JP4090813B2 - Composite material with lignin matrix - Google Patents

Description

【００２２】
このように、反応性の異なる架橋性基導入部位を有するフェノール誘導体や、導入部位数がないか、あるいは異なるフェノール誘導体を１種あるいは２種以上組み合わせてリグニンに導入することにより、後で架橋性基の導入時に、架橋性基の導入部位や数を制御することができ、結果として、架橋性体を架橋して得られる架橋体の架橋密度も制御することができる。
【００２３】
また、第一のユニットを有する一次誘導体を得るには、少なくとも一つのオルト位（好ましくは全てのオルト位）に置換基を有していないフェノール誘導体を用いる。また、少なくとも一つのオルト位（２位あるいは６位）が置換基を有さず、パラ位（４位）に置換基を有するフェノール誘導体（典型的には、２，４位置換１価フェノール誘導体）が好ましい。最も好ましくは、全てのオルト位が置換基を有さず、パラ位に置換基を有するフェノール誘導体（典型的には、４位置換１価フェノール誘導体）である。したがって、４位置換フェノール誘導体及び２，４位置換フェノール誘導体を１種あるいは２種以上組み合わせて用いることができる。
【００２４】
第二のユニットを有する一次誘導体を得るには、パラ位に置換基を有していないフェノール誘導体（典型的には、２位（あるいは６位）置換１価フェノール誘導体）が好ましく、より好ましくは、同時に、オルト位（好ましくは、全てのオルト位）に置換基を有するフェノール誘導（典型的には２，６位置換１価フェノール誘導体）を用いる。すなわち、２位（あるいは６位）置換フェノール誘導体及び２、６位置換フェノールのうち１種あるいは２種以上を組み合わせて用いることが好ましい。
【００２５】
フェノール誘導体の好ましい具体例としては、ｐ−クレゾール、２，６−ジメチルフェノール、２，４−ジメチルフェノール、２−メトキシフェノール（Guaiacol）、２，６−ジメトキシフェノール、カテコール、レゾルシノール、ホモカテコール、ピロガロール及びフロログルシノールなどが挙げられる。
特に、第一のユニットをリグノフェノール誘導体中に構築するには、ｐ−クレゾール及び／又は２，４−ジメチルフェノールを用いることができる。第二のユニットを構築するには、２，６−ジメチルフェノールを用いることができる。
【００２６】
リグノセルロース系材料に添加する酸としては、特に限定しないが、セルロースを膨潤させる作用を有していることが好ましい。例えば、６５重量％以上の硫酸（好ましくは、７２重量％の硫酸）、８５重量％以上のリン酸、３８重量％以上の塩酸、ｐ−トルエンスルホン酸、トリフルオロ酢酸、トリクロロ酢酸、ギ酸などを挙げることができる。好ましい酸は、８５重量％以上（好ましくは９５重量％以上）のリン酸、トリフルオロ酢酸、又はギ酸である。また、セルロース、ヘミセルロース由来の水溶性多糖、オリゴ糖、単糖を効率的に回収するには、硫酸を用いることが好ましく、セルロースの高次構造をある程度保持した形で回収するには、リン酸など酸強度の低い酸を用いることが好ましい。
【００２７】
リグノセルロース系材料中のリグニンを、リグノフェノール誘導体に変換し、分離する方法としては以下の３つの方法を挙げることができる。なお、これらの方法に限定されるものではない。
第１の方法は、特開平２−２３３７０１号公報に記載されている方法である。この方法は、木粉等のリグノセルロース系材料に液体状のフェノール誘導体（上記で説明したもの、例えば、ｐ−クレゾール又は２，４−ジメチルフェノール）を浸透させ、リグニンをフェノール誘導体により溶媒和させ、次に、リグノセルロース系材料に濃酸（上記で説明したもの、例えば、７２％硫酸）を添加し混合して、セルロース成分を溶解する。この方法によると、図１に示すように、リグニンを溶媒和したフェノール誘導体と、セルロース成分を溶解した濃酸とが２相分離系を形成する。フェノール誘導体により溶媒和されたリグニンは、フェノール誘導体相が濃酸相と接触する界面においてのみ、酸と接触され、反応が生じる。すなわち、酸との界面接触により生じたリグニン基本構成単位の高反応サイトである側鎖Ｃ１位（ベンジル位）のカチオンが、フェノール誘導体により攻撃される。その結果、前記Ｃ１位にフェノール誘導体がＣ−Ｃ結合で導入され、またベンジルアリールエーテル結合が開裂することにより低分子化される。これによりリグニンが低分子化され、同時にその基本構成単位のＣ１位にフェノール誘導体が導入されたリグノフェノール誘導体がフェノール誘導体相に生成される。このフェノール誘導体相から、リグノフェノール誘導体が抽出される。一次誘導体は、リグニン中のベンジルアリールエーテル結合が開裂して低分子化されたリグニンの低分子化体の集合体として得られる。なお、ベンジル位へのフェノール誘導体の導入形態は、そのフェノール性水酸基を介して導入されているものもあることが知られている。
図２には、アリールプロパンユニットを有する天然リグニンに対して相分離処理を行うことにより、本発明における第一のユニットを有する一次誘導体が得られることを示す。
【００２８】
フェノール誘導体相からの一次誘導体の抽出は、例えば、次の方法で行うことができる。すなわち、フェノール誘導体相を、大過剰のエチルエーテルに加えて得た沈殿物を集めて、アセトンに溶解する。アセトン不溶部を遠心分離により除去し、アセトン可溶部を濃縮する。このアセトン可溶部を、大過剰のエチルエーテルに滴下し、沈殿区分を集める。この沈殿区分から溶媒留去し、一次誘導体を得る。なお、粗一次誘導体は、フェノール誘導体相を単に減圧蒸留により除去することによって得られる。
【００２９】
第２および第３の方法は、リグノセルロース系材料に、固体状あるいは液体状のフェノール誘導体（例えば、ｐ−クレゾール又は２，４−ジメチルフェノールなど）を溶解した溶媒（例えば、エタノールあるいはアセトン）を浸透させた後、溶媒を留去する（フェノール誘導体の収着工程）。次に、このリグノセルロース系材料に濃酸を添加してセルロース成分を溶解する。この結果、第１の方法と同様、フェノール誘導体により溶媒和されたリグニンは、濃酸と接触して生じたリグニンの高反応サイト（側鎖Ｃ１位）のカチオンがフェノール誘導体により攻撃されて、フェノール誘導体が導入される。また、ベンジルアリールエーテル結合が開裂してリグニンが低分子化される。得られる一次誘導体の特性は、第１の方法で得られるものと同様である。そして、第１の方法と同様にして、フェノール誘導体化されたリグノフェノール誘導体を液体フェノール誘導体にて抽出する。液体フェノール誘導体相からの一次誘導体の抽出も、第１の方法と同様にして行うことができる（これを第２の方法と称する）。あるいは、濃酸処理後の全反応液を過剰の水中に投入し、不溶区分を遠心分離にて集め、脱酸後、乾燥する。この乾燥物にアセトンあるいはアルコールを加えてリグノフェノール誘導体を抽出する。さらに、この可溶区分を第１の方法と同様に、過剰のエチルエーテル等に滴下して、一次誘導体を不溶区分として得る（これを第３の方法と称する）。以上、リグノフェノール誘導体の調製方法の具体例を説明したが、これらに限定されるわけではなく、これらに適宜改良を加えた方法で調製することもできる。
【００３０】
このようにして、少なくとも第一のユニットを有する他、使用したフェノール誘導体のオルト位あるいはパラ位でリグニンのフェニルプロパンユニットのＣ１位に当該フェノール誘導体がグラフトされた、１，１−ビス（アリール）プロパンユニットを有する一次誘導体を得ることができる。なお、得られる一次誘導体においては、通常、フェノールがグラフトされていないアリールプロパンユニットも残存している。
２種類以上のフェノール誘導体を導入した一次誘導体を得ようとする場合、前記相分離処理におけるフェノール収着工程でリグノセルロース系材料に２種類以上のフェノール誘導体を同時に使用することにより得ることもできる。また、リグノセルロース系材料に対して単一のフェノール誘導体を導入したものを混合することができる。前者の場合、コポリマー的であり、後者の場合ポリマーブレンド的である。これらの態様は、必要に応じて選択することができるが、得られる一次誘導体の分子内スイッチ的な機能や架橋度を調整する観点からは、前者の態様（コポリマー的態様）で一次誘導体を得ることが有用である。
【００３１】
なお、フェノール誘導体の導入頻度は、導入しようとするフェノール誘導体の置換基の有無、位置、大きさ等によって変動する。したがって、導入頻度を調節することができる。特に、置換基の大きさによる立体障害によって導入頻度を容易に調節することができる。置換基を利用して導入位置などを制御しようとする場合、置換基として低級アルキル基を利用すると、炭素数や分枝形態によって容易に導入頻度を調節できる。置換基をメチル基とすると、導入頻度を高く維持して導入位置を制御できる。
以下に、リグノセルロース系材料から得られる一次誘導体の有する全体的、一般的性質を挙げる。ただし、本発明におけるリグノフェノール誘導体を、以下の性質を有するものに限定する趣旨ではない。
（１）重量平均分子量が約２０００〜２００００程度である。
（２）分子内に共役系をほとんど有さずその色調は極めて淡色である。典型的には淡いピンク系白色粉末である。
（３）針葉樹由来で約１７０℃、広葉樹由来で約１３０℃に固−液相転移点を有する。
（４）メタノール、エタノール、アセトン、ジオキサン、ピリジン、テトラヒドロフラン、ジメチルホルムアミドなどに容易に溶解する。
【００３２】
この一次誘導体に対して、アルカリ処理、架橋性導入反応、水酸基保護処理などを行うことにより、リグニンの更なる誘導体（二次誘導体）を得ることができる。すなわち、アルカリ処理体、架橋性体（プレポリマー）が得られ、水酸基保護処理体を得ることができる。また、いずれかの誘導体化処理を行った二次誘導体に対して、さらに、異なる誘導体化処理を施すことにより、高次誘導体を得ることができる。
リグノフェノール誘導体は本来的に粘結性を有しており、リグニン系マトリックスの構成材料として使用されるとき、フィラーなどの被複合化材料を良好に拘束して、複合化されたリグニン系マトリックスを構成することができる。
以下、二次誘導体と誘導体化工程について説明する。
【００３３】
（架橋性基導入反応）
プレポリマーは、一次誘導体を、アルカリ条件下で架橋性基形成化合物と反応させて、リグノフェノール誘導体中のフェノール性水酸基のオルト位及び／又はパラ位に架橋性基を導入することにより、得ることができる。
すなわち、本プレポリマーは、用いる一次誘導体のフェノール性水酸基を解離しうる状態下において、一次誘導体に架橋性基形成化合物を混合して反応させることによって得られる。一次誘導体のフェノール性水酸基が解離しうる状態は、通常、適当なアルカリ溶液中において形成される。使用するアルカリの種類、濃度及び溶媒は一次誘導体のフェノール性水酸基が解離するものであれば、特に限定されない。例えば、０．１Ｎの水酸化ナトリウム水溶液を使用できる。
【００３４】
このような条件下において、架橋性基はフェノール性水酸基のオルト位又はパラ位に導入されるので、用いたフェノール誘導体の種類や組み合わせによって、架橋性基の導入位置がおおよそ決定される。すなわち、オルト位及びパラ位において２置換されている場合には、導入フェノール核には架橋性基は導入されず、リグニン母体側のフェノール性芳香核に導入されることになる。母体側のフェノール性芳香核は、主として一次誘導体のポリマー末端に存在するため、主としてポリマー末端に架橋性基が導入されたプレポリマーが得られる。図３上段には、２，４−ジメチルフェノールを導入フェノール誘導体として用いて得た一次誘導体において、架橋性基としてヒドロキシメチル基が導入された（メチロール化された）プレポリマーが例示されている。
また、オルト位及びパラ位において１置換以下の場合には、導入フェノール核とリグニン母体のフェノール性芳香核に架橋性基が導入されることになる。したがって、ポリマー鎖の端末の他、その長さにわたって架橋性基が導入され、多官能性のプレポリマーが得られる。図３に、ｐ−クレゾールを導入フェノール誘導体として用いて得られた一次誘導体に対して、ヒドロキシルメチル基が導入された（メチロール化された）プレポリマーが示されている。
【００３５】
したがって、２置換フェノール誘導体と１置換以下のフェノール誘導体とを組み合わせることで、架橋性を調節することができる。本発明においては、２，４−ジメチルフェノール及び／又は２，６−ジメチルフェノールに代表される２置換フェノール誘導体が用いられている場合、プレポリマーにリニアポリマー形成能が付与される（図３右側）。また、ｐ−クレゾールに代表される１置換以下のフェノール誘導体が用いられている場合、プレポリマーにネットワークポリマー形成能が付与される（図３左側）。２置換フェノール誘導体と１置換以下フェノール誘導体とを組み合わせて用いることにより、ネットワーク性を調節することができる。
【００３６】
一次誘導体に導入する架橋性基の種類は特に限定されない。リグニン母体側の芳香核、あるいは、導入フェノール誘導体の芳香核に導入可能なものであればよい。架橋性基としては、ヒドロキシメチル基、ヒドロキシエチル基、ヒドロキシプロピル基、１−ヒドロキシバレルアルデヒド基等を挙げることができる。架橋性基形成化合物としては、求核性化合物であって、結合後に架橋性基を形成するかあるいは保持する化合物である。たとえば、ホルムアルデヒドやアセトアルデヒド、プロピオンアルデヒド、グルタルアルデヒド類などを挙げることができる。導入効率等を考慮すると、ホルムアルデヒドを用いることが好ましい。また、各種ジイソシアネート類等の重合性化合物を用いることができる。
【００３７】
一次誘導体と架橋性基形成化合物とを混合するに際して、架橋性基を効率よく導入する観点からは、架橋性基形成化合物をリグノフェノール誘導体中のリグニンのアリールプロパン単位の芳香核及び／又は導入フェノール核の１モル倍以上添加することが好ましい。より好ましくは、１０モル倍以上であり、さらに好ましくは２０モル倍以上である。
【００３８】
次に、アルカリ液中にリグノフェノール誘導体と架橋性基形成化合物が存在する状態で、必要によりこの液を加熱することにより、架橋性基がフェノール核に導入される。加熱条件は、架橋性基が導入される限り、特に限定されないが、４０〜１００℃が好ましい。４０℃未満では架橋性基形成化合物の反応率が非常に低く好ましくなく、１００℃より高いと架橋性基形成化合物自身の反応などリグニンへの架橋性基導入以外の副反応が活発化するので好ましくない。より好ましくは、５０〜８０℃であり、例えば約６０℃が特に好ましい。反応は、反応液を冷却等することにより停止し、適当な濃度の塩酸等により酸性化（ｐＨ２程度）し、洗浄、透析などにより酸、未反応の架橋性基形成化合物を除去する。透析後凍結乾燥などにより試料を回収する。必要であれば、五酸化二リン上で減圧乾燥する。
【００３９】
こうして得られるプレポリマーは、第一のユニットや第二のユニットを含む１，１−ビス（アリール）プロパンユニットやリグニンのアリールプロパンユニット内のフェノール性水酸基に対するオルト位および／またはパラ位に架橋性基を有するようになる。
第１の好ましい架橋性体は、第一及び／又は第二のユニット中の導入フェノール核のフェノール性水酸基に対してオルト位及び／又はパラ位に架橋性基を備える架橋性ユニットを備えていることを特徴とする。また、第２の好ましい架橋性体は、第一及び／又は第二のユニット及び／又はフェニルプロパンユニット中の、リグニン母体側のフェノール核のフェノール性水酸基のオルト位及び／又はパラ位にのみ架橋性基を備える架橋性ユニットを備えていることを特徴とする。さらに、第３の架橋性体は、上記第１の架橋性ユニットと第２の架橋性ユニットとを備えていることを特徴とする。
【００４０】
本プレポリマーの重量平均分子量は特に限定されないが、通常は２０００〜２００００、好ましくは２０００〜１００００程度である。また、架橋性基の導入量は通常、０．０１〜１．５モル／Ｃ９単位程度であることが多い。
【００４１】
（水酸基保護処理）
水酸基保護処理は、リグノフェノール誘導体におけるフェノール性及びアルコール性水酸基に対して、アシル基（アセチル基、プロピオニル基、ブチリル基、バレリル基、ベンゾイル基、トルオイル基、好ましくはアセチル基）を導入することによって行うことが好ましい。具体的には、無水酢酸などと接触させることにより行う。当該アシル化処理により、水酸基が保護される。このため、水酸基による特性発現が抑制される。たとえば、水素結合が低減されて、会合性を低下させることができる場合がある。
【００４２】
（アルカリ処理）
アルカリ処理は、リグノフェノール誘導体を、アルカリと接触させることにより行う。好ましくは加熱する。アルカリ処理においては、図４に示すように、第一のユニットにおける導入フェノール誘導体のフェノキシドイオンによるＣ２位炭素の攻撃が生じる。すなわち、一旦この反応が生じれば、Ｃ２アリールエーテル結合が開裂する。本発明は、第一のユニットに導入されたフェノール誘導体を脱複合のためのスイッチング素子として使用する。すなわち、得られた二次誘導体においては、第一のユニットが保持されている必要がある。したがって、誘導体化工程としてのアルカリ処理は、全ての第一のユニットにおいてＣ２アリールエーテル結合を開裂させない程度に行い、最終的には第一のユニットを維持できるような不完全なアルカリ処理を要することになる。
【００４３】
例えば、緩和なアルカリ処理では、図４に示すように、一次誘導体が第一のユニットを有する場合、当該導入フェノール誘導体の当該フェノール性水酸基が開裂し、生じたフェノキシドイオンが、Ｃ２アリールエーテル結合を構成するＣ２位を分子内求核反応的にアタックして、当該エーテル結合を開裂させて低分子化することができる。
Ｃ２アリールエーテル結合の開裂により、リグニンの母核にフェノール性水酸基が生成されることになる（図４右側、点線円内参照）。また、当該分子内求核反応により、導入フェノール核が、それが導入されたフェニルプロパン単位とクマラン骨格を形成した構造（アリールクマラン単位）が発現される。
これらの結果、フェノール誘導体側にあったフェノール性水酸基（図４左側、点線円内）が、リグニン母核側（図４右側、点線円内）に移動されたことになる。導入フェノール誘導体からのフェノール性水酸基の消失は、疎水性の向上に寄与することができる。
このため、第一のユニットを有するリグノフェノール誘導体においては、第一のユニットの存在部位において（１）Ｃ２アリールエーテル結の開裂による低分子化、（２）アリールクマラン構造の発現、（３）Ｃ２アリールエーテル結合で結合されていたリグニン母核側におけるフェノール性水酸基が発現する。
【００４４】
当該アルカリ処理は、具体的には、リグノフェノール誘導体の架橋体をアルカリ溶液に溶解し、一定時間反応させ、必要であれば、加熱することにより行う。この処理に用いることのできるアルカリ溶液は、リグノフェノール誘導体中の導入フェノール誘導体のフェノール性水酸基を解離させることができるものであればよく、特に、アルカリの種類及び濃度、溶媒の種類等は限定されない。アルカリ下において前記フェノール性水酸基の解離が生じれば、隣接基関与効果により、クマラン構造が形成されるからである。例えば、ｐ−クレゾールを導入したリグノフェノール誘導体では、水酸化ナトリウム溶液を用いることができる。例えば、アルカリ溶液のアルカリ濃度範囲は０．５〜２Ｎとし、処理時間は１〜５時間程度とすることができる。また、アルカリ溶液中のリグノフェノール誘導体は、加熱されることにより、容易にクマラン構造を発現する。加熱に際しての、温度、圧力等の条件は、特に限定することなく設定することができる。例えば、アルカリ溶液を１００℃以上（例えば、１４０℃程度）に加熱することによりリグノフェノール誘導体の架橋体の低分子化を達成することができる。さらに、アルカリ溶液を加圧下においてその沸点以上に加熱してリグノフェノール誘導体の架橋体の低分子化を行ってもよい。
【００４５】
