JP4022132B2 - Silica gel containing organic group - Google Patents

Description

【００３０】
これら酸素がＳｉの周りに４つ結合したケイ素は、一般にＱサイトと総称される。本発明においては、Ｑサイトに由来するＱ⁰〜Ｑ⁴の各ピークをＱⁿピーク群と呼ぶこととする。シリカゲルのＱⁿピーク群は、通常はケミカルシフト−８０〜−１３０ｐｐｍの領域に連続した多峰性のピークとして観測される。
【００３１】
これに対し、酸素原子が３つ結合し、それ以外の原子（通常は炭素である）が１つ結合しているケイ素は、一般にＴサイトと総称される。Ｔサイトに由来するピークは、Ｑサイトの場合と同様に、Ｔ⁰〜Ｔ³の各ピークとして観測される。本発明においては、Ｔサイトに由来する各ピークをＴⁿピーク群と呼ぶこととする。シリカゲルのＴⁿピーク群は、一般にＱⁿピーク群より高磁場側（通常ケミカルシフト−２０〜−１００ｐｐｍ）の領域に連続した多峰性のピークとして観測される。
【００３２】
本発明の有機基含有シリカゲルの固体Ｓｉ−ＮＭＲスペクトルを測定すると、シリカゲルに導入された有機基の炭素が直接結合したケイ素に由来するＴⁿピーク群と、有機基の炭素と結合していないケイ素に由来するＱⁿピーク群が各々異なる領域に出現する。これらＱⁿとＴⁿのピークの面積の比は、そのピークに対応する環境におかれたケイ素のモル比と等しく、全ピークの面積を全ケイ素のモル量とすることで、Ｔⁿピーク群の合計面積はこれに対する炭素原子と直接結合した全ケイ素のモル量と対応する。
【００３３】
すなわち、Ｑⁿピーク群の合計面積をＡ、Ｔⁿピーク群の合計面積をＢとしたとき、全ケイ素原子中炭素原子と直接結合したケイ素原子の割合Ｘ（％）は、以下の式で表される。
【数１】

【００３４】
本発明の有機基含有シリカゲルに導入される有機基の種類は、いわゆるシランカップリング剤の有機基として公知のものを、いずれも選択して使用することができる。本発明において特に有用な有機基とは、以下のＹに表される群（有用有機基群）から選ばれるものである。
【００３５】
Ｙ：Ｃ１からＣ１０００（好ましくはＣ１〜Ｃ５００、更に好ましくはＣ１〜Ｃ１００、特に好ましくはＣ１〜Ｃ５０）の脂肪族化合物、脂環式化合物、芳香族化合物、脂肪芳香族化合物より誘導される１価以上の有機基であり、Ｙの水素の少なくとも一部が下記に示す原子及び／又は有機官能基で置換されていても良い。Ｙの複数の水素が下記に示す原子及び／又は有機官能基で置換されていても良く、この場合は、下記に示す原子及び／又は有機官能基の中から選択した１種又は２種以上の組み合わせにより置換されていても良い。さらに、上記全ての場合において、下記に示す有機官能基の水素の少なくとも一部がＦ，Ｃｌ，Ｂｒ，Ｉで置換されていても良い。また、Ｙはその中に連結基としてＯ、Ｎ、又はＳ等の各種の原子または原子団を有するものであっても良い。なお、下記に示す有機官能基は導入しやすいものの一例であり、使用目的に応じてこの他各種の化学的反応性、物理化学的機能性を持つ有機官能基を導入しても良い。
【００３６】
例えば、上記有用有機基群から選ばれた有機基を導入し、シリカ表面の一部又はほぼ全部を疎水化したものは、有害な有機化合物の吸着剤として極めて有用である。この際の有機基としては脂肪族炭化水素基や芳香族炭化水基等が挙げられ、具体的には例えばメチル基、エチル基、プロピル基、ブチル基、ヘキシル基、オクチル基等の直鎖状炭化水素基や、フェニル基、ナフチル基、トルイル基等の芳香族炭化水素基等が挙げられる。中でもメチル基やフェニル基の様に、珪素−炭素結合の耐熱性が高くなるような有機基が好ましい。
また、炭素数の小さい炭化水素基、例えば炭素数１〜４程度の低級アルキル基などは、その分子量が小さいので、本発明のシリカ単位体積あたりへの有機基導入量を多くすることが出来るので、好ましい。
【００３７】
＜Ｙの水素と置換可能な元素及び有機官能基の例＞
Ｆ、Ｃｌ、Ｂｒ、Ｉ、ビニル基、メタクリロキシ基、アクリロキシ基、スチリル基、メルカプト基、エポキシ基、エポキシシクロヘキシル基、グリシドキシ基、アミノ基、シアノ基、ニトロ基、スルホン酸基、カルボキシ基、ヒドロキシ基、アシル基、アルコキシ基、アンモニウム基、アリル基。
【００３８】
本発明の有機基含有シリカゲルは、上記範囲の中で構造の異なる各種の有機基Ｙの中から選択した１種、又は任意の組み合わせの２種以上を目的有機基として同時に含有することが出来る。これらの有機基Ｙは本発明のシリカゲル中において、有機基Ｙの価数に応じた数のケイ素原子と共有結合により直接結合していることを特徴とする。これらのケイ素原子はシリカゲル骨格を形成するものの一部であり、有機基Ｙは実質的にシリカゲル骨格に直接導入された状態となっている。このような状態で有機基Ｙをシリカゲルへ導入するためには、有機基Ｙにシロキサン結合を形成し得る反応性末端が導入された試薬を用いればよい。このような試薬として最も入手が容易であり代表的なものは、下記に示すシランカップリング剤である。このほかにもシラノールと反応し、シロキサン結合を形成する一般合成試薬（以下、有機基導入試薬と表記）が数種あるが、工業的な入手が容易ではなく、また反応条件に制限のあることが多い。本発明においてシランカップリング剤とは、ケイ素原子に前述のような有機基Ｙが直結しているものの総称であり、以下の式（Ｉ）〜（ＩＶ）に示される化合物である。
【００３９】
（Ｉ）Ｘ₃ＳｉＹ
Ｘ：水溶液中、空気中の水分、または無機質表面に吸着された水分などにより加水分解されて、反応性に富むシラノール基を生成する加水分解性シリル基であり、従来より公知のものを使用することが出来る。例えば、Ｃ１〜Ｃ４の低級アルコキシ基、アセトキシ基、ブタノキシム基、クロル基等が挙げられ、これらの加水分解性基は１種、又は２種以上を組み合わせた状態で、含有することができる。
Ｙ：上記有機基Ｙであり、（Ｉ）の場合、１価の有機基である。
【００４０】
このようなシランカップリング剤（Ｉ）はもっとも汎用であり、具体例としては、３−グリシドキシプロピルトリメトキシシラン、２−（３，４−エポキシシクロヘキシル）エチルトリメトキシシラン、３−アミノプロピルトリメトキシシラン、３−アミノプロピルトリエトキシシラン、４−アミノブチルトリエトキシシラン、ｐ−アミノフェニルトリメトキシシラン、Ｎ−（２−アミノエチル）−３−アミノプロピルトリメトキシシラン、アミノエチルアミノメチルフェネチルトリメトキシシラン、Ｎ−（６−アミノヘキシル）アミノプロピルトリメトキシシラン、３−クロロプロピルトリメトキシシラン、３−クロロプロピルトリクロロシラン、（ｐ−クロロメチル）フェニルトリメトキシシラン、４−クロロフェニルトリメトキシシラン、３−メタクリロキシプロピルトリメトキシシラン、３−メタクリロキシプロピルトリエトキシシラン、３−アクリロキシプロピルトリメトキシシラン、スチリルエチルトリメトキシシラン、３−メルカプトプロピルトリメトキシシラン、ビニルトリメトキシシラン、ビニルトリエトキシシラン、ビニルトリクロロシラン、ビニルトリアセトキシシラン、ビニルトリス（２−メトキシエトキシ）シラン、トリフルオロプロピルトリメトキシシラン等を挙げることが出来る。
【００４１】
（ＩＩ）Ｘ₂ＳｉＹ¹Ｙ²
Ｘ：（Ｉ）のＸと同様の加水分解性シリル基である。
Ｙ¹，Ｙ²：各々（Ｉ）のＹと同様の１価の有機基であり、Ｙ¹，Ｙ²は同じ基であっても各々異なる基であってもよい。
【００４２】
このようなシランカップリング剤（ＩＩ）の具体例としては、ジメチルジメトキシシラン、ジメチルジエトキシシラン、ジフェニルジメトキシシラン、ジフェニルジエトキシシラン、ジフェニルジクロロシラン等を挙げることが出来る。
【００４３】
（ＩＩＩ）ＸＳｉＹ¹Ｙ²Ｙ³
Ｘ：（Ｉ）のＸと同様の加水分解性シリル基である。
Ｙ¹，Ｙ²，Ｙ³：各々（Ｉ）のＹと同様の１価の有機基であり、Ｙ¹，Ｙ²，Ｙ³は同じ基であっても各々異なる基であっても良い。このようなシランカップリング剤（ＩＩＩ）の具体例としては、トリメチルメトキシシラン、トリメチルエトキシシラン、トリメチルクロロシラン、トリフェニルクロロシラン等を挙げることが出来る。
【００４４】
（ＩＶ）（Ｘ₃Ｓｉ）_nＹ
Ｘ：（Ｉ）のＸと同様の加水分解性シリル基である。
Ｙ：上記官能基Ｙであり、この場合Ｙはｎ価の有機基である。このようなシランカップリング剤の具体例としては、各種有機ポリマーやオリゴマーに側鎖として加水分解性シリル基が複数結合しているものが挙げられる。
【００４５】
これら（Ｉ）〜（ＩＶ）に具体的に例示した化合物は、入手容易な市販のシランカップリング剤の一部であり、更に詳しくは、科学技術総合研究所発行の「カップリング剤最適利用技術」９章のカップリング剤及び関連製品一覧表により示すことが出来る。また、当然のことながら、本発明に使用できるシランカップリング剤は、これらの例示により制限されるものではない。
【００４６】
以上説明してきた物性を有する本発明の有機基含有シリカゲルは、細孔制御のための水熱処理の前にシリカヒドロゲルを熟成しないという点を除けば、その製造方法は実質的に制限されるべきではない。
例えば、有機基を水熱処理前に導入させた有機基含有シリカゲルを製造する場合には、シリコンアルコキシドを加水分解する際に、前述の有用有機基群より選ばれる少なくとも一種の有機基（目的有機基）について、その有機基を含むシランカップリング剤（もしくは有機基導入試薬）を添加した後ゲル化させ、得られたシリカヒドロゲルを用いて、水熱処理による方法を応用して製造することができる。水熱処理による方法の応用例として、好ましくはシリコンアルコキシドと最低１種類の有機基を含むシランカップリング剤を加水分解する方法が挙げられる。なお、この工程においては、有機基導入試薬のうち水分により失活するものを用いることはできない。
【００４７】
目的有機基を含むシランカップリング剤又は有機基導入試薬は、シリコンアルデヒドを加水分解しシリカヒドロゲルを得る工程において、１種又は２種以上系内に添加される。有機基導入試薬の種類及び量などについては、均質なシリカヒドロゲルの形成を妨げない範囲であれば特に限定されず、これらの目的有機基を有するシランカップリング剤又は有機基導入試薬は、それらの試薬自身や反応に伴う分解生成物が、均質なヒドロゲルの形成を妨げない限り、どのような種類のものを用いても良い。また、高純度なシリカゲルを得る観点から、目的有機基を含むシランカップリング剤又は有機基導入試薬も、高純度なものを用いることが好ましい。
【００４８】
目的有機基を含むシランカップリング剤又は有機基導入試薬の添加方法は、均質なシリカヒドロゲルの形成を妨げない方法であれば特に限定されず、目的有機基を含むシランカップリング剤又は有機基導入試薬をシリコンアルコキシド加水分解のための水に添加しても、シリコンアルコキシドに添加しても、加水分解直後に均一溶液となったヒドロゾルに添加してもよく、操作性に応じ適宜選択される。また、必要であれば、目的有機基を含むシランカップリング剤又は有機基導入試薬を前もって加水分解した後に上記の系に添加したり、逆に、シリコンアルコキシドの部分加水分解を行なった後に目的有機基を含むシランカップリング剤又は有機基導入試薬を添加したりしてもよい。
【００４９】
