JP3973305B2 - High oil absorption silica gel and method for producing the same - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、シリカゲルおよびその製造方法に関する。特に、高吸油量のシリカゲルおよびその製造方法に関する。
【０００２】
【従来の技術】
粉体が油性の液体を吸収して保持する性質は、吸油量で表される。例えば、高吸油量のシリカは、医農薬等の担体、化粧品・トイレタリー原料、新聞紙の裏抜け防止材、インクジェットプリンタ用記録媒体のコーティング材またはフィラー、電池のセパレータ、塗料添加剤、触媒担体などに使用されている。
【０００３】
従来、代表的な高吸油量シリカとして、いわゆる沈降性シリカが知られている。沈降性シリカは、例えば、ケイ酸アルカリ水溶液に硫酸を加えて中和し、生成した粒子を分離洗浄して製造されている。沈降性シリカは、比表面積が３００ｍ2 ／ｇ以下であることが特徴である。アルカリ性で比較的高温の条件を経ることから、５００ｍ2 ／ｇ以上の比表面積を持つ沈降性シリカを得ることはできない。沈降性シリカの一次粒子径は通常１５ｎｍ以上である。
【０００４】
特開平６−４０７１４号公報には、沈降性シリカを超臨界乾燥することにより乾燥時のシリカの収縮を防止して、吸油量が３５０ｍｌ／１００ｇ以上の高吸油量のシリカを得る方法が開示されている。しかし、これも本質的に沈降性シリカであり比表面積は概略４００ｍ2 ／ｇである。
【０００５】
国際特許公開ＷＯ９７／４５３６６号には、沈降性シリカを電池のセパレータに使用することが開示されている。この沈降性シリカの比表面積は６０〜２００ｍ2 ／ｇ、吸油量は１８０〜３００ｍｌ／１００ｇである。
一方、乾燥剤などに用いる通常のシリカゲルは、比表面積は３５０〜７００ｍ2 ／ｇと沈降性シリカより高いが、吸油量は１００〜１７０ｍｌ／ｇ程度である。
【０００６】
【発明が解決しようとする課題】
従来高吸油量の沈降性シリカが使用されていた分野で、機能を改善するため、または新規な機能を得るためには、より高吸油量でかつ高比表面積のシリカが望まれている。本発明の目的は、高吸油量、かつ高比表面積のシリカゲルを提供することである。
【０００７】
【課題を解決するための手段】
本発明は、窒素吸着法による細孔半径１〜１００ｎｍの範囲の細孔容積が１．５〜３．５ｍｌ／ｇ、比表面積が５００〜１０００ｍ2 ／ｇ、吸油量が３００ｍｌ／１００ｇ以上のシリカゲルであって、電気伝導度が１μＳ／ｃｍ以下の水にこのシリカゲルを１重量％を分散した後分離し、さらに静置式乾燥機を用いて１２０℃で５時間乾燥して得られるシリカゲルの、窒素吸着法による細孔半径１〜１００ｎｍの範囲の細孔容積および吸油量が、それぞれ水に分散する前の値の９０％以上である高吸油量シリカゲルを提供する。
【０００８】
本発明のシリカゲルは、窒素吸着法による細孔半径１〜１００ｎｍの範囲の細孔容積が１．５〜３．５ｍｌ／ｇである。以下、単に細孔容積というときは、窒素吸着法による細孔半径１〜１００ｎｍの範囲の細孔容積を意味するものとする。細孔容積が１．８〜３．５ｍｌ／ｇである場合はさらに好ましい。細孔容積は、窒素吸着法により窒素相対圧０〜０．９９で測定した結果を、ＢＪＨ法で解析して求める。測定には、例えばカンタクローム社製、商品名カンタクロームオートソーブを用いることができる。
【０００９】
本発明のシリカゲルは、比表面積は５００〜１０００ｍ2 ／ｇである。比表面積が大きい方が表面の吸着サイトが増えるので好ましい。比表面積が６００〜１０００ｍ2 ／ｇである場合はさらに好ましい。従来の沈降性シリカは、前述のとおりその比表面積は概ね４００ｍ2 ／ｇ以下であるが、本発明のシリカゲルはそれに比べて高い比表面積を有する。このシリカゲルの一次粒子径は、シリカの真比重を２．２ｇ／ｃｍ3 の球形の無孔質粒子と仮定して計算すると４〜７ｎｍであり、一次粒子径が１５ｎｍ以上の沈降性シリカと区別できる。比表面積も細孔容積の場合と同様、窒素吸着法により窒素相対圧０〜０．９９で測定した結果を、ＢＥＴ法で解析して求める。
【００１０】