なお、同じアルカリ溶液で同濃度においては、加熱温度が１２０℃〜１４０℃の範囲では、加熱温度が高い程、Ｃ２−アリールエーテル結合の開裂による低分子化が促進されることがわかっている。また、該温度範囲で、加熱温度が高い程、リグニン母体由来の芳香核由来のフェノール性水酸基が増加し、導入されたフェノール誘導体由来のフェノール性水酸基が減少することがわかっている。したがって、低分子化の程度及びフェノール性水酸基部位のＣ１位導入フェノール誘導体側からリグニン母体のフェノール核への変換の程度を、反応温度により調整することができる。すなわち、低分子化が促進され、あるいは、より多くのフェノール性水酸基部位がＣ１位導入フェノール誘導体側からリグニン母体へ変換されたアリールクマラン体を得るには８０〜１４０℃程度の反応温度が好ましい。
【００４６】
Ｃ１フェノール核の隣接基関与によるＣ２−アリールエーテルの開裂は、上述したようにアリールクマラン構造の形成を伴うが、リグノフェノール誘導体の架橋体の低分子化は、必ずしもアリールクラマンが効率よく生成する条件下（１４０℃付近）で行う必要はなく、材料によって、あるいは目的によってより高い温度（例えば１７０℃付近）で行うこともできる。この場合、一旦生成したクラマン環は開裂し、導入フェノール誘導体側にフェノール性水酸基が再生される結果、１４０℃処理物とは特性の異なるよりフェノール活性が高い素材を誘導することができる。
【００４７】
以上のことから、アルカリ処理における加熱温度は、特に限定されないが好ましくは８０℃以上２００℃以下である。８０℃を大きく下回ると、反応が十分に進行せず、２００℃を大きく越えると好ましくない副反応が派生しやすくなるからである。
【００４８】
クラマン構造の形成とそれに伴う低分子化のための処理の好ましい一例としては、０．５Ｎの水酸化ナトリウム水溶液をアルカリ溶液として用い、オートクレーブ内１４０℃で加熱時間６０分という条件を挙げることができる。特に、この処理条件は、ｐ−クレゾール又は２，４−ジメチルフェノールで誘導体化したリグノフェノール誘導体に好ましく用いられる。
【００４９】
（高次誘導体）
これらの二次誘導体化処理により各種二次誘導体を得ることができる。
さらに、これらの二次誘導体に対して、さらに上記した各処理（好ましくは種類の異なる処理）を行うことにより、高次誘導体化することができる。
この場合、施された処理によって発生した構造的特徴を組み合わせて保持する高次誘導体を得ることができる。例えば、アルカリ処理と架橋性導入反応、アルカリ処理と水酸基保護処理、架橋性基導入反応と水酸基保護処理とを組み合わせることができる。
【００５０】
（複合材料用組成物）
複合材料は、このようなリグニン系ポリマー（架橋体以外の各種誘導体）とリグニン系マトリックスに複合化されるフィラーなどの他の材料（被複合化材料）とを含有する複合材料用組成物を成形することによって得ることができる。
リグニン系マトリックスに複合化される他の材料としては、特に限定しないで、有機系材料や無機系材料を用いることができる。有機系材料としては、各種天然あるいは合成樹脂を用いることができる。たとえば、セルロース系材料を用いることができる。
【００５１】
無機系材料としては、セラミックス、ガラス、金属、無機塩類などとすることができる。リグニン系マトリックスは良好な拘束力を有しているため、自己集合性の少ない材料であっても良好にマトリックス内に保持することができる。したがって、材料の形態も繊維状などの交絡性を有するものの他、球形の粒子状、針状、チップ状等の各種形態を問わずに採用することができる。
無機系材料は、アルカリ処理による物理的及び／又は化学的変化が比較的小さいため、脱複合後において、再利用性を確保しやすい点において好ましい。
図５に、各種のリグノフェノール誘導体と、無機系材料とを複合化するスキームを例示している。
【００５２】
アルカリ処理による脱複合を考慮すると、被複合化材料はアルカリ膨潤性を有していることが好ましい。すなわち、アルカリにより組織が軟化あるいは膨潤することが好ましい。同時に、親水性であることも好ましい。アルカリ膨潤性と親水性とを備えている場合には、アルカリ処理時におけるアルカリ液がリグニンマトリックスの高分子材料にアクセスしやすくなり、その結果、導入された脱複合素子による高分子骨格の崩壊が生じ易くなる。
なお、アルカリ膨潤性材料は、そのアルカリ膨潤性をある温度域で発揮することが好ましい。すなわち、実施しようとするアルカリ処理のための温度域においてアルカリにより膨潤することが好ましい。あるいは、使用するアルカリ膨潤性材料のアルカリ膨潤性の温度依存性に基づいてアルカリ処理温度を設定することも可能である。
【００５３】
また、アルカリ膨潤性を有していない被複合化材料を用いる場合には、アルカリ膨潤性を有する被複合化材料と組み合わせて用いることにより、アルカリによる第１の素子へのアクセスビリティーを高めることができて、良好な脱複合を実現することができる。また、緩和な条件で脱複合を実現することができる。さらに緩和な条件での脱複合を実現できることにより、リグニン系マトリックスを構成するリグニン系ポリマー及び被複合化材料の構造変換レベルを最小限にすることができ、分離される脱複合後のリグニン系ポリマー（低分子化されている）の誘導体化の自由度を高めることができると同時に、被複合化材料の逐次利用も確保できるようになる。
リグニン系マトリックスにおいて高い耐水性を確保する観点からは、被複合化材料は、アルカリ非膨潤性材料を主体とし、アルカリ膨潤性材料を含有するように調製することが好ましい。
また、リグニン系マトリックス中で生成されるリグニン系ポリマーが、架橋体であって、ネットワーク型高分子材料である場合（複合材料用組成物がネットワーク型高分子を構成する架橋性体をリグニン系ポリマーとして含有する場合）には、特に、アルカリによるアクセスビリティーを確保する観点から、アルカリ膨潤性材料を含有するようにすることが好ましい。
【００５４】
なお、アルカリ膨潤性材料は、アルカリの浸透性を確保するなどの観点から、均一分散性を確保しやすいことが好ましい。したがって、少なくとも複合化前の形態としては、粉末状、繊維状などの形態を有することが好ましい。繊維状であれば、単繊維状であってもよいし、複合繊維状であってもよい。さらには、繊維状体を構成成分とするネットワーク状あるいはシート状体であってもよい。
このようなアルカリ膨潤性材料としては、材質としては、セルロース（分離された天然セルロース）の他、カルボキシメチルセルロース、ヒドロキシエチルセルロース、酢酸セルロース、メチルセルロース、ヒドロキシセルロースなどの各種セルロース誘導体などの親水性高分子を用いることができる。また、リグニンと複合状態のセルロースを含むリグノセルロースも用いることができる。
したがって、具体的なアルカリ膨潤性材料としては、セルロース系繊維（微細繊維の粉末含む）、セルロース系粉末、リグノセルロース系繊維（微細繊維粉末含む）、リグノセルロース系粉末等を用いることができる。
なお、アルカリ膨潤性材料の含有量は、得ようとするリグニン系マトリックスの架橋構造やその他の被複合化材料の種類や配合によって相違してくるが、その適切な含有量は、複合材料のアルカリ処理による脱複合試験により容易に確認することができる。たとえば、ｐ−クレゾールを導入フェノール誘導体として用いた一次誘導体をメチロール化して得たプレポリマーをリグニン系ポリマーとして使用する場合、このリグニン系ポリマー１００重量部、セルロース粉末１００重量部、及びタルク８００重量部を含有する複合材料用組成物を調製することにより、アルカリ処理による脱複合によって回収されるリグニン系ポリマーの回収率は、セルロース系粉末を含有しない場合に比較して著しく向上される。
【００５５】
さらに、本組成物においては、上記した材料の他、複合材料の用途に応じて、各種添加剤を含めることができる。特に、フィラーとしては、常温で可塑性を有する、あるいは可撓性を有するフィラーを用いることにより、複合材料に内部応力の緩和性や靭性を付与することができる。形状的には、球状や不定形状などでもよいが、好ましくは繊維状である。また、典型的にはセルロース系繊維あるいはセルロース系粉末（微細繊維の粉末含む）を用いることができる。したがって、セルロース系繊維あるいはセルロース系微細繊維粉末は、アルカリ膨潤性としても良質なフィラーとしても有用である。
【００５６】
本組成物においては、上記した各種の被複合化材料を１種あるいは２種以上を組み合わせることができる。また、本組成物におけるリグニン系ポリマーと被複合化材料との比率は、複合材料に付与したい機能や成形方法を考慮して適宜設定することができる。
また、本組成物には、本組成物を成形して得られる複合材料をアルカリ処理することにより、この複合材料を脱複合させるのに十分な量のリグニン系ポリマーが複合材料中に存在するように、リグニン系ポリマーを含有することが好ましい。複合材料における脱複合のための適切な量は、最終的に得られる複合材料中のリグニン系ポリマーの種類や被複合材料の種類によっても異なるが、その適切な含有量は、複合材料のアルカリ処理による脱複合試験により容易に確認することができる。
【００５７】
複合材料用組成物の調製方法や組成物形態は、被複合化材料の形態などを考慮して適宜選択して、各種形態を採ることができる。粉末状のリグノフェノール誘導体と被複合化材料とを混合して得ることもできるし、固形状の被複合化材料に、適当な溶媒に溶解したリグノフェノール誘導体を浸透させ、乾燥することによっても得ることができる。さらに、仮成形された被複合化材料に対して、リグノフェノール誘導体液を浸透させ、乾燥することによっても得ることができる。
【００５８】
（複合材料）
複合材料用組成物を、加熱及び／又は加圧することによって、形状を付与するとともにリグニン系マトリックスを形成して本複合材料を得ることができる。
成形方法は特に限定しないで、圧縮成形、射出成形、押出成形、ブロー成形、発泡成形、キャスティング成形、紡糸など必要に応じて各種成形方法を採用することができる。
リグノフェノール誘導体は、本来的に粘結性を有しているため、加圧することによっても拘束力を発揮しうる。好ましくは、加熱された状態で加圧することが好ましい。加熱と加圧とは同時であってもよいし、逐次的に行ってもよい。
リグニン系ポリマーとして、プレポリマーを含有する場合、加熱により架橋させて、成形と同時に複合材料のマトリックス中に図６に示すような架橋構造を得ることができる。
【００５９】
熱架橋の条件は、架橋反応を進行できる限り、特に限定されない。例えば、１℃〜２℃／分の昇温プログラム条件で１５０℃〜１８０℃程度まで加熱し、その後冷却することができる。また、昇温後、最高設定温度に達してから１時間保持した後、冷却する条件を挙げることができる。各種の架橋構造を図６に示す。
【００６０】
架橋によって構築される架橋体構造は、上述のとおり、導入フェノール核の置換部位と置換数とによって決まってくる。図６の左側は、１置換フェノールとして例えば、ｐ−クレゾールを用いたリグノフェノール誘導体をメチロールしてプレポリマーとし、熱架橋することにより、ネットワーク型の高分子材料ができることを示している。このプレポリマーでは、分子鎖の全体にわたって架橋性基が導入されているからである。
【００６１】
一方、図６の右側には、二置換フェノールとして２，４−ジメチルフェノールを用いたリグノフェノール誘導体をメチロール化してプレポリマーとし、熱架橋することにより、リニア型の架橋構造が形成されることが示されている。このようなプレポリマーでは、主としてポリマー末端に架橋性基が導入されているからである。
【００６２】
さらに、図６の中央には、導入フェノール誘導体として、１置換フェノールと二置換フェノールとを用いることにより（典型的には、ｐ−クレゾールと２，４−ジメチルフェノール）、両者に基づく第一のユニットを備えた一次誘導体に架橋性基を導入してプレポリマーとし、結果として、ネットワーク型とリニア型とを混成させた高分子材料が得られることが示されている。
【００６３】
このようにして得られた複合材料は、リグニン系ポリマーによるマトリックスの特性と被複合化材料との特性を備えている。リグニン系マトリックスが、成形時に生成された架橋構造を有さず、一次誘導体、二次誘導体及び高次誘導体であるリグニン系ポリマーを主体とする場合でも、その本来的な粘結性に基づいてマトリックスを構成する。
また、リグニン系マトリックスが成形時に新たに生成されたネットワーク状〜リニア状の架橋構造を有する場合には、本来的な粘結性とその架橋構造によりマトリックスを構成する。架橋構造の形態（ネットワーク型とリニア型）にかかわらず、架橋体はマトリックスに均一に分布し、かつ、おおよそ近似した強度的特性や寸法安定性（耐水性ないし吸水性）を付与することができる。したがって、特に、材料相互間の相互作用が小さいかほとんどなく化学的にも安定した材料（典型的には無機系材料）を用いた場合には、複合材料の機械的強度や寸法安定性をリグニン系マトリックスによって大きく影響されにくく、無機系材料の特性を出しやすいというメリットがある。
【００６４】
一方、リグノフェノール誘導体に対して親和性の高い溶媒、たとえば、ＴＨＦに浸漬した場合、成形時に形成された架橋構造のリニア性が高いほど、容易にＴＨＦに溶解し、複合材料は崩壊した。特に、１置換以下フェノール誘導体（たとえば、ｐ−クレゾール）のみを用いた一次誘導体のプレポリマーを架橋させた場合には、そのネットワーク構造が被複合化材料を強固に拘束し、複合材料の形状を維持させることが可能である。また、２，４−置換フェノール誘導体（たとえば、２，４−ジメチルフェノール）のみを用いた一次誘導体のプレポリマーを架橋させた場合には、リグノフェノール誘導体親和性溶媒に対する浸漬処理によって、容易に複合形態を崩壊させることが可能である。
【００６５】
本発明においては、リグノフェノール誘導体が第一のユニットを有すること及び架橋体が第一のユニット中に第一の素子（オルト位で導入されたフェノール誘導体）を保持していることに基づいて、アルカリ処理によってこれらを低分子化させることができる。すなわち、本発明の複合材料をアルカリ処理することによって、リグニン系マトリックスにおいて図４及び／又は図７に示す反応を生じさせ、リグニン系ポリマーを低分子化させて複合材料の脱複合を実現することができる。
アルカリ処理は、複合材料をそのまま、好ましくは粉砕等により小片化あるいは粉末化したものに対して行う。アルカリ処理条件は、複合材料を脱複合させることができればよく特に限定しない。上記したアルカリ処理の項において開示した各種の条件を採用できる。例えば、０．１Ｎ〜０．５Ｎ程度のＮａＯＨなどのアルカリ溶液を１００℃以上（例えば、１４０℃程度）に加熱することによりリグノフェノール誘導体及びその架橋体の低分子化を達成することができる。加圧下で沸点以上に加熱することもできる。緩和な条件としては、約８０℃以上約１５０℃以下を採用することができる。また、約１５０℃以上約１７０℃以下で行うこともできる。
【００６６】
このアルカリ処理によれば、リグノフェノール誘導体や架橋体内部の第一の素子において選択的にこれらを低分子化させて、リグニン系マトリクスを崩壊させることができる。当該低分子化によって、リグニン系マトリックスのリグノフェノール誘導体等のリグニン系ポリマーは容易に分離回収される。また、被複合化材料も容易に分離回収される。したがって、これらの材料は、いずれも、逐次利用が容易に確保される。
特に、リグニン系ポリマーは、アルカリ処理により低分子化とともに、新たな部分構造やフェノール性水酸基などが発現されることにより、さらなる誘導体化の自由度が高くなっている。
さらに、アルカリ処理という簡易な工程により脱複合されることは、再利用のコストを低減できる点において有利である。特に、緩和なアルカリ条件でも脱複合できる点は有利である。
【００６７】
特に、本発明においては、脱複合が、リグニン系マトリックスの高分子内部のフェノール誘導体（スイッチング素子）において容易に達成される。したがって、上述のとおり、導入するフェノール誘導体の種類や導入頻度を容易に制御できるため、スイッチング素子の導入量も制御することができ、結果として、得ようとする複合材料に応じた脱複合性能や脱複合形態を付与することができる。
また、上述したように、架橋構造を有するリグニン系マトリックスにあっては、架橋構造にかかわらず近似した物理化学的特性を発揮する一方、架橋構造の相違によって、溶媒溶解性能と後述する脱複合性能とが大きく相違することになる。このことは、溶解溶媒性能と脱複合性能が、架橋構造の相違によって調節できることを意味している。
【００６８】
また、必要に応じて、リグニン系マトリックス中のリグニン系ポリマーに対するアルカリのアクセスビリティをアルカリ膨潤性材料の使用により容易に調節し、脱複合性能も調節することができる。
【００６９】
なお、脱複合に際しては、同時にあるいは別個にリグノフェノール誘導体親和性溶媒による溶解処理も行うことができる。ここで、当該親和性溶媒としては、メタノール、エタノール、アセトン、ジオキサン、ピリジン、テトラヒドロフラン、及びジメチルホルムアミドから選択される１種あるいは２種以上の溶媒を同時あるいは逐次使用することができる。この溶解処理は、前記アルカリ処理による脱複合工程に先だって行うこともできるし、後段で行うこともできる。
【００７０】
【実施例】
以下、本発明を具体例について説明する。本発明は以下の実施例に限定されるものではない。
（実施例１）
一次誘導体の調製
ヒノキ（Chamaecyparis obtusa）の木粉（リグノセルロース系材料）の脱脂試料の約１０００ｇを、５００ｍｌ容ビーカーにとり、各種フェノール誘導体（ｐ−クレゾール、ｐ−クレゾール：２，４−ジメチルフェノール＝１：１、２，４−ジメチルフェノール）のアセトン溶液（リグニンＣ９単位当たり３モル倍量のフェノール誘導体を含む）を加え、ガラス棒で撹拌し、アルミホイルおよびパラフィルムでビーカーに蓋をし、２４時間静置させた。その後、ドラフト内で木粉を激しく撹拌し、アセトンを完全に留去して、各種フェノール誘導体収着木粉を得た。
この留去物に対して、７２ｗｔ％硫酸５０００ｍｌを加え、３０℃で、１時間激しく撹拌した後、混合物を大過剰の水に投入、不溶解区分を遠心分離（３５００ｒｐｍ、１０分、２５℃）にて回収、脱酸し、凍結乾燥して、３種類の一次誘導体を得た。
【００７１】
（実施例２）
一次誘導体への架橋性基の導入
実施例１で得られた３種類の一次誘導体各５ｇを、０．１ＮＮａＯＨ水溶液５００ｍｌに溶解し、ホルムアルデヒド３７％水溶液約４５ｍｌを添加して、窒素雰囲気下、６０℃で３時間反応させた。反応終了後、１Ｎ塩酸を加えてｐＨ２まで酸性化した後、生じた沈殿を遠心分離（条件等）して回収し、脱酸後、凍結乾燥することにより、ヒドロキシメチル基を導入（メチロール化）した３種類のプレポリマーを得た。以下、これらのプレポリマーを用いたフェノール誘導体の組成に基づいて、ＨＭ−リグノ−ｐ−クレゾール、ＨＭ−リグノ−ｐ−クレゾール：２，４−ジメチルフェノール＝１：１、ＨＭ−リグノ−２，４−ジメチルフェノールと称する。なお、得られたプレポリマーは-80℃にて保存した。
【００７２】
（実施例３）
複合材料の作製
実施例２で得られたプレポリマー各１００ｍｇをテトラヒドロフラン（ＴＨＦ）１０ｍｌに溶解後、この溶液をタルク９００ｍｇ（粒径約１０〜約５０μm）に添加して、よく混合した後、連続的攪拌してテトラヒドロフランを留去することにより、タルクに各プレポリマーを収着させた。
この収着試料の各全量を、ＳＨＩＭＡＺＵフローテスターＣＦＴ−５００ＤにてInitial Temp．；７０℃、Final Temp.;１８０℃、Rate；１．５℃／分、１００ｋｇで圧縮成形して前記各プレポリマーを架橋させ、架橋体を含有する円柱状複合材料（成形体）（直径１０mm）を作製した。なお、タルク１０００ｍｇから同様の成形条件にて成形体を作製し、コントロール成形体とした。
【００７３】
（実施例４）
複合材料の作製
さらに、実施例２で得られたプレポリマーのうち、ＨＭ−リグノ−ｐ−クレゾール１００ｍｇのテトラヒドロフラン溶液を、上記と同様のタルク８００ｍｇとセルロースの微小繊維の粉末１００ｍｇとの混合物に添加してよく混合した後、連続攪拌してテトラヒドロフランを留去することにより、当該混合物にこのプレポリマーを収着させ、上記と同様の圧縮成型条件により架橋体を含有する成形体を作成し、セルロース含有成形体を作製した。
【００７４】
（実施例５）
複合材料の評価
１．外観、寸法等
使用したタルクは、凹凸に富む表面を有しているものの、自己凝集性がほとんどないため、コントロール成形体は非常に脆く、強く触れると容易に崩壊した。一方、実施例３の各種成形体は、いずれも、薄いベージュ色で表面平滑性に優れていた。