また、本発明の有機基含有シリカゲルは、細孔制御後の高純度シリカゲルに目的有機基を含む化合物を後担持させる方法でも製造できる。この場合、まず、シリカゲル細孔中に目的有機基を含むシランカップリング剤又は有機基導入試薬を導入する。その方法としては、例えば、無機粉体のシランカップリング剤処理法としてよく知られている湿式処理法（水溶媒系、非水溶媒系）、乾式処理法、スラリー法、スプレー法、ドライコンセントレート法等の公知の方法の何れを用いても良い。
【００５０】
目的有機基は、シリコンアルコキシドを加水分解し、熟成すること無しに水熱処理して得られたシリカゲルに、上記の方法で導入させることができるが、目的有機基の種類及び量は、目的有機基が機能性を発現する範囲であれば特に限定されず、これらの目的有機基を有するシランカップリング剤又は有機基導入試薬は、どのような種類のものを用いても良い。また、高純度な有機基含有シリカゲルを得る観点から、目的有機基を含むシランカップリング剤又は有機基導入試薬も高純度なものを用いることが好ましい。目的有機基を後担持させる場合には、担体となる高純度シリカゲルに対して前処理を行なってもよい。例えば、担体となるシリカゲルの原料であるシリコンアルコキシド等に由来する炭素分が含まれている場合には、必要に応じて、通常４００〜６００℃で焼成除去してもよい。さらに、表面状態をコントロールするために、最高９００℃の温度で焼成したり、無機酸により煮沸処理したりしてもよい。
【００５１】
なお、本発明の目的有機基の選択対象となる有機基のうち特に有用なものは、Ｃ１〜Ｃ５０の有機基Ｙ、及びＹの水素がＦ，Ｃ１，Ｂｒ，Ｉなどの原子に置換されたものの他、フェニル基、ビニル基、メタクリロキシ基、アクリロキシ基、スチリル基、メルカプト基、エポキシ基、エポキシシクロヘキシル基、グリシドキシ基、アミノ基、アンモニウム基、シアノ基、ニトロ基、スルホン酸基、カルボキシ基、ヒドロキシ基、アシル基、アルコキシ基、アリル基等で置換されたものである。本発明の有機基含有シリカゲルにこれらの有機基を導入すると、上記有機官能基の各々の官能基特性に基づいた機能性が発現するわけであるが、どのような官能基を選択するかは、官能基を導入したシリカ材料の用途に負うところが大きい。
【００５２】
シリカ材料のような無機材料の表面を改質する場合、望まれる特性のひとつに有機物質との親和性向上がある。この目的のために、有機基ＹとしてＣ１〜５０の直鎖アルキル基が直接使用される他、導入される有機官能基として、ビニル基、メタクリロキシ基、アクリロキシ基、スチリル基、メルカプト基、エポキシ基、エポキシシクロヘキシル基、グリシドキシ基等のような有機樹脂等のマトリックスとの親和性もしくは化学反応性が高い官能基が選択される。中でも、ビニル基、メタクリロキシ基、アクリロキシ基、スチリル基は、官能基内に二重結合を持ち、同様に二重結合を有する有機樹脂と共有結合により強固に結合するので、得られた有機−無機複合材料が高い構造強度及び耐水性を発現する。また、各種の機能性材料の骨格としても用いられる。
【００５３】
反応性の極性基や水溶性の物質と複合化する場合、シリカ材料の表面にメルカプト基、エポキシ基、エポキシシクロヘキシル基、グリシドキシ基、アミノ基、カルボキシ基、ヒドロキシ基、スルホン酸基などの官能基を導入することがそれらの化学的特性を最大限に利用できて好ましい。
【００５４】
一般の触媒担体用途において、シリカゲル表面に触媒活性を持つ金属又は金属イオンを把持するにあたり、補助となる官能基を導入することがある。この場合、アミノ基、スルホン酸基、カルボキシ基等のイオン交換可能な基や、メルカプト基、ヒドロキシ基等の親水性の有機官能基、又はそれらを化学的に修飾した有機官能基が好ましい。
【００５５】
バイオ技術における固定化酵素用担体などの用途では、シリカゲル表面に酵素やタンパク質、アミノ酸等を固定化するための補助となる官能基を導入することがある。この場合、アミノ基、カルボキシ基などのペプチド結合を形成出来る官能基が好ましい。また、メルカプト基も同様に結合を形成でき、一般に金属または金属イオンと強く相互作用するので好ましい。
【００５６】
クロマトグラフィー分野では、表面を疎水化した材料が広く用いられており、通常はアルキル基を結合させる。また、光学活性物質の分離用途では、光学活性物質を持った有機化合物を結合させるため、アミノ基等が広く用いられる。また、有機基ＹにＦを導入したパーフルオロアルキル基等を官能基として導入し、シリカ材料の表面を高度に疎水化することも行われる。勿論、これらの用例は一例であり、好ましい官能基の例はこれらに限定されるわけではない。
【００５７】
本発明の有機基含有シリカゲルの原料として使用されるシリコンアルコキシドとしては、トリメトキシシラン、テトラメトキシシラン、トリエトキシシラン、テトラエトキシシラン、テトラプロポキシシラン、テトラブトキシシラン等の炭素数１〜４の低級アルキル基を有するトリまたはテトラアルコキシシラン或いはそれらのオリゴマーが挙げられるが、好ましくはテトラメトキシシラン、テトラエトキシシラン及びそれらのオリゴマーである。以上のシリコンアルコキシドは蒸留により容易に精製し得るので、高純度の有機基含有シリカゲルの原料として好適である。シリコンアルコキシド中のアルカリ金属又はアルカリ土類金属に属する不純物元素（金属不純物）の総含有率は、通常好ましくは１００ｐｐｍ以下、更に好ましくは５０ｐｐｍ以下である。これらのいわば金属不純物の含有率は、一般的なシリカゲル中の不純物含有率の測定法と同じ方法で測定できる。
【００５８】
シリコンアルコキシドの加水分解は、シリコンアルコキシド単独で加水分解する場合、シリコンアルコキシド１モルに対して、通常２〜５０モル、好ましくは３〜４０モル、特に好ましくは４〜３０モルの水を用いて行なう。この工程の途中において、任意の方法により目的有機基を含むシランカップリング剤又は有機基導入試薬を添加することによって、シリコンアルコキシドの加水分解により、目的有機基を含むシリカのヒドロゲルとアルコールとが生成する。シランカップリング剤とシリコンアルコキシドとを同時に加水分解する場合、加水分解量は添加するシランカップリング剤の種類や量によって適する範囲が異なるが、概ね総Ｓｉ量に対して３〜３０モルである。この反応によって、有機基は共有結合によりシリカヒドロゲルに導入される。
【００５９】
目的有機基を後担持により導入する場合には、シリコンアルコキシドのみを同様に加水分解して、シリカヒドロゲルを得る。この加水分解反応は、通常、室温から１００℃程度であるが、加圧下で液相を維持することで、より高い温度で行なうことも可能である。また、加水分解時には必要に応じて、水と相溶性のあるアルコール類等の溶媒を添加してもよい。具体的には、炭素数１〜３の低級アルコール類、ジメチルホルムアミド、ジメチルスルホキシド、アセトン、テトラヒドロフラン、メチルセロルブ、エチルセロルブ、メチルエチルケトン、その他の水と任意に混合できる有機溶媒を任意に用いることができるが、中でも強い酸性や塩基性を示さないものが、均一なシリカヒドロゲルを生成できる理由から好ましい。
【００６０】
結晶構造を有するシリカゲルは、水中熱安定性に乏しくなる傾向にあり、ゲル中に細孔を形成するのに用いられる界面活性剤等のテンプレートの存在下でシリコンアルコキシドを加水分解すると、ゲルは容易に結晶構造を含むものとなる。従って、本発明においては、界面活性剤等のテンプレートの非存在下で、すなわち、これらがテンプレートとしての機能を発揮するほどの量は存在しない条件下で加水分解するのが好ましい。
【００６１】
反応時間は、反応液組成（シリコンアルコキシドの種類や、水とのモル比）並びに反応温度や添加するシランカップリング剤、有機基導入試薬の種類及び量などに依存し、ゲル化するまでの時間が異なるので、一概には規定されない。なお、反応系に触媒として、酸、アルカリ、塩類などを添加することで加水分解を促進させることができる。しかしながら、かかる添加物の使用は、後述するように、生成したヒドロゲルの熟成を引き起こすことになるので、本発明の有機基含有シリカゲルの製造においてはあまり好ましくない。
【００６２】
上記のシリコンアルコキシドの加水分解反応では、シリコンアルコキシドが加水分解してシリケートが生成するが、引き続いて該シリケートの縮合反応が起こり、反応液の粘度が上昇し、最終的にゲル化してシリカヒドロゲルとなる。本発明の有機基含有シリカゲルを製造するためには、シリカヒドロゲルを実質的に熟成することなく、直ちに水熱処理を行なうことが重要である。
【００６３】
この水熱処理の条件としては、水の状態が液体、気体のいずれでもよく、溶媒や他の気体によって希釈されていてもよいが、好ましくは液体の水が使われる。水熱処理を行ない易いように粗砕されたシリカのヒドロゲルに対して、通常０．１〜１０重量倍、好ましくは０．５〜５重量倍、特に好ましくは１〜３重量倍の水を加えてスラリー状とし、通常４０〜２５０℃、好ましくは５０〜２００℃の温度で、通常０．１〜１００時間、好ましくは１〜１０時間実施される。水熱処理に使用される水には低級アルコール類、メタノール、エタノール、プロパノールや、ジメチルホルムアミド（ＤＭＦ）やジメチルスルホキシド（ＤＭＳＯ）、その他の有機溶媒などが含まれてもよい。また、メンブランリアクターなどを作る目的で、シリカゲルを膜状あるいは層状に粒子、基板、あるいは管などの基体上に形成させた材料の場合にも、この水熱処理方法は適用される。なお、加水分解反応の反応器を用い、続けて温度条件変更により水熱処理を行なうことも可能であるが、加水分解反応とその後の水熱処理では最適条件が通常は異なっているため、この方法で本発明の有機基含有シリカゲルを得ることは一般的には難しい。
【００６４】
以上の水熱処理条件において温度を高くすると、得られるシリカゲルの細孔径、細孔容積が大きくなる傾向がある。水熱処理温度としては、１００〜２００℃の範囲であることが好ましい。また、処理時間とともに、得られるシリカゲルの比表面積は、一度極大に達した後、緩やかに減少する傾向がある。以上の傾向を踏まえて、所望の物性値に応じて条件を適宜選択する必要があるが、水熱処理は、シリカゲルの物性を変化させる目的なので、通常、前記の加水分解の反応条件より高温条件とすることが好ましい。
【００６５】
水熱処理の温度、時間を上記範囲外に設定すると本発明の有機基含有シリカゲルを得ることが困難となる。例えば、水熱処理の温度が高すぎると、シリカゲルの細孔径、細孔容積が大きくなりすぎ、また、細孔分布も広がる。逆に、水熱処理の温度が低過ぎると、生成するシリカゲルは、架橋度が低く、熱安定性に乏しくなり、細孔分布にピークが発現しなくなる傾向がある。
【００６６】
なお、水熱処理をアンモニア水中で行なうと、純水中で行なう場合よりも低温で同様の効果が得られる。また、アンモニア水中で水熱処理すると、純水中で処理する場合と比較して、最終的に得られるシリカゲルは一般に疎水性となるが、通常３０〜２５０℃、好ましくは４０〜２００℃という比較的高温で水熱処理すると、特に疎水性が高くなる。ここでのアンモニア水のアンモニア濃度としては、好ましくは０．００１〜１０％、特に好ましくは０．００５〜５％である。
【００６７】
水熱処理されたシリカヒドロゲルは、通常４０〜２００℃、好ましくは６０〜１２０℃で乾燥する。乾燥方法は特に限定されるものではなく、バッチ式でも連続式でもよく、且つ、常圧下でも減圧下でも乾燥することができる。目的有機基を予め導入した場合には、この状態で本発明の有機基含有シリカゲルとなる。目的有機基を後担持により導入する場合には、この後に前述の処理方法を実施して目的有機基を含む化合物を導入することにより、本発明の有機基含有シリカゲルを得る。
【００６８】
