JP4251513B2 - Liquid crystal polymer composition, retardation plate and elliptically polarizing plate - Google Patents

Description

（式中、Ｒ¹ は水素原子またはメチル基を、Ｘ¹ は−ＣＯＯ−基または−ＯＣＯ−基を、ｍおよびｎはそれぞれ独立に１〜６の整数を、ｐとｑはそれぞれ独立に１または２（ただし、ｐ＋ｑ≦３を満足する。）を、ｒは０または１を示す。）で表されるモノマーユニットがあげられる。上記の一般式（ａ１）で表されるモノマーユニットとしては、Ｒ¹ が水素原子、Ｘ¹ が−ＣＯＯ−基、ｍが２〜６の整数、ｎが１または２、ｐが１、ｑが２、ｒが０または１のものが好ましい。
本発明の側鎖型液晶ポリマー（Ａ）中の末端にアクリロイル基を有するモノマーユニットの割合は特に制限されないが、通常、側鎖型液晶ポリマー（Ａ）を構成する液晶性の側鎖を有するモノマーユニットの１モル％以上５０モル％以下とするのが好ましい。また、末端にアクリロイル基を有するモノマーユニットの割合が少なくなると側鎖型液晶ポリマー（Ａ）が傾斜配向を取り難くなる傾向があることから、末端にアクリロイル基を有するモノマーユニットの割合は、１０モル％以上とするのがより好ましい。一方、末端にアクリロイル基を有するモノマーユニットの割合が多くなると側鎖型液晶ポリマー（Ａ）の配向性が低下し均一性を維持できなくなる傾向があることから、末端にアクリロイル基を有するモノマーユニットの割合は、４０モル％以下とするのがより好ましい。
【００２２】
前記モノマーユニットとともに側鎖型液晶ポリマー（Ａ）を構成する液晶性の側鎖を有するモノマーユニットは、特に制限されないが、本発明の側鎖型液晶ポリマー（Ａ）は、正の誘電異方性を有するネマチック液晶性を示すことが好ましいため、ネマチック液晶性を示すモノマーユニットとして、特に、（ｂ）末端にシアノ基を有するモノマーユニットが好ましい。なお、（ｂ）末端にシアノ基を有するモノマーユニット以外のネマチック液晶性を示すモノマーユニットとしては、（ｃ）光学活性基を有するモノマーユニットや（ｄ）末端架橋基を有するモノマーユニットがあげられ、これらのモノマーユニットは、必要に応じて、側鎖型液晶ポリマー（Ａ）のモノマーユニットとするのが好ましい。
【００２３】
前記（ｂ）末端にシアノ基を有するモノマーユニットとしては、たとえば、一般式（ｂ１）：
【化４】

（式中、Ｒ² は水素原子またはメチル基を、Ｘ² は−ＣＯＯ−基または−ＯＣＯ−基を、j はｌ〜６の正の整数を、ｓおよびｔはそれぞれ独立に１または２（ただし、ｓ＋ｔ≦３を満足する。）を示す）で表されるモノマーユニットがあげられる。
【００２４】
また、（ｃ）光学活性基を有するモノマーユニットとしては、たとえば、一般式（ｃ１）：
【化５】

（式中、Ｒ³ は水素原子またはメチル基を、Ｒ⁴ は
【化６】

（式中、Ｒ⁵ は
【化７】

を示す）を、Ｘ³ は−ＣＯＯ−基または−ＯＣＯ−基を、ｋは１〜６の整数、を示す）で表されるモノマーユニットがあげられる。
【００２５】
また、（ｄ）末端架橋基を有するモノマーユニットとしては、モノマーユニットの側鎖の末端に、アクリロイル基以外の架橋基、たとえば、シクロヘキセン環等の不飽和二重結合を有するものがあげられる。
【００２６】
側鎖型液晶ポリマー（Ａ）の調製は、前記各モノマーユニットに対応する各種アクリル系またはメタクリル系液晶モノマー（以下、これらを単に（メタ）アクリル系液晶モノマーという）を、例えばラジカル重合方式、カチオン重合方式、アニオン重合方式などの通例の（メタ）アクリル系液晶モノマーの重合方式に準じて共重合することにより行うことができるが、前記末端にアクリロイル基を有するモノマーユニットや（ｄ）末端架橋基を有するモノマーユニットは、対応する（メタ）アクリル系モノマーを重合すると末端のアクリロイル基や架橋基も同時に重合するため、たとえば、一般式（ｅ）：
【化８】