また、重量、寸法、密度についての測定結果を図８に示す。寸法は、実施例３の各種成形体について安定しており、密度はいずれも約１．８であった。
【００７５】
２．ＳＥＭ観察
ＳＥＭにより実施例の各種成形体表面を観察したところ、架橋体の明確なマトリックス相は観察されなかった。このことは、使用したリグニン系ポリマーが、タルク間において均一なフィルム状に分布してバインダとして良好に機能していることを意味している。
【００７６】
３．硬さ試験（Brinell Hardness）
SHIMADZU AG-1 10kNにてJIS2117に準じて行った。各種成形体の上面中央部に直径10mmの硬球を0.5mm/分の速度で圧入し、硬球が1/πmm=0.32mmの深さまで陥入するのに必要な荷重P(N)を測定し，以下の式（１）を用いて硬さH_B(MPa)を測定した。
H_B=P/10 （１）
H_B : ブリネル硬さ (MPa)
P : 荷重 (N)
【００７７】
結果は図９に示すように、コントロール成形体が０．７ＭＰａであったのに対し、３種類の実施例３の成形体は、いずれもおおよそ９〜１０ＭＰａであり、どの架橋体も同様のタルク粒子を強固に集合化し、物理的強度の向上に寄与していることがわかった。しかしながら、実施例３の成形体はいずれも、試験中容易にクラックを生じて割れる傾向にあった。
これに対して、実施例４のセルロース含有成形体は、ブリネル硬さに相違はなかったものの、クラックの形成が抑制される結果が得られた。この結果によれば、セルロースなどの可撓性のある繊維状体を複合系マトリックス中に用いることにより、成形体内部で生じた応力を効果的に緩和できることがわかった。すなわち、フィラーの選択により、複合材料の弾性特性を容易に調整することができることがわかった。
【００７８】
４．圧縮弾性率（ＭＯＥ）
実施例３で得られた成形体について、圧縮弾性率を測定した。なお、荷重速度は、９６０Ｎ／ｃｍ・分とした。
結果は、図１０に示すように、コントロール成形体が１２ＭＰａであったのに対し、実施例３の３種類の成形体は、いずれもおおよそ５０〜６０ＭＰａであり、どの架橋体含有成形体も、ほぼ同等の圧縮弾性率を有していた。
【００７９】
５．吸水試験
実施例３の成形体をステンレス製ネットに置き，成型体の底面から3cmの深さまで水を張った容器に沈めた。成型体が浮上する場合には、成形体の上面から1〜2mm上にステンレス製ネットを設置し、それ以上の浮上を抑制した。室温にて60分間水に浸漬後、成形体を取り出し、ろ紙上で転がして表面の水分を手早く除去した。60℃にて3日間乾燥させた。その際，吸水前，吸水後，乾燥後の重量および寸法を測定し，以下の式（２）、（３）を用いて吸水率Aw%、体積膨張率Vol%を求めた。
Aw%=(Wt’−Wt)/Wt × 100 （２）
Vol%=(Vol’−Vol)/Vol × 100 （３）
Aw% : 吸水率 (% to sample weight)
Wt : 試料重量 (g)
Wt’ : 吸水試験後の試料重量 (g)
Vol% : 体積膨張率 (% to sample volume)
Vol : 試料体積 (cm³)
Vol’ : 吸水試験後または再乾燥後の試料体積 (cm³)
【００８０】
結果は、図１１に示すように、実施例３の成形体はいずれも高い撥水性を示し、１時間水浸漬後の吸水率は０．６ｗ％以下であり、吸水・乾燥条件下における体積膨張率も１%以下であった。これらの結果は、各成形体がタルクの有する撥水性を有し、水による膨潤性を有していないことに基づくものである。
【００８１】
（実施例６）
複合材料からの架橋体の溶出試験
実施例３の３種類の成形体を、それぞれテトラヒドロフラン１０ｍｌに２５℃で２４時間浸漬して、テトラヒドロフラン中に溶出した架橋体量を測定し、成形体中に含まれていた架橋体量に対する割合（％）を溶出率として算出した。なお、テトラヒドロフラン中の架橋体量は、溶出液を蒸発させた残渣の重量を測定することで求めた。また、成形体中に含まれていた架橋体量は、１００ｍｇとして計算した。
結果は、図１２に示すように、タルク−ＨＭ−リグノ−ｐ−クレゾール複合体からは、架橋体は全く溶出されず、このため、成形体形状を完全に維持していた。また、タルク−ＨＭ−リグノ−ｐ−クレゾール：２，４−ジメチルフェノール＝１：１複合体についてもほとんど溶出されず、成形体形状を維持していた。これに対し、タルク−ＨＭ−リグノ−２，４−ジメチルフェノールは、速やかにおおよそ３割の架橋体が溶出され、成形体は崩壊した。
以上の結果より、ＨＭ−リグノ−ｐ−クレゾールの架橋体は、ネットワーク型の高分子構造を形成して、強固にタルク粒子を保持していることがわかった。
【００８２】
（実施例７）
複合材料からの脱複合処理
実施例３の３種類の成形体及び実施例４の成形体を粉砕した後、０．５ＮのＮａＯＨを加え、１４０℃で１時間、１７０℃で1時間及び２時間加熱してアルカリ処理した。その後、アルカリ処理液をろ過により不溶画分と可溶画分とに分離し、不溶画分は乾燥後、重量を測定した。可溶画分は、全容量を測定後、２９３ｎｍにおける吸光度を測定し、回収された架橋体のアルカリ処理体量を算出し、成形体中に含まれる架橋体量（１００ｍｇ）に対する割合（％）を求めた。
なお、アルカリ処理体量の算出にあたっては、ｐ−クレゾールを用いて得られた一次誘導体（リグノ−ｐ−クレゾール）の１４０℃及び１７０℃における０．５ＮＮａＯＨによる加熱処理後の二次誘導体につき、２９３ｎｍにおける吸光度を基に作成した検量線を作成し、この検量線を用いた。なお、結果を図１３に示す。
【００８３】
図１３に示すように、いずれの成形体においても、アルカリ処理のエネルギーレベルが高まるにつれ回収率が向上した。タルク−ＨＭ−ｐ−クレゾール複合体（ネットワーク型架橋構造をマトリックス中に含む）の場合、最も緩和なアルカリ処理条件（１４０℃、１時間）では、アルカリ可溶化されたアルカリ処理体量は約２０％程度であり、最もエネルギーレベルの高いアルカリ処理条件（１７０℃、２時間）でも、約７０％程度であった。これに対して、タルク−ＨＭ−２，４−ジメチルフェノール複合体（リニア型架橋構造をマトリックス中に含む）、及びタルク−ｐ−クレゾール：２，４−ジメチルフェノール＝１：１複合体の場合、最も緩和なアルカリ処理条件でも、高い分離率を得ることができた。
【００８４】
さらに、実施例４の成形体であるタルク−セルロース−ＨＭ−ｐ−クレゾール複合体では、１４０℃におけるアルカリ処理条件下ではセルロースを含有しない複合体と回収率に大きな相違はなかったが、１７０℃によるアルカリ処理条件下において飛躍的に回収率が向上した。これは、１７０℃条件下にてセルロースが膨潤し、そのために架橋体とアルカリとの接触頻度が向上したためである。したがって、被複合化材料のアルカリ膨潤性、さらにはその温度依存性を用いて、アルカリ処理による脱複合の効果をコントロールできることがわかった。
【００８５】
（実施例８）
アルカリ処理体の分子量
実施例７で得られたアルカリ可溶画分の一部を採取し、塩酸を添加してｐＨ２まで酸性化した後、沈殿区分を遠心分離にて回収し、その平均分子量をＧＰＣにて測定した。なお、分子量測定用試料は、以下のようにして調製した。
□試料１ｍｇを精留済みのＧＰＣ溶離液（ＴＨＦ）に溶かし、試料とした。なお、ｐ−クレゾールを内部標準物質として使用した。
なお、測定は、以下の条件で行った。
装置：SHIMAZU LC−10システム、LC10AD、SPD−10A
カラム：Sodwex ＫＦ804、ＫＦ803、ＫＦ802、ＫＦ801
溶離液：テトラヒドロフラン（ＴＨＦ）
流速：１ｍｌ／分
圧力：５５ｋｇ／ｃｍ²
検出器：ＵＶ（２８０）
レンジ：０．３２
サンプル量：２５μｌ
検量線は基準物質としてポリスチレン４０００００、２３３０００、１０００００、２５０００、９０００、４０００、２０００、９０６、ビスフェノールＡ及びｐ−クレゾールを用い作成した。
分子量の測定結果を結果を図１４に示し、また、ＧＰＣチャートを図１５にそれぞれ示す。
【００８６】
図１４及び図１５に示すように、アルカリ可溶化後の分子量は、ＨＭ−リグノ−ｐ−クレゾールにおいて高いレベルに維持され、ＨＭ−リグノ−ｐ−クレゾール：２，４−ジメチルフェノール＝１：１やＨＭ−２，４−ジメチルフェノールにおいては、大きく低分子化された。このことは、実施例７におけるアルカリ可溶化の結果とよく対応している。この分子量の測定結果から、架橋体における形態、すなわち、ネットワーク型構造の有無やその割合などにより、アルカリ処理による低分子化の程度が大きく変化し、脱複合レベルもそれに応じて変化することがわかった。
【図面の簡単な説明】
【図１】リグノフェノール誘導体（一次誘導体）の製造プロセスの原理を示す図である。
【図２】アリールプロパンユニットを有する天然リグニンに対する相分離処理により、第一のユニットを有する一次誘導体が得られることを示す図である。
【図３】図３の上段には、フェノール誘導体として２，４−ジメチルフェノールを導入して得た一次誘導体に架橋性基（ＨＭ基）を付加したプレポリマーを示し、下段には、これを架橋した状態を示す。
【図４】一次誘導体における脱複合メカニズムを示す図である。
【図５】各種リグノフェノール誘導体と無機系材料とを複合化するスキームを示す図である。
【図６】複合材料のマトリックス中に得られる架橋構造の態様を示す図である。
【図７】架橋体における脱複合メカニズムを示す図である。
【図８】実施例３で得た複合体の重量、寸法、密度等を示す表である。
【図９】ブリネル硬さの試験結果を示す図である。
【図１０】弾性圧縮率の試験結果を示す図である。
【図１１】実施例３で得た複合体の吸水率を示す図（ａ）と体積膨張率を示す図（ｂ）とを組み合わせた図である。
【図１２】実施例３で得た複合体からの架橋体の溶出率を示す表である。
【図１３】実施例３及び４で得た複合体の脱複合処理後におけるアルカリ処理体の回収率を示すグラフである。
【図１４】脱複合処理により得られたアルカリ可溶画分中のアルカリ処理体の分子量の測定結果を示す図である。
【図１５】脱複合処理により得られたアルカリ可溶画分中のアルカリ処理体の分子量の測定時に得られたＧＰＣチャートを示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a composite material using a lignophenol derivative derived from lignin, a secondary derivative thereof and a higher derivative as a matrix. Specifically, by using a lignophenol derivative and / or its secondary derivative as a matrix, a dispersion material such as a filler is assembled into a composite material, while the derivative is structurally converted by physicochemical treatment to decomposite the matrix. It relates to possible composite technology.
[0002]
[Prior art]
Artificial structures are often composite materials such as fiber reinforced plastic and reinforced concrete in which a filler as a reinforcing material is held in a matrix. However, artificial composite materials have been pursued with priority on functions such as strength. For this reason, at the time of compounding, a method for rationally disassembling the complexed matrix and the dispersion material and use at the next stage are not considered at all. Therefore, these artificial structures cannot be decomposed into their respective materials once they are constructed and then used, so they are either discarded as they are or crushed and used for aggregates, roadbed materials, etc. There is almost no reuse.
[0003]
On the other hand, a typical composite material in nature has a plant cell wall. The plant cell wall expresses high physical strength and durability by forming a strong composite structure of cellulose and lignin. In other words, in the plant cell wall, cellulose microfibrils aggregated with linear cellulose are entangled in different orientations to form a skeleton, and the skeletal space is filled with lignin, which is a hydrophobic network polymer. is doing. Furthermore, hemicellulose is present so as to cover the cellulose skeleton, strengthening the affinity with lignin and contributing to toughening of the composite structure.
The lignocellulosic composite structure in the plant body maintains its composite state over a long period of time, and once returned to the soil, the composite state is easily released by underground microorganisms and allowed to flow into the natural carbon cycle. Can do.
That is, it can be said that the lignocellulosic composite is an important and enormous carbon resource that plays a role in regulating the carbon supply balance throughout the earth. Therefore, when considering the use of the complex, it is important to use cellulose and lignin for a long time in order to maintain the carbon supply balance.
[0004]
To date, the lignocellulosic composites are used in various forms, but are often used in combination with other materials as molding materials such as fibers and chips in addition to woodwork. From the functional viewpoint of the molded body, these molding materials are combined with a thermosetting resin to form a molded body. However, since the thermosetting resin is used, it is difficult to separate the fiber and the chip at the time of disposal, and as a result, it is difficult to reuse the lignocellulosic resources.
On the other hand, the cellulose in the lignocellulosic composite is reused by repeating the fiberization and the sheet formation. However, the lignin separated at the same time is mainly consumed as fuel, and a part of it is only reused for limited purposes.
[0005]
The inventors of the present invention, based on the previous research, combined the destruction of the tissue structure based on the swelling of carbohydrates with concentrated acid and the solvation of lignin with a phenol derivative, while suppressing the inactivation of lignin, and the lignocellulosic material Has been developed (Japanese Patent Application Laid-Open No. Hei 2-233701) to separate carbohydrate into a phenol derivative of lignin (hereinafter referred to as lignophenol derivative). As a method of utilizing the lignophenol derivative obtained by this method, for example, it has been reported that a molded body is produced by applying it to a molding material such as cellulose fiber (Japanese Patent Laid-Open No. 9-278904). Such a lignophenol derivative is a lignin-based polymer having 1,1-bis (aryl) propane as a high-frequency constituent unit, and has been found to have a high caking property (Japanese Patent Application Laid-Open No. Hei 9). -278904).
Furthermore, such lignophenol derivatives can be imparted with crosslinkability by methylolation, and can form a linear or network-like crosslinked structure, and at the same time, can be reduced in molecular weight and dissolved in a solvent by alkali treatment. It has been found by the present inventors (Japanese Patent Laid-Open No. 2001-261839).