なお、以上の操作により細孔内に目的有機基を導入した後、必要に応じて２００〜４００℃で焼成することにより、目的有機基を含む化合物とシリカゲルとの間の架橋反応を促進させたり、目的有機基を残しつつ、溶媒等の不要な有機成分を除去したりすることができる。必要であれば、目的有機基の前駆体となる有機基を導入した後に酸化や還元等の化学処理を行ない、本来の目的有機基に変換しても良い。更に、必要に応じて粉砕、分級することで、最終的に目的としていた本発明の有機基含有シリカゲルを得る。
【００６９】
本発明の有機基含有シリカゲルは、従来からのシリカゲルの用途の他、いかなる用途においても利用することができる。このうち従来の用途としては、以下のようなものが挙げられる。
【００７０】
例えば、産業用設備で製品の製造及び処理に用いられる用途分野においては、各種触媒及び触媒担体（酸塩基触媒、光触媒、貴金属触媒等）、廃水・廃油処理剤、臭気処理剤、ガス分離剤、工業用乾燥剤、バイオリアクター、バイオセパレーター、メンブランリアクター等の用途が挙げられる。建材用途では、調湿剤、防音・吸音材、耐火物、断熱材等の用途が挙げられる。また、空調分野の用途では、デシカント空調機用調湿剤、ヒートポンプ用蓄熱剤等が挙げられる。塗料・インク用途分野においては、艶消し剤、粘度調整剤、色度調整剤、沈降防止剤、消泡剤、インク裏抜け防止剤、スタンピングホイル用、壁紙用等の用途が挙げられる。樹脂用添加剤用途分野においては、フィルム用アンチブロッキング剤（ポリオレフィンフィルム等）、プレートアウト防止剤、シリコーン樹脂用補強剤、ゴム用補強剤（タイヤ用・一般ゴム用等）、流動性改良材、パウダー状樹脂の固結防止剤、印刷適性改良剤、合成皮革やコーティングフィルム用の艶消し剤、接着剤・粘着テープ用充填剤、透光性調整剤、防眩性調整剤、多孔性ポリマーシート用フィラー等の用途が挙げられる。また、製紙用途分野においては、感熱紙用フィラー（カス付着防止剤等）、インクジェット紙画像向上用フィラー（インク吸収剤等）、ジアゾ感光紙用フィラー（感光濃度向上剤等）、トレーシングペーパー用筆記性改良剤、コート紙用フィラー（筆記性、インク吸収性、アンチブロッキング性改良剤等）、静電記録用フィラー等の用途が挙げられる。食品用途分野においては、ビール用濾過助剤、醤油・清酒・ワイン等発酵製品のおり下げ剤、各種発酵飲料の安定化剤（混濁因子タンパクや酵母の除去等）、食品添加剤、粉末食品の固結防止剤等の用途が挙げられる。医農薬分野においては、薬品等の打錠助剤、粉砕助剤、分散・医薬用担体（分散・徐放・デリバリー性改善等）、農薬用担体（油状農薬キャリア・水和分散性改善、徐放・デリバリー性改善等）、医薬用添加剤（固結防止剤・粉粒性改良剤等）・農薬用添加剤（固結防止剤・沈降防止剤等）等が挙げられる。分離材料分野では、クロマトグラフィー用充填剤、分離剤、フラーレン分離剤、吸着剤（タンパク質・色素・臭等）、脱湿剤等の用途が挙げられる。農業用分野では、飼料用添加剤、肥料用添加剤が挙げられる。さらにその他の用途として、生活関連分野では、調湿剤、乾燥剤、化粧品添加剤、抗菌剤、消臭・脱臭・芳香剤、洗剤用添加剤（界面活性剤粉末化等）、研磨剤（歯磨き用等）、粉末消火剤（粉粒性改良剤・固結防止剤等）、消泡剤、バッテリーセパレーター等が挙げられる。
【００７１】
これらの中でも、特に制御された細孔特性が要求されるとともに、長期にわたって物性変化の少ないことが要求され、且つ、特定の有用な有機基の含有による機能付与が要求される分野において、本発明の有機基含有シリカゲルは好適に用いることができる。
【００７２】
【実施例】
以下、本発明を実施例により更に詳細に説明するが、本発明はその要旨を超えない限り、以下の実施例に制約されるものではない。
【００７３】
（１）有機基含有シリカゲルの分析方法：
１−１）細孔容積、比表面積：
カンタクローム社製ＡＳ−１にてＢＥＴ窒素吸着等温線を測定し、細孔容積、比表面積を求めた。具体的には細孔容積は相対圧Ｐ／Ｐ₀＝０．９８のときの値を採用し、比表面積はＰ／Ｐ₀＝０．１，０．２，０．３の３点の窒素吸着量よりＢＥＴ多点法を用いて算出した。また、ＢＪＨ法で細孔分布曲線及び最頻直径（Ｄ_max）における微分細孔容積を求めた。測定する相対圧の各点の間隔は０．０２５とした。
【００７４】
１−２）粉末Ｘ線回折：
理学電機社製ＲＡＤ−ＲＢ装置を用い、ＣｕＫαを線源として測定を行なった。発散スリット１／２ｄｅｇ、散乱スリット１／２ｄｅｇ、受光スリット０．１５ｍｍとした。
【００７５】
１−３）金属不純物の含有量：
試料２．５ｇにフッ酸を加えて加熱し、乾涸させたのち、水を加えて５０ｍｌとした。この水溶液を用いてＩＣＰ発光分析を行なった。なお、ナトリウム及びカリウムはフレーム炎光法で分析した。
【００７６】
１−４）全ケイ素中の炭素と結合したケイ素の含有量の測定：
Ｂｒｕｋｅｒ社製固体ＮＭＲ装置（「ＭＳＬ３００」）を使用するとともに、共鳴周波数５９．２ＭＨｚ（７．０５テスラ）、７ｍｍのサンプルチューブを使用し、ＣＰ／ＭＡＳ（Cross Polarization / Magic Angle Spinning）プローブの条件で測定した。具体的な測定条件を下の表１に示す。
【００７７】
【表１】

【００７８】
測定データの解析（各々のピークの分離）は、ピーク分割によって各ピークを抽出する方法で行なう。具体的には、ガウス関数を使用した波形分離解析を行なう。この解析には、サーモガラテック（Thermogalatic）社製の波形処理ソフト「ＧＲＡＭＳ３８６」を使用することが出来る。測定により得られた個体Ｓｉ−ＮＭＲスペクトルのＱⁿピークの面積の積分値をＡ、Ｔⁿピークの面積の積分値をＢとして、下記式により全ケイ素中の炭素と結合したケイ素の含有率Ｘ（％）を算出した。
【数２】

【００７９】
（２）有機基含有シリカゲルの製造、評価：
・実施例１：
ガラス製で上部に大気解放の水冷コンデンサが取り付けてある１Ｌセバラブルフラスコ（ジャケット付き）に純水４４６．１ｇを仕込んだ。これを８０ｒｐｍで攪拌しながら、テトラメトキシシラン１５０ｇ及びビニルトリメトキシシラン３７．５ｇ（テトラメトキシシランの２５重量％）の混合液を、１分間かけて加えた。水／（テトラメトキシシラン＋ビニルメトキシシラン）のモル比は約２０である。セバラブルフラスコのジャケットには５０℃の温水を通水した。引き続き攪拌を継続し、内容物が沸点に到達した時点で攪拌を停止した。引き続きジャケットに５０℃の温水を通水して、生成したゾルをゲル化させた。その後、速やかにゲルを取り出し、目開き６００μｍのナイロン製網を通してゲルを粉砕し、粉体状のウエットゲル（シリカヒドロゲル）を得た。このヒドロゲル２０ｇと純水２０ｇを容量６０ｍ１のミクロボンベに仕込み、１３０℃で３時間水熱処理を行なった。水熱処理の終了後、Ｎｏ．５Ａ濾紙で濾過し、濾滓を水洗することなく１００℃で恒量となるまで減圧乾燥した。得られたシリカゲル（実施例１の有機基含有シリカゲル）の諸物性を下の表２に示す。
【００８０】
得られたシリカゲルは、非常に多くの有機基を含有し、かつ従来の有機基含有シリカゲルと比して制御されたシャープな細孔分布を有しており、非常に高純度な新規シリカゲルであった。このシリカゲルはビニル基を有していることから、有機樹脂や塗料、インク等との親和性、反応性に富み、新規な充填剤、各種担体、有機・無機複合材料、吸着材料、分離材料などへの応用が期待でき、高純度であることから物性安定性にも優れていると考えられる。
【００８１】
【表２】

【００８２】
【発明の効果】
本発明の新規な有機基含有シリカゲルは、従来からの有機基含有シリカゲルと比較して、目的とする有機基を高濃度で含有するとともに、不純物金属量が少なく、生産性に優れ、シャープな細孔分布を示し、且つ耐熱性、耐水性、物性安定性（熱安定性等）などにも優れている。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a novel silica gel with high purity, controlled pore properties and containing useful organic groups.
[0002]
[Prior art]
Silica gel has been widely used as a desiccant for a long time, but recently its use has expanded to catalyst carriers, separating agents, adsorbents, etc., and the demand for silica gel performance varies according to the spread of such applications. It has become. The performance of silica gel is determined by physical properties such as surface area, pore diameter, pore volume, pore diameter distribution and the like of silica gel.
[0003]
By the way, in recent years, it has been desired to provide silica gel with surface properties that could not be obtained with pure silica gel, for example, chemical reactivity, hydrophobicity, hydrophilicity, or physicochemical properties found in organic materials. .
[0004]
Therefore, in order to provide functionality that cannot be expressed by silica gel alone, the surface of silica gel is treated with a silane coupling agent or an organic synthesis reagent that reacts with silanol, and various organic groups are introduced. Techniques for imparting various functions derived from organic groups to silica gel are known. For example, by introducing an organic group having an unsaturated bond into silica gel, an example of producing a filler that has good dispersibility in the resin and can be firmly bonded to the resin by covalent bond, Introducing organic groups that adjust the separation performance to make it suitable for use as a liquid chromatography carrier or various separation materials, and also by changing other powder properties, hydrophobic fillers There are examples in which an immobilized enzyme carrier is produced by introducing an amino group, a carboxyl group or the like.