本発明のシリカゲルは、吸油量が３００ｍｌ／１００ｇ以上である。吸油量が３５０ｍｌ／１００ｇ以上である場合はさらに好ましい。吸油量は、ＪＩＳ Ｋ５１０１に準じて測定する。すなわち、試料全体が一かたまりとなるまで、練りながら試料に煮アマニ油を加えていく。吸油量は、試料１００ｇあたりの煮アマニ油の容積で表わす。以下、この測定法による吸油量を、単に吸油量という。
【００１１】
本発明のシリカゲルは、電気伝導度が１μＳ／ｃｍ以下の水にこのシリカゲルを１重量％を分散した後分離し、さらに静置式乾燥機を用いて１２０℃で５時間乾燥して得られるシリカゲルの、窒素吸着法による細孔半径１〜１００ｎｍの範囲の細孔容積および吸油量が、それぞれ水に分散する前の値の９０％以上である。
【００１２】
従来、超臨界乾燥により高吸油量のシリカは得られているが、このシリカは、水などの溶媒に入れて再度乾燥すると、その細孔容積、吸油量は極端に小さくなる。本発明のシリカゲルは高吸油量であり、水などの溶媒に入れて再度乾燥しても、その細孔容積、吸油量はほとんど変化しない。したがって、紙などのフィラーやコート材として使用した場合、乾燥時の、細孔容積の減少やみかけの体積の収縮がなく、吸油量も大きいまま維持できるのこれらの用途に好適である。
【００１３】
本発明のシリカゲルの平均粒子径は、その使用方法により任意に選べるが、１〜１００μｍであることが好ましい。平均粒子径が、１〜７０μｍである場合は、さらに好ましい。さらに、シリカゲルの粒子形状が球状である場合は、樹脂、塗料に配合するときの分散性の向上、化粧品に配合したときの感触の向上、医農薬などの担体として使用するときの流動性の向上などの点で好ましい。ここで、球状とは真球状だけでなく、多少いびつなものも含む。この場合、長径に対する短径の比は、０．８〜１．０であることが好ましい。
【００１４】
この球状の高吸油量シリカゲルは、ケイ酸アルカリ水溶液中のケイ酸成分をＳｉＯ2 に換算したとき、該ＳｉＯ2 １モルに対して、塩化物イオン、硫酸イオン、硝酸イオンおよびフッ化物イオンからなる群より選ばれるアニオンの１種以上を合計で０．１〜０．５当量の割合で含有するケイ酸アルカリ水溶液を、有機溶媒中で乳化し、炭酸ガスでゲル化させることにより製造するのが好ましい。
【００１５】
【発明の実施の形態】
本発明のシリカゲルは、アルカリ金属塩またはアルカリ土類金属塩を含有したケイ酸アルカリ水溶液を有機溶媒中で乳化し、炭酸ガスでゲル化させることにより得られる。
ケイ酸アルカリとしては、ケイ酸ナトリウム、ケイ酸カリウムなどが使用できる。ケイ酸ナトリウムが経済的である点で好ましい。以下、ケイ酸ナトリウムを例にとって説明するが、ケイ酸カリウムを用いる場合も同様である。
【００１６】
ケイ酸ナトリウム水溶液中のケイ酸成分は、ＳｉＯ2 に換算して３〜２０重量％であることが好ましい。以下、ケイ酸成分の量はＳｉＯ2 に換算して示すものとする。ケイ酸ナトリウム水溶液中のＳｉＯ2 濃度のより好ましい範囲は５〜１５重量％である。ケイ酸ナトリウム水溶液のＳｉＯ2 ／Ｎａ2 Ｏ比は１〜４であることが好ましい。ＳｉＯ2 ／Ｎａ2 Ｏ比のより好ましい範囲は２．５〜３．５である。
【００１７】
ケイ酸ナトリウム水溶液中には、塩化物イオン、硫酸イオン、硝酸イオンおよびフッ化物イオンからなる群より選ばれるアニオンの１種以上を、ケイ酸ナトリウム水溶液中のＳｉＯ2 １モルに対して０．１〜０．５当量の割合で含むことが好ましい。より好ましい範囲は、０．２〜０．４当量である。
【００１８】
ケイ酸ナトリウム水溶液中に上記アニオンを含ませるには、水可溶性の金属塩化物、金属硫酸塩、金属硝酸塩、金属フッ化物を添加することにより行うのが好ましい。具体的には、アルカリ金属塩化物、アルカリ金属硫酸塩、アルカリ金属硝酸塩、アルカリ金属フッ化物、アルカリ土類金属塩化物、アルカリ土類金属硝酸塩が好ましい。特に、塩化ナトリウム、塩化カリウム、硫酸ナトリウムなどのアルカリ金属塩化物、アルカリ金属硫酸塩が好ましい。
【００１９】
ケイ酸ナトリウム水溶液を乳化させる有機溶剤としては、炭酸ガスが溶解できる物質が好ましい。このような有機溶媒として、例えば、ヘキサン、オクタンなどの脂肪族炭化水素、キシレン、トルエンなどの芳香族炭化水素、クロロホルム、トリクロロエチレン、テトラクロロエチレンなどの塩素化炭化水素、トリクロロトリフルオロエタン、ジクロロトリフルオロエタン、ジクロロフルオロエタン、ジクロロペンタフルオロプロパンなどの塩素化フッ素化炭化水素が好ましい。
