JP3572213B2 - Low substituted hydroxypropylcellulose - Google Patents
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- C08B11/00—Preparation of cellulose ethers
- C08B11/02—Alkyl or cycloalkyl ethers
- C08B11/04—Alkyl or cycloalkyl ethers with substituted hydrocarbon radicals
- C08B11/08—Alkyl or cycloalkyl ethers with substituted hydrocarbon radicals with hydroxylated hydrocarbon radicals; Esters, ethers, or acetals thereof
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Description
【０００１】
【発明の属する技術分野】
本発明は、アルカリ水溶液に対して広い温度範囲で安定した溶解性と高い溶液透明性を示す低置換度ヒドロキシプロピルセルロースに関する。
【０００２】
【従来技術】
ヒドロキシプロピルセルロースは、セルロースの構造単位であるグルコース単位（Ｃ６Ｈ１０Ｏ５）の３個の水酸基をヒドロキシプロピル基でエーテル化した非イオン性ポリマーで、様々な有用な特性を有することから広い用途分野に利用されている。
ヒドロキシプロピルセルロースの特性は、そのヒドロキシプロピル基置換量によって大きく異なっている。置換度の表出方法としては、グルコース単位当りの置換基の平均置換モル数（ＭＳ）で表わす方法が最も一般的で広く使用されている。
【０００３】
置換度の高いヒドロキシプロピルセルロース、平均置換モル数は２〜３のものは、冷水溶解性、熱水不溶解性でアルコール等の有機溶媒類に可溶である。置換度の低いものは水や有機溶媒類には溶解せず、水に接触すると膨潤し、水酸化アルカリ等のアルカリ水溶液に溶解する性質を有している。
これらの性質から低置換度ヒドロキシプロピルセルロースは、医薬品の崩壊剤や結合剤として用いられ、アルカリ溶液の増粘剤として利用されている。
【０００４】
低置換度ヒドロキシプロピルセルロースとしては、特公昭４８―３８８５８号公報、特公昭５７―５３１００号公報等にグルコース単位当りのヒドロキシプロピル基の平均置換モル数が０．０５〜１．０であるものの製造方法が開示されている。しかしながら、これらの方法によって製造されたものはアルカリ水溶液に可溶性を示すものの、多くの未溶解分を含むためその溶液の透明性は低いものであった。また、これらはアルカリ水溶液に対する溶解性が温度によって大きく異なるため、溶液の安定性が要求される用途では使用条件が限られるという問題があった。
【０００５】
【発明が解決しようとする課題】
低置換度ヒドロキシプロピルセルロースのアルカリ水溶液に対する溶解性は、ヒドロキシプロピル基置換度に大きく影響される。良好な溶解性を示す低置換度ヒドロキシプロピルセルロースを得るためには、ヒドロキシプロピル基の置換量の管理、すなわち、その構造単位であるグルコース単位当りのヒドロキシプロピル基の平均置換モル数とヒドロキシプロピル基置換モル数の異なる置換体の比率が重要である。
このようにヒドロキシプロピル基の置換量を制御して、溶液の透明性に優れ、広い温度範囲で安定した溶液状態を提供する低置換度ヒドロキシプロピルセルロースの出現が望まれていたが、十分に満足するものは未だない。
【０００６】
【課題を解決するための手段】
本発明者らは、上記課題の解決のために鋭意検討した結果、グルコース単位（Ｃ６Ｈ１０Ｏ５）当りのヒドロキシプロピル基の平均置換モル数が０．１〜０．４の低置換度ヒドロキシプロピルセルロースにおいて、２モル以上のヒドロキシプロピル基で置換されているグルコース単位の数が、全グルコース単位の数に対して５％以下であって、かつ、１０重量％水酸化ナトリウム水溶液に対して２重量％濃度に溶解した溶液における１０℃〜５０℃での透光度が９０％以上であることを特徴とする低置換度ヒドロキシプロピルセルロースが、アルカリ溶液に溶解して高い透明性を示し、広範囲の温度下で溶液状態が安定であることを見い出し、本発明をなすに至ったものである。
【０００７】
【発明の実施の形態】
以下、本発明につき更に詳しく説明する
本発明の低置換度ヒドロキシプロピルセルロースは、グルコース単位当りのヒドロキシプロピル基の平均置換モル数が０．１〜０．４である。平均置換モル数が０．１より低い場合は、アルカリ溶液に溶解した際に未溶解物によって溶液が不透明となり、０．４を超える場合は、溶液が白濁化していずれも不透明な溶液となる。
【０００８】
また、本発明の低置換度ヒドロキシプロピルセルロースは、ヒドロキシプロピル基置換モル数が２以上である置換体（グルコース単位）の数が、全グルコース単位の数に対して５％以下であることが好ましい。ヒドロキシプロピル基置換モル数２以上の置換体の比率が５％を超えると、上記同様、溶液が白濁して不透明な溶液となる。これはアルカリ溶液に対する溶解性が低い無置換体及びヒドロキシプロピル基置換モル数が２以上の置換体の比率が増えることによって、溶液の透明性が失われるためである。
【０００９】
本発明の低置換度ヒドロキシプロピルセルロースの製造は、第一段階ではセルロースを水酸化アルカリと反応させてアルカリセルロースを生成させる。
アルカリセルロース調製方法としては、原料パルプを水酸化アルカリ水溶液に浸漬後、圧搾して余剰の水酸化アルカリ水溶液を除き、所望のアルカリセルロースの組成とする方法が好適である。
