes high and the operation becomes difficult due to boiling or the like, and therefore a temperature of 120 ° C. or lower is preferable. The time required for peptization tends to be shortened as the content of acid as a peptizer increases, but about 1 to 72 hours is usually appropriate.
[0036]
In the present invention, ultrasonic treatment of an alumina hydrate slurry can be used as a peptization method in addition to or in place of the above heat treatment. The ultrasonic treatment is particularly preferably performed after the heat treatment.
[0037]
The secondary particle diameter of the alumina sol particles can be easily adjusted by the above-described peptization treatment. An average secondary particle diameter of 50 to 1000 nm is preferable because the alumina hydrate powder obtained by drying the sol has a large pore diameter and pore volume and can produce an alumina sol with high transparency. In addition, since the alumina hydrate powder obtained by drying the alumina sol contains an acid that is a peptizer, it can be easily re-peptized when mixed with a binder. In addition, it is possible to provide a coating liquid capable of forming a highly transparent ink receiving layer. The drying temperature of the alumina sol at this time is preferably 50 ° C. or higher because it takes a long time if it is too low.
[0038]
According to the method of the present invention, the alumina hydrate powder having a large pore diameter and pore volume, and the alumina hydrate powder obtained by drying the sol have a large pore diameter and pore volume and high transparency. Alumina sol can be easily manufactured. Then, the alumina sol and the alumina hydrate powder obtained by the method of the present invention are appropriately mixed with a binder, coated on a substrate and dried to form an ink receiving layer, whereby a recording medium having good ink absorbability is obtained. It is done. Moreover, if a transparent base material is used, a transparent recording medium can also be obtained.
[0039]
Specifically, when the characteristics of the alumina sol obtained according to the present invention are listed, the transmittance of light having a wavelength of 530 nm of the alumina sol adjusted to a sol concentration of 0.5% by weight is 5 to 70% when measured at an optical path length of 10 mm. And the average pore radius of alumina hydrate powder is 5 nm or more, and the total pore volume of pore radius 1-100 nm is 0.50-2.00 cc / g. The alumina hydrate powder here refers to a xerogel obtained by drying an alumina sol to a constant weight at 140 ° C., and the sol concentration refers to a solid content concentration calculated based on the xerogel in the alumina sol.
[0040]
The sol particles and the alumina hydrate powder in the alumina sol according to the present invention have the composition formula AlOOH · xH. 2 An alumina hydrate having a boehmite structure represented by O (0 ≦ x <2) is preferable. The crystal having a boehmite structure in the alumina sol and alumina hydrate powder of the present invention preferably has a crystal thickness (hereinafter referred to as crystal size) in the direction perpendicular to the (010) plane of 6 nm or more. If the crystal size is less than 6 nm, an ink receiving layer having excellent absorbability cannot be formed.
[0041]
This crystal size is determined by X-ray diffraction analysis of alumina hydrate powder obtained by drying alumina sol to a constant weight at 140 ° C., and (020) plane peak diffraction angle 2θ (°) and half width B ( rad) is a value obtained using Scherrer's equation (t = 0.9λ / Bcos θ). In this equation, t is the crystal size (nm), and λ is the X-ray wavelength (nm).
[0042]
【Example】
Hereinafter, the production method of the present invention will be described in detail by Examples (Examples 1 to 8, 12) and Comparative Examples (Examples 9 to 11). Various physical properties were evaluated by the following (1) to (4). The measurement results are summarized in Table 1. In the following examples, the alumina hydrate powder refers to a xerogel obtained by drying an alumina sol to a constant weight at 140 ° C., and the sol concentration is a solid content of the alumina sol calculated based on the xerogel. Refers to the concentration.
[0043]
(1) Particle size (unit: nm): The average secondary particle size of sol particles of alumina sol was measured with a laser scattering particle size measuring device LPA-3000 / 3100 manufactured by Otsuka Electronics.
(2) Light transmittance (unit:%): The sol concentration of alumina sol is diluted to 0.5% by weight, and using a spectrophotometer UV-1200 type manufactured by Shimadzu Corporation, the optical path length is 10 mm and the wavelength is 530 nm. The light transmittance was measured.