【００２０】
有機溶媒には、界面活性剤を溶解して使用するのが好ましい。界面活性剤としては、ポリエチレングリコール脂肪酸エステル、ポリオキシエチレンアルキルフェニルエーテル、ポリオキシエチレンアルキルエーテル、ソルビタン脂肪酸エステル、ポリオキシエチレンソルビタン脂肪酸エステルが好ましい。その使用量は、有機溶媒に対して０．０５〜１０重量％が好ましい。
【００２１】
ケイ酸ナトリウム水溶液を有機溶剤に加えて乳化する場合、Ｗ／Ｏ型の乳化液が形成されるように、有機溶剤に対しケイ酸ナトリウム水溶液を容積比で０．１〜１の範囲で加えるのが好ましい。乳化は、タービン式撹拌機、高速せん断式乳化機などの手段によって行うのが好ましい。乳化液において、ケイ酸ナトリウム水溶液の液滴は、平均粒子径が１〜１００μｍであることが好ましい。
【００２２】
次に、乳化液に炭酸ガスを導入することにより、ケイ酸アルカリ水溶液をゲル化させる。乳化させた状態でゲル化させるため、球状のシリカゲルが得られる。炭酸ガスの分圧、流量などは適宜選定できる。
ゲル化終了後は、有機溶媒を除去し、適宜加熱処理や薬液処理し、洗浄し乾燥する。ゲル化終了時にすでに高吸油量、高比表面積のシリカゲルが生成しているので、従来高吸油量のシリカを得るために行われているアルカリ条件下での加熱処理や水熱処理はここでは行わない。
【００２３】
乾燥方法としては、公知の方法が使用できるが、乾燥時の細孔の収縮を防止するために、気流乾燥、スプレードライ、凍結乾燥、超臨界乾燥などが好適に使用できる。また、乾燥前に、水と相溶性があり表面張力の低い有機溶媒で水を置換した後乾燥することもできる。こうすることにより乾燥時の細孔の収縮を防止することができる。
このようにして得られる高吸油量シリカゲルは、さらに焼成してもよい。焼成温度、焼成時間は、比表面積が５００ｍ2 ／ｇ以下にならないように適宜選択できる。
【００２４】
本発明の高吸油量シリカゲルは、無機塩類、またはその加水分解物で表面処理することができる。例えば、塩化アルミニウム水溶液中に入れ、ろ過、乾燥することにより塩化アルミニウム処理をすることができる。またこれを加水分解すると水酸化アルミニウム処理された高吸油量シリカゲルを得ることができる。この他、カルシウム塩、マグネシウム塩などでも同様に処理できる。
また、シランカップリング剤、シリコーンオイル、フッ素系表面処理剤、チタネート系カップリング剤、アルコール、界面活性剤、その他の表面処理剤、表面改質剤によって表面処理することができる。
【００２５】
本発明の球状シリカゲルは、粉砕して使用してもよい。粉砕方法としてはジェット粉砕機のような公知の方法を採用できる。粉砕した場合も、高い吸油量と、高い比表面積を維持したシリカゲルとして使用することができる。
【００２６】
【実施例】
例１
ＳｉＯ2 濃度１０．０重量％、ＳｉＯ2 ／Ｎａ2 Ｏモル比２．７のケイ酸ナトリウム水溶液２４０ｍｌに、塩化ナトリウムを塩化物イオンがＳｉＯ2 １モルに対して０．３６当量となるように溶解した。この水溶液を、トリクロロトリフルオロエタン９６０ｍｌにソルビタンモノオレイン酸エステル３．３６ｇを溶解した溶液に投入し、ホモミキサーで乳化させた。
【００２７】
この乳化液に、空気で希釈した炭酸ガス（ＣＯ2 濃度３０容積％）を吹き込み、１５℃でゲル化させた。炭酸ガスを１５分間吹き込んだ後、トリクロロトリフルオロエタンを分離し、球状シリカと水からなるスラリーを得た。このスラリーのｐＨは９．０であった。このスラリーに硫酸を加え、ｐＨ２．５に調整し、６０℃で１時間加熱処理した。
【００２８】
このスラリーを濾過し、そのケーキを固形分の１００倍のイオン交換水で洗浄し、スプレードライヤーで乾燥し、球状シリカゲルを得た。細孔容積は２．８ｍｌ／ｇ、比表面積は７５８ｍ2 ／ｇ、吸油量は５５０ｍｌ／１００ｇ、平均粒子径は４．８μｍであった。この球状シリカゲルの長径に対する短径の比は、０．９以上であった。
【００２９】
この球状シリカゲル１ｇを電気伝導度が０．５μＳ／ｃｍのイオン交換水９９ｇに分散し、さらに静置式乾燥機を用いて１２０℃で５時間乾燥してシリカゲルを得た。この処理の後のシリカゲルについて同様に細孔特性を評価したところ、細孔容積は２．８ｍｌ／ｇ、比表面積は７６０ｍ2 ／ｇ、吸油量は５５３ｍｌ／１００ｇであった。