【００１０】
原料として使用されるセルロースには、木材パルプ、リンターパルプ等が挙げられ、シート状のもの、粉砕して粉末状にしたもの等形状による限定はなくいずれのものも使用することができる。
また、水酸化アルカリ水溶液としては、水酸化ナトリウム、水酸化カリウム、水酸化リチウム等の水溶液が用いられるが、水酸化ナトリウムが好適である。
水酸化アルカリ水溶液の濃度は２０〜４５重量％、特に３０〜４０重量％の濃度のものが好ましい。水酸化アルカリ水溶液の濃度が２０重量％より低いと、セルロースの膨潤が不充分で活性化されず、続くエーテル化反応が十分進行しない。一方、４５重量％を超えると、調製されたアルカリセルロースの組成が不均一となり、アルカリ溶液に対する溶解性が温度によって異なり、溶液物性の温度変化が大きくなってしまう。
【００１１】
アルカリセルロース調製方法としては、他にパルプを有機溶剤等の分散媒中で水酸化アルカリ水溶液と混合する方法やパルプに水酸化アルカリ水溶液を直接噴霧する方法等があるが、水酸化アルカリ水溶液に浸漬して得られるアルカリセルロースに比べて組成が不均一であり、目的とするアルカリ溶液溶解性の良好な低置換度ヒドロキシプロピルセルロースの製造には不適当である。
【００１２】
アルカリセルロース中の水酸化アルカリは、プロピレンオキシドの反応に対しては触媒として重要な働きをするとともにセルロースの反応性を高め活性化するための役割も持つ。一方、アルカリセルロース中の水分は、プロピレンオキシドと反応して生成物から除去されなければならない不純物を生じ望ましくない。
従って、アルカリセルロースとプロピレンオキシドとの反応によって低置換度ヒドロキシプロピルセルロースを効果的に製造するためには、アルカリセルロースの調製に際し、アルカリセルロース中の水酸化アルカリ量と水分量とを制御する必要がある。
【００１３】
本発明の低置換度ヒドロキシプロピルセルロースの製造におけるアルカリセルロース中の水酸化アルカリ量と水分量は、セルロースに対する重量比で水酸化アルカリ量は０．１〜１．０、特に０．２〜０．８が好ましく、水分量は０．１〜２．０、特に０．３〜１．０が好ましい。
セルロースに対する重量比で水酸化アルカリ量及び水分量が上記範囲より小さいと、反応が十分に進行しない一方、水酸化アルカリ量及び水分量が上記範囲より大きいと、プロピレンオキシドが水と反応して好ましくない不純物の生成を増加させてしまい、所定量のヒドロキシプロピル基置換度のものが得られず、副生する不純物の除去ために多大な労力を必要とするため、いずれの場合も所望のヒドロキシプロピル基置換量の制御が困難となる。
従って、本発明の低置換度ヒドロキシプロピルセルロースの製造における第一段階であるアルカリセルロース調製方法としては、原料パルプを水酸化アルカリ水溶液に浸漬後、圧搾して余剰の水酸化アルカリ水溶液を除き、所望のアルカリセルロースの組成とする方法が好適である。
【００１４】
本発明の低置換度ヒドロキシプロピルセルロースの製造における第二段階では、アルカリセルロースとプロピレンオキシドとを十分に混合して反応させるが、反応温度は３０〜８０℃、特に４０〜７０℃が好ましく、セルロースに対するモル比で０．１５〜２．０のプロピレンオキシドを加えて反応する。
反応温度が３０℃よりも低いと、反応進行が極端に遅くなって長時間にわたるため実用的とはいえず、８０℃よりも高いと、ヒドロキシプロピルセルロース中のヒドロキシプロピル基置換モル数が２以上の多置換体の生成比率が増加したり、プロピレンオキシドと水との反応による不純物の生成量が増大し、好ましくない。
プロピレンオキシドの添加量の範囲を外れると、所定量のヒドロキシプロピル基置換度のものが得られない。
【００１５】
プロピレンオキシドの添加方法として、所定量のプロピレンオキシドを一度に全量添加する方法、数回に分けたり連続的に添加する等のいずれの方法も実施することができる。また、本反応は、プロピレンオキシドとの反応性が小さい有機溶媒を分散媒体として用いて実施することも可能である。
【００１６】
本発明における反応生成物は、水酸化アルカリやプロピレンオキシドと水との反応より生ずる不純物等を含んでいるが、公知の方法によって容易に精製でき、不純物を含まない純度の高い目的の低置換度ヒドロキシプロピルセルロースとして得られる。
【００１７】
本発明によって得られた低置換度ヒドロキシプロピルセルロースの置換体組成は、既知の方法、例えばＣａｒｂｈｙｄｒｏ．Ｒｅｓ．，ｖｏｌ．１７０，ｐ．２０７（１９８７）に記載の方法等によって求めることができる。
置換体組成の測定方法を例示すれば、アルカリ存在下ヨードメタン等のメチル化剤と反応させて遊離の水酸基をメチル化した低置換度ヒドロキシプロピルセルロースを、トリフルオロ酢酸等により酸分解した後、還元してソルビトール誘導体とする。無水酢酸等を用いてアセチル化したものをガスクロマトグラフィーに供すれば、ヒドロキシプロピル基の置換数及び置換位置の異なるものが分離され、それぞれの比率を求めることができる。
【００１８】
本発明によって得られた低置換度ヒドロキシプロピルセルロースの透明性は、透光度によって判断できる。透光度とは、光電比色計を用いて測定した精製水の光透過率を１００としたときの同一条件下での低置換ヒドロキシプロピルセルロース溶液の透過率をいう。その測定方法は、具体的には、実施例に記載する。
【００１９】
【実施例】
以下、本発明を実施例及び比較例によってさらに詳細に説明するが、本発明はこれらの実施例の記載に限定されるものではない。
（実施例１）
（１）低置換度ヒドロキシプロピルセルロースの製造