[0044]
(3) Crystal size (unit: nm): The alumina hydrate powder was determined by X-ray diffraction.
(4) Pore volume (unit: cc / g), pore radius (unit: nm), specific surface area (unit: m 2 / G): Alumina hydrate powder 1 × 10 at 120 ° C. -2 After vacuum degassing for 2 hours with Torr, the measurement was performed using a nitrogen adsorption / desorption device Omnisoap Model 100 manufactured by Coulter. In this example and comparative example, the pore volume represents the total pore volume having a pore radius of 1 to 100 nm, and the pore radius is the average pore radius.
[0045]
[Example 1]
In a glass reaction vessel with a capacity of 2000 cc, Al 2 O Three 140 cc of an aluminum nitrate aqueous solution having a concentration of 5% by weight and 1500 cc of ion-exchanged water were charged and heated to 95 ° C. While maintaining this solution at 95 ° C., while stirring, Al 2 O Three An aqueous sodium aluminate solution having a concentration of 20% by weight in terms of conversion was added until the pH of the solution was 9.5. After maintaining the pH at 9.5 for 5 minutes, an aqueous aluminum nitrate solution having a concentration of 5% by weight was added until the pH of the solution reached 3.5. After maintaining the pH at 3.5 for 5 minutes, again add 20 wt% sodium aluminate aqueous solution until the pH of the solution reaches 9.5, and hold at the pH of 9.5 for 5 minutes. did. In the same manner, pH between 3.5 and 9.5 was repeated 8 times, and then cooled to room temperature to obtain a liquid in which fine particles of alumina were suspended.
[0046]
This solution was subjected to ultrafiltration using an ultrafiltration device until the electric conductivity of the filtrate decreased to 10 μS / cm or less while keeping the volume of the solution constant while adding ion exchange water. Thereafter, an aqueous solution of sodium hydroxide was added until the pH of the solution reached 10.0, and the solution was again heated to 95 ° C. and agglomerated for 48 hours while maintaining vigorous stirring at 95 to 97 ° C. . A reaction vessel having a capacity of 2000 cc with four baffle plates was used as a reaction vessel, and stirring was performed at 600 rpm using an anchor blade as a stirring blade. The effective power consumption of stirring at this time is 1.5 kW / m Three Met.
[0047]
Thereafter, 0.025 equivalent of acetic acid is added to 1 mol of aluminum atom, peptization is maintained at 95 to 97 ° C. for 24 hours, and then concentrated until the sol concentration becomes 10% by weight. Thus, an alumina sol was obtained.
[0048]
[Example 2]
After ultrafiltration, the rotation speed of stirring is 700 rpm, and the effective power consumption of stirring is 2.0 kW / m. Three Alumina sol was produced in the same manner as in Example 1 except that the agglomeration treatment was performed for 34 hours.
[0049]
[Example 9]
After ultrafiltration , Alumina sol was produced in the same manner as in Example 1 except that the agglomeration treatment was not performed and acetic acid was added and peptized immediately after the temperature was raised.
[0050]
[Example 3]
Capacity 3.0m Three In a glass reaction vessel 2 O Three Charge 451kg and 2053kg of ion-exchanged water of 11.5% by weight of aluminum chloride aqueous solution. 2 O Three 339 kg of a 20.0% by weight aqueous sodium aluminate solution was added to adjust the pH to 5.0 to obtain a slurry of alumina hydrate. A 48 wt% aqueous sodium hydroxide solution was added to the slurry to adjust the pH of the slurry to 11.0, and the mixture was heated to 95 ° C. and coagulated for 27 hours while maintaining the temperature at 95 ° C. with vigorous stirring. At this time, a Faudler blade is used as a stirring blade, and the effective power consumption of stirring is 0.7 kW / m. Three Met.