[0005]
Such methods for introducing various organic groups into silica gel can be broadly divided into (1) a method of adding a substance containing an organic group to be introduced at the time of silica hydrogel production, and then performing pore control. (2) There are two methods of post-supporting a substance containing an organic group to be introduced onto silica gel after controlling the pores. As a substance for introducing an organic group, for example, an organic group introduction reagent containing a target functional group can be used in addition to a silane coupling agent containing a hydrolyzable silyl group. From the aspect, the former is mainly used.
[0006]
However, among the above-mentioned conventional techniques, in the technique of (1), when water glass is used as the silica source, the pH of the solution is high, and thus a highly reactive substance such as a silane coupling agent or an organic group introduction reagent. It was very difficult to stably contain in the system. Furthermore, in a general sol-gel technique using alkoxysilane as a silica source, a method in which alkoxysilane is hydrolyzed together with a silane coupling agent and used as a hard coat agent or paint additive (for example, Patent Document 1 and Patent Document) 2) and a method for obtaining a porous material by gelling, drying and firing (for example, the technology described in Non-Patent Document 1), but controlled while retaining the organic group. An example of producing silica gel having a sharp pore distribution has not yet been reported.
[0007]
Furthermore, the micelle template silica in which the organic groups are oriented in the pores is obtained by hydrolyzing and gelling together the alkoxysilane, various silane coupling agents and the organic template, and removing only the organic template by baking or solvent washing. Technology (eg, Non-Patent Document 2) has also been reported. Silica obtained by this technique has a very sharp pore distribution, and the regularity of the pore arrangement is characterized by a peak in the X-ray diffraction spectrum. However, there is a problem that there are many impurity metals and thermal stability and hydrothermal stability are low. Furthermore, since the organic template is expensive, the manufacturing cost is high, and the manufacturing process is complicated, resulting in low productivity.
[0008]
As an example of the technique (2), a method of performing surface modification by subjecting a silica material as a raw material to silane coupling treatment in a liquid phase or a gas phase is widely known. This technique has been applied to various porous silicas, and an example of application to crystalline micelle template silica has also been reported (Non-patent Document 3). However, the silica obtained by this technique has a problem that since the pore walls are very thin, the mechanical strength is weak and the pore characteristics are likely to change during the treatment. Furthermore, the mode diameter of the pore (D_max) Is also known to be subjected to silane coupling treatment on conventional silica gel of 20 nm or less. However, the pore distribution is not sufficiently sharp, and the pore characteristics may change due to the pore distribution expanding or becoming smaller in the process.
[0009]
The silane coupling treatment in the technique (2) is widely used as a surface treatment technique, but it has been very difficult to obtain a sufficient effect while maintaining controlled porosity. For example, many variable factors such as temperature, time, amount of reagent used, water content, solvent, etc. had to be set for each silane coupling agent, and it was often impossible to optimize. Moreover, even if it can be optimized, the conventional silica gel cannot satisfy the stability as a product and the porous physical properties. In addition, such a tendency to easily change the physical properties appears more remarkably when the silica gel serving as the carrier has a large amount of metal impurities. On the other hand, when silicon alkoxide is used as a raw material, high-purity silica gel can be obtained. However, since no technology for obtaining silica gel with sufficiently sharp pore distribution has been reported yet, it can be used as a carrier for silica gel of the present invention. It was insufficient.
[0010]
In this way, even with the conventional techniques such as (1) and (2), the desired organic group is contained at a high concentration, the amount of impurity metals is small, and a sharp pore distribution is exhibited. It was not possible to obtain an organic group-containing silica gel having excellent properties and productivity, that is, satisfying various physical properties in a well-balanced manner.