シート状のパルプ１００重量部を４０重量％水酸化ナトリウム水溶液に浸漬してパルプに水酸化ナトリウム水溶液を吸収させた後、３ｋｇ／ｃｍ２に加圧圧搾して余剰分の水酸化ナトリウム水溶液を除き、セルロースに対する重量比で水酸化アルカリ量を０．５５、水分量を０．９０に調整した。調製したアルカリセルロースを細かくして、内部撹拌機を備えた加圧反応器に入れ、器内を十分に窒素置換した後、プロピレンオキシド２４重量部（セルロースに対するモル比０．６７）を仕込み、５０℃で３時間反応を行った。
反応物は酢酸で残存する水酸化ナトリウムを中和処理した後、５０〜６０℃の温水を用いて洗浄した。８０℃で送風乾燥して無色固体の低置換度ヒドロキシプロピルセルロース１０８重量部を得た。Ｚｅｉｓｅｌ法により求めたヒドロキシプロピル基の平均置換モル数は０．２６であった。
【００２０】
（２）置換体組成
（１）で得られた低置換度ヒドロキシプロピルセルロース３重量部をジメチルスルフォキシド２５０重量部に溶解した。この溶液に粉末状の水酸化ナトリウム３０重量部を加えた後、撹拌しながらヨウ化メチル１００重量部を加え、６０℃で４時間反応した。反応物を１００００重量部の熱水に注ぎ込んでメチル化ヒドロキシプロピルセルロースを析出させた。析出物を回収して７０℃下、６時間乾燥した。得られたメチル化ヒドロキシプロピルセルロース５重量部に２ｍｏｌ％トリフルオロ酢酸水溶液３００重量を加えて１２０℃で３時間処理した後、炭酸バリウムを用いてｐＨを７に調整した。これに水素化ホウ素ナトリウム１．５重量部を加えて室温下１時間撹拌した後、１００℃で蒸発乾固させた。残った内容物に無水酢酸１００重量部、ピリジン２００重量部を加え、１２０℃で３時間処理した。冷却後水５００重量部を加えたものを、四塩化炭素５０重量部を用いて２回抽出した。四塩化炭素を蒸発させ残留物をＧＣ分析に供した。ＧＣ分析上のピーク面積より、ヒドロキシプロピル基置換モル数が２以上の多置換体の合計の比率及び無置換体の組成比率を求めた結果を表１に示した。
【００２１】
（３）溶液物性及び固体物性
で得られた低置換度ヒドロキシプロピルセルロースを、１０重量％水酸化ナトリウム水溶液に、低置換度ヒドロキシプロピルセルロースの濃度が２重量％となるように溶解した。溶解温度を１０℃、３０℃、５０℃と変えて調製した溶液を、Ｂ型粘度計を用いて粘度を測定し、光電比色計（５Ｅ型）を用いてブランク（水）に対する可視光線の透過率を測定した。以上の測定結果を表１に示した。本品のアルカリ溶液は広い温度範囲で高い透明性を示すものであった。
【００２２】
（実施例２）
粉末状のパルプ１００重量部を４５重量％水酸化ナトリウム水溶液に浸漬した後、加圧圧搾してセルロースに対する重量比が水酸化アルカリ量０．４６、水分量０．６４のアルカリセルロースを調製した。プロピレンオキシド３２重量部（セルロースに対するモル比０．８９）を加えて７５〜８０℃で２時間反応を行う以外は、実施例１の（１）と同様な方法によって製造を行い、低置換度ヒドロキシプロピルセルロース１１２重量部を得た。ヒドロキシプロピル基の平均置換モル数は０．３９であった。
このものの置換体組成及び溶液物性を実施例１と同様の方法で求めた結果を表１に示した。本品のアルカリ溶液は広い温度範囲で高い透明性を示した。
【００２３】
（実施例３）
シート状のパルプ１００重量部を２５重量％水酸化ナトリウム水溶液に浸漬した後、加圧圧搾してセルロースに対する重量比が水酸化アルカリ量０．２０、水分量０．６７のアルカリセルロースを調製した。プロピレンオキシド８．７重量部（セルロースに対するモル比０．２４）を加えて３５〜４０℃で４時間反応を行う以外は、実施例１の（１）と同様な方法によって製造を行い、低置換度ヒドロキシプロピルセルロース１０３重量部を得た。ヒドロキシプロピル基の平均置換モル数は０．１１であった。
このものの置換体組成および溶液物性を実施例１と同様の方法で求めた結果を表１に示した。本品のアルカリ溶液は広い温度範囲で高い透明性を示した。
【００２４】
（比較例１）
プロピレンオキシドの仕込み量が４５重量部（セルロースに対するモル比１．２６）である以外は、実施例１の（１）と同様な方法によって製造を行い、低置換度ヒドロキシプロピルセルロース１１５重量部を得た。ヒドロキシプロピル基の平均置換モル数は０．４５であった。
このものの置換体組成及び溶液物性を実施例１と同様の方法で求めた結果を表１に示した。本品のアルカリ溶液は白濁して透明性が低くいものであった。
【００２５】
（比較例２）
反応温度を８５〜１００℃で１．５時間実施する以外は、実施例１の（１）と同様な方法によって製造を行い、低置換度ヒドロキシプロピルセルロース１０６重量部を得た。ヒドロキシプロピル基の平均置換モル数は０．２４であった。
このものの置換体組成および溶液物性を実施例１と同様の方法で求めた結果を表１に示した。本品のアルカリ溶液は白濁して透明性が低くいものであった。
【００２６】
（比較例３）
シート状パルプ１００重量部８重量％濃度の水酸化ナトリウム水溶液に浸漬して、セルロースに対する重量比が水酸化アルカリ量を０．０８、水分量を１．０に調製したアルカリセルロースを用いる以外は、実施例２と同様な方法により製造を行って、低置換度ヒドロキシプロピルセルロース１０１重量部を得た。ヒドロキシプロピル基の平均置換モル数は０．０６であった。
このものの置換体組成および溶液物性を実施例１と同様の方法で求めた結果を表１に示した。本品は水酸化ナトリウム水溶液に対しほとんど溶解しなかった。
【００２７】
【表１】
２）「置換体組成」として、
「無置換体」は、ヒドロキシプロピル基置換モル数０の置換体を表し、
「一置換体」は、ヒドロキシプロピル基置換モル数１の置換体を表し、
「多置換体」は、ヒドロキシプロピル基置換モル数２以上の置換体の総和を表す。
ＧＣ測定条件は、
装置：Ｈｅｗｌｅｔｔ Ｐａｃｋａｒｄ社製 ５９８０ ＳＥＲＩＥＳ ＩＩ ＧＡＳ ＣＨＲＯＭＡＴＯＧＲＡＰＨ