（式中、Ｒ¹ 、Ｘ¹ 、ｍ、ｎ、ｐ、ｑ、ｒは前記と同じ。）で表される（ｅ）末端に水酸基を有するモノマーユニットを共重合した共重合体を調製した後に、当該水酸基に塩化アクリロイル等を反応させることにより、末端にアクリロイル基を有するモノマーユニットや（ｄ）末端架橋基を有するモノマーユニットを側鎖型液晶ポリマー（Ａ）中に導入するのが好ましい。その場合、側鎖型液晶ポリマー（Ａ）は、残存する（ｅ）末端に水酸基を有するモノマーユニットを含有してもよい。
【００２７】
また、前記（ｅ）末端に水酸基を有するモノマーユニットに対応する（メタ）アクリル系液晶モノマーの調製段階で、末端水酸基を保護する必要があるときは、水酸基を保護した形態の（メタ）アクリル系液晶モノマーを共重合して側鎖型液晶ポリマーを製造した後に、当該保護基の脱離をすることにより、（ｅ）末端に水酸基を有するモノマーユニットを側鎖型液晶ポリマーに導入することもできる。
【００２８】
なお、ラジカル重合方式を適用する場合、各種の重合開始剤を用いうるが、そのうちアゾビスイソブチロニトリルや過酸化ベンゾイルなどの分解温度が高くもなく、かつ低くもない中間的温度で分解するものが好ましい。
【００２９】
側鎖型液晶ポリマー（Ａ）の分子量は、通常、重量平均分子量に基づき２千〜１０万程度とされる。また、重量平均分子量が過少では、位相差板を調製する際に基板上に形成される液晶ポリマー組成物からなるフィルムの成膜性が乏しくなることから、重量平均分子量は２．５千以上とするのが好ましい。一方、重量平均分子量が過多では液晶としての配向性、特にラビング配向膜等を介したモノドメイン化に乏しくなって均一な配向状態を形成しにくくなることから、重量平均分子量は５万以下とするのが好ましい。
【００３０】
側鎖型液晶ポリマー（Ａ）に混合する、両末端にアクリロイル基を有し分子量６６２以下の液晶性低分子化合物（Ｂ）は、液晶性を有し、かつ分子末端（両端）にアクリロイル基を有する低分子化合物であればその骨格に特に限定はないが、側鎖型液晶ポリマー（Ａ）に混合した場合に、側鎖型液晶ポリマー（Ａ）の配向を乱さないような骨格のものが望ましい。
【００３１】
かかる液晶性低分子化合物（Ｂ）としては、たとえば、一般式（Ｂ１）：
【化９】