[0011]
[Non-Patent Document 1]
Separation and Purification Technology, 16, 139 (1999)
[Non-Patent Document 2]
Chem. Mater, 12., 188 (2000)
[Non-Patent Document 3]
Science, 276, 923 (1997)
[Patent Document 1]
JP-A-10-251516
[Patent Document 2]
Japanese Patent Laid-Open No. 9-40907
[0012]
[Problems to be solved by the invention]
From the above background, it contains the target organic group at a high concentration, has a small amount of impurity metal, shows a sharp pore distribution, has excellent physical property stability, and is excellent in productivity. A well-balanced organic group-containing silica gel has been desired.
[0013]
The present invention has been made in view of the above-described problems. That is, the object of the present invention is not only large pore volume and specific surface area, but also narrow pore distribution, can contain useful organic groups, can suppress the amount of unnecessary metal impurities, and has heat resistance, The object is to provide a novel organic group-containing silica gel excellent in water resistance, physical property stability (thermal stability, etc.) and the like.
[0014]
[Means for Solving the Problems]
Therefore, as a result of intensive studies to solve the above problems, the present inventors have achieved that the organic group-containing silica gel produced by a specific method satisfies various properties in a well-balanced manner and effectively solves the above problems. As a result, the present invention has been completed.
[0015]
That is, the gist of the present invention is that (a) the pore volume is 0.5 to 1.6 ml / g, and (b) the specific surface area is 300 to 1000 m.²/ G, (c) the mode diameter of the pores (D_max) Is less than 20 nm, and (d) the diameter is D_maxThe total volume of pores within the range of ± 20% is 40% or more of the total volume of all pores, (e) amorphous, and (f) the total content of metal impurities is 500 ppm or less. And (g) the organic group-containing silica gel, wherein the proportion of silicon atoms directly bonded to carbon atoms among all silicon atoms is 0.1% or more.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
One of the characteristics of the organic group-containing silica gel of the present invention is that the pore volume and specific surface area are in a range larger than usual. Specifically, the value of the pore volume is usually in the range of 0.5 to 1.6 ml / g, preferably in the range of 0.6 to 1.6 ml / g, and the value of the specific surface area is usually 300 to 1000m²/ G, preferably 400-1000m²/ G. These pore volume and specific surface area values are measured by the BET method by nitrogen gas adsorption / desorption.
[0017]
In addition, the organic group-containing silica gel of the present invention is obtained from an isothermal desorption curve measured by a nitrogen gas adsorption / desorption method, from EP Barrett, LG Joyner, PH Haklenda, J. Amer. Chem. Soc., Vol. The pore distribution curve calculated by the BJH method described in the above, that is, the differential nitrogen gas adsorption amount (ΔV / Δ (logd); V is the nitrogen gas adsorption volume) plotted against the pore diameter d (nm) The most frequent diameter (D_max) Is less than 20 nm, and the lower limit is not particularly limited, but is preferably 2 nm or more. This means that the mode diameter (D of the pores of the organic group-containing silica gel of the present invention (D_max) Is present in a smaller range than ordinary silica gel.
[0018]
Furthermore, the organic group-containing silica gel of the present invention has the above-mentioned mode diameter (D_max), The total volume of pores in the range of ± 20% is usually 40% or more, preferably 50% or more, particularly preferably 60% or more of the total volume of all pores. . Also, the mode diameter (D_maxThe total volume of pores in the range of ± 20% centering on the value of) is usually 90% or less of the total pore volume. This indicates that the pore diameter of the organic group-containing silica gel of the present invention is the mode diameter (D_max) Means that the pores are aligned in the vicinity.
[0019]
In relation to such characteristics, the organic group-containing silica gel of the present invention has a mode diameter (D) calculated by the BJH method._maxThe differential pore volume [Delta] V / [Delta] (logd) is usually 2 to 20 ml / g, particularly 3 to 12 ml / g (where d is the pore diameter (nm), V is the nitrogen gas adsorption volume). The differential pore volume ΔV / Δ (logd) included in the above range is the mode diameter (D_maxIt can be said that the absolute amount of pores aligned in the vicinity of) is extremely large.
[0020]
Further, the organic group-containing silica gel of the present invention is characterized in that, in addition to the above-mentioned features of the pore structure, the three-dimensional structure is amorphous, that is, no crystalline structure is observed. To do. This means that when the organic group-containing silica gel of the present invention is analyzed by X-ray diffraction, substantially no crystalline peak is observed. In this specification, the non-amorphous silica gel refers to a silica having a peak of at least one crystal structure at a position exceeding 6 angstroms (Å Units d-spacing) in the X-ray diffraction pattern. An example of such a silica material is micelle template silica that forms pores using an organic template. Amorphous silica gel is extremely excellent in productivity as compared with crystalline silica gel.
[0021]
A further feature of the organic group-containing silica gel of the present invention is the total content of metal elements (metal impurities) belonging to the group consisting of alkali metals, alkaline earth metals, groups 13, 14 and 15 of the periodic table and transition metals. The rate is usually as low as 500 ppm or less, particularly 300 ppm or less, preferably 100 ppm or less, more preferably 10 ppm or less, and extremely high purity. Such a small influence of impurities is one of the major factors that enable the organic group-containing silica gel of the present invention to exhibit excellent properties such as high heat resistance and water resistance.
[0022]
The presence of impurities in the silica gel has a great influence on the performance of the silica gel even if the total content is as small as several hundred ppm. For example, 1) the presence of these impurities promotes crystallization of silica gel at high temperatures, and 2) the presence of these impurities promotes the hydrothermal reaction of silica gel in the presence of water, resulting in pore size and pore size. 3) These impurities lower the sintering temperature, and heating silica gel containing these impurities promotes a reduction in specific surface area, resulting in an increase in volume, a decrease in specific surface area, and an increase in pore distribution. And the like. Such an effect is particularly strong in impurities including elements belonging to alkali metals and alkaline earth metals.
[0023]
As a result of further studies, the present inventors have found that it is preferable to minimize the impurity metal concentration of the silica source in order to introduce the organic group while satisfying the physical properties of the present invention. It is not clear what components of these impurity metals have any particular influence, but when the silica source is highly purified, the organic groups are contained in a high concentration in any of the conventional techniques (1) and (2). In addition, it has been found that an excellent organic group-containing silica gel having both controlled pore characteristics can be obtained.
[0024]
The reason why these impurity metals adversely affect the introduction of organic groups is not clear, but the following points are considered.
(1) The portion where the impurity metal exists promotes the adsorption and assembly of the silane coupling agent and the organic group introduction reagent, and inhibits uniform dispersion of the silane coupling agent.
(2) When the organic group is post-supported, the presence of the impurity metal adversely affects the stability of the silane coupling agent and the organic group introduction reagent during the silane coupling treatment.
(3) After the organic group is introduced into the silica gel, it is decomposed by the catalytic action of the impurity metal and detached from the silica gel.
[0025]
Specifically, for example, when a large amount of aluminum is used as the impurity metal, a large amount of silane coupling agent is adsorbed at that location. Moreover, when there is much titanium, an organic group tends to receive modification | denaturation. Furthermore, it is known that an alkali metal or an alkaline earth metal easily exchanges ions with silanol and inhibits binding of a silane coupling agent.
As described above, it is considered that the metal impurity affects the physical property change of the silica gel containing no organic group, and also affects the introduction of the organic group.
[0026]
In addition to the various features described above, the organic group-containing silica gel of the present invention has a ratio of silicon atoms directly bonded to carbon atoms out of all silicon atoms, usually 0.1% or more, preferably 0.2% or more, More preferably, it is 1% or more, and the upper limit is not particularly limited, but is preferably 100%. The presence of silicon atoms directly bonded to these carbon atoms indicates that the organic group has been covalently introduced into the silica gel skeleton. The presence state of these organic groups is arbitrary. For example, they may be uniformly dispersed in the silica gel skeleton, or they may be attached to and adhered to the surface of the silica gel. Further, a part of them may be aggregated to form a fine particle, but the size is generally the mode diameter of the pore (D_max) Is preferably 2.5 times or less.
[0027]
The amount of silicon atoms directly bonded to carbon atoms in all silicon atoms defined in the present invention (hereinafter referred to as X (%)) may be determined by any method, but as an example, a solid Si-NMR spectrum of silica gel. T shown inⁿPeak and QⁿA method for obtaining the peak area ratio is given.
[0028]
The silica gel of the present invention is represented by the above-mentioned formula, but structurally, O is bonded to each vertex of the Si tetrahedron, and Si is further bonded to these Os to expand in a net shape. Have In the repeating unit of Si—O—Si—O—, a part of O is another member (eg, —H, —CH_ThreeIn the case of focusing on one Si, as shown in the following formula (A), Si having four —OSi (Q^Four), Si (Q having three -OSi as shown in the following formula (B)^Three(In the following formulas (A) and (B), the tetrahedral structure is ignored and the Si—O net structure is represented in a plane). And in solid Si-NMR measurement, the peak based on each said Si is Q in order.^FourPeak, Q^ThreeCalled the peak.
[0029]
[Chemical 1]

[0030]
Silicon in which four oxygen atoms are bonded around Si is generally referred to as a Q site. In the present invention, Q derived from the Q site⁰~ Q^FourQ for each peakⁿThis is called a peak group. Q of silica gelⁿThe peak group is usually observed as a multimodal peak continuous in the region of chemical shift of −80 to −130 ppm.
[0031]
In contrast, silicon in which three oxygen atoms are bonded and one other atom (usually carbon) is bonded is generally referred to as a T site. The peak derived from the T site is the same as that of the Q site.⁰~ T^ThreeIt is observed as each peak. In the present invention, each peak derived from the T site is represented by TⁿThis is called a peak group. T of silica gelⁿThe peak group is generally QⁿIt is observed as a multimodal peak continuous in the region on the high magnetic field side (usually chemical shift of -20 to -100 ppm) from the peak group.