カラム：５％フェニルメチルシリコーン ０．２ｍｍφ×２５ｍ、
サンプル：１μｌ、
インジェクターおよびデテクター温度：２５０℃、
オーブン温度：１７０〜３００℃まで昇温（昇温速度２．５℃／分）、
であった。
３）「溶液物性」は、ヒドロキシプロピルセルロースを１０重量％水酸化ナトリウム水溶液中に２重量％の濃度となるように溶解した溶液を用いて測定した。
４）「透光度」は、光電比色計５Ｅ型、２０ｍｍセル、可視光線を用いて測定した。
５）「粘度」は、Ｂ型粘度計を用いて、１０℃にて測定した。
【００２８】
【発明の効果】
本発明の低置換度ヒドロキシプロピルセルロースは、従来の低置換度ヒドロキシプロピルセルロースに比較してアルカリ水溶液に溶解した際の透明性に優れ、温度によってその溶解性が変化しないことから広い温度範囲で安定した溶液を提供できるため、アルカリ水溶液の増粘剤等として様々な用途で使用できる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a low-substituted hydroxypropylcellulose showing stable solubility and high solution transparency in a wide temperature range with respect to an alkaline aqueous solution.
[0002]
[Prior art]
Hydroxypropylcellulose is a nonionic polymer obtained by etherifying three hydroxyl groups of a glucose unit (C 6 H 10 O 5 ), which is a structural unit of cellulose, with a hydroxypropyl group, and has various useful properties. Used in application fields.
The properties of hydroxypropylcellulose vary greatly depending on the amount of hydroxypropyl group substitution. As a method of expressing the degree of substitution, a method of expressing the average number of moles of substituents per glucose unit (MS) (MS) is the most common and widely used method.
[0003]
Hydroxypropylcellulose having a high degree of substitution and having an average number of moles of substitution of 2 to 3 is soluble in cold water, insoluble in hot water, and soluble in organic solvents such as alcohol. Those having a low degree of substitution do not dissolve in water or organic solvents, but swell when contacted with water and have the property of dissolving in an aqueous alkali solution such as alkali hydroxide.
Due to these properties, low-substituted hydroxypropylcellulose is used as a disintegrant or binder for pharmaceuticals, and is used as a thickener for alkaline solutions.
[0004]
Examples of low-substituted hydroxypropylcellulose include those disclosed in JP-B-48-38858, JP-B-57-53100 and the like in which the average number of moles of substituted hydroxypropyl groups per glucose unit is 0.05 to 1.0. A method is disclosed. However, those produced by these methods are soluble in an alkaline aqueous solution, but contain a large amount of undissolved components, so that the transparency of the solution was low. In addition, since the solubility of these in an alkaline aqueous solution greatly varies depending on the temperature, there has been a problem that use conditions are limited in applications where the stability of the solution is required.