【００３０】
例２
例１の塩化ナトリウムを、硫酸ナトリウム（硫酸イオンがＳｉＯ2 １モルに対して０．３０当量となる量）に変更し、球状シリカゲルを得た。細孔容積は２．３ｍｌ／ｇ、比表面積は８１０ｍ2 ／ｇ、吸油量は４４０ｍｌ／１００ｇ、平均粒子径は５．２μｍであった。この球状シリカゲルの長径に対する短径の比は、０．９以上であった。
【００３１】
この球状シリカゲル１ｇを電気伝導度が０．５μＳ／ｃｍのイオン交換水９９ｇに分散し、さらに静置式乾燥機を用いて１２０℃で５時間乾燥してシリカゲルを得た。この処理の後のシリカゲルについて同様に細孔特性を評価したところ、細孔容積、比表面積、吸油量は、実質的に変化していなかった。すなわち、それぞれ水に分散する前の値の９０％以上であった。
【００３２】
例３
例１の塩化ナトリウムの添加量を、塩化物イオンがＳｉＯ2 １モルに対して０．３２当量となる量に変更して、球状シリカゲルを得た。細孔容積は２．１ｍｌ／ｇ、比表面積は７９７ｍ2 ／ｇ、吸油量は４２０ｍｌ／１００ｇ、平均粒子径は４．６μｍであった。この球状シリカゲルの長径に対する短径の比は、０．９以上であった。
【００３３】
この球状シリカゲル１ｇを電気伝導度が０．５μＳ／ｃｍのイオン交換水９９ｇに分散し、さらに静置式乾燥機を用いて１２０℃で５時間乾燥してシリカゲルを得た。この処理の後のシリカゲルについて同様に細孔特性を評価したところ、細孔容積、比表面積、吸油量は、実質的に変化していなかった。すなわち、それぞれ水に分散する前の値の９０％以上であった。
【００３４】
例４
例１で得られた球状シリカゲルを、ジェット粉砕機で処理し、微粉末シリカゲルを得た。このシリカゲルは、細孔容積は２．３ｍｌ／ｇ、比表面積は７４３ｍ2 ／ｇ、吸油量は４５０ｍｌ／１００ｇ、平均粒子径は１．２μｍであった。
【００３５】
このシリカゲル１ｇを電気伝導度が０．５μＳ／ｃｍのイオン交換水９９ｇに分散し、さらに静置式乾燥機を用いて１２０℃で５時間乾燥してシリカゲルを得た。この処理の後のシリカゲルについて同様に細孔特性を評価したところ、細孔容積は２．３ｍｌ／ｇ、比表面積は７５５ｍ2 ／ｇ、吸油量は４４３ｍｌ／１００ｇであった。
【００３６】
例５（比較例）
テトラエチルシリケートをエタノール中で酸性条件下で加水分解した後、水をエタノールで置換し、圧力、温度をエタノールの超臨界点以上にした後、その温度を維持したまま超臨界乾燥したシリカゲルについて、同様に細孔特性を評価した。細孔容積は６．９ｍｌ／ｇ、比表面積は４５３ｍ2 ／ｇ、吸油量は６４０ｍｌ／１００ｇ、平均粒子径は１．２μｍであった。
【００３７】
このシリカゲル１ｇを電気伝導度が０．５μＳ／ｃｍのイオン交換水９９ｇに分散し、さらに静置式乾燥機を用いて１２０℃で５時間乾燥してシリカゲルを得た。この処理の後のシリカゲルについて同様に細孔特性を評価したところ、細孔容積は１．８ｍｌ／ｇ、比表面積は４７５ｍ2 ／ｇ、吸油量は２６５ｍｌ／１００ｇであった。
【００３８】
【発明の効果】
本発明の高吸油量シリカゲルは、従来の沈降性シリカと比較して大きな比表面積を有し、医農薬等の担体、化粧品・トイレタリー原料、新聞紙の裏抜け防止材、インクジェットプリンタ用記録媒体のコーティング材またはフィラー、電池のセパレータ、塗料添加剤、触媒担体、軽量化材、断熱材、樹脂・ゴムへの充填剤などの用途に好適に使用される。
【００３９】
本発明の球状シリカゲルを使用したインクジェットプリンタ用記録媒体は、インクの吸収速度が速く、色濃度が高い。また、本発明の球状シリカゲルを使用した電池のセパレータは、電気抵抗が低い。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to silica gel and a method for producing the same. In particular, the present invention relates to a high oil absorption silica gel and a method for producing the same.