[0032]
When the solid Si-NMR spectrum of the organic group-containing silica gel of the present invention was measured, T derived from silicon in which the carbon of the organic group introduced into the silica gel was directly bonded.ⁿPeak group and Q derived from silicon not bonded to organic carbonⁿPeak groups appear in different areas. These QⁿAnd TⁿThe ratio of the areas of the peaks is equal to the molar ratio of silicon placed in the environment corresponding to the peaks, and the area of all the peaks is defined as the molar amount of all silicon.ⁿThe total area of the peak group corresponds to the molar amount of all silicon directly bonded to the carbon atom.
[0033]
That is, QⁿThe total area of the peak group is A, TⁿWhen the total area of the peak group is B, the ratio X (%) of silicon atoms directly bonded to carbon atoms in all silicon atoms is represented by the following formula.
[Expression 1]

[0034]
As the kind of organic group introduced into the organic group-containing silica gel of the present invention, any known organic group of a so-called silane coupling agent can be selected and used. Particularly useful organic groups in the present invention are those selected from the following group represented by Y (useful organic group group).
[0035]
Y: monovalent derived from an aliphatic compound, alicyclic compound, aromatic compound or aliphatic aromatic compound of C1 to C1000 (preferably C1 to C500, more preferably C1 to C100, particularly preferably C1 to C50) It is the above organic group, and at least a part of the hydrogen of Y may be substituted with the following atoms and / or organic functional groups. A plurality of hydrogen atoms of Y may be substituted with the atoms and / or organic functional groups shown below. In this case, one or more kinds selected from the atoms and / or organic functional groups shown below are used. It may be replaced by a combination. Furthermore, in all the above cases, at least a part of hydrogen of the organic functional group shown below may be substituted with F, Cl, Br, or I. Y may have various atoms or atomic groups such as O, N, or S as a linking group. In addition, the organic functional group shown below is an example of what is easy to introduce | transduce, According to the intended purpose, you may introduce | transduce other organic functional groups with various chemical reactivity and physicochemical functionality.
[0036]
For example, those obtained by introducing an organic group selected from the group of useful organic groups and hydrophobizing a part or almost all of the silica surface are extremely useful as adsorbents for harmful organic compounds. Examples of the organic group in this case include an aliphatic hydrocarbon group and an aromatic hydrocarbon group. Specifically, for example, linear groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, and an octyl group. Examples thereof include hydrocarbon groups and aromatic hydrocarbon groups such as phenyl group, naphthyl group, and toluyl group. Of these, organic groups that increase the heat resistance of silicon-carbon bonds, such as methyl groups and phenyl groups, are preferred.
Moreover, since the molecular weight of a hydrocarbon group having a small number of carbon atoms, such as a lower alkyl group having about 1 to 4 carbon atoms, is small, the amount of organic group introduced per unit silica volume of the present invention can be increased. ,preferable.
[0037]
<Examples of elements and organic functional groups that can be substituted for hydrogen of Y>
F, Cl, Br, I, vinyl group, methacryloxy group, acryloxy group, styryl group, mercapto group, epoxy group, epoxycyclohexyl group, glycidoxy group, amino group, cyano group, nitro group, sulfonic acid group, carboxy group, hydroxy Group, acyl group, alkoxy group, ammonium group, allyl group.
[0038]
The organic group-containing silica gel of the present invention can simultaneously contain, as the target organic group, one type selected from various organic groups Y having different structures within the above range, or any combination of two or more types. These organic groups Y are characterized in that in the silica gel of the present invention, the number of silicon atoms corresponding to the valence of the organic group Y is directly bonded by a covalent bond. These silicon atoms are part of what forms a silica gel skeleton, and the organic group Y is substantially directly introduced into the silica gel skeleton. In order to introduce the organic group Y into the silica gel in such a state, a reagent in which a reactive terminal capable of forming a siloxane bond is introduced into the organic group Y may be used. The most readily available and typical examples of such reagents are the silane coupling agents shown below. In addition to these, there are several general synthetic reagents that react with silanol to form siloxane bonds (hereinafter referred to as organic group introduction reagents). However, industrial availability is not easy, and reaction conditions are limited. There are many. In the present invention, the silane coupling agent is a general term for those in which the organic group Y is directly bonded to a silicon atom, and is a compound represented by the following formulas (I) to (IV).
[0039]
(I) X_ThreeSiY
X: A hydrolyzable silyl group that is hydrolyzed by water in the aqueous solution, air in the air, or water adsorbed on the inorganic surface to generate a highly reactive silanol group, and conventionally known ones are used. I can do it. For example, a C1-C4 lower alkoxy group, an acetoxy group, a butanoxime group, a chloro group, etc. are mentioned, These hydrolyzable groups can be contained in the state which combined 1 type or 2 types or more.
Y: The above organic group Y. In the case of (I), it is a monovalent organic group.
[0040]
Such silane coupling agents (I) are the most versatile, and specific examples include 3-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyl. Trimethoxysilane, 3-aminopropyltriethoxysilane, 4-aminobutyltriethoxysilane, p-aminophenyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, aminoethylaminomethylphenethyl Trimethoxysilane, N- (6-aminohexyl) aminopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltrichlorosilane, (p-chloromethyl) phenyltrimethoxysilane, 4-chlorophenyltrimethoxysila , 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, styrylethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxy Examples thereof include silane, vinyltrichlorosilane, vinyltriacetoxysilane, vinyltris (2-methoxyethoxy) silane, and trifluoropropyltrimethoxysilane.
[0041]
(II) X₂SiY¹Y²
X: A hydrolyzable silyl group similar to X in (I).
Y¹, Y²: Each is a monovalent organic group similar to Y in (I), Y¹, Y²May be the same group or different groups.
[0042]
Specific examples of such silane coupling agent (II) include dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldichlorosilane and the like.
[0043]
(III) XSiY¹Y²Y^Three
X: A hydrolyzable silyl group similar to X in (I).
Y¹, Y², Y^Three: Each is a monovalent organic group similar to Y in (I), Y¹, Y², Y^ThreeMay be the same group or different groups. Specific examples of such silane coupling agent (III) include trimethylmethoxysilane, trimethylethoxysilane, trimethylchlorosilane, triphenylchlorosilane and the like.
[0044]
(IV) (X_ThreeSi)_nY
X: A hydrolyzable silyl group similar to X in (I).
Y: the functional group Y, where Y is an n-valent organic group. Specific examples of such silane coupling agents include those in which a plurality of hydrolyzable silyl groups are bonded as side chains to various organic polymers and oligomers.
[0045]
The compounds specifically exemplified in (I) to (IV) are a part of commercially available silane coupling agents that are readily available. "It can be shown by the list of coupling agents and related products in Chapter 9. Naturally, the silane coupling agent that can be used in the present invention is not limited by these examples.
[0046]
The organic group-containing silica gel of the present invention having the physical properties described above should be substantially limited in its production method, except that the silica hydrogel is not aged before hydrothermal treatment for pore control. Absent.
For example, in the case of producing an organic group-containing silica gel in which an organic group is introduced before hydrothermal treatment, at the time of hydrolyzing silicon alkoxide, at least one organic group selected from the above-mentioned useful organic group group (target organic group) ), A silane coupling agent containing the organic group (or an organic group introduction reagent) is added and gelled, and the resulting silica hydrogel can be used by applying a hydrothermal treatment method. As an application example of the method by hydrothermal treatment, a method of hydrolyzing a silane coupling agent preferably containing silicon alkoxide and at least one organic group is mentioned. In this step, an organic group-introducing reagent that cannot be deactivated by moisture cannot be used.
[0047]
The silane coupling agent or organic group introduction reagent containing the target organic group is added to the system in one or more types in the step of hydrolyzing silicon aldehyde to obtain a silica hydrogel. The type and amount of the organic group introduction reagent are not particularly limited as long as they do not interfere with the formation of a homogeneous silica hydrogel, and the silane coupling agent or organic group introduction reagent having these target organic groups can be used. Any type of reagent may be used as long as the reagent itself and the decomposition products accompanying the reaction do not interfere with the formation of a homogeneous hydrogel. Further, from the viewpoint of obtaining high-purity silica gel, it is preferable to use a high-purity silane coupling agent or organic group-introducing reagent containing a target organic group.
[0048]
The addition method of the silane coupling agent or organic group introduction reagent containing the target organic group is not particularly limited as long as it does not prevent the formation of a homogeneous silica hydrogel, and the silane coupling agent or organic group introduction containing the target organic group is introduced. The reagent may be added to water for hydrolyzing silicon alkoxide, added to silicon alkoxide, or added to a hydrosol that has become a homogeneous solution immediately after hydrolysis, and is appropriately selected according to operability. If necessary, the target silane coupling agent or organic group-introducing reagent containing the target organic group is previously hydrolyzed and then added to the above system, or conversely, after partial hydrolysis of the silicon alkoxide, the target organic group is added. A silane coupling agent containing a group or an organic group introduction reagent may be added.
[0049]
The organic group-containing silica gel of the present invention can also be produced by a method in which a compound containing a target organic group is post-supported on high-purity silica gel after pore control. In this case, first, a silane coupling agent or an organic group introduction reagent containing a target organic group is introduced into the silica gel pores. As the method, for example, wet processing methods (aqueous solvent system, non-aqueous solvent system) well known as silane coupling agent processing methods for inorganic powders, dry processing methods, slurry methods, spray methods, dry concentrates. Any known method such as a method may be used.