[0051]
The slurry after the coagulation treatment was subjected to ultrafiltration using an ultrafiltration device until the electric conductivity of the filtrate decreased to 15 μS / cm or less while keeping the amount of the solution constant while adding ion exchange water. To this slurry, 0.05 equivalent of acetic acid per 1 mol of aluminum atoms was added, peptized while maintaining at 95-97 ° C. for 24 hours, and then concentrated until the sol concentration became 10% by weight. Alumina sol was produced by sonication.
[0052]
[Example 4]
A slurry of 1930 g of alumina hydrate having a pH of 5.0 obtained in the same manner as in Example 3 was placed in 4 glass reactors with a baffle with a capacity of 2000 cc, and a 48 wt% aqueous sodium hydroxide solution was added. The slurry was adjusted to a pH of 11.0, and was agglomerated for 20 hours while maintaining the temperature at 95 ° C. while stirring vigorously at 95 ° C. An anchor blade was used as a stirring blade, and stirring was performed at 600 rpm. The effective power consumption of stirring is 1.5 kW / m Three Met. Subsequently, purification and peptization were performed in the same manner as in Example 3 to produce an alumina sol.
[0053]
[Example 5]
An alumina sol was produced in the same manner as in Example 4 except that the coagulation treatment time was 96 hours.
[0054]
[Example 6]
Capacity 3.0m Three A slurry of alumina hydrate having a pH of 5.0 was obtained in the same manner as in Example 3 except that four glass reaction vessels with baffles were used. A 48 wt% aqueous sodium hydroxide solution was added to the slurry to adjust the pH of the slurry to 11.0, and the mixture was agglomerated for 11 hours while maintaining the temperature at 95 ° C. while heating to 95 ° C. and stirring vigorously. At this time, a 5-stage paddle blade was used as a stirring blade, and stirring was performed at 84 rpm. The effective power consumption of stirring at this time is 3.6 kW / m Three Met. Subsequently, purification and peptization were performed in the same manner as in Example 3 to produce an alumina sol.
[0055]
[Example 10]
An alumina sol was produced in the same manner as in Example 3 except that the slurry of alumina hydrate having a pH of 5.0 obtained in the same manner as in Example 3 was not subjected to agglomeration treatment.
[0056]
[Example 7]
A slurry obtained by adding 600 cc of ion-exchanged water to 75 g of commercially available boehmite particles (average secondary particle size: 60 μm) was pulverized by a medium stirring mill using zirconia beads having a diameter of 0.3 mm, and the average secondary particle size was 285 nm. It was. Next, this slurry is put in a glass reaction vessel having a capacity of 2000 cc and equipped with 4 baffle plates, 825 cc of ion exchange water is added, and 1 milliequivalent sodium hydroxide aqueous solution is added to 1 mol of aluminum atoms to adjust the pH. Was 9.4, the temperature was raised to 90 ° C., and the agglomeration treatment was performed for 9 hours. At this time, an anchor blade was used as a stirring blade, and stirring was performed at 570 rpm. Effective power consumption of stirring is 1.7 kW / m Three Met.
[0057]
Without purifying this slurry, 0.025 equivalents of acetic acid per 1 mol of aluminum atoms was added, peptized while maintaining at 90 ° C. for 14 hours, and then concentrated until the sol concentration became 10% by weight. Then, ultrasonic treatment was performed to produce an alumina sol.
[0058]
[Example 11]
Without pulverizing the commercially available boehmite particles used in Example 7, ion-exchanged water was added to a slurry so that the concentration of alumina was 10% by weight, and 0.2 equivalent of acetic acid per 1 mol of aluminum atoms was added. The mixture was added, held at 95 ° C. for 72 hours, and further subjected to ultrasonic treatment, but the secondary particle size could not be reduced to 1 μm or less.
[0059]
[Example 8]
After agglomeration treatment and purification in the same manner as in Example 4, the light transmittance was measured without performing the peptization treatment, and then dried at 140 ° C. to obtain an alumina hydrate powder.