[0006]
[Problems to be solved by the invention]
However, to date, the lignin-derived segment of the lignocellulose complex is used as a matrix to form an artificial composite material, and the complex structure is released based on the structural transformation of the lignin-derived segment, that is, decomposited. Nothing has been found to do. In addition, it is not known at all that the lignin-derived sections are sequentially used by going through a complex-state decomplexing process by this structural transformation.
[0007]
Therefore, an object of the present invention is to provide a composite material that uses a lignophenol derivative and is easily decomposited.
In addition, the present invention provides a method for ensuring the long-term utilization of lignin resources by using the lignophenol derivative and / or a further derivative thereof as a constituent material of the lignin matrix to realize sequential utilization of the lignin matrix. The purpose is to do.
Furthermore, another object of the present invention is to provide a composite technology in which an inorganic material that is highly stable in nature and a lignophenol derivative are combined, and the composite components can be easily recycled.
[0008]
[Means for Solving the Problems]
When the lignophenol derivative and further derivatives thereof have a specific unit, the present inventors can constrain materials other than self well to construct a matrix of a composite material, and at the same time reduce the molecular weight and convert the structure based on the presence of this unit. Thus, the present inventors have found that the composite material can be decomposited to complete the present invention. Further, the present inventors have found that a new composite material can be provided by sequentially using the matrix by utilizing the fact that further derivatization is possible even after the decomposition.
That is, according to the present invention, the following means are provided.
[0009]
(1) A composite material having a lignin matrix,
The lignin matrix includes the following (a) to (e):
(A) a lignophenol having a first 1,1-bis (aryl) propane unit in which the carbon atom in the ortho position relative to the phenolic hydroxyl group of the phenol derivative is bonded to the carbon atom in the C1 position of the arylpropane unit of lignin Derivative
(B) A secondary derivative obtained by performing one kind of reaction selected from a hydroxyl group protection treatment, an alkali treatment, and a crosslinkable group introduction reaction on the lignophenol derivative and having the first unit.
(C) A higher-order derivative obtained by performing two or more kinds of reactions selected from a hydroxyl group protection treatment, an alkali treatment, and a crosslinkable group introduction reaction on the lignophenol derivative and having the first unit. ,
(D) a crosslinked derivative of a secondary derivative obtained by crosslinking a secondary derivative obtained by a crosslinkable group introduction reaction among the secondary derivatives, and
(E) Of the higher-order derivatives, a crosslinked product of a higher-order derivative in which a higher-order derivative obtained through a crosslinkable group introduction reaction is crosslinked
Having one or more lignin polymers selected from the group consisting of:
A composite material that can be decomposited by alkali treatment of the composite material.
(2) The (a) lignophenol derivative includes a lignocellulosic material to which one or more phenol derivatives including a phenol derivative in which at least one ortho position with respect to the phenolic hydroxyl group is not substituted, an acid, The composite material according to (1), obtained by contacting
(3) The composite material according to (1) or (2), wherein the phenol derivative has a substituent at the para position and the remaining ortho position is not substituted.
(4) The composite material according to (3), wherein the phenol derivative is p-cresol.
(5) The composite material according to (1) or (2), wherein the phenol derivative has a substituent at the para position and the remaining ortho position.
(6) The composite material according to (5), wherein the phenol derivative is 2,4-dimethylphenol.
(7) The phenol derivative is a phenol derivative having a substituent at the para position and having no remaining ortho position substituted, and a phenol derivative having a substituent at the para position and the remaining ortho position (1) Or the composite material as described in (2).
(8) The composite material according to (7), wherein the phenol derivative is p-cresol and 2,4-dimethylphenol.
(9) The lignophenol derivative is a second 1,1-bis (aryl) in which the carbon atom at the para position relative to the phenolic hydroxyl group of the phenol derivative is bonded to the carbon atom at the C1 position of the arylpropane unit of lignin. The composite material according to any one of (1) to (8), having a propane unit.
(10) The lignophenol derivative comprises a lignocellulosic material to which is added a phenol derivative containing a phenol derivative in which at least one ortho position with respect to the phenolic hydroxyl group is not substituted and a phenol derivative in which at least the para position is not substituted; The composite material according to (9), obtained by contacting with an acid.
(11) The composite material according to (9) or (10), wherein the phenol derivative constituting the second unit has a substituent at two ortho positions.
(12) The composite material according to (11), wherein the phenol derivative is 2,6-dimethylphenol.
(13) The composite material according to any one of (1) to (12), wherein the lignin matrix contains an inorganic material.
(14) The composite material according to (13), wherein the inorganic material is a metal salt.
(15) The composite material according to (13) or (14), wherein the inorganic material is non-alkali swellable.
(16) The composite material according to any one of (1) to (14), which contains an alkali-swellable material.
(17) The composite material according to (9), wherein the alkali-swellable material is a cellulosic material.
(18) The composite material according to any one of (1) to (10), further including a fiber material.
(19) A method for producing a composite material having a lignin matrix,
The following (a) to (c):
(A) a lignophenol having a first 1,1-bis (aryl) propane unit in which the carbon atom in the ortho position relative to the phenolic hydroxyl group of the phenol derivative is bonded to the carbon atom in the C1 position of the arylpropane unit of lignin Derivative
(B) A secondary derivative obtained by performing one kind of reaction selected from hydroxyl group protection treatment, alkali treatment, and crosslinkable group introduction reaction on the lignophenol derivative and having the first unit, as well as
(C) A higher-order derivative obtained by performing two or more kinds of reactions selected from a hydroxyl group protection treatment, an alkali treatment, and a crosslinkable group introduction reaction on the lignophenol derivative and having the first unit.
A sufficient amount of one or more lignin-based polymers selected from the group consisting of:
Other constituent materials compounded with the lignin matrix,
And a step of forming a matrix composition containing the above by pressing and / or heating.
(20) The method according to (19), wherein the lignin-based matrix contains at least the lignin-based polymer that has undergone a crosslinkable group introduction reaction, and is crosslinked during the molding step.
(21) The lignophenol derivative in the lignin polymer that has undergone the crosslinkable functional group introduction reaction is such that the phenol derivative constituting the first unit has a substituent at the para position and the remaining ortho position is substituted. The method according to (19) or (20), wherein the phenol derivative and / or the para position and the remaining ortho position are not substituted.
(22) A method of using a composite material,
A composite material having a lignin matrix,
The lignin matrix includes the following (a) to (e):
(A) a lignophenol having a first 1,1-bis (aryl) propane unit in which the carbon atom in the ortho position relative to the phenolic hydroxyl group of the phenol derivative is bonded to the carbon atom in the C1 position of the arylpropane unit of lignin Derivative
(B) A secondary derivative obtained by performing one kind of reaction selected from a hydroxyl group protection treatment, an alkali treatment, and a crosslinkable group introduction reaction on the lignophenol derivative and having the first unit.