[0002]
[Prior art]
The property that the powder absorbs and retains the oily liquid is represented by the oil absorption. For example, high oil-absorbing silica is used as a carrier for medicines and agrochemicals, cosmetics and toiletry materials, anti-back-through materials for newspapers, coating materials or fillers for recording media for inkjet printers, battery separators, paint additives, catalyst carriers, etc. in use.
[0003]
Conventionally, so-called precipitated silica is known as a typical high oil absorption silica. Precipitating silica is produced, for example, by adding sulfuric acid to an aqueous alkali silicate solution to neutralize it, and separating and washing the generated particles. Precipitated silica is characterized by a specific surface area of 300 m 2 / g or less. Precipitating silica having a specific surface area of 500 m 2 / g or more cannot be obtained because it is alkaline and undergoes relatively high temperature conditions. The primary particle size of precipitated silica is usually 15 nm or more.
[0004]
Japanese Patent Application Laid-Open No. 6-40714 discloses a method of obtaining silica having a high oil absorption amount of 350 ml / 100 g or more by preventing the silica from shrinking during drying by supercritical drying of the precipitated silica. ing. However, this is also essentially precipitated silica with a specific surface area of approximately 400 m 2 / g.
[0005]
International Patent Publication No. WO 97/45366 discloses the use of precipitated silica in battery separators. The sedimentary silica has a specific surface area of 60 to 200 m 2 / g and an oil absorption of 180 to 300 ml / 100 g.
On the other hand, a normal silica gel used as a desiccant has a specific surface area of 350 to 700 m 2 / g, which is higher than that of precipitated silica, but has an oil absorption of about 100 to 170 ml / g.
[0006]
[Problems to be solved by the invention]
In order to improve the function or obtain a new function in a field where a high oil absorption amount of precipitating silica has been used, a silica having a higher oil absorption amount and a higher specific surface area is desired. An object of the present invention is to provide a silica gel having a high oil absorption and a high specific surface area.
[0007]
[Means for Solving the Problems]
The present invention is a silica gel having a pore volume in the range of pore radius of 1 to 100 nm by a nitrogen adsorption method of 1.5 to 3.5 ml / g, a specific surface area of 500 to 1000 m 2 / g, and an oil absorption of 300 ml / 100 g or more. The silica gel obtained by dispersing 1% by weight of this silica gel in water having an electric conductivity of 1 μS / cm or less and then separating the silica gel and further drying it at 120 ° C. for 5 hours using a stationary dryer. Provided is a high oil absorption silica gel in which the pore volume and the oil absorption amount in the pore radius range of 1 to 100 nm by the adsorption method are each 90% or more of the value before being dispersed in water.
[0008]
The silica gel of the present invention has a pore volume of 1.5 to 3.5 ml / g in a pore radius range of 1 to 100 nm by a nitrogen adsorption method. Hereinafter, the simple pore volume means a pore volume within a pore radius range of 1 to 100 nm by a nitrogen adsorption method. More preferably, the pore volume is 1.8 to 3.5 ml / g. The pore volume is obtained by analyzing the result of measurement at a nitrogen relative pressure of 0 to 0.99 by the nitrogen adsorption method by the BJH method. For the measurement, for example, a product name Cantachrome Autosorb manufactured by Cantachrome Co., Ltd. can be used.
[0009]
The silica gel of the present invention has a specific surface area of 500 to 1000 m 2 / g. A larger specific surface area is preferred because the number of adsorption sites on the surface increases. More preferably, the specific surface area is 600 to 1000 m 2 / g. As described above, the conventional precipitated silica has a specific surface area of approximately 400 m 2 / g or less, but the silica gel of the present invention has a higher specific surface area. The primary particle diameter of this silica gel is 4 to 7 nm when calculated on the assumption that the true specific gravity of silica is 2.2 g / cm 3 of spherical nonporous particles, and is distinguished from precipitated silica having a primary particle diameter of 15 nm or more. it can. Similarly to the case of the pore volume, the specific surface area is obtained by analyzing the result of measurement by the nitrogen adsorption method at a nitrogen relative pressure of 0 to 0.99 by the BET method.
[0010]
The silica gel of the present invention has an oil absorption of 300 ml / 100 g or more. More preferably, the oil absorption is 350 ml / 100 g or more. The oil absorption is measured according to JIS K5101. That is, boiled linseed oil is added to the sample while kneading until the whole sample becomes a lump. Oil absorption is expressed as the volume of boiled linseed oil per 100 g of sample. Hereinafter, the oil absorption amount by this measuring method is simply referred to as the oil absorption amount.