[0060]
[Example 12]
Capacity 3.0m Three In a glass reaction vessel, a basicity of 84%, Al 2 O Three In terms of conversion, 491 kg of polyaluminum chloride aqueous solution (trade name: Takibaine # 1500, manufactured by Taki Chemical Co., Ltd.) 491 kg and 2053 kg of ion exchange water were charged, and the liquid temperature was heated to 95 ° C. with a mantle heater. Next, while maintaining at 95 ° C., Al 2 O Three A 20.0% by weight sodium aluminate aqueous solution in terms of conversion was added to adjust the pH to 8.7, and an alumina hydrate slurry was obtained.
[0061]
A 48 wt% aqueous sodium hydroxide solution was added to the slurry to adjust the slurry pH to 11.0, and the mixture was heated to 95 ° C. and agglomerated for 18 hours while maintaining the temperature at 95 ° C. with vigorous stirring. At this time, a 5-stage paddle blade was used as a stirring blade, and stirring was performed at 90 rpm. The effective power consumption of stirring at this time is 4.2 kW / m Three Met. Further, filtration and peptization were conducted in the same manner as in Example 3 to produce an alumina sol.
[0062]
[Table 1]
Comparing Examples 1 to 6 and Examples 9 to 10, it can be seen that the crystal growth and aggregation of the alumina hydrate particles proceed sufficiently by the aggregation treatment, and the pore volume and pore radius increase.
[0064]
When Example 1 and Example 2, and Examples 3, 4, and 6 are compared, if the effective power consumption of stirring in the agglomeration treatment is large, the crystal growth and agglomeration of the alumina hydrate particles can proceed sufficiently in a short time. Recognize. Further, when Example 4 and Example 5 are compared, it can be seen that the longer the agglomeration time, the larger the pore volume and pore radius of the alumina hydrate powder.
[0065]
Comparing Example 7 and Example 11, when boehmite particles having a small pore volume and a small pore radius and hardly peptized are used as raw materials, pulverization with a medium agitating mill or the like and coagulation treatment result in hydration of alumina. It can be seen that a highly transparent alumina sol having a large pore volume and pore radius of the product powder can be obtained.
[0066]
Further, when Example 8 and Example 4 are compared, it can be seen that the alumina hydrate powder obtained by drying without performing the peptization treatment has a very large pore volume and pore radius although the transparency is low.
[0067]
【The invention's effect】
Alumina hydrate powder having a large pore diameter and pore volume by the method of the present invention, and an alumina sol having a large pore diameter and pore volume of alumina hydrate obtained by removing the solvent from the sol and having high transparency Can be easily manufactured. When the alumina hydrate powder is appropriately mixed with a binder to form a coating liquid, which is coated on a substrate and dried to form an ink receiving layer, a recording medium having good ink absorbability can be formed.
[0068]
Also, the alumina sol and the alumina hydrate powder obtained by removing the medium from the alumina sol are appropriately mixed with a binder, and if necessary, a dispersion medium is further added to form a coating liquid, which is applied onto the substrate. When the ink receiving layer is formed by drying, a recording medium having an ink receiving layer having good transparency and good ink absorbability is obtained. In particular, when an ink receiving layer is formed on a transparent substrate, a recording medium suitable as an OHP sheet can be obtained. Even if an ink receiving layer is formed on an opaque substrate, clear recording with a high color density is possible.