(C) A higher-order derivative obtained by performing two or more kinds of reactions selected from a hydroxyl group protection treatment, an alkali treatment, and a crosslinkable group introduction reaction on the lignophenol derivative and having the first unit. ,
(D) a crosslinked derivative of a secondary derivative obtained by crosslinking a secondary derivative obtained by a crosslinkable group introduction reaction among the secondary derivatives, and
(E) Of the higher-order derivatives, a crosslinked product of a higher-order derivative in which a higher-order derivative obtained through a crosslinkable group introduction reaction is crosslinked
A step of decomposing a composite material having one or more lignin polymers selected from the group consisting of:
One or more reactions selected from hydroxyl group protection treatment, alkali treatment, and crosslinkable group introduction reaction on the lignin polymer in the alkali-treated lignin matrix obtained in the decomposition step. To obtain a higher order derivative,
A method comprising:
[0010]
According to the means of (1) to (18), the first unit provided in the lignophenol derivative, secondary derivative and higher derivative in the polymer material is low in the crosslinked product of these derivatives by alkali treatment. It causes molecularization and structural transformation. As a result, the lignin-based matrix loosens or collapses, and at the same time, other composite materials are separated from the lignin-based matrix, and as a result, the composite material is decomposited. Here, decompositing means loosening or at least partial collapse of the composite state of the composite material. Decomposition also means separation of the matrix constituent material from the composite material to an extent that allows at least partial recovery of the matrix constituent material.
Moreover, according to the means of (19) to (21), a composite material that can be easily decomposited is provided.
According to the means (22), the lignophenol derivative, secondary derivative, higher derivative and cross-linked product in the polymer material are reduced in molecular weight and converted in structure by decomposition by alkali treatment. These various derivatives can be derivatized by the above-described various reactions even after molecular weight reduction and structural conversion. For this reason, according to this method, the lignin matrix can be used over a long period of time while changing the structure sequentially.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
The composite material of the present invention is characterized in that the lignin matrix has one or more of the above lignin polymers (a) to (e). Such a composite material can be obtained by pressurizing and / or heating the composite material composition containing the lignin-based polymers of the above (a), (b) and (c). In particular, when these lignin-based polymers have been subjected to a crosslinkable group introduction reaction, composites having a matrix containing the lignin-based polymers (d) and (e) above under predetermined heating conditions Material can be obtained.
Hereinafter, the matrix composition will be described, and then the composite material finally obtained and its use will be described.
[0012]
The lignin polymers of the above (a), (b) and (c), which are both components of the composite material composition and the lignin matrix of the composite material in the present invention, will be described.
The lignin-based polymer (a) has a first 1-position in which the carbon atom in the ortho position with respect to the phenolic hydroxyl group of the phenol derivative is bonded to the carbon atom in the benzyl position (side chain C1 position) of the phenylpropane unit of lignin. , A lignophenol derivative having a 1-bis (aryl) propane unit. The lignin polymers of (b) and (c) are both obtained by further derivatizing the lignophenol derivative of (a).
These lignin-based polymers have a second 1,1-bis (aryl) in which the carbon atom at the para position relative to the phenolic hydroxyl group of the phenol derivative is bonded to the carbon atom at the C1 position of the arylpropane unit of lignin. Lignophenol derivatives having propane units can also be included.
[0013]
Each of these various lignin-based polymers has the first unit described above. In addition, the introduced phenol derivative in the first unit is also retained in the above (d) and (e), which are crosslinked products of these lignin polymers. That is, in these lignin-based polymers, the introduced phenol derivative in the first unit can be used as a switching element (first element) for deconjugation, and the polymer skeleton can be cleaved at the element site. .
Therefore, by using the lignin polymers of the above (a) to (e), it is possible to achieve both complexation and decomplexation with a lignin matrix.
On the other hand, unlike the first unit, the second unit suppresses cleavage of the polymer skeleton at the site. That is, the introduced phenol derivative in the second unit can be used as an element (second element) that restricts decomposition.
In the following description, the lignophenol derivative having the first unit, which is the lignin-based polymer of (a), is referred to as a primary derivative, a secondary derivative (above (b)) produced from this primary derivative, and a high The concept including the next derivative (above (c)) is referred to as a lignophenol derivative, and is particularly referred to as a lignophenol derivative when the type of derivative is not specified. Further, when specifically referring to the respective derivatives, they are described as a primary derivative, a secondary derivative, and a higher-order derivative, respectively. In the secondary derivative and the higher derivative, those having a crosslinkable group introduction reaction and a crosslinkable group introduced are referred to as crosslinkable bodies. Further, the term “crosslinked product of lignophenol derivative” includes both a crosslinked product of the secondary derivative (above (d)) and a crosslinked product of the higher derivative (above (e)). When there is no cross-linked product, it is called a cross-linked product, and when distinguishing between a cross-linked product of a secondary derivative and a cross-linked product of a higher-order derivative, it is called a secondary cross-linked product and a high-order cross-linked product, respectively.
[0014]
(Lignophenol derivative)
(Primary derivative)
The primary derivative can usually be obtained by contacting an acid with a lignin-containing material, preferably a lignocellulosic material, which is affinityd by a predetermined phenol derivative. As for more general description of lignophenol derivatives and the production process thereof, JP-A-2-23701, JP-A-9-278904 and International Publication WO99 / 14223, 2001-64494, No. 2001-261839, 2001-131201, and 2001-34233 (the contents described in these patent documents are all incorporated herein by reference).
[0015]
Hereinafter, this manufacturing process will be described.
As shown in FIG. 1, the present production process is particularly effective in that the lignocellulosic material is solvated with a phenol derivative in advance, or the phenol derivative is sorbed onto the lignocellulosic material, and then the lignocellulosic material is mixed with an acid. By contacting, the complex state of lignocellulose is relaxed, and at the same time, the phenol derivative is selectively grafted to the C1 position (benzyl position) of the arylpropane unit of natural lignin to produce a lignophenol derivative, This method can be separated into cellulose and lignophenol derivatives.
A lignophenol derivative means a polymer containing a 1,1-bis (aryl) propane unit in which a phenol derivative is introduced by a C—C bond at the C1 position of an arylpropane unit of lignin. The lignophenol derivative itself is a mixture of lignin-derived polymers obtained by reaction and separation from lignocellulosic materials, and the amount and molecular weight of the introduced phenol derivative in the obtained polymer are the lignocellulosic materials used as raw materials. Varies with material and reaction conditions.
[0016]
The “lignocellulosic material” used in the present invention is a woody material, various materials mainly wood, for example, wood flour, chips, agricultural waste associated with wood resources such as waste wood, scraps, waste paper, etc. And industrial waste. In addition, as a kind of wood to be used, any kind of wood such as conifers and hardwoods can be used. Furthermore, various herbaceous plants and related agricultural and industrial wastes can be used.
[0017]
A monovalent phenol derivative, a divalent phenol derivative, a trivalent phenol derivative, or the like can be used as a phenol derivative for solvating a lignocellulose-based substance on a solvated or lignocellulose-based material.
Specific examples of the monovalent phenol derivative include phenol which may have one or more substituents, naphthol which may have one or more substituents, and one or more substituents. A good anthrol, an anthroquinone all optionally having one or more substituents, and the like can be mentioned.
Specific examples of the divalent phenol derivative include catechol which may have one or more substituents, resorcinol which may have one or more substituents, and one or more substituents. Examples include good hydroquinone.
Specific examples of the trivalent phenol derivative include pyrogallol, which may have one or more substituents.
In the present invention, one or more of monovalent phenol derivatives, divalent phenol derivatives and trivalent phenol derivatives can be used, and monovalent phenol is preferably used.
[0018]
The type of substituent that the monovalent to trivalent phenol derivative may have is not particularly limited, and may have an arbitrary substituent, but preferably an electron-withdrawing group (such as a halogen atom). A lower alkyl group-containing substituent having 1 to 4 carbon atoms, preferably 1 to 3 carbon atoms. Examples of the lower alkyl group-containing substituent include a lower alkyl group (such as a methyl group, an ethyl group, and a propyl group) and a lower alkoxy group (such as a methoxy group, an ethoxy group, and a propoxy group). Further, it may have an aromatic substituent such as an aryl group (such as a phenyl group). Further, it may be a hydroxyl group-containing substituent.
[0019]
These phenol derivatives are introduced into the phenylpropane unit by bonding a carbon atom in the ortho or para position to the phenolic hydroxyl group to the carbon at the C1 position of the phenylpropane unit of lignin. Therefore, in order to secure at least one introduction site, it is preferable that a substituent is not present in at least one of the ortho and para positions.
[0020]
From the above, in the present invention, in addition to the unsubstituted phenol derivative, at least one phenol derivative in various substituted forms having at least one unsubstituted ortho-position or para-position may be appropriately selected and used. it can.
[0021]
In this process, by selecting the type of the phenol derivative to be used, the frequency of introduction of the crosslinkable functional group into the resulting primary derivative can be adjusted, and as a result, the crosslinking reactivity of the prepolymer can be controlled.
That is, the introduction site of the crosslinkable group is ortho and para to the phenolic hydroxyl group. Further, the introduction site of the introduced phenol lignin into the phenylpropane unit is also in the ortho position or the para position with respect to the phenolic hydroxyl group. Therefore, the introduction site and the introduction amount of the crosslinkable functional group to the introduced phenol derivative are controlled by the introduction mode of the substituents at the ortho position and the para position (up to 3 sites) with respect to the phenolic hydroxyl group in the introduced phenol derivative. The amount introduced into the lignin matrix can also be controlled. For example, the substitution mode of the introduced phenol derivative, the binding site to lignin, and the introduction site of the crosslinkable group are as shown in the following table.
[Table 1]

[0022]
In this way, phenol derivatives having crosslinkable group introduction sites with different reactivities, or the number of introduction sites, or one or two or more different phenol derivatives are introduced into lignin to be later crosslinked. At the time of introduction of the group, the introduction site and number of the crosslinkable group can be controlled, and as a result, the crosslink density of the crosslinkable product obtained by crosslinking the crosslinkable product can also be controlled.
[0023]
In order to obtain a primary derivative having the first unit, a phenol derivative having no substituent at at least one ortho position (preferably all ortho positions) is used. Also, a phenol derivative (typically a 2,4-positioned monohydric phenol derivative having at least one ortho position (2-position or 6-position) having no substituent and a para-position (4-position) ) Is preferred. Most preferably, it is a phenol derivative (typically a 4-position substituted monohydric phenol derivative) in which all the ortho positions do not have a substituent and has a substituent in the para position. Therefore, the 4-position substituted phenol derivative and the 2,4-position substituted phenol derivative can be used alone or in combination of two or more.
[0024]
In order to obtain a primary derivative having the second unit, a phenol derivative (typically a 2-position (or 6-position) substituted monohydric phenol derivative) having no substituent at the para position is preferred, and more preferably At the same time, a phenol derivative (typically a 2,6-substituted monohydric phenol derivative) having a substituent at the ortho position (preferably, all ortho positions) is used. That is, it is preferable to use one or two or more of 2-position (or 6-position) substituted phenol derivative and 2,6-position substituted phenol.
[0025]
Preferable specific examples of the phenol derivative include p-cresol, 2,6-dimethylphenol, 2,4-dimethylphenol, 2-methoxyphenol (Guaiacol), 2,6-dimethoxyphenol, catechol, resorcinol, homocatechol, pyrogallol And phloroglucinol.
In particular, p-cresol and / or 2,4-dimethylphenol can be used to construct the first unit in the lignophenol derivative. To construct the second unit, 2,6-dimethylphenol can be used.
[0026]
Although it does not specifically limit as an acid added to a lignocellulosic material, It is preferable to have the effect | action which swells a cellulose. For example, 65 wt% or more sulfuric acid (preferably 72 wt% sulfuric acid), 85 wt% or more phosphoric acid, 38 wt% or more hydrochloric acid, p-toluenesulfonic acid, trifluoroacetic acid, trichloroacetic acid, formic acid, etc. Can be mentioned. A preferred acid is 85% by weight or more (preferably 95% by weight or more) phosphoric acid, trifluoroacetic acid, or formic acid. In order to efficiently recover cellulose, water-soluble polysaccharides derived from hemicellulose, oligosaccharides and monosaccharides, it is preferable to use sulfuric acid. To recover cellulose in a form that retains the higher order structure of cellulose, phosphoric acid is preferred. It is preferable to use an acid having a low acid strength.
[0027]
As a method for converting lignin in the lignocellulosic material into a lignophenol derivative and separating it, the following three methods can be mentioned. Note that the present invention is not limited to these methods.
The first method is the method described in JP-A-2-233701. In this method, a lignocellulosic material such as wood flour is infiltrated with a liquid phenol derivative (as described above, for example, p-cresol or 2,4-dimethylphenol), and lignin is solvated with the phenol derivative. Next, a concentrated acid (as described above, for example, 72% sulfuric acid) is added to the lignocellulosic material and mixed to dissolve the cellulose component. According to this method, as shown in FIG. 1, a phenol derivative solvated with lignin and a concentrated acid in which a cellulose component is dissolved forms a two-phase separation system. The lignin solvated by the phenol derivative is contacted with the acid only at the interface where the phenol derivative phase is in contact with the concentrated acid phase, and a reaction occurs. That is, the cation at the side chain C1 position (benzyl position), which is a highly reactive site of the basic structural unit of lignin generated by interfacial contact with an acid, is attacked by the phenol derivative. As a result, the phenol derivative is introduced at the C1 position by a C—C bond, and the benzyl aryl ether bond is cleaved to reduce the molecular weight. As a result, the molecular weight of lignin is reduced, and at the same time, a lignophenol derivative in which a phenol derivative is introduced at the C1 position of the basic structural unit is produced in the phenol derivative phase. From this phenol derivative phase, a lignophenol derivative is extracted. The primary derivative is obtained as an assembly of low molecular weight forms of lignin in which the benzyl aryl ether bond in lignin is cleaved to reduce the molecular weight. It is known that some phenol derivatives are introduced into the benzyl position through the phenolic hydroxyl group.
FIG. 2 shows that a primary derivative having the first unit in the present invention can be obtained by subjecting natural lignin having an arylpropane unit to phase separation.
[0028]
The extraction of the primary derivative from the phenol derivative phase can be performed, for example, by the following method. That is, the precipitate obtained by adding the phenol derivative phase to a large excess of ethyl ether is collected and dissolved in acetone. The acetone insoluble part is removed by centrifugation, and the acetone soluble part is concentrated. The acetone soluble part is dropped into a large excess of ethyl ether, and the precipitate section is collected. The solvent is distilled off from this precipitation section to obtain the primary derivative. The crude primary derivative can be obtained by simply removing the phenol derivative phase by distillation under reduced pressure.
[0029]
In the second and third methods, a solvent (for example, ethanol or acetone) in which a solid or liquid phenol derivative (for example, p-cresol or 2,4-dimethylphenol) is dissolved in a lignocellulosic material is used. After permeation, the solvent is distilled off (phenol derivative sorption step). Next, a concentrated acid is added to the lignocellulosic material to dissolve the cellulose component. As a result, as in the first method, the lignin solvated with the phenol derivative is attacked by the phenol derivative with the cation at the highly reactive site (side chain C1 position) of the lignin generated in contact with the concentrated acid. Derivatives are introduced. In addition, the benzyl aryl ether bond is cleaved to lower the molecular weight of lignin. The characteristics of the obtained primary derivative are the same as those obtained by the first method. Then, in the same manner as in the first method, the phenol-derivatized lignophenol derivative is extracted with a liquid phenol derivative. The extraction of the primary derivative from the liquid phenol derivative phase can also be performed in the same manner as in the first method (this is referred to as the second method). Alternatively, the entire reaction solution after the concentrated acid treatment is put into excess water, the insoluble sections are collected by centrifugation, deacidified and then dried. The lignophenol derivative is extracted by adding acetone or alcohol to the dried product. Further, this soluble segment is dropped into excess ethyl ether or the like in the same manner as in the first method to obtain a primary derivative as an insoluble segment (this is referred to as a third method). Specific examples of the preparation method of the lignophenol derivative have been described above, but the preparation method is not limited to these, and it can be prepared by a method in which these are appropriately improved.