[0011]
Silica gel of the present invention, silica gel electrical conductivity separated was dispersed 1 by weight% of the silica gel in the following water 1 [mu] S / cm, obtained by further dried for 5 hours at 120 ° C. using a stationary type dryer The pore volume and the oil absorption amount in the range of the pore radius of 1 to 100 nm by the nitrogen adsorption method are 90% or more of the values before being dispersed in water, respectively.
[0012]
Conventionally, high oil absorption silica has been obtained by supercritical drying, but when this silica is dried again in a solvent such as water, its pore volume and oil absorption become extremely small. The silica gel of the present invention has a high oil absorption, and even if it is dried again in a solvent such as water, its pore volume and oil absorption hardly change. Therefore, when used as a filler or a coating material such as paper, there is no reduction in pore volume or shrinkage of the apparent volume during drying, and it is suitable for these applications because the oil absorption amount can be kept large.
[0013]
Although the average particle diameter of the silica gel of the present invention can be arbitrarily selected depending on the method of use, it is preferably 1 to 100 μm. The average particle size is more preferably 1 to 70 μm. In addition, when the silica gel particle shape is spherical, it improves dispersibility when blended with resins and paints, improves feel when blended with cosmetics, and improves fluidity when used as a carrier for pharmaceuticals and agricultural chemicals. It is preferable at such points. Here, the spherical shape includes not only a true spherical shape but also a somewhat irregular shape. In this case, the ratio of the minor axis to the major axis is preferably 0.8 to 1.0.
[0014]
High oil absorption silica gel This spherical, when converted to silicic acid component in the aqueous alkali silicate solution into SiO 2, relative to the SiO 2 1 mol, consists of chloride ions, sulfate ions, nitrate ions and fluoride ions It is produced by emulsifying an alkali silicate aqueous solution containing at least one kind of anion selected from the group in a proportion of 0.1 to 0.5 equivalent in an organic solvent and gelling with carbon dioxide gas. preferable.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The silica gel of the present invention can be obtained by emulsifying an alkali silicate aqueous solution containing an alkali metal salt or an alkaline earth metal salt in an organic solvent and gelling it with carbon dioxide gas.
As the alkali silicate, sodium silicate, potassium silicate and the like can be used. Sodium silicate is preferred because it is economical. Hereinafter, although it demonstrates taking sodium silicate as an example, it is the same also when using potassium silicate.
[0016]
Silicic acid component in an aqueous sodium silicate solution is preferably from 3 to 20% by weight in terms of SiO 2. Hereinafter, the amount of the silicic acid component is shown in terms of SiO 2 . A more preferable range of the SiO 2 concentration in the aqueous sodium silicate solution is 5 to 15% by weight. The SiO 2 / Na 2 O ratio of the aqueous sodium silicate solution is preferably 1 to 4. A more preferable range of the SiO 2 / Na 2 O ratio is 2.5 to 3.5.
[0017]
In the sodium silicate aqueous solution, one or more anions selected from the group consisting of chloride ion, sulfate ion, nitrate ion and fluoride ion are added in an amount of 0.1 to 1 mol of SiO 2 in the sodium silicate aqueous solution. It is preferable to contain in the ratio of -0.5 equivalent. A more preferable range is 0.2 to 0.4 equivalent.
[0018]
In order to include the anion in the aqueous sodium silicate solution, it is preferable to add a water-soluble metal chloride, metal sulfate, metal nitrate, or metal fluoride. Specifically, alkali metal chloride, alkali metal sulfate, alkali metal nitrate, alkali metal fluoride, alkaline earth metal chloride, and alkaline earth metal nitrate are preferable. In particular, alkali metal chlorides such as sodium chloride, potassium chloride and sodium sulfate, and alkali metal sulfates are preferred.
[0019]
As the organic solvent for emulsifying the sodium silicate aqueous solution, a substance capable of dissolving carbon dioxide gas is preferable. Examples of such organic solvents include aliphatic hydrocarbons such as hexane and octane, aromatic hydrocarbons such as xylene and toluene, chlorinated hydrocarbons such as chloroform, trichloroethylene, and tetrachloroethylene, trichlorotrifluoroethane, and dichlorotrifluoroethane. Chlorinated fluorinated hydrocarbons such as dichlorofluoroethane and dichloropentafluoropropane are preferred.
[0020]
The organic solvent is preferably used after dissolving the surfactant. As the surfactant, polyethylene glycol fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, sorbitan fatty acid ester, and polyoxyethylene sorbitan fatty acid ester are preferable. The amount used is preferably 0.05 to 10% by weight with respect to the organic solvent.
[0021]
When emulsifying by adding an aqueous sodium silicate solution to an organic solvent, the aqueous sodium silicate solution is added to the organic solvent in a volume ratio of 0.1 to 1 so that a W / O type emulsion is formed. Is preferred. The emulsification is preferably carried out by means such as a turbine type stirrer or a high speed shearing type emulsifier. In the emulsion, the droplets of the aqueous sodium silicate solution preferably have an average particle size of 1 to 100 μm.