（式中、ＡおよびＤはそれぞれ独立して１，４−フェニレン基または１，４−シクロヘキシレン基を、Ｂは１，４−フェニレン基、１，４−シクロヘキシレン基、４，４' −ビフェニレン基または４，４' −ビシクロヘキシレン基を、Ｘ⁴ およびＸ⁵ はそれぞれ独立して−ＣＯＯ−基、−ＯＣＯ−基または−Ｏ−基を、ｇおよびｈはそれぞれ独立して２〜６の整数を示す）で表される化合物があげられる。かかる一般式（Ｂ１）で表される化合物としては、Ａ、ＢおよびＤがいずれも１，４−フェニレン基、Ｘ⁴ が−ＣＯＯ−基、Ｘ⁵ が−ＯＣＯ−基、ｇおよびｈがいずれも２の化合物が好ましい。
【００３２】
本発明の液晶ポリマー組成物は、側鎖型液晶ポリマー（Ａ）および液晶性低分子化合物（Ｂ）を含有してなり、側鎖型液晶ポリマー（Ａ）に混合する液晶性低分子化合物（Ｂ）の添加量により、当該液晶ポリマー組成物からなるフィルムの傾斜配向の度合い（平均傾斜角）を連続的に制御可能としたものである。
【００３３】
側鎖型液晶ポリマー（Ａ）に混合する液晶性低分子化合物（Ｂ）の添加量は、特に制限されないが、通常、側鎖型液晶ポリマー（Ａ）１００重量部に対して、５重量部以上５０重量部以下が望ましい。液晶性低分子化合物（Ｂ）の添加量が少ないと、本発明の液晶ポリマー組成物からなるフィルムが十分な傾斜配向をとり難いため、液晶性低分子化合物（Ｂ）の添加量は１０重量部以上とするのがより好ましい。一方、液晶性低分子化合物（Ｂ）の添加量が多くなると本発明の液晶ポリマー組成物からなるフィルムの配向性が低下し均一性に劣るため、液晶性低分子化合物（Ｂ）の添加量は４０重量部以下とするのがより好ましい。
【００３４】
本発明の液晶ポリマー組成物から、得られるフィルム面に対し液晶ポリマー組成物の配向方向が傾斜しているフィルムを形成する方法は、従来の配向処理に準じた方法を採用できる。
【００３５】
かかる方法としては、たとえば、基板上にポリイミドやポリビニルアルコール等からなる配向膜を形成してそれをレーヨン布等でラビング処理した後、その上に液晶ポリマー組成物を展開し、次いで液晶ポリマー組成物のガラス転移温度以上、等方相転移温度未満に加熱して液晶ポリマー組成物の分子を傾斜配向させた後、その傾斜配向した状態でガラス転移温度未満に冷却してガラス状態とし、当該液晶ポリマー組成物の配向を固定化してフィルムを形成する方法等が挙げられる。かかる方法において配向処理効率の点から配向処理温度は、液晶ポリマー組成物のガラス転移温度よりも３０〜７０℃、就中、約５０℃高い温度に加熱してするのが好ましい。
【００３６】
前記基板としてはガラス板等の無機質材料や、プラスチックフィルム等の高分子材料を使用できる。プラスチック基板としては、トリアセチルセルロース、ポリカーボネート、ポリスルホン、ポリエーテルスルホン、ポリエチレンテレフタレートなどが好ましい。
【００３７】
また、液晶ポリマー組成物の配向処理方法としては、上記配向膜をラビングする方法の代わりに、延伸フィルムを配向膜として用いる方法や、シンナメートやアゾベンゼンを有するポリマーまたはポリイミドに偏光紫外線を照射して配向膜として用いる方法を採用することもできる。
【００３８】
液晶ポリマー組成物の基板上への展開は、加熱溶融方式によってもよいし、溶剤に溶解した溶液として展開することもできる。当該溶剤としては、例えば塩化メチレンやシクロヘキサノン、トリクロロエチレンやテトラクロロエタン、Ｎ−メチルピロリドンやテトラヒドロフラン，ジメチルホルムアミドなどを適宜に選択して使用できる。展開にあたっては、ノアーコーターやスピナー、ロールコーターなどの塗工機を適宜に使用することができる。
【００３９】
なお、液晶ポリマー組成物をフィルム化し、次いで配向させたのち、必要に応じて、末端にアクリロイル基を有するモノマーユニットの末端アクリロイル基、（ｄ）末端架橋基を有するモノマーユニットの末端架橋基や、液晶性低分子化合物（Ｂ）の末端アクリロイル基を架橋させて、液晶ポリマー組成物の配向をさらに固定化することもできる。架橋させるにはＵＶ、電子線などの電磁波が使用できる。特に電子線照射による架橋は、液晶ポリマー組成物の配向性低下を招きやすい開始剤を必要としないので有利である。
【００４０】
基板上に形成する液晶ポリマー組成物からなるフィルムの厚さは、補償すべき液晶セルの特性によって適宜に調整すればよいが、通常０．１〜１０μｍ程度、就中０．２〜３μｍが好ましい。
【００４１】
このように配向処理して基板上に形成した液晶ポリマー組成物からなるフィルムは、液晶ポリマー組成物の配向方向がフィルム面に対し傾斜しており、液晶セルの視野角を補償するための位相差板として使用される。位相差板は液晶セルの片側または両側に配置される。また、複数の位相差板を積層した構造としてもよく、その場合、板面の遅相軸の方向をずらして積層してもよい（例えば２枚の位相差板を直交させる）。
【００４２】
かかる位相差板は、単独で液晶セルに適用することもできるが、偏光板と貼り合わせ積層体とした楕円偏光板として使用することもできる。楕円偏光板の液晶セルに対する配置位置は特に制限されないが、位相差板が偏光板と液晶セルの間になるように配置するのが一般的である。
【００４３】
偏光板としては、偏光機能を有するものを特に制限なく使用できる。具体的には、ポリビニルアルコール系フィルム、部分ホルマール化ポリビニルアルコール系フィルム、エチレン・酢酸ビニル共重合体系部分ケン化フィルム等の親水性高分子フィルムに、ヨウ素や二色性染料等を吸収させ延伸したもの、ポリビニルアルコールの脱水処理物やポリ塩化ビニルの脱塩酸処理物等のポリエン配向フィルム等にトリアセチルセルロース等の保護フィルム層を設けたものがあげられ、これらを適宜に選択して使用できる。偏光板の厚さは、特に制限されないが、通常１００〜２５０μｍ程度とするのが好ましい。
【００４４】
位相差板と偏光板と貼り合わせは、通常、当該位相差板を形成した配向膜に複屈折が生じている場合には、転写により、位相差板を偏光板に貼り合わせる。一方、位相差板を形成した配向膜がトリアセチルセルロース等のように複屈折が小さい基材の場合には、基材上に形成したフィルムをそのまま位相差板として、偏光板に貼り合わせて用いることもできる。位相差板とともに偏光板に貼り合わされたトリアセチルセルロース等の基板は偏光板の保護フィルムとして使用される。なお、楕円偏光板の作製にあたっての、偏光板と位相差板との貼り合わせ角度は任意に選ぶことができる。また、位相差板と偏光板との貼り合わせには、必要に応じて接着剤を使用できる。
【００４５】
また、楕円偏光板は、偏光板に、直接、位相差板（傾斜配向したフィルム）を形成することにより作製することもできる。
【００４６】
【実施例】
以下に、合成例および実施例をあげて本発明を詳細に説明するが、本発明はこれら各例に制限されるものではない。
【００４７】
合成例１
（１）：（ｅ）末端に水酸基を有するモノマーの合成
【化１０】