[0030]
Thus, in addition to having at least the first unit, 1,1-bis (aryl) in which the phenol derivative is grafted to the C1 position of the phenylpropane unit of lignin at the ortho or para position of the used phenol derivative A primary derivative having a propane unit can be obtained. In the obtained primary derivative, an arylpropane unit to which no phenol is grafted usually remains.
When trying to obtain a primary derivative into which two or more phenol derivatives are introduced, it can also be obtained by simultaneously using two or more phenol derivatives in the lignocellulosic material in the phenol sorption step in the phase separation treatment. Moreover, what introduce | transduced the single phenol derivative with respect to lignocellulosic material can be mixed. In the former case, it is like a copolymer, and in the latter case, it is like a polymer blend. These embodiments can be selected as necessary. From the viewpoint of adjusting the intramolecular switching function and the degree of crosslinking of the obtained primary derivative, the former derivative (copolymer-like embodiment) is obtained. It is useful.
[0031]
The frequency of introduction of the phenol derivative varies depending on the presence / absence, position, size, etc. of the substituent of the phenol derivative to be introduced. Therefore, the introduction frequency can be adjusted. In particular, the introduction frequency can be easily adjusted by steric hindrance due to the size of the substituent. When the introduction position or the like is to be controlled using a substituent, the introduction frequency can be easily adjusted depending on the number of carbon atoms and the branched form when a lower alkyl group is used as the substituent. When the substituent is a methyl group, the introduction position can be controlled while maintaining a high introduction frequency.
The general and general properties of the primary derivative obtained from the lignocellulosic material are listed below. However, the lignophenol derivative in the present invention is not intended to be limited to those having the following properties.
(1) The weight average molecular weight is about 2000 to 20000.
(2) There is almost no conjugated system in the molecule, and the color tone is very light. Typically a pale pink white powder.
(3) It has a solid-liquid phase transition point at about 170 ° C. derived from conifers and at about 130 ° C. derived from hardwoods.
(4) Easily soluble in methanol, ethanol, acetone, dioxane, pyridine, tetrahydrofuran, dimethylformamide and the like.
[0032]
A further derivative (secondary derivative) of lignin can be obtained by subjecting this primary derivative to an alkali treatment, a crosslinkable introduction reaction, a hydroxyl group protection treatment and the like. That is, an alkali-treated product and a crosslinkable product (prepolymer) are obtained, and a hydroxyl group-protected product can be obtained. Further, a higher-order derivative can be obtained by subjecting the secondary derivative subjected to any derivatization treatment to a different derivatization treatment.
Lignophenol derivatives inherently have caking properties, and when used as a constituent material of a lignin-based matrix, the composite material such as filler is well constrained to form a composite lignin-based matrix. Can be configured.
Hereinafter, the secondary derivative and the derivatization step will be described.
[0033]
(Crosslinkable group introduction reaction)
A prepolymer is obtained by reacting a primary derivative with a crosslinkable group-forming compound under alkaline conditions to introduce a crosslinkable group at the ortho-position and / or para-position of the phenolic hydroxyl group in the lignophenol derivative. Can do.
That is, the present prepolymer can be obtained by mixing and reacting the primary derivative with a crosslinkable group-forming compound in a state where the phenolic hydroxyl group of the primary derivative used can be dissociated. The state in which the phenolic hydroxyl group of the primary derivative can be dissociated is usually formed in a suitable alkaline solution. The kind, concentration and solvent of the alkali used are not particularly limited as long as the phenolic hydroxyl group of the primary derivative is dissociated. For example, a 0.1N sodium hydroxide aqueous solution can be used.
[0034]
Under such conditions, the crosslinkable group is introduced at the ortho-position or para-position of the phenolic hydroxyl group, and the introduction position of the crosslinkable group is roughly determined depending on the type and combination of the phenol derivatives used. That is, when the ortho-position and the para-position are disubstituted, a crosslinkable group is not introduced into the introduced phenol nucleus, but is introduced into the phenolic aromatic nucleus on the lignin base side. Since the phenolic aromatic nucleus on the base side is mainly present at the polymer terminal of the primary derivative, a prepolymer having a crosslinkable group introduced mainly at the polymer terminal is obtained. The upper part of FIG. 3 illustrates a prepolymer in which a hydroxymethyl group is introduced as a crosslinkable group (methylolated) in a primary derivative obtained using 2,4-dimethylphenol as an introduced phenol derivative.
In the case of 1 substitution or less at the ortho position and the para position, a crosslinkable group is introduced into the introduced phenol nucleus and the phenolic aromatic nucleus of the lignin matrix. Therefore, in addition to the end of the polymer chain, a crosslinkable group is introduced over the length, and a polyfunctional prepolymer is obtained. FIG. 3 shows a prepolymer in which a hydroxylmethyl group is introduced (methylolated) with respect to a primary derivative obtained using p-cresol as an introduced phenol derivative.
[0035]
Therefore, crosslinkability can be adjusted by combining a 2-substituted phenol derivative and a phenol derivative having 1 or less substitution. In the present invention, when a disubstituted phenol derivative typified by 2,4-dimethylphenol and / or 2,6-dimethylphenol is used, the prepolymer is imparted with a linear polymer forming ability (right side of FIG. 3). ). Moreover, when the phenol derivative below 1 substitution represented by p-cresol is used, network polymer formation ability is provided to a prepolymer (left side of FIG. 3). By using a combination of a 2-substituted phenol derivative and a mono- or lower substituted phenol derivative, the network property can be adjusted.
[0036]
The kind of the crosslinkable group introduced into the primary derivative is not particularly limited. Any material that can be introduced into the aromatic nucleus of the lignin matrix or the aromatic nucleus of the introduced phenol derivative may be used. Examples of the crosslinkable group include a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, and a 1-hydroxyvaleraldehyde group. The crosslinkable group forming compound is a nucleophilic compound that forms or retains a crosslinkable group after bonding. For example, formaldehyde, acetaldehyde, propionaldehyde, glutaraldehyde, etc. can be mentioned. Considering introduction efficiency and the like, it is preferable to use formaldehyde. In addition, polymerizable compounds such as various diisocyanates can be used.
[0037]
When mixing the primary derivative and the crosslinkable group-forming compound, from the viewpoint of efficiently introducing the crosslinkable group, the crosslinkable group forming compound is converted to an aromatic nucleus and / or an introduced phenol of the lignin arylpropane unit in the lignophenol derivative. It is preferable to add 1 mol times or more of the nucleus. More preferably, it is 10 mol times or more, More preferably, it is 20 mol times or more.
[0038]
Next, in a state where the lignophenol derivative and the crosslinkable group forming compound are present in the alkaline liquid, the crosslinkable group is introduced into the phenol nucleus by heating the liquid as necessary. The heating conditions are not particularly limited as long as the crosslinkable group is introduced, but 40 to 100 ° C. is preferable. Less than 40 ° C. is not preferable because the reaction rate of the crosslinkable group forming compound is very low, and higher than 100 ° C. is preferable because side reactions other than the introduction of the crosslinkable group into lignin such as the reaction of the crosslinkable group forming compound itself are activated. Absent. More preferably, it is 50-80 degreeC, for example, about 60 degreeC is especially preferable. The reaction is stopped by cooling the reaction solution, acidified (about pH 2) with an appropriate concentration of hydrochloric acid, etc., and the acid and unreacted crosslinkable group forming compound are removed by washing, dialysis and the like. Collect the sample by lyophilization after dialysis. If necessary, vacuum dry over diphosphorus pentoxide.
[0039]
The prepolymer thus obtained is crosslinkable at the ortho position and / or para position with respect to the phenolic hydroxyl group in the 1,1-bis (aryl) propane unit containing the first unit or the second unit or the arylpropane unit of lignin. Have a group.
The first preferable crosslinkable body includes a crosslinkable unit having a crosslinkable group at the ortho position and / or the para position with respect to the phenolic hydroxyl group of the introduced phenol nucleus in the first and / or second unit. It is characterized by that. In addition, the second preferred crosslinkable substance is crosslinked only at the ortho position and / or the para position of the phenolic hydroxyl group of the phenol nucleus on the lignin base side in the first and / or second unit and / or phenylpropane unit. A crosslinkable unit having a functional group is provided. Furthermore, the third crosslinkable body is characterized by comprising the first crosslinkable unit and the second crosslinkable unit.
[0040]
Although the weight average molecular weight of this prepolymer is not specifically limited, Usually, it is 2000-20000, Preferably it is about 2000-10000. Moreover, the introduction amount of the crosslinkable group is usually about 0.01 to 1.5 mol / C9 unit in many cases.
[0041]
(Hydroxyl protection treatment)
Hydroxyl group protection treatment introduces an acyl group (acetyl group, propionyl group, butyryl group, valeryl group, benzoyl group, toluoyl group, preferably acetyl group) to the phenolic and alcoholic hydroxyl groups in the lignophenol derivative. Preferably it is done. Specifically, it is carried out by contacting with acetic anhydride or the like. By the acylation treatment, the hydroxyl group is protected. For this reason, the characteristic expression by a hydroxyl group is suppressed. For example, hydrogen bonding may be reduced and association may be reduced.
[0042]
(Alkali treatment)
The alkali treatment is performed by bringing the lignophenol derivative into contact with an alkali. Preferably it heats. In the alkali treatment, as shown in FIG. 4, the C2-position carbon is attacked by the phenoxide ion of the introduced phenol derivative in the first unit. That is, once this reaction occurs, the C2 aryl ether bond is cleaved. In the present invention, the phenol derivative introduced into the first unit is used as a switching element for decomposition. That is, in the obtained secondary derivative, the first unit needs to be retained. Therefore, the alkali treatment as the derivatization step should be performed to such an extent that the C2 aryl ether bond is not cleaved in all the first units, and finally an incomplete alkali treatment that can maintain the first unit is required. become.
[0043]
For example, in a mild alkali treatment, as shown in FIG. 4, when the primary derivative has a first unit, the phenolic hydroxyl group of the introduced phenol derivative is cleaved, and the resulting phenoxide ion has a C2 aryl ether bond. The constituting C2 position can be attacked in an intramolecular nucleophilic reaction to cleave the ether bond to reduce the molecular weight.
By cleaving the C2 aryl ether bond, a phenolic hydroxyl group is generated in the mother nucleus of lignin (refer to the right side of FIG. 4, dotted line circle). In addition, the intramolecular nucleophilic reaction expresses a structure (arylcoumaran unit) in which the introduced phenol nucleus forms a coumaran skeleton with the phenylpropane unit into which the introduced phenol nucleus is introduced.
As a result, the phenolic hydroxyl group on the phenol derivative side (left side of FIG. 4, dotted circle) is moved to the lignin mother nucleus side (right side of FIG. 4, dotted circle). The disappearance of the phenolic hydroxyl group from the introduced phenol derivative can contribute to the improvement of hydrophobicity.
Therefore, in the lignophenol derivative having the first unit, (1) low molecular weight by cleavage of C2 aryl ether bond at the site where the first unit is present, (2) expression of arylcoumaran structure, (3) A phenolic hydroxyl group on the side of the lignin mother nucleus bonded with a C2 aryl ether bond is expressed.
[0044]
Specifically, the alkali treatment is performed by dissolving a cross-linked lignophenol derivative in an alkali solution, reacting for a predetermined time, and heating if necessary. The alkali solution that can be used in this treatment is not particularly limited as long as it can dissociate the phenolic hydroxyl group of the introduced phenol derivative in the lignophenol derivative, and the type and concentration of alkali and the type of solvent are not particularly limited. . This is because if the phenolic hydroxyl group is dissociated under an alkali, a coumaran structure is formed due to the effect of neighboring group participation. For example, in a lignophenol derivative into which p-cresol is introduced, a sodium hydroxide solution can be used. For example, the alkali concentration range of the alkaline solution can be 0.5 to 2 N, and the treatment time can be about 1 to 5 hours. The lignophenol derivative in the alkaline solution easily develops a coumaran structure when heated. Conditions such as temperature and pressure during heating can be set without any particular limitation. For example, by reducing the alkaline solution to 100 ° C. or higher (for example, about 140 ° C.), it is possible to reduce the molecular weight of the cross-linked lignophenol derivative. Furthermore, the molecular weight of the crosslinked product of the lignophenol derivative may be reduced by heating the alkaline solution to the boiling point or higher under pressure.
[0045]
It has been found that at the same concentration in the same alkaline solution, when the heating temperature is in the range of 120 ° C. to 140 ° C., the higher the heating temperature, the lower the molecular weight due to the cleavage of the C2-aryl ether bond. In addition, it has been found that the higher the heating temperature in this temperature range, the more phenolic hydroxyl groups derived from the aromatic lignin derived from the lignin matrix and the fewer phenolic hydroxyl groups derived from the introduced phenol derivative. Therefore, the degree of molecular weight reduction and the degree of conversion of the phenolic hydroxyl moiety from the C1-introduced phenol derivative side to the phenol nucleus of the lignin matrix can be adjusted by the reaction temperature. That is, a reaction temperature of about 80 to 140 ° C. is preferred in order to obtain an aryl coumaran body in which low molecular weight is promoted or more phenolic hydroxyl sites are converted from the C1-introduced phenol derivative side to the lignin matrix. .
[0046]
Although the cleavage of C2-aryl ether by participation of adjacent group of C1 phenol nucleus is accompanied by the formation of arylcoumaran structure as described above, the reduction of the molecular weight of the cross-linked lignophenol derivative is not necessarily generated efficiently by aryl claman. It is not necessary to carry out under the condition (around 140 ° C.), and it can be carried out at a higher temperature (for example, around 170 ° C.) depending on the material or purpose. In this case, once the generated claman ring is cleaved and the phenolic hydroxyl group is regenerated on the introduced phenol derivative side, a material having higher phenol activity than that of the 140 ° C. treated product can be induced.
[0047]
From the above, the heating temperature in the alkali treatment is not particularly limited, but is preferably 80 ° C. or higher and 200 ° C. or lower. This is because the reaction does not proceed sufficiently when the temperature is greatly below 80 ° C., and an undesirable side reaction tends to be easily induced when the temperature is greatly above 200 ° C.
[0048]
As a preferable example of the treatment for formation of the Kuraman structure and the accompanying reduction in molecular weight, a 0.5N sodium hydroxide aqueous solution is used as an alkaline solution, and a heating time of 60 minutes at 140 ° C. in an autoclave can be exemplified. . In particular, this treatment condition is preferably used for lignophenol derivatives derivatized with p-cresol or 2,4-dimethylphenol.
[0049]
(Higher derivative)
Various secondary derivatives can be obtained by these secondary derivatization treatments.
Further, these secondary derivatives can be further derivatized by performing the above-described treatments (preferably different types of treatment).
In this case, it is possible to obtain a higher-order derivative that retains a combination of structural features generated by the applied treatment. For example, alkali treatment and crosslinkable introduction reaction, alkali treatment and hydroxyl group protection treatment, crosslinkable group introduction reaction and hydroxyl group protection treatment can be combined.