[0005]
[Problems to be solved by the invention]
The solubility of low-substituted hydroxypropylcellulose in an aqueous alkaline solution is greatly affected by the degree of hydroxypropyl group substitution. In order to obtain a low-substituted hydroxypropylcellulose exhibiting good solubility, the amount of hydroxypropyl groups to be substituted is controlled, that is, the average number of moles of substituted hydroxypropyl groups per glucose unit, which is a structural unit thereof, and the number of hydroxypropyl groups The ratio of the substituents having different moles of substitution is important.
By controlling the amount of substitution of the hydroxypropyl group in this way, the appearance of a low-substituted hydroxypropylcellulose which is excellent in solution transparency and provides a stable solution state in a wide temperature range has been desired, but has been sufficiently satisfactory. There is nothing to do yet.
[0006]
[Means for Solving the Problems]
Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that the average substitution mole number of hydroxypropyl groups per glucose unit (C 6 H 10 O 5 ) is 0.1 to 0.4. In hydroxypropylcellulose, the number of glucose units substituted with 2 mol or more of hydroxypropyl groups is 5% or less based on the total number of glucose units, and is 10% by weight based on an aqueous sodium hydroxide solution. A low-substituted hydroxypropylcellulose characterized by having a transmittance of at least 90% at 10 ° C. to 50 ° C. in a solution dissolved at a concentration of 2% by weight shows high transparency when dissolved in an alkaline solution, The inventors have found that the solution state is stable over a wide range of temperatures, and have accomplished the present invention.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the low-substituted hydroxypropylcellulose of the present invention, which will be described in more detail in the present invention, has an average number of moles of substituted hydroxypropyl groups per glucose unit of 0.1 to 0.4. When the average substitution mole number is lower than 0.1, the solution becomes opaque due to undissolved substances when dissolved in an alkaline solution, and when it exceeds 0.4, the solution becomes cloudy and all become opaque solutions.
[0008]
Further, in the low-substituted hydroxypropylcellulose of the present invention, the number of substituents (glucose units) having a hydroxypropyl group substitution mole number of 2 or more is preferably 5% or less based on the total number of glucose units. . When the ratio of the substituted product having a hydroxypropyl group substitution mole number of 2 or more exceeds 5%, the solution becomes cloudy and becomes an opaque solution as described above. This is because the transparency of the solution is lost due to an increase in the ratio of the unsubstituted compound having a low solubility in an alkaline solution and the substituted compound having a hydroxypropyl group substitution mole number of 2 or more.
[0009]
In the production of the low-substituted hydroxypropylcellulose of the present invention, in the first step, the cellulose is reacted with an alkali hydroxide to produce alkali cellulose.
As a method for preparing alkali cellulose, a method in which a raw pulp is immersed in an aqueous alkali hydroxide solution and then squeezed to remove excess alkali hydroxide aqueous solution to obtain a desired alkali cellulose composition is suitable.
[0010]
Examples of the cellulose used as a raw material include wood pulp and linter pulp, and there is no limitation on the shape such as a sheet-like material or a pulverized material, and any material can be used.
As the aqueous alkali hydroxide solution, an aqueous solution of sodium hydroxide, potassium hydroxide, lithium hydroxide or the like is used, and sodium hydroxide is preferable.
The concentration of the aqueous alkali hydroxide solution is preferably 20 to 45% by weight, particularly preferably 30 to 40% by weight. When the concentration of the aqueous alkali hydroxide solution is lower than 20% by weight, swelling of the cellulose is insufficient and the cellulose hydroxide is not activated, and the subsequent etherification reaction does not sufficiently proceed. On the other hand, when the content exceeds 45% by weight, the composition of the prepared alkali cellulose becomes non-uniform, the solubility in an alkaline solution varies depending on the temperature, and the temperature change of the solution physical properties becomes large.
[0011]
Other methods for preparing alkali cellulose include a method of mixing pulp with an aqueous solution of alkali hydroxide in a dispersion medium such as an organic solvent and a method of directly spraying an aqueous solution of alkali hydroxide on pulp. The composition is not uniform as compared with the alkali cellulose obtained by the above method, and is unsuitable for producing a low-substituted hydroxypropylcellulose having a desired alkali solution solubility.
[0012]
The alkali hydroxide in the alkali cellulose plays an important role as a catalyst for the reaction of propylene oxide, and also has a role to increase the reactivity of the cellulose and activate it. On the other hand, the moisture in the alkali cellulose reacts with the propylene oxide to produce impurities that must be removed from the product, which is undesirable.
Therefore, in order to effectively produce low-substituted hydroxypropylcellulose by the reaction of alkali cellulose and propylene oxide, it is necessary to control the amount of alkali hydroxide and the amount of water in the alkali cellulose during the preparation of the alkali cellulose. is there.
[0013]
In the production of the low-substituted hydroxypropylcellulose of the present invention, the amount of alkali hydroxide and the amount of water in the alkali cellulose are 0.1 to 1.0, particularly 0.2 to 0. 8 is preferable, and the water content is 0.1 to 2.0, particularly preferably 0.3 to 1.0.