Claims (9)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP35150997A JP3923159B2 (en) | 1996-12-26 | 1997-12-19 | Method for producing alumina sol and alumina hydrate powder and recording medium |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8-348611 | 1996-12-26 | ||
| JP34861196 | 1996-12-26 | ||
| JP35150997A JP3923159B2 (en) | 1996-12-26 | 1997-12-19 | Method for producing alumina sol and alumina hydrate powder and recording medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10236820A JPH10236820A (en) | 1998-09-08 |
| JP3923159B2 true JP3923159B2 (en) | 2007-05-30 |
Family
ID=26578788
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP35150997A Expired - Fee Related JP3923159B2 (en) | 1996-12-26 | 1997-12-19 | Method for producing alumina sol and alumina hydrate powder and recording medium |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3923159B2 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2781477B1 (en) * | 1998-07-22 | 2000-12-08 | Inst Francais Du Petrole | PROCESS FOR THE SYNTHESIS OF ALUMINS IN A BASIC MEDIUM |
| DE102005059961A1 (en) * | 2005-12-15 | 2007-06-28 | Degussa Gmbh | Highly filled alumina-containing dispersions |
| DE102006012268A1 (en) * | 2006-03-15 | 2007-09-27 | Nabaltec Ag | Fine crystalline boehmite and process for its preparation |
| JP6008642B2 (en) * | 2012-07-31 | 2016-10-19 | 日揮触媒化成株式会社 | Flat crystalline alumina composite oxide fine particle aggregate, crystalline alumina composite oxide particle comprising flat crystalline alumina composite oxide fine particle aggregate, flat crystalline alumina composite oxide fine particle aggregate, and crystalline alumina Method for producing composite oxide particles |
| CN110876948B (en) * | 2018-09-05 | 2022-11-15 | 中国石油化工股份有限公司 | Aluminum sol, preparation method and application thereof, and preparation method of catalytic cracking catalyst |
| CN113546613A (en) * | 2021-06-24 | 2021-10-26 | 北京佳安氢源科技股份有限公司 | Preparation method and application of aluminum sol |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3377799B2 (en) * | 1991-07-26 | 2003-02-17 | 旭硝子株式会社 | Recording sheet |
-
1997
- 1997-12-19 JP JP35150997A patent/JP3923159B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH10236820A (en) | 1998-09-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0849223B1 (en) | Alumina sol, alumina hydrate powder and processes for their production | |
| CA2343260C (en) | Moniliform silica sol, method for producing it and ink jet recording medium | |
| Yu et al. | Fabrication of hollow inorganic microspheres by chemically induced self‐transformation | |
| US4117105A (en) | Process for preparing dispersible boehmite alumina | |
| CA2519501C (en) | Nanoporous ultrafine alpha-alumina powders and sol-gel process of preparing same | |
| JPS58176123A (en) | Superpure boehmite and pseudoboehmite and manufacture thereof | |
| CN106186008B (en) | Boehmite for lithium battery diaphragm coating and hydrothermal preparation method thereof | |
| KR19990087539A (en) | Alumina sol and its preparation method, and alumina molding method using them, and alumina catalyst obtained from alumina molding | |
| JP4051726B2 (en) | Method for producing acidic aqueous alumina sol | |
| WO1999064354A1 (en) | Silica-alumina composite sol, processes for producing the same, and recording medium | |
| JPH0664918A (en) | Production of alumina hydrate and alumina sol | |
| JP4368118B2 (en) | Boehmite slurry manufacturing method, boehmite sol manufacturing method, boehmite sol, boehmite, recording medium manufacturing method, and recording medium | |
| JP3923159B2 (en) | Method for producing alumina sol and alumina hydrate powder and recording medium | |
| JP2004051390A (en) | Tabular alumina particle and its manufacturing method | |
| JPWO2003055799A1 (en) | Inorganic porous fine particles | |
| WO2010050225A1 (en) | Porous alumina free-standing film, alumina sol and methods for producing same | |
| JP3577681B2 (en) | Method for producing mesoporous metallosilicate | |
| JP4936720B2 (en) | Anisotropic shaped alumina hydrate sol and process for producing the same | |
| JPH08333115A (en) | Alumina sol and recording sheet | |
| JP2000178020A (en) | High purity silica aqueous sol and its production | |
| JP2003226516A (en) | Silica and method for producing the same | |
| JP3568234B2 (en) | Silica-modified alumina sol and method for producing the same | |
| JP2000256011A (en) | Boehmite and its production | |
| KR101517369B1 (en) | Process for preparing zirconia sol | |
| JP3610510B2 (en) | Method for producing alumina hydrate dispersion |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20060908 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20061114 |
|
| A711 | Notification of change in applicant |
Free format text: JAPANESE INTERMEDIATE CODE: A711 Effective date: 20061208 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A821 Effective date: 20061208 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20070206 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20070221 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100302 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110302 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110302 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120302 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120302 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130302 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130302 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140302 Year of fee payment: 7 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| LAPS | Cancellation because of no payment of annual fees |