[0050]
(Composition for composite materials)
Composite materials are molded compositions for composite materials containing such lignin-based polymers (various derivatives other than cross-linked products) and other materials such as fillers to be combined with lignin-based matrices (materials to be composited). Can be obtained.
There are no particular limitations on other materials that are combined with the lignin matrix, and organic or inorganic materials can be used. As the organic material, various natural or synthetic resins can be used. For example, a cellulosic material can be used.
[0051]
Examples of the inorganic material include ceramics, glass, metal, and inorganic salts. Since the lignin-based matrix has a good binding force, even a material having a low self-assembly property can be well held in the matrix. Therefore, the material can be employed regardless of various forms such as spherical particles, needles, chips, etc., as well as those having a confounding property such as fibers.
Inorganic materials are preferable in that reusability is easily ensured after decompositing because physical and / or chemical changes due to alkali treatment are relatively small.
FIG. 5 illustrates a scheme in which various lignophenol derivatives and an inorganic material are combined.
[0052]
Considering decompositing by alkali treatment, the composite material preferably has alkali swellability. That is, the structure is preferably softened or swollen by alkali. At the same time, hydrophilicity is also preferred. In the case of having alkali swellability and hydrophilicity, the alkali solution at the time of alkali treatment becomes easy to access the polymer material of the lignin matrix, and as a result, the polymer skeleton is collapsed by the introduced decompositing element. It tends to occur.
The alkali swellable material preferably exhibits its alkali swellability in a certain temperature range. That is, it is preferable to swell with alkali in the temperature range for the alkali treatment to be carried out. Alternatively, the alkali treatment temperature can be set based on the temperature dependence of the alkali swellability of the alkali swellable material to be used.
[0053]
In addition, when a composite material that does not have alkali swellability is used, it is used in combination with a composite material that has alkali swellability, thereby increasing the accessibility to the first element by alkali. And good decomposition can be realized. Further, decompositing can be realized under mild conditions. The ability to realize decomposition under more relaxed conditions can minimize the structural conversion level of the lignin polymer and the composite material constituting the lignin matrix, and the separated lignin polymer to be separated. The degree of freedom of derivatization (which has a low molecular weight) can be increased, and at the same time, the sequential use of the composite material can be ensured.
From the viewpoint of ensuring high water resistance in the lignin matrix, the composite material is preferably prepared so as to mainly contain an alkali non-swellable material and contain an alkali swellable material.
Further, when the lignin polymer produced in the lignin matrix is a crosslinked polymer and is a network type polymer material (the composition for a composite material is a lignin polymer that is a crosslinkable material constituting the network polymer). In particular, it is preferable to contain an alkali swellable material from the viewpoint of ensuring accessibility by alkali.
[0054]
The alkali-swellable material is preferably easy to ensure uniform dispersibility from the viewpoint of ensuring alkali permeability. Therefore, it is preferable to have a powder form, a fiber form, etc. at least as a form before complexation. As long as it is fibrous, it may be a single fiber or a composite fiber. Furthermore, it may be a network-like or sheet-like body having a fibrous body as a constituent component.
As such an alkali-swellable material, as a material, in addition to cellulose (isolated natural cellulose), hydrophilic polymers such as various cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, cellulose acetate, methyl cellulose, hydroxy cellulose and the like are used. Can be used. Lignocellulose containing cellulose in a complex state with lignin can also be used.
Therefore, as specific alkali-swellable materials, cellulose fibers (including fine fiber powders), cellulose powders, lignocellulose fibers (including fine fiber powders), lignocellulose powders, and the like can be used.
The content of the alkali-swellable material varies depending on the cross-linked structure of the lignin matrix to be obtained and the type and composition of the other composite material, but the appropriate content depends on the alkali content of the composite material. It can be easily confirmed by a decompositing test by treatment. For example, when a prepolymer obtained by methylolating a primary derivative using p-cresol as an introduced phenol derivative is used as a lignin polymer, 100 parts by weight of the lignin polymer, 100 parts by weight of cellulose powder, and 800 parts by weight of talc. By preparing a composition for a composite material containing lignin, the recovery rate of the lignin polymer recovered by decomposition by alkali treatment is significantly improved as compared with the case where no cellulose powder is contained.
[0055]
Furthermore, in this composition, various additives can be included according to the use of the composite material in addition to the above-described materials. In particular, by using a filler that has plasticity or flexibility at room temperature, the composite material can be provided with internal stress relaxation and toughness. The shape may be spherical or indefinite, but is preferably fibrous. Typically, cellulose fibers or cellulose powders (including fine fiber powders) can be used. Therefore, the cellulosic fiber or the cellulosic fine fiber powder is useful as an alkali swellable or good quality filler.
[0056]
In the present composition, one or two or more of the various composite materials described above can be combined. Further, the ratio of the lignin polymer to the composite material in the present composition can be appropriately set in consideration of the function desired to be imparted to the composite material and the molding method.
In addition, in the present composition, the composite material obtained by molding the present composition is treated with an alkali so that a sufficient amount of lignin polymer is present in the composite material to decomposit the composite material. It is preferable to contain a lignin polymer. The appropriate amount for decompositing in the composite material depends on the type of lignin polymer in the final composite material and the type of composite material, but the appropriate content depends on the alkali treatment of the composite material. It can be easily confirmed by a decomposite test by.
[0057]
The preparation method and composition form of the composition for composite materials can be appropriately selected in consideration of the form of the material to be composited, and various forms can be adopted. It can be obtained by mixing the powdered lignophenol derivative and the composite material, or by impregnating the solid composite material with the lignophenol derivative dissolved in an appropriate solvent and drying it. be able to. Furthermore, it can also obtain by making a lignophenol derivative liquid osmose | permeate with respect to the to-be-composed composite material, and drying.
[0058]
(Composite material)
By heating and / or pressurizing the composite material composition, the composite material can be obtained by imparting a shape and forming a lignin matrix.
The molding method is not particularly limited, and various molding methods such as compression molding, injection molding, extrusion molding, blow molding, foam molding, casting molding, and spinning can be adopted as necessary.
Since lignophenol derivatives inherently have caking properties, they can also exert a binding force when pressurized. Preferably, pressurization is performed in a heated state. Heating and pressurization may be performed simultaneously or sequentially.
When the prepolymer is contained as the lignin-based polymer, it can be crosslinked by heating to obtain a crosslinked structure as shown in FIG. 6 in the matrix of the composite material at the same time as molding.
[0059]
The conditions for thermal crosslinking are not particularly limited as long as the crosslinking reaction can proceed. For example, it can be heated to about 150 ° C. to 180 ° C. under a temperature rising program condition of 1 ° C. to 2 ° C./min, and then cooled. Moreover, after temperature rising, after reaching | attaining maximum setting temperature, after hold | maintaining for 1 hour, the conditions to cool can be mentioned. Various cross-linked structures are shown in FIG.
[0060]
As described above, the crosslinked structure constructed by crosslinking is determined by the substitution site and the number of substitutions of the introduced phenol nucleus. The left side of FIG. 6 shows that, for example, a lignophenol derivative using p-cresol as a mono-substituted phenol is methyloled into a prepolymer and thermally crosslinked to form a network type polymer material. This is because in this prepolymer, crosslinkable groups are introduced throughout the molecular chain.
[0061]
On the other hand, on the right side of FIG. 6, a lignophenol derivative using 2,4-dimethylphenol as a disubstituted phenol is converted into a methylol to form a prepolymer and thermally crosslinked, thereby forming a linear crosslinked structure. It is shown. This is because in such a prepolymer, a crosslinkable group is introduced mainly at the polymer terminal.
[0062]
Furthermore, in the center of FIG. 6, by using monosubstituted phenol and disubstituted phenol as the introduced phenol derivative (typically, p-cresol and 2,4-dimethylphenol), It has been shown that a crosslinkable group is introduced into a primary derivative having a unit to form a prepolymer, and as a result, a polymer material in which a network type and a linear type are hybridized is obtained.
[0063]
The composite material thus obtained has the characteristics of a matrix made of a lignin polymer and the characteristics of the material to be composited. Even if the lignin matrix does not have a cross-linked structure formed during molding and is mainly composed of lignin polymers that are primary derivatives, secondary derivatives and higher derivatives, the matrix is based on its inherent caking properties. Configure.
Further, when the lignin-based matrix has a network-to-linear crosslinked structure newly formed at the time of molding, the matrix is constituted by the inherent caking property and the crosslinked structure. Regardless of the form of the cross-linked structure (network type and linear type), the cross-linked product is uniformly distributed in the matrix, and can give roughly approximate strength characteristics and dimensional stability (water resistance or water absorption). . Therefore, the mechanical strength and dimensional stability of composite materials are lignined, especially when materials that have little or little interaction between them and are chemically stable (typically inorganic materials) are used. There is a merit that it is not easily influenced by the matrix, and the characteristics of the inorganic material are easily obtained.
[0064]
On the other hand, when immersed in a solvent having high affinity for the lignophenol derivative, for example, THF, the higher the linearity of the cross-linked structure formed at the time of molding, the easier it was dissolved in THF and the composite material collapsed. In particular, when a prepolymer of a primary derivative using only one or less substituted phenol derivative (for example, p-cresol) is cross-linked, the network structure strongly restrains the composite material, and the shape of the composite material is reduced. Can be maintained. In addition, when a prepolymer of a primary derivative using only a 2,4-substituted phenol derivative (for example, 2,4-dimethylphenol) is cross-linked, it can be easily combined by immersion in a lignophenol derivative affinity solvent. It is possible to collapse the form.
[0065]
In the present invention, based on the fact that the lignophenol derivative has the first unit and the crosslinked body holds the first element (phenol derivative introduced at the ortho position) in the first unit, These can be reduced in molecular weight by alkali treatment. That is, by subjecting the composite material of the present invention to an alkali treatment, the reaction shown in FIG. 4 and / or FIG. 7 is caused in the lignin-based matrix, and the lignin-based polymer is reduced in molecular weight to realize the decomposition of the composite material. Can do.
The alkali treatment is performed on the composite material as it is, preferably on a piece or powder obtained by pulverization or the like. The alkali treatment conditions are not particularly limited as long as the composite material can be decomposited. Various conditions disclosed in the above-mentioned alkali treatment section can be adopted. For example, by reducing an alkaline solution such as NaOH of about 0.1N to 0.5N to 100 ° C. or higher (for example, about 140 ° C.), the molecular weight of the lignophenol derivative and its crosslinked product can be reduced. It can also be heated above the boiling point under pressure. As a mild condition, a temperature of about 80 ° C. or higher and about 150 ° C. or lower can be employed. Moreover, it can also carry out at about 150 degreeC or more and about 170 degrees C or less.
[0066]
According to this alkali treatment, the lignin matrix can be disrupted by selectively reducing the molecular weight of the lignophenol derivative or the first element inside the crosslinked body. Due to the low molecular weight, the lignin polymer such as the lignophenol derivative of the lignin matrix can be easily separated and recovered. In addition, the composite material can be easily separated and recovered. Therefore, any of these materials can be easily used sequentially.
In particular, the lignin-based polymer has a higher degree of freedom in derivatization due to the lowering of the molecule by the alkali treatment and the emergence of a new partial structure and phenolic hydroxyl group.
Further, decomposing by a simple process of alkali treatment is advantageous in that the cost of reuse can be reduced. In particular, it is advantageous that it can be decomposited even under mild alkaline conditions.
[0067]
In particular, in the present invention, deconjugation is easily achieved in the phenol derivative (switching element) inside the polymer of the lignin matrix. Therefore, as described above, the type of phenol derivative to be introduced and the frequency of introduction can be easily controlled, so that the introduction amount of the switching element can also be controlled. As a result, the decomposition performance according to the composite material to be obtained A decomposited form can be imparted.
In addition, as described above, the lignin matrix having a cross-linked structure exhibits approximate physicochemical properties regardless of the cross-linked structure. Is a big difference. This means that the dissolution solvent performance and the decomposition performance can be adjusted by the difference in the crosslinked structure.
[0068]
Further, if necessary, the accessibility of alkali to the lignin polymer in the lignin matrix can be easily adjusted by using an alkali swellable material, and the decompositing performance can also be adjusted.
[0069]
In addition, at the time of decomplexing, dissolution treatment with a lignophenol derivative affinity solvent can be performed simultaneously or separately. Here, as the affinity solvent, one or more solvents selected from methanol, ethanol, acetone, dioxane, pyridine, tetrahydrofuran, and dimethylformamide can be used simultaneously or sequentially. This dissolution treatment can be performed prior to the decompositing step by the alkali treatment or can be performed at a later stage.
[0070]
【Example】
Hereinafter, specific examples of the present invention will be described. The present invention is not limited to the following examples.
Example 1
Preparation of primary derivatives
About 1000 g of degreased cypress (Chamaecyparis obtusa) wood flour (lignocellulosic material) is placed in a 500 ml beaker and various phenol derivatives (p-cresol, p-cresol: 2,4-dimethylphenol = 1: 1, 2,4-dimethylphenol) in acetone (containing 3 moles of phenol derivative per unit of lignin C9), stir with a glass rod, cover the beaker with aluminum foil and parafilm, and let stand for 24 hours I let you. Thereafter, the wood flour was vigorously stirred in a fume hood, and acetone was completely distilled off to obtain various phenol derivative sorbent wood flours.
To this distillate, 5000 ml of 72 wt% sulfuric acid was added and stirred vigorously at 30 ° C. for 1 hour, then the mixture was poured into a large excess of water, and the insoluble fraction was centrifuged (3500 rpm, 10 minutes, 25 ° C.). The product was recovered, deacidified and freeze-dried to obtain three types of primary derivatives.
[0071]
(Example 2)
Introduction of crosslinkable groups into primary derivatives
5 g of each of the three types of primary derivatives obtained in Example 1 were dissolved in 500 ml of 0.1N NaOH aqueous solution, about 45 ml of 37% aqueous formaldehyde solution was added, and reacted at 60 ° C. for 3 hours in a nitrogen atmosphere. After completion of the reaction, 1N hydrochloric acid was added to acidify to pH 2. The resulting precipitate was collected by centrifugation (conditions, etc.), deoxidized, and lyophilized to introduce a hydroxymethyl group (methylolation). Three types of prepolymers were obtained. Hereinafter, based on the composition of the phenol derivative using these prepolymers, HM-ligno-p-cresol, HM-ligno-p-cresol: 2,4-dimethylphenol = 1: 1, HM-ligno-2, It is called 4-dimethylphenol. The obtained prepolymer was stored at -80 ° C.
[0072]
(Example 3)
Fabrication of composite materials
100 mg of each prepolymer obtained in Example 2 was dissolved in 10 ml of tetrahydrofuran (THF), and this solution was added to 900 mg of talc (particle size: about 10 to about 50 μm), mixed well, and then continuously stirred. Each prepolymer was sorbed onto talc by distilling off the tetrahydrofuran.
Each total amount of this sorption sample was transferred to the initial temp. Using a SHIMAZU flow tester CFT-500D. 70 ° C., Final Temp .; 180 ° C., Rate; 1.5 ° C./min, compression molding at 100 kg to cross-link each of the prepolymers, and a cylindrical composite material (molded body) containing a crosslinked body (diameter 10 mm) ) Was produced. A molded body was produced from 1000 mg of talc under the same molding conditions as a control molded body.
[0073]
Example 4
Fabrication of composite materials
Further, among the prepolymers obtained in Example 2, 100 mg of HM-ligno-p-cresol in tetrahydrofuran was added to the same mixture of 800 mg of talc and 100 mg of cellulose microfiber powder and mixed well. Then, by continuously stirring and distilling off the tetrahydrofuran, the prepolymer is sorbed into the mixture, and a molded body containing a crosslinked body is produced under the same compression molding conditions as above, and a cellulose-containing molded body is obtained. Produced.