[0022]
Next, the aqueous alkali silicate solution is gelled by introducing carbon dioxide into the emulsion. Since gelation is performed in the emulsified state, spherical silica gel is obtained. Carbon dioxide partial pressure, flow rate, and the like can be selected as appropriate.
After the gelation is completed, the organic solvent is removed, and heat treatment or chemical treatment is appropriately performed, followed by washing and drying. Since silica gel with high oil absorption and high specific surface area has already been generated at the end of gelation, heat treatment and hydrothermal treatment under alkaline conditions that have been conventionally used to obtain silica with high oil absorption are not performed here. .
[0023]
As a drying method, a known method can be used, but airflow drying, spray drying, freeze drying, supercritical drying and the like can be preferably used in order to prevent pore shrinkage during drying. Moreover, it is also possible to dry after replacing water with an organic solvent that is compatible with water and has a low surface tension before drying. By doing so, shrinkage of the pores during drying can be prevented.
The high oil absorption silica gel thus obtained may be further baked. The firing temperature and firing time can be appropriately selected so that the specific surface area does not become 500 m 2 / g or less.
[0024]
The high oil absorption silica gel of the present invention can be surface-treated with inorganic salts or a hydrolyzate thereof. For example, the aluminum chloride treatment can be performed by placing in an aluminum chloride aqueous solution, filtering and drying. When this is hydrolyzed, a high oil absorption silica gel treated with aluminum hydroxide can be obtained. In addition, the same treatment can be performed with calcium salt, magnesium salt and the like.
Moreover, it can surface-treat with a silane coupling agent, silicone oil, a fluorine-type surface treatment agent, a titanate-type coupling agent, alcohol, surfactant, another surface treatment agent, and a surface modifier.
[0025]
The spherical silica gel of the present invention may be used after being pulverized. As the pulverization method, a known method such as a jet pulverizer can be employed. Even when pulverized, it can be used as silica gel maintaining a high oil absorption and a high specific surface area.
[0026]
【Example】
Example 1
Sodium chloride is added to 240 ml of an aqueous solution of sodium silicate having a SiO 2 concentration of 10.0% by weight and a SiO 2 / Na 2 O molar ratio of 2.7 so that the chloride ion is 0.36 equivalent to 1 mol of SiO 2 Dissolved. This aqueous solution was put into a solution obtained by dissolving 3.36 g of sorbitan monooleate in 960 ml of trichlorotrifluoroethane, and emulsified with a homomixer.
[0027]
Carbon dioxide gas diluted with air (CO 2 concentration: 30% by volume) was blown into the emulsified liquid, and gelled at 15 ° C. After blowing carbon dioxide gas for 15 minutes, trichlorotrifluoroethane was separated to obtain a slurry composed of spherical silica and water. The pH of this slurry was 9.0. Sulfuric acid was added to this slurry, adjusted to pH 2.5, and heat-treated at 60 ° C. for 1 hour.
[0028]
This slurry was filtered, and the cake was washed with ion exchange water having a solid content of 100 times and dried with a spray dryer to obtain spherical silica gel. The pore volume was 2.8 ml / g, the specific surface area was 758 m 2 / g, the oil absorption was 550 ml / 100 g, and the average particle size was 4.8 μm. The ratio of the minor axis to the major axis of the spherical silica gel was 0.9 or more.
[0029]
1 g of this spherical silica gel was dispersed in 99 g of ion-exchanged water having an electric conductivity of 0.5 μS / cm, and further dried at 120 ° C. for 5 hours using a stationary dryer to obtain silica gel. The silica gel after this treatment was similarly evaluated for pore characteristics. As a result, the pore volume was 2.8 ml / g, the specific surface area was 760 m 2 / g, and the oil absorption was 553 ml / 100 g.
[0030]
Example 2
The sodium chloride in Example 1 was changed to sodium sulfate (amount of sulfate ions to be 0.30 equivalent to 1 mol of SiO 2 ) to obtain spherical silica gel. The pore volume was 2.3 ml / g, the specific surface area was 810 m 2 / g, the oil absorption was 440 ml / 100 g, and the average particle size was 5.2 μm. The ratio of the minor axis to the major axis of the spherical silica gel was 0.9 or more.
[0031]
1 g of this spherical silica gel was dispersed in 99 g of ion-exchanged water having an electric conductivity of 0.5 μS / cm, and further dried at 120 ° C. for 5 hours using a stationary dryer to obtain silica gel. When the pore characteristics of the silica gel after this treatment were similarly evaluated, the pore volume, specific surface area, and oil absorption amount were not substantially changed. That is, it was 90% or more of the value before being dispersed in water.