When the amount of alkali hydroxide and the amount of water are smaller than the above ranges, the reaction does not proceed sufficiently, and when the amount of alkali hydroxide and the amount of water are larger than the above ranges, propylene oxide is preferably reacted with water. In this case, a desired amount of hydroxypropyl group is not obtained, and a large amount of effort is required to remove by-produced impurities. It becomes difficult to control the amount of group substitution.
Therefore, as the alkali cellulose preparation method, which is the first step in the production of the low-substituted hydroxypropylcellulose of the present invention, the raw pulp is immersed in an aqueous alkali hydroxide solution and then squeezed to remove excess alkali hydroxide aqueous solution. The method of making the composition of the alkali cellulose is preferable.
[0014]
In the second step in the production of the low-substituted hydroxypropylcellulose of the present invention, the alkali cellulose and propylene oxide are sufficiently mixed and reacted, and the reaction temperature is preferably 30 to 80 ° C, particularly preferably 40 to 70 ° C. The reaction is carried out by adding propylene oxide in a molar ratio of 0.15 to 2.0 with respect to.
When the reaction temperature is lower than 30 ° C., the reaction progress is extremely slow and it takes a long time, which is not practical. When the reaction temperature is higher than 80 ° C., the number of moles of hydroxypropyl group substitution in hydroxypropyl cellulose is 2 or more. This is not preferred because the production ratio of the polysubstituted product increases and the amount of impurities produced by the reaction between propylene oxide and water increases.
If the amount of propylene oxide is out of the range, a certain amount of hydroxypropyl group cannot be obtained.
[0015]
As a method for adding propylene oxide, any of a method of adding a predetermined amount of propylene oxide at a time, a method of adding several times or a method of continuously adding propylene oxide, and the like can be used. This reaction can also be carried out using an organic solvent having low reactivity with propylene oxide as a dispersion medium.
[0016]
The reaction product in the present invention contains impurities and the like resulting from the reaction of alkali hydroxide or propylene oxide with water, but can be easily purified by a known method, and has a high degree of purity and a low degree of substitution without impurities. Obtained as hydroxypropyl cellulose.
[0017]
The substituted composition of the low-substituted hydroxypropylcellulose obtained by the present invention can be prepared by a known method, for example, Carbhydro. Res. , Vol. 170 , p. 207 (1987).
An example of a method for measuring the composition of the substituted product is as follows: a low-substituted hydroxypropylcellulose in which a free hydroxyl group is methylated by reacting with a methylating agent such as iodomethane in the presence of an alkali is subjected to acid decomposition with trifluoroacetic acid or the like, and then reduced To obtain a sorbitol derivative. If the product acetylated with acetic anhydride or the like is subjected to gas chromatography, those having different hydroxypropyl group substitution numbers and substitution positions are separated, and the respective ratios can be determined.
[0018]
The transparency of the low-substituted hydroxypropylcellulose obtained by the present invention can be judged by the light transmittance. The light transmittance refers to the transmittance of a low-substituted hydroxypropylcellulose solution under the same conditions assuming that the light transmittance of purified water measured using a photoelectric colorimeter is 100. The measuring method is specifically described in Examples.
[0019]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the descriptions of these Examples.
(Example 1)
(1) Production of low-substituted hydroxypropylcellulose 100 parts by weight of sheet pulp is immersed in a 40% by weight aqueous solution of sodium hydroxide to absorb the aqueous solution of sodium hydroxide into the pulp, and then pressurized to 3 kg / cm 2. Excess sodium hydroxide aqueous solution was removed to adjust the amount of alkali hydroxide to 0.55 and the amount of water to 0.90 by weight to cellulose. The prepared alkali cellulose was pulverized, put into a pressurized reactor equipped with an internal stirrer, and sufficiently purged with nitrogen. Then, 24 parts by weight of propylene oxide (molar ratio to cellulose: 0.67) was charged, and 50 The reaction was carried out at a temperature of 3 hours.
The reaction product was neutralized with acetic acid to remove residual sodium hydroxide, and then washed with warm water at 50 to 60 ° C. It was blow-dried at 80 ° C to obtain 108 parts by weight of a low-substituted hydroxypropylcellulose as a colorless solid. The average number of moles of substituted hydroxypropyl groups determined by the Zeisel method was 0.26.
[0020]
(2) 3 parts by weight of the low-substituted hydroxypropylcellulose obtained in the substituted composition (1) were dissolved in 250 parts by weight of dimethyl sulfoxide. After adding 30 parts by weight of powdery sodium hydroxide to this solution, 100 parts by weight of methyl iodide was added with stirring, and the mixture was reacted at 60 ° C. for 4 hours. The reaction product was poured into 10000 parts by weight of hot water to precipitate methylated hydroxypropylcellulose. The precipitate was recovered and dried at 70 ° C. for 6 hours. 300 parts by weight of a 2 mol% aqueous solution of trifluoroacetic acid was added to 5 parts by weight of the obtained methylated hydroxypropyl cellulose, and the mixture was treated at 120 ° C. for 3 hours, and then the pH was adjusted to 7 with barium carbonate. 1.5 parts by weight of sodium borohydride was added thereto, and the mixture was stirred at room temperature for 1 hour, and then evaporated to dryness at 100 ° C. 100 parts by weight of acetic anhydride and 200 parts by weight of pyridine were added to the remaining contents, followed by treatment at 120 ° C. for 3 hours. After cooling, 500 parts by weight of water was added and extracted twice with 50 parts by weight of carbon tetrachloride. The carbon tetrachloride was evaporated and the residue was subjected to GC analysis. Table 1 shows the results of the determination of the total ratio of the polysubstituted compounds having 2 or more hydroxypropyl group substitution moles and the composition ratio of the unsubstituted products based on the peak area in GC analysis.