３リットル容の３つ口フラスコ中で、４，４' −ビフェノール（２００ｇ，１．０８モル）をテトラヒドロフラン（以下、ＴＨＦという）２リットルに溶解させ、室温で攪拌しているところへ、１２Ｎ塩酸を１０滴加えた。そこへ、３，４−ジヒドロ−２Ｈ−ピラン（９０．３ｇ，１．０８モル，式中のＤＨＰ）を４５分かけて滴下し終夜攪拌した。次いで、反応溶液にトリエチルアミンを加えて、ｐＨ８程度に調製してから溶媒のＴＨＦを４／５ほど留去した後、塩化メチレン２リットルを加えた。さらに、２Ｎ水酸化ナトリウム水溶液２リットルを加えて攪拌すると光沢のある白い沈殿が生じた。この沈殿を濾別し、再び塩化メチレンに分散させた後、酢酸３０ｍｌを加えて塩を中和させｐＨ４にした。完全に溶解するように更に塩化メチレンとＴＨＦを加えた後、飽和炭酸水素ナトリウム水溶液、飽和食塩水（各１リットル）で洗浄した後、無水硫酸マグネシウムで乾燥した。溶媒を留去し、４−（４' −ヒドロキシビフェニル）テトラヒドロピラニルエーテル（式中、ＴＨＰはテトラヒドロピラニル基を示す）の白色粉末を得た（収量２９０．４ｇ，収率５８％，純度９２％）。
【００４８】
次いで、３リットル容のナスフラスコに、４−（４' −ヒドロキシビフェニル）テトラヒドロピラニルエーテル（１７０．７ｇ，６３１ミリモル）、４−（２−プロペノイルオキシエトキシ）安息香酸（１５８．１ｇ，６６９ミリモル）、ジメチルアミノピリジン（８．０７ｇ，６６ミリモル，式中ＤＭＡＰ）、少量の重合禁止剤としてブチルヒドロキシトルエンおよび塩化メチレン２．５リットルを仕込んで溶液とした後、塩化メチレン１５０ｍｌで希釈したジシクロヘキシルカルボジイミド（１３８．０ｇ，６６９ミリモル、式中ＤＣＣ）を少量ずつ加え終夜攪拌した。析出したＤＣウレアをろ別した後、塩化メチレンを加えて全量を１リットルにしてから、ろ液を０．５Ｎ塩酸、飽和炭酸水素ナトリウム水溶液、飽和食塩水で洗浄し、無水硫酸マグネシウムで乾燥し、溶媒を留去した。粗生成物をイソプロピルアルコール２．５リットルとトルエン２５０ｍｌからなる加熱した混合溶媒に溶解し、セライトろ過した後、室温に冷却させることで再結晶させて、化１０に示す、末端水酸基をＴＨＰで保護したモノマーの沈殿を得た（収量１８６．３ｇ，収率５７％，純度９６％）
（２）：（ｂ）末端にシアノ基を有するモノマーの合成
【化１１】