[0032]
Example 3
The amount of sodium chloride added in Example 1 was changed to an amount such that the chloride ion was 0.32 equivalent to 1 mol of SiO 2 to obtain spherical silica gel. The pore volume was 2.1 ml / g, the specific surface area was 797 m 2 / g, the oil absorption was 420 ml / 100 g, and the average particle size was 4.6 μm. The ratio of the minor axis to the major axis of the spherical silica gel was 0.9 or more.
[0033]
1 g of this spherical silica gel was dispersed in 99 g of ion-exchanged water having an electric conductivity of 0.5 μS / cm, and further dried at 120 ° C. for 5 hours using a stationary dryer to obtain silica gel. When the pore characteristics of the silica gel after this treatment were similarly evaluated, the pore volume, specific surface area, and oil absorption amount were not substantially changed. That is, it was 90% or more of the value before being dispersed in water.
[0034]
Example 4
The spherical silica gel obtained in Example 1 was treated with a jet pulverizer to obtain fine powder silica gel. This silica gel had a pore volume of 2.3 ml / g, a specific surface area of 743 m 2 / g, an oil absorption of 450 ml / 100 g, and an average particle size of 1.2 μm.
[0035]
1 g of this silica gel was dispersed in 99 g of ion-exchanged water having an electric conductivity of 0.5 μS / cm, and further dried at 120 ° C. for 5 hours using a stationary drier to obtain silica gel. The silica gel after this treatment was similarly evaluated for pore characteristics. As a result, the pore volume was 2.3 ml / g, the specific surface area was 755 m 2 / g, and the oil absorption was 443 ml / 100 g.
[0036]
Example 5 (comparative example)
After hydrolyzing tetraethyl silicate in ethanol under acidic conditions, water was replaced with ethanol, the pressure and temperature were made higher than the supercritical point of ethanol, and the same was applied to silica gel that was supercritically dried while maintaining the temperature. The pore characteristics were evaluated. The pore volume was 6.9 ml / g, the specific surface area was 453 m 2 / g, the oil absorption was 640 ml / 100 g, and the average particle size was 1.2 μm.
[0037]
1 g of this silica gel was dispersed in 99 g of ion-exchanged water having an electric conductivity of 0.5 μS / cm, and further dried at 120 ° C. for 5 hours using a stationary dryer to obtain silica gel. When the pore characteristics of the silica gel after this treatment were similarly evaluated, the pore volume was 1.8 ml / g, the specific surface area was 475 m 2 / g, and the oil absorption was 265 ml / 100 g.
[0038]
【The invention's effect】
The high oil absorption silica gel of the present invention has a large specific surface area compared to conventional precipitated silica, a carrier such as medical and agricultural chemicals, cosmetics / toiletries raw material, anti-back-through material for newspapers, and coating for recording media for ink jet printers. It is suitably used for applications such as materials or fillers, battery separators, paint additives, catalyst carriers, lightening materials, heat insulating materials, and fillers for resins and rubbers.
[0039]
The recording medium for an ink jet printer using the spherical silica gel of the present invention has a high ink absorption speed and a high color density. Moreover, the battery separator using the spherical silica gel of the present invention has a low electric resistance.
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31240098A JP3973305B2 (en) | 1998-11-02 | 1998-11-02 | High oil absorption silica gel and method for producing the same |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31240098A JP3973305B2 (en) | 1998-11-02 | 1998-11-02 | High oil absorption silica gel and method for producing the same |
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| JP2000143228A JP2000143228A (en) | 2000-05-23 |
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| JP3973305B2 true JP3973305B2 (en) | 2007-09-12 |
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| EP1627629A4 (en) * | 2003-02-05 | 2006-11-29 | Miyoshi Kasei Inc | Skin lotion |
| JP2007517770A (en) * | 2003-10-03 | 2007-07-05 | ザ プロクター アンド ギャンブル カンパニー | Topical composition |
| JP4515824B2 (en) | 2004-05-27 | 2010-08-04 | Ｎｔｎ株式会社 | High precision plain bearing |
| JP4960534B1 (en) | 2010-10-25 | 2012-06-27 | 株式会社トクヤマ | Airgel and method for producing the same |
| EP2703348B1 (en) * | 2011-04-28 | 2023-06-28 | Tokuyama Corporation | Metal oxide powder and method for producing same |
| JP6196462B2 (en) * | 2013-04-11 | 2017-09-13 | 株式会社トクヤマ | Porous spherical metal oxide |
| JP6247067B2 (en) * | 2013-09-27 | 2017-12-13 | 株式会社トクヤマ | Silicone filler and silicone composition |
| JP6241252B2 (en) * | 2013-12-16 | 2017-12-06 | 旭硝子株式会社 | Method for producing spherical silica |
| KR101901196B1 (en) * | 2017-07-17 | 2018-09-21 | 휴먼켐 주식회사 | the high oil-uptake ball shaped silica making method and the silica |
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