[0050]
The target organic group can be introduced into the silica gel obtained by hydrothermal treatment without hydrolyzing and aging the silicon alkoxide by the above method. Is not particularly limited as long as it exhibits functionality, and any type of silane coupling agent or organic group introduction reagent having these target organic groups may be used. Further, from the viewpoint of obtaining a high-purity organic group-containing silica gel, it is preferable to use a high-purity silane coupling agent or organic group introduction reagent containing a target organic group. When the target organic group is post-supported, pretreatment may be performed on high-purity silica gel serving as a carrier. For example, when carbon content derived from silicon alkoxide or the like, which is a raw material of silica gel used as a carrier, is contained, it may be removed usually by baking at 400 to 600 ° C. as necessary. Furthermore, in order to control a surface state, you may bake at the temperature of a maximum of 900 degreeC, or you may boil with an inorganic acid.
[0051]
Of the organic groups to be selected for the purpose of the present invention, organic groups Y of C1 to C50 and hydrogen of Y are substituted with atoms such as F, C1, Br, and I. Other than those, phenyl group, vinyl group, methacryloxy group, acryloxy group, styryl group, mercapto group, epoxy group, epoxycyclohexyl group, glycidoxy group, amino group, ammonium group, cyano group, nitro group, sulfonic acid group, carboxy group, It is substituted with a hydroxy group, an acyl group, an alkoxy group, an allyl group, or the like. When these organic groups are introduced into the organic group-containing silica gel of the present invention, functionality based on the functional group characteristics of each of the organic functional groups is expressed. It depends greatly on the use of the silica material into which the functional group is introduced.
[0052]
When modifying the surface of an inorganic material such as a silica material, one of the desired properties is an improved affinity with an organic substance. For this purpose, a C1-50 linear alkyl group is directly used as the organic group Y, and the introduced organic functional group includes a vinyl group, a methacryloxy group, an acryloxy group, a styryl group, a mercapto group, and an epoxy group. A functional group having a high affinity or chemical reactivity with a matrix such as an organic resin such as an epoxycyclohexyl group or a glycidoxy group is selected. Among them, vinyl group, methacryloxy group, acryloxy group, and styryl group have a double bond in the functional group, and are similarly strongly bonded to an organic resin having a double bond by a covalent bond. The composite material exhibits high structural strength and water resistance. It is also used as a skeleton for various functional materials.
[0053]
When compounding with reactive polar groups or water-soluble substances, functional groups such as mercapto group, epoxy group, epoxycyclohexyl group, glycidoxy group, amino group, carboxy group, hydroxy group, sulfonic acid group on the surface of silica material It is preferable to introduce the chemicals because the chemical properties can be utilized to the maximum.
[0054]
In general catalyst support applications, an auxiliary functional group may be introduced to hold a metal or metal ion having catalytic activity on the silica gel surface. In this case, ion-exchangeable groups such as amino group, sulfonic acid group and carboxy group, hydrophilic organic functional groups such as mercapto group and hydroxy group, or organic functional groups obtained by chemically modifying them are preferable.
[0055]
In applications such as a carrier for immobilized enzyme in biotechnology, a functional group that assists in immobilizing an enzyme, protein, amino acid, or the like may be introduced on the surface of silica gel. In this case, a functional group capable of forming a peptide bond such as an amino group or a carboxy group is preferred. Mercapto groups are also preferred because they can form bonds similarly and generally interact strongly with metals or metal ions.
[0056]
In the chromatography field, materials having a hydrophobic surface are widely used, and usually an alkyl group is bonded. Further, in the separation of optically active substances, amino groups and the like are widely used to bind organic compounds having optically active substances. In addition, a perfluoroalkyl group in which F is introduced into the organic group Y is introduced as a functional group to highly hydrophobize the surface of the silica material. Of course, these examples are merely examples, and examples of preferred functional groups are not limited thereto.
[0057]
The silicon alkoxide used as a raw material for the organic group-containing silica gel of the present invention is a lower one having 1 to 4 carbon atoms such as trimethoxysilane, tetramethoxysilane, triethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane. Examples thereof include tri- or tetraalkoxysilane having an alkyl group or oligomers thereof, and tetramethoxysilane, tetraethoxysilane and oligomers thereof are preferable. Since the above silicon alkoxide can be easily purified by distillation, it is suitable as a raw material for high-purity organic group-containing silica gel. The total content of impurity elements (metal impurities) belonging to the alkali metal or alkaline earth metal in the silicon alkoxide is usually preferably 100 ppm or less, more preferably 50 ppm or less. These so-called metal impurity contents can be measured by the same method as the method for measuring the impurity contents in general silica gel.
[0058]
When hydrolyzing silicon alkoxide alone, it is usually performed using 2 to 50 moles, preferably 3 to 40 moles, particularly preferably 4 to 30 moles of water per mole of silicon alkoxide. . In the middle of this process, by adding a silane coupling agent or organic group introduction reagent containing the target organic group by any method, hydrogel of silica containing the target organic group and alcohol are generated by hydrolysis of the silicon alkoxide. To do. When the silane coupling agent and silicon alkoxide are hydrolyzed at the same time, the amount of hydrolysis varies depending on the type and amount of the silane coupling agent to be added, but is generally 3 to 30 mol with respect to the total Si amount. By this reaction, organic groups are introduced into the silica hydrogel by covalent bonds.
[0059]
When the target organic group is introduced by post-supporting, only the silicon alkoxide is similarly hydrolyzed to obtain a silica hydrogel. This hydrolysis reaction is usually from room temperature to about 100 ° C., but it can also be performed at a higher temperature by maintaining the liquid phase under pressure. Moreover, you may add solvents, such as alcohol compatible with water, as needed at the time of a hydrolysis. Specifically, lower alcohols having 1 to 3 carbon atoms, dimethylformamide, dimethyl sulfoxide, acetone, tetrahydrofuran, methyl cellolbu, ethyl cellolb, methyl ethyl ketone, and other organic solvents that can be arbitrarily mixed with water can be arbitrarily used. Among them, those that do not exhibit strong acidity or basicity are preferable because a uniform silica hydrogel can be produced.
[0060]
Silica gel with a crystal structure tends to have poor thermal stability in water, and gels are easy to hydrolyze silicon alkoxide in the presence of a template such as a surfactant used to form pores in the gel. Includes a crystal structure. Therefore, in the present invention, it is preferable to hydrolyze in the absence of a template such as a surfactant, that is, in a condition where there is no such an amount that it functions as a template.
[0061]
The reaction time depends on the composition of the reaction solution (type of silicon alkoxide and molar ratio with water), the reaction temperature, the silane coupling agent to be added, the type and amount of the organic group introduction reagent, and the time until gelation. Are different, so they are not generally specified. In addition, hydrolysis can be accelerated | stimulated by adding an acid, an alkali, salts, etc. to a reaction system as a catalyst. However, the use of such an additive causes aging of the produced hydrogel, as will be described later, and thus is not preferable in the production of the organic group-containing silica gel of the present invention.
[0062]
In the above silicon alkoxide hydrolysis reaction, the silicon alkoxide is hydrolyzed to produce a silicate. Subsequently, a condensation reaction of the silicate occurs, the viscosity of the reaction solution rises, and finally gelates to form a silica hydrogel. Become. In order to produce the organic group-containing silica gel of the present invention, it is important to immediately perform a hydrothermal treatment without substantially aging the silica hydrogel.
[0063]
As conditions for this hydrothermal treatment, the state of water may be either liquid or gas, and it may be diluted with a solvent or other gas, but preferably liquid water is used. 0.1 to 10 times by weight, preferably 0.5 to 5 times by weight, particularly preferably 1 to 3 times by weight of water is added to the silica hydrogel coarsely crushed so as to facilitate hydrothermal treatment. It is made into a slurry form and is usually carried out at a temperature of 40 to 250 ° C., preferably 50 to 200 ° C., usually for 0.1 to 100 hours, preferably 1 to 10 hours. The water used for hydrothermal treatment may contain lower alcohols, methanol, ethanol, propanol, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and other organic solvents. The hydrothermal treatment method is also applied to a material in which silica gel is formed on a substrate such as a particle, a substrate, or a tube in the form of a film or a layer for the purpose of making a membrane reactor or the like. It is also possible to perform hydrothermal treatment by changing the temperature conditions using a hydrolysis reaction reactor, but the optimum conditions are usually different between the hydrolysis reaction and the subsequent hydrothermal treatment. It is generally difficult to obtain the organic group-containing silica gel of the present invention.
[0064]
When the temperature is increased under the hydrothermal treatment conditions described above, the pore diameter and pore volume of the resulting silica gel tend to increase. The hydrothermal treatment temperature is preferably in the range of 100 to 200 ° C. Further, with the treatment time, the specific surface area of the silica gel obtained tends to decrease gradually after reaching the maximum once. Based on the above tendency, it is necessary to appropriately select the conditions according to the desired physical property values, but since hydrothermal treatment is intended to change the physical properties of silica gel, it is usually at a higher temperature than the hydrolysis reaction conditions described above. It is preferable to do.
[0065]
If the hydrothermal treatment temperature and time are set outside the above ranges, it will be difficult to obtain the organic group-containing silica gel of the present invention. For example, if the hydrothermal treatment temperature is too high, the pore diameter and pore volume of the silica gel become too large, and the pore distribution is also widened. On the other hand, when the temperature of the hydrothermal treatment is too low, the silica gel to be produced has a low degree of crosslinking, poor thermal stability, and no peak in the pore distribution.
[0066]
When the hydrothermal treatment is performed in ammonia water, the same effect can be obtained at a lower temperature than in pure water. In addition, when hydrothermal treatment is performed in ammonia water, the silica gel finally obtained is generally hydrophobic as compared with the case of treatment in pure water, but is usually 30 to 250 ° C, preferably 40 to 200 ° C. When hydrothermal treatment is performed at a high temperature, the hydrophobicity becomes particularly high. The ammonia concentration here is preferably 0.001 to 10%, particularly preferably 0.005 to 5%.