[0074]
(Example 5)
Evaluation of composite materials
1. Appearance, dimensions, etc.
Although the talc used has a surface rich in irregularities, it has almost no self-aggregation property, so that the control molded body was very brittle and disintegrated easily when strongly touched. On the other hand, the various molded products of Example 3 were all light beige and excellent in surface smoothness.
Moreover, the measurement result about a weight, a dimension, and a density is shown in FIG. The dimensions were stable for the various molded articles of Example 3, and the density was about 1.8.
[0075]
2. SEM observation
When the surfaces of various molded bodies of the examples were observed by SEM, no clear matrix phase of the crosslinked body was observed. This means that the used lignin-based polymer is distributed in a uniform film form between talcs and functions well as a binder.
[0076]
3. Hardness test (Brinell Hardness)
The test was conducted in accordance with JIS2117 using SHIMADZU AG-1 10kN. A hard ball with a diameter of 10 mm is press-fitted into the center of the upper surface of each molded body at a speed of 0.5 mm / min, and the load P (N) required for the hard ball to intrude to a depth of 1 / πmm = 0.32 mm is measured. Hardness H using the following formula (1)_B(MPa) was measured.
H_B= P / 10 (1)
H_B: Brinell hardness (MPa)
P: Load (N)
[0077]
As shown in FIG. 9, the control molded body was 0.7 MPa, whereas the three types of molded bodies of Example 3 were all about 9 to 10 MPa, and all the crosslinked bodies had the same talc. It was found that the particles were firmly assembled and contributed to the improvement of physical strength. However, all of the molded articles of Example 3 tended to crack easily during the test.
On the other hand, although the cellulose containing molded object of Example 4 did not have a difference in Brinell hardness, the result by which formation of a crack was suppressed was obtained. According to this result, it was found that by using a flexible fibrous body such as cellulose in the composite matrix, the stress generated inside the molded body can be effectively relieved. That is, it was found that the elastic properties of the composite material can be easily adjusted by selecting the filler.
[0078]
4). Compression modulus (MOE)
The compression modulus of the molded body obtained in Example 3 was measured. The load speed was 960 N / cm · min.
As a result, as shown in FIG. 10, the control molded body was 12 MPa, whereas the three types of molded bodies of Example 3 were all about 50 to 60 MPa. It had almost the same compression modulus.
[0079]
5. Water absorption test
The molded body of Example 3 was placed on a stainless steel net and submerged in a container filled with water to a depth of 3 cm from the bottom of the molded body. When the molded body floated, a stainless steel net was installed 1 to 2 mm above the upper surface of the molded body to suppress further floating. After being immersed in water at room temperature for 60 minutes, the molded body was taken out and rolled on a filter paper to quickly remove the water on the surface. Dry at 60 ° C. for 3 days. At that time, the weight and dimensions before water absorption, after water absorption, and after drying were measured, and the water absorption rate Aw% and the volume expansion rate Vol% were obtained using the following formulas (2) and (3).
Aw% = (Wt’−Wt) / Wt × 100 (2)
Vol% = (Vol’−Vol) / Vol × 100 (3)
Aw%: Water absorption (% to sample weight)
Wt: Sample weight (g)
Wt ’: Sample weight after water absorption test (g)
Vol%: Volume expansion rate (% to sample volume)
Vol: Sample volume (cm^Three)
Vol ’: Sample volume after water absorption test or after re-drying (cm^Three)
[0080]
As a result, as shown in FIG. 11, all of the molded articles of Example 3 showed high water repellency, the water absorption after 1 hour water immersion was 0.6 w% or less, and the volume expansion under water absorption and drying conditions. The rate was also 1% or less. These results are based on the fact that each molded body has the water repellency possessed by talc and does not have water swellability.
[0081]
(Example 6)
Dissolution test of crosslinked products from composite materials
The three types of molded bodies of Example 3 were each immersed in 10 ml of tetrahydrofuran at 25 ° C. for 24 hours, and the amount of crosslinked body eluted in tetrahydrofuran was measured. The ratio to the amount of crosslinked body contained in the molded body ( %) Was calculated as the dissolution rate. The amount of the crosslinked product in tetrahydrofuran was determined by measuring the weight of the residue obtained by evaporating the eluate. Moreover, the amount of the crosslinked body contained in the molded body was calculated as 100 mg.
As a result, as shown in FIG. 12, from the talc-HM-ligno-p-cresol complex, the cross-linked product was not eluted at all, and the shape of the molded product was completely maintained. Further, the talc-HM-ligno-p-cresol: 2,4-dimethylphenol = 1: 1 complex was hardly eluted and the molded product shape was maintained. On the other hand, about 30% of the crosslinked product was rapidly eluted from talc-HM-ligno-2,4-dimethylphenol, and the molded product collapsed.
From the above results, it was found that the cross-linked HM-ligno-p-cresol formed a network type polymer structure and retained talc particles firmly.
[0082]
(Example 7)
Decompositing from composite materials
After pulverizing the three types of molded articles of Example 3 and the molded article of Example 4, 0.5N NaOH was added, followed by alkali treatment by heating at 140 ° C. for 1 hour, 170 ° C. for 1 hour and 2 hours. Thereafter, the alkali-treated liquid was separated into an insoluble fraction and a soluble fraction by filtration, and the insoluble fraction was dried and then weighed. For the soluble fraction, after measuring the total volume, the absorbance at 293 nm is measured, the amount of the recovered crosslinked product obtained by alkali treatment is calculated, and the ratio (%) to the amount of crosslinked product (100 mg) contained in the molded product Asked.
In calculating the amount of the alkali-treated material, the primary derivative (ligno-p-cresol) obtained using p-cresol was 293 nm per secondary derivative after heat treatment with 0.5N NaOH at 140 ° C. and 170 ° C. A calibration curve prepared based on the absorbance at was prepared, and this calibration curve was used. The results are shown in FIG.
[0083]
As shown in FIG. 13, in any of the molded bodies, the recovery rate improved as the energy level of the alkali treatment increased. In the case of the talc-HM-p-cresol complex (including a network type cross-linked structure in the matrix), the amount of alkali-solubilized alkali-treated material is about 20 at the most mild alkali treatment conditions (140 ° C., 1 hour). The alkali treatment conditions (170 ° C., 2 hours) with the highest energy level were about 70%. On the other hand, in the case of talc-HM-2,4-dimethylphenol complex (including a linear cross-linked structure in the matrix) and talc-p-cresol: 2,4-dimethylphenol = 1: 1 complex Even under the mildest alkali treatment conditions, a high separation rate could be obtained.
[0084]
Furthermore, in the talc-cellulose-HM-p-cresol composite, which is the molded product of Example 4, there was no significant difference in the recovery rate from the composite containing no cellulose under the alkali treatment conditions at 140 ° C. The recovery rate improved dramatically under the alkaline treatment conditions. This is because the cellulose swells under the condition of 170 ° C., and the contact frequency between the crosslinked body and the alkali is improved. Therefore, it was found that the effect of decompositing by the alkali treatment can be controlled by using the alkali swellability of the composite material and further its temperature dependency.
[0085]
(Example 8)
Molecular weight of alkali-treated material
A part of the alkali-soluble fraction obtained in Example 7 was collected, acidified to pH 2 by adding hydrochloric acid, the precipitate fraction was collected by centrifugation, and the average molecular weight was measured by GPC. . In addition, the sample for molecular weight measurement was prepared as follows.
□ 1 mg of sample was dissolved in rectified GPC eluent (THF) to prepare a sample. In addition, p-cresol was used as an internal standard substance.
The measurement was performed under the following conditions.
Equipment: SHIMAZU LC-10 system, LC10AD, SPD-10A
Column: Sodwex KF804, KF803, KF802, KF801
Eluent: Tetrahydrofuran (THF)
Flow rate: 1 ml / min
Pressure: 55kg / cm²
Detector: UV (280)
Range: 0.32
Sample volume: 25 μl
The calibration curve was prepared using polystyrene 400000, 233000, 100000, 25000, 9000, 4000, 2000, 906, bisphenol A and p-cresol as reference materials.
The measurement results of the molecular weight are shown in FIG. 14, and the GPC chart is shown in FIG.
[0086]
As shown in FIGS. 14 and 15, the molecular weight after alkali solubilization is maintained at a high level in HM-ligno-p-cresol, and HM-ligno-p-cresol: 2,4-dimethylphenol = 1: 1. In HM-2,4-dimethylphenol, the molecular weight was greatly reduced. This corresponds well with the results of alkali solubilization in Example 7. From the molecular weight measurement results, it can be seen that the degree of molecular weight reduction due to alkali treatment varies greatly depending on the morphology of the crosslinked product, that is, the presence or proportion of the network structure, and the decomplexation level changes accordingly. It was.
[Brief description of the drawings]
FIG. 1 is a diagram showing the principle of a production process of a lignophenol derivative (primary derivative).
FIG. 2 is a diagram showing that a primary derivative having a first unit is obtained by phase separation treatment for natural lignin having an arylpropane unit.
3 shows a prepolymer obtained by adding a crosslinkable group (HM group) to a primary derivative obtained by introducing 2,4-dimethylphenol as a phenol derivative in the upper part of FIG. 3, and this is shown in the lower part. The crosslinked state is shown.
FIG. 4 is a diagram showing a decomplexing mechanism in a primary derivative.
FIG. 5 is a diagram showing a scheme for compounding various lignophenol derivatives with inorganic materials.
FIG. 6 is a diagram showing an embodiment of a crosslinked structure obtained in a matrix of a composite material.
FIG. 7 is a diagram showing a decomplexing mechanism in a crosslinked body.
8 is a table showing the weight, dimensions, density, and the like of the composite obtained in Example 3. FIG.
FIG. 9 is a diagram showing a test result of Brinell hardness.
FIG. 10 is a diagram showing a test result of an elastic compressibility.
FIG. 11 is a combination of a diagram (a) showing the water absorption rate of the composite obtained in Example 3 and a diagram (b) showing the volume expansion coefficient.
12 is a table showing the elution rate of a crosslinked product from the composite obtained in Example 3. FIG.
FIG. 13 is a graph showing the recovery rate of the alkali-treated product after the decompositing treatment of the composites obtained in Examples 3 and 4.
FIG. 14 is a graph showing the measurement results of the molecular weight of the alkali-treated product in the alkali-soluble fraction obtained by the decompositing treatment.
FIG. 15 is a diagram showing a GPC chart obtained when measuring the molecular weight of the alkali-treated product in the alkali-soluble fraction obtained by the decompositing treatment.

Claims (22)

A method for producing a composite material having a lignin matrix,
The following (a) to (c):
(A) A lignophenol having a first 1,1-bis (aryl) propane unit in which the carbon atom in the ortho position with respect to the phenolic hydroxyl group of the phenol derivative is bonded to the carbon atom in the C1 position of the arylpropane unit of lignin. Derivative (b) A secondary derivative obtained by performing one kind of reaction selected from hydroxyl group protection treatment, alkali treatment and crosslinkable group introduction reaction on the lignophenol derivative and having the first unit And (c) the lignophenol derivative obtained by carrying out two or more kinds of reactions selected from a hydroxyl group protection treatment, an alkali treatment, and a crosslinkable group introduction reaction, and having the first unit be one or two or more of lignin polymer selected from the group consisting of the following derivatives via at least crosslinking groups introduced reaction Lignin-based polymer, and an amount sufficient to de-complex the alkali treatment the composite material of interest,
Other constituent materials combined with the lignin matrix,
And a step of forming a matrix composition containing the above by pressurizing and / or heating and crosslinking the introduced crosslinkable group . The (a) lignophenol derivative is obtained by contacting an acid with a lignocellulosic material to which one or more phenol derivatives including a phenol derivative in which at least one ortho position with respect to a phenolic hydroxyl group is not substituted is added. The manufacturing method of Claim 1 obtained by making it carry out . The manufacturing method according to claim 1 or 2, wherein the phenol derivative has a substituent at the para position and the remaining ortho position is not substituted. The production method according to claim 3, wherein the phenol derivative is p-cresol. The said phenol derivative is a manufacturing method of Claim 1 or 2 which has a substituent in para position and the remaining ortho position. The production method according to claim 5, wherein the phenol derivative is 2,4-dimethylphenol. The phenol derivative includes a phenol derivative ortho positions not substituted remaining substituted at the para-position, and a phenol derivative having an ortho-position and the substituent groups remaining para-position, according to claim 1 or 2 The manufacturing method as described in. The production method according to claim 7, wherein the phenol derivatives are p-cresol and 2,4-dimethylphenol. The lignophenol derivative comprises a second 1,1-bis (aryl) propane unit in which the carbon atom in the para position with respect to the phenolic hydroxyl group of the phenol derivative is bonded to the carbon atom in the C1 position of the arylpropane unit of lignin. The manufacturing method in any one of Claims 1-8 which has. The lignophenol derivative comprises a lignocellulosic material to which is added a phenol derivative containing a phenol derivative in which at least one ortho position with respect to the phenolic hydroxyl group is not substituted and a phenol derivative in which at least the para position is not substituted, an acid, The manufacturing method of Claim 9 obtained by making these contact. The production method according to claim 9 or 10, wherein the phenol derivative constituting the second unit has a substituent at two ortho positions. The method according to claim 11, wherein the phenol derivative is 2,6-dimethylphenol. The manufacturing method according to claim 1, wherein the lignin matrix contains an inorganic material. The manufacturing method according to claim 13, wherein the inorganic material is a metal salt. The manufacturing method according to claim 13 or 14, wherein the inorganic material is alkali non-swellable. The manufacturing method in any one of Claims 1-15 containing an alkali swellable material. The manufacturing method according to claim 16 , wherein the alkali-swellable material is a cellulosic material. Furthermore, the manufacturing method in any one of Claims 1-17 containing a fiber material. A method of using a composite material,
A composite material having a lignin matrix,
The lignin matrix includes the following (a) to (e):
(A) a lignophenol having a first 1,1-bis (aryl) propane unit in which the carbon atom in the ortho position relative to the phenolic hydroxyl group of the phenol derivative is bonded to the carbon atom in the C1 position of the arylpropane unit of lignin Derivative (b) A secondary derivative obtained by performing one kind of reaction selected from hydroxyl group protection treatment, alkali treatment, and crosslinkable group introduction reaction on the lignophenol derivative and having the first unit. (C) A higher-order derivative obtained by performing two or more kinds of reactions selected from a hydroxyl group protection treatment, an alkali treatment, and a crosslinkable group introduction reaction on the lignophenol derivative and having the first unit. ,
(D) A crosslinked derivative of a secondary derivative obtained by crosslinking a secondary derivative obtained by a crosslinkable group introduction reaction among the secondary derivatives, and (e) a crosslinkable group introduction reaction among the higher derivatives. A step of subjecting a composite material having one or more lignin-based polymers selected from the group consisting of a crosslinked derivative of a higher-order derivative to which the resulting higher-order derivative is crosslinked, to alkali treatment and decompositing;
One or more reactions selected from hydroxyl group protection treatment, alkali treatment, and crosslinkable group introduction reaction on the lignin polymer in the alkali-treated lignin matrix obtained in the decomposition step. To obtain a higher order derivative,
A method comprising:   The said phenol derivative contains the phenol derivative which has a substituent in the para position, and the remaining ortho position is not substituted, and / or the phenol derivative which has a substituent in the para position and the remaining ortho position. How to use.   The lignin matrix The use according to claim 20, which contains an inorganic material. Method.   The method according to any one of claims 19 to 21, comprising an alkali-swellable material.

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