[0021]
(3) The low-substituted hydroxypropylcellulose obtained in solution properties and solid properties was dissolved in a 10% by weight aqueous sodium hydroxide solution so that the concentration of the low-substituted hydroxypropylcellulose was 2% by weight. The viscosity of a solution prepared by changing the dissolution temperature to 10 ° C., 30 ° C., and 50 ° C. was measured using a B-type viscometer, and the visible light with respect to a blank (water) was measured using a photoelectric colorimeter (5E). The transmittance was measured. Table 1 shows the above measurement results. The alkali solution of the product showed high transparency over a wide temperature range.
[0022]
(Example 2)
After 100 parts by weight of the powdery pulp was immersed in a 45% by weight aqueous sodium hydroxide solution, it was pressed under pressure to prepare alkali cellulose having a weight ratio to cellulose of 0.46 for alkali hydroxide and 0.64 for moisture. Production was carried out in the same manner as in (1) of Example 1, except that 32 parts by weight of propylene oxide (molar ratio to cellulose: 0.89) was added and the reaction was carried out at 75 to 80 ° C. for 2 hours. 112 parts by weight of propylcellulose were obtained. The average number of moles of substituted hydroxypropyl groups was 0.39.
The composition and solution properties of the substituted product were determined in the same manner as in Example 1, and the results are shown in Table 1. The alkaline solution of this product showed high transparency over a wide temperature range.
[0023]
(Example 3)
After 100 parts by weight of the sheet pulp was immersed in a 25% by weight aqueous solution of sodium hydroxide, it was pressed under pressure to prepare alkali cellulose having a weight ratio to cellulose of 0.20 of alkali hydroxide and 0.67 of water. Except that 8.7 parts by weight of propylene oxide (molar ratio to cellulose: 0.24) was added and the reaction was carried out at 35 to 40 ° C. for 4 hours, the production was carried out by the same method as in (1) of Example 1, Thus, 103 parts by weight of hydroxypropylcellulose was obtained. The average number of moles of substituted hydroxypropyl groups was 0.11.
The composition and solution properties of the substituted product were determined in the same manner as in Example 1, and the results are shown in Table 1. The alkaline solution of this product showed high transparency over a wide temperature range.
[0024]
(Comparative Example 1)
Except that the charged amount of propylene oxide is 45 parts by weight (molar ratio to cellulose: 1.26), production is carried out in the same manner as in (1) of Example 1 to obtain 115 parts by weight of low-substituted hydroxypropylcellulose. Was. The average number of moles of substituted hydroxypropyl groups was 0.45.
The composition and solution properties of the substituted product were determined in the same manner as in Example 1, and the results are shown in Table 1. The alkaline solution of this product was cloudy and had low transparency.
[0025]
(Comparative Example 2)
Production was carried out in the same manner as in Example 1, (1) except that the reaction was carried out at a temperature of 85 to 100 ° C for 1.5 hours, to obtain 106 parts by weight of low-substituted hydroxypropylcellulose. The average number of moles of substituted hydroxypropyl groups was 0.24.
The composition and solution properties of the substituted product were determined in the same manner as in Example 1, and the results are shown in Table 1. The alkaline solution of this product was cloudy and had low transparency.
[0026]
(Comparative Example 3)
100% by weight of sheet pulp is immersed in an 8% by weight aqueous solution of sodium hydroxide, and the weight ratio to cellulose is adjusted to an alkali hydroxide amount of 0.08 and a water amount of 1.0, except that alkali cellulose is used. Production was carried out in the same manner as in Example 2 to obtain 101 parts by weight of low-substituted hydroxypropylcellulose. The average number of moles of substituted hydroxypropyl groups was 0.06.
The composition and solution properties of the substituted product were determined in the same manner as in Example 1, and the results are shown in Table 1. This product hardly dissolved in aqueous sodium hydroxide solution.
[0027]
[Table 1]
2) As the “substitution composition”,
"Unsubstituted" refers to a hydroxypropyl group-substituted substituent having 0 moles,
"Mono-substituted" represents a substituted product having 1 hydroxypropyl group substitution mole number,
“Poly-substituted” refers to the sum of substituted hydroxypropyl groups having 2 or more moles.
GC measurement conditions are
Apparatus: 5980 SERIES II GAS CHROMATOGRAPH manufactured by Hewlett Packard
Column: 5% phenylmethylsilicone 0.2mmφ × 25m,
Sample: 1 μl,
Injector and detector temperature: 250 ° C.
Oven temperature: raised to 170-300 ° C (heating rate 2.5 ° C / min),
Met.
3) "Solution physical property" was measured using a solution in which hydroxypropyl cellulose was dissolved in a 10% by weight aqueous sodium hydroxide solution to a concentration of 2% by weight.