[0067]
The hydrothermally treated silica hydrogel is usually dried at 40 to 200 ° C, preferably 60 to 120 ° C. The drying method is not particularly limited, and may be a batch type or a continuous type, and can be dried under normal pressure or reduced pressure. When the target organic group is introduced in advance, the organic group-containing silica gel of the present invention is obtained in this state. When the target organic group is introduced by post-supporting, the organic group-containing silica gel of the present invention is obtained by introducing the compound containing the target organic group by carrying out the above-mentioned treatment method after this.
[0068]
In addition, after introducing the target organic group into the pores by the above operation, the crosslinking reaction between the compound containing the target organic group and silica gel is promoted by firing at 200 to 400 ° C. as necessary. In addition, unnecessary organic components such as a solvent can be removed while leaving the target organic group. If necessary, after introducing an organic group as a precursor of the target organic group, chemical treatment such as oxidation or reduction may be performed to convert the target organic group into the original target organic group. Furthermore, the organic group-containing silica gel of the present invention, which is the final object, is obtained by pulverizing and classifying as necessary.
[0069]
The organic group-containing silica gel of the present invention can be used in any application other than conventional silica gel applications. Among these, conventional applications include the following.
[0070]
For example, in application fields used for manufacturing and processing products in industrial facilities, various catalysts and catalyst carriers (acid-base catalysts, photocatalysts, noble metal catalysts, etc.), wastewater / waste oil treatment agents, odor treatment agents, gas separation agents, Applications include industrial desiccants, bioreactors, bioseparators, membrane reactors and the like. Examples of building materials include humidity control agents, soundproofing / absorbing materials, refractories, and heat insulating materials. Moreover, in applications in the air conditioning field, desiccant air conditioners, heat pump heat storage agents, and the like. In the paint / ink application field, matting agents, viscosity adjusting agents, chromaticity adjusting agents, anti-settling agents, antifoaming agents, ink back-through preventing agents, stamping foils, and wallpapering applications may be mentioned. In the field of resin additives, anti-blocking agents for films (polyolefin films, etc.), plate-out inhibitors, silicone resin reinforcing agents, rubber reinforcing agents (for tires, general rubbers, etc.), fluidity improvers, Anti-caking agent for powdered resin, printability improver, matting agent for synthetic leather and coating film, filler for adhesive / adhesive tape, translucency adjuster, antiglare adjuster, porous polymer sheet Uses for fillers and the like. In the papermaking field, thermal paper fillers (such as residue adhesion inhibitors), ink jet paper image enhancement fillers (ink absorbers, etc.), diazo photosensitive paper fillers (sensitivity density improvers, etc.), and tracing paper Uses such as a writing property improving agent, a filler for coated paper (writing property, ink absorbability, anti-blocking property improving agent, etc.), a filler for electrostatic recording and the like can be mentioned. In food applications, beer filter aids, soy sauce, sake, wine and other fermented product lowering agents, various fermented beverage stabilizers (such as turbidity factor protein and yeast removal), food additives, and powdered foods Uses such as anti-caking agents are mentioned. In the medical and agrochemical field, tableting aids for pharmaceuticals, grinding aids, dispersion / pharmaceutical carriers (dispersion, sustained release, improved delivery, etc.), agrochemical carriers (oily agrochemical carrier, improved hydration dispersibility, sustained release) -Delivery improvement etc.), Additives for medicine (anti-caking agent / powdering improver, etc.), additives for agricultural chemicals (anti-caking agent, anti-settling agent, etc.), etc. In the field of separation materials, there are applications such as chromatographic fillers, separation agents, fullerene separation agents, adsorbents (proteins, dyes, odors, etc.), and dehumidifiers. In the agricultural field, feed additives and fertilizer additives can be mentioned. As other applications, in life-related fields, humidity control agent, desiccant, cosmetic additive, antibacterial agent, deodorant / deodorant / fragrance, detergent additive (surfactant powder, etc.), abrasive (toothpaste) Etc.), powder fire extinguishing agents (powdering property improver, anti-caking agent, etc.), antifoaming agents, battery separators and the like.
[0071]
Among these, in the field where controlled pore characteristics are required, physical property change over a long period is required, and functional addition due to the inclusion of a specific useful organic group is required, the present invention. The organic group-containing silica gel can be preferably used.
[0072]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not restrict | limited to a following example, unless the summary is exceeded.
[0073]
(1) Analytical method of organic group-containing silica gel:
1-1) Pore volume, specific surface area:
The BET nitrogen adsorption isotherm was measured with AS-1 manufactured by Cantachrome, and the pore volume and specific surface area were determined. Specifically, the pore volume is relative pressure P / P₀= 0.98 is adopted, and the specific surface area is P / P₀= Calculated using the BET multipoint method from three points of nitrogen adsorption amounts of 0.1, 0.2, and 0.3. Also, pore distribution curve and mode diameter (D_max) Differential pore volume was determined. The interval between each point of the relative pressure to be measured was 0.025.
[0074]
1-2) Powder X-ray diffraction:
Using a RAD-RB apparatus manufactured by Rigaku Corporation, measurement was performed using CuKα as a radiation source. The divergence slit was ½ deg, the scattering slit was ½ deg, and the light receiving slit was 0.15 mm.
[0075]
1-3) Content of metal impurities:
Hydrofluoric acid was added to 2.5 g of the sample and heated to dryness, and then water was added to make 50 ml. ICP emission analysis was performed using this aqueous solution. Sodium and potassium were analyzed by flame flame light method.
[0076]
1-4) Measurement of content of silicon bonded to carbon in all silicon:
Conditions of CP / MAS (Cross Polarization / Magic Angle Spinning) probe using a Bruker solid-state NMR device (“MSL300”), a resonance frequency of 59.2 MHz (7.05 Tesla), and a 7 mm sample tube Measured with Specific measurement conditions are shown in Table 1 below.
[0077]
[Table 1]

[0078]
Analysis of measurement data (separation of each peak) is performed by a method of extracting each peak by peak division. Specifically, waveform separation analysis using a Gaussian function is performed. For this analysis, waveform processing software “GRAMS386” manufactured by Thermogalatic can be used. Q of solid Si-NMR spectrum obtained by measurementⁿThe integrated value of the peak area is A, TⁿWith the integrated value of the peak area as B, the content X (%) of silicon bonded to carbon in all silicon was calculated by the following formula.
[Expression 2]

[0079]
(2) Production and evaluation of organic group-containing silica gel:
Example 1:
446.1 g of pure water was charged into a 1 L separable flask (with a jacket) made of glass and provided with a water-cooled condenser open to the atmosphere on the top. While stirring this at 80 rpm, a mixed liquid of 150 g of tetramethoxysilane and 37.5 g of vinyltrimethoxysilane (25% by weight of tetramethoxysilane) was added over 1 minute. The water / (tetramethoxysilane + vinylmethoxysilane) molar ratio is about 20. Warm water of 50 ° C. was passed through the jacket of the separable flask. Stirring was continued, and stirring was stopped when the contents reached the boiling point. Subsequently, hot water at 50 ° C. was passed through the jacket to gel the produced sol. Thereafter, the gel was quickly taken out, and the gel was pulverized through a nylon net having an opening of 600 μm to obtain a powdery wet gel (silica hydrogel). 20 g of this hydrogel and 20 g of pure water were placed in a microbomb having a capacity of 60 ml and hydrothermally treated at 130 ° C. for 3 hours. After the hydrothermal treatment, It filtered with 5A filter paper, and it dried under reduced pressure until it became constant weight at 100 degreeC, without washing with water. Various physical properties of the obtained silica gel (organic group-containing silica gel of Example 1) are shown in Table 2 below.
[0080]
The obtained silica gel contains a large number of organic groups and has a sharp pore distribution controlled compared to conventional organic group-containing silica gels, and is a novel silica gel with very high purity. It was. Because this silica gel has a vinyl group, it has a high affinity and reactivity with organic resins, paints, inks, etc., new fillers, various carriers, organic / inorganic composite materials, adsorbent materials, separation materials, etc. It can be expected that it will be applied to the surface, and because of its high purity, it is considered to have excellent physical property stability.
[0081]
[Table 2]

[0082]
【The invention's effect】
The novel organic group-containing silica gel of the present invention contains the target organic group at a high concentration as compared with conventional organic group-containing silica gels, has a small amount of impurity metals, is excellent in productivity, is sharp and fine. It exhibits pore distribution and is excellent in heat resistance, water resistance, physical property stability (thermal stability, etc.) and the like.

Claims (7)

(A) the pore volume is 0.5 to 1.6 ml / g,
(B) the specific surface area is 300 to 1000 m ² / g,
(C) the mode diameter (D _max ) of the pores is less than 20 nm,
(D) the total volume of pores having a diameter in the range of D _max ± 20% is 40% or more of the total volume of all pores;
(E) is amorphous,
(F) the total content of metal impurities is 500 ppm or less, and
(G) The organic group-containing silica gel, wherein a ratio of silicon atoms directly bonded to carbon atoms among all silicon atoms is 0.1% or more. 2. The organic group-containing silica gel according to claim 1, wherein the pore volume is 0.6 to 1.6 ml / g. The organic group-containing silica gel according to claim 1 or ^{2, wherein the} specific surface area is 400 to 1000 m ² / g. The organic group-containing silica gel according to any one of claims 1 to 3, wherein the mode diameter ( _Dmax ) of the pores is 2 nm or more. 5. The organic group-containing composition according to claim 1, wherein the total volume of pores having a diameter within D _max ± 20% is 50% or more of the total volume of all pores. silica gel. The organic group-containing silica gel according to any one of claims 1 to 5, wherein the metal impurity content is 100 ppm or less. The organic group-containing silica gel according to any one of claims 1 to 6, wherein a differential pore volume at a mode diameter ( _Dmax ) is 2 to 20 ml / g.