4) "Transparency" was measured using a photoelectric colorimeter 5E type, 20 mm cell, and visible light.
5) “Viscosity” was measured at 10 ° C. using a B-type viscometer.
[0028]
【The invention's effect】
The low-substituted hydroxypropylcellulose of the present invention is excellent in transparency when dissolved in an aqueous alkaline solution as compared with conventional low-substituted hydroxypropylcellulose, and is stable over a wide temperature range because its solubility does not change with temperature. Since such a solution can be provided, it can be used in various applications as a thickener or the like for an alkaline aqueous solution.
Claims (1)
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00863699A JP3572213B2 (en) | 1999-01-18 | 1999-01-18 | Low substituted hydroxypropylcellulose |
| KR10-2000-0001937A KR100464749B1 (en) | 1999-01-18 | 2000-01-17 | Low Substituted Hydroxypropyl Cellulose |
| TW089100652A TWI224111B (en) | 1999-01-18 | 2000-01-17 | Low substitution degree hydroxy-propyl cellulose |
| CN00100989A CN1123576C (en) | 1999-01-18 | 2000-01-17 | Low substitution degree hydroxy-propyl cellulose |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP00863699A JP3572213B2 (en) | 1999-01-18 | 1999-01-18 | Low substituted hydroxypropylcellulose |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000204195A JP2000204195A (en) | 2000-07-25 |
| JP3572213B2 true JP3572213B2 (en) | 2004-09-29 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP00863699A Expired - Lifetime JP3572213B2 (en) | 1999-01-18 | 1999-01-18 | Low substituted hydroxypropylcellulose |
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| Country | Link |
|---|---|
| JP (1) | JP3572213B2 (en) |
| KR (1) | KR100464749B1 (en) |
| CN (1) | CN1123576C (en) |
| TW (1) | TWI224111B (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2000327701A (en) * | 1999-05-18 | 2000-11-28 | Shin Etsu Chem Co Ltd | Hydroxypropyl cellulose having low degree of substitution and solid formulation |
| JP2002207030A (en) * | 2001-01-09 | 2002-07-26 | Nippon Soda Co Ltd | Method and apparatus for measuring content of hydroxypropyl group |
| KR100525252B1 (en) * | 2003-12-16 | 2005-10-31 | 삼성정밀화학 주식회사 | Method for preparation of fine powdered Cellulose ethers |
| JP5377816B2 (en) * | 2005-06-16 | 2013-12-25 | 信越化学工業株式会社 | Method for producing cellulose ether |
| GB0516154D0 (en) * | 2005-08-05 | 2005-09-14 | Ntnu Technology Transfer As | Carbon membranes |
| JP5089287B2 (en) * | 2006-08-08 | 2012-12-05 | 信越化学工業株式会社 | Method for producing low substituted hydroxypropylcellulose powder |
| CN101555285B (en) * | 2008-12-19 | 2010-12-01 | 浙江中维药业有限公司 | Preparation method of low-substituted hydroxypropyl cellulose |
| JP5586575B2 (en) * | 2009-02-20 | 2014-09-10 | 住友精化株式会社 | Method for producing hydroxyalkyl cellulose |
| KR102469464B1 (en) * | 2016-10-07 | 2022-11-22 | 신에쓰 가가꾸 고교 가부시끼가이샤 | Low-substituted hydroxypropyl cellulose, production method thereof, and solid preparation |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61100519A (en) * | 1984-10-23 | 1986-05-19 | Shin Etsu Chem Co Ltd | Hard capsule for drug |
| JP2602535B2 (en) * | 1988-09-02 | 1997-04-23 | ダイセル化学工業株式会社 | Aminoethylated water-soluble polymer and its production method |
| JP3059004B2 (en) * | 1992-09-18 | 2000-07-04 | ダイセル化学工業株式会社 | Low-substituted hydroxypropylcellulose having high solubility in aqueous alkali solution and method for producing the same |
| DE19504832A1 (en) * | 1995-02-14 | 1996-08-22 | Basf Ag | Solid drug preparations |
| JP3947244B2 (en) * | 1996-04-04 | 2007-07-18 | 日清ファルマ株式会社 | Preparation for peptic ulcer treatment |
| JP3718341B2 (en) * | 1998-05-12 | 2005-11-24 | 信越化学工業株式会社 | Low substituted hydroxypropylcellulose and process for producing the same |
-
1999
- 1999-01-18 JP JP00863699A patent/JP3572213B2/en not_active Expired - Lifetime
-
2000
- 2000-01-17 TW TW089100652A patent/TWI224111B/en not_active IP Right Cessation
- 2000-01-17 KR KR10-2000-0001937A patent/KR100464749B1/en active IP Right Grant
- 2000-01-17 CN CN00100989A patent/CN1123576C/en not_active Expired - Lifetime
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| Publication number | Publication date |
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| KR20000062477A (en) | 2000-10-25 |
| JP2000204195A (en) | 2000-07-25 |
| TWI224111B (en) | 2004-11-21 |
| CN1261603A (en) | 2000-08-02 |
| CN1123576C (en) | 2003-10-08 |
| KR100464749B1 (en) | 2005-01-07 |
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