水酸化カリウムアルコール性水溶液（水酸化カリウム３００ｇ，エタノール７００ｍｌ，水３００ｍｌ）に、４−ヒドロキシ安息香酸（２７６ｇ，２モル）と触媒量の沃化カリウムを加えて溶解した。加温状態でエチレンクロロヒドリン（１７７ｇ，２．２モル）をゆっくり加えて、約１５時間還流した。反応とともに塩化カリウムが析出した。反応終了後、エタノールを留去し、水２リットル中に反応溶液を加えた。この反応水溶液をジエチルエーテルで２回洗浄後、水層を４Ｎ塩酸で酸性とした。得られた沈殿物をろ過、乾燥後、エタノールで再結晶し、４−（２−ヒドロキシエトキシ）安息香酸（収量２９０ｇ，収率８２％，純度９８％）を得た。
【００４９】
次いで、４−（２−ヒドロキシエトキシ）安息香酸（１８２ｇ，１モル）、ヒドロキノン（４０ｇ）、ｐ−トルエンスルホン酸（４０ｇ）およびアクリル酸（６００ｍｌ）をベンゼン／トルエンの１／１混合溶媒（６００ｍｌ）に溶解した溶液を、Ｄｅａｎ−Ｓｔａｒｋ管を用いて理論量の水が分離されるまで還流（約１５時間）した。反応溶液をジエチルエーテル４リットルに入れ、温水洗浄を行なった。さらに飽和食塩水で洗浄後、無水硫酸ナトリウムで乾燥した。溶媒を留去し、得られた固体をアセトン／ヘキサンで再結晶し、４−（２−プロペノイルオキシエトキシ）安息香酸（収量１５３ｇ，収率６５％，純度９７％）を得た。
【００５０】
次いで、４−（２−プロペノイルオキシエトキシ）安息香酸（２３．６ｇ，０．１モル）にアセトン４００ｍｌに加えて溶解した後、さらにトリフルオロ酢酸無水物（２０．８ｍｌ，０．１５モル）を加えて攪拌した。当該反応溶液に、４−シアノ−４' −ヒドロキシビフェニル（１９．５ｇ，０．１モル）を加え室温で６時間反応させた。反応溶液からアセトンを留去し、ジエチルエーテルを加えて溶解した後、水、炭酸水素ナトリウム飽和水溶液及び飽和食塩水で洗浄してから、無水硫酸ナトリウムで乾燥した。溶媒を留去し、得られた固体をアセトニトリル６００ｍｌで再結晶し、化１１に示す、末端にシアノ基を有するモノマー（収量２９．３ｇ，収率７１％，純度９９％）を得た。
【００５１】
（３）：側鎖型液晶ポリマー（Ａ）の合成
【化１２】

合成例１（１）で得られた末端水酸基をＴＨＰで保護したモノマー（５．２０ｇ，１０．２ミリモル）と合成例１（２）で得られた末端にシアノ基を有するモノマー（１０．３ｇ，２３．９ミリモル）をＴＨＦ３００ｍｌに加え、窒素気流下で還流攪拌して各モノマーをＴＨＦに完全に溶解した。そこへ、少量のＴＨＦに溶解したアゾビスイソブチロニトリル（０．５８４ｇ，式中ＡＩＢＮ）を滴下した。４時間還流した後、ｐ−トルエンスルホン酸一水和物（３．５ｇ，式中ｐ−ＴｓOH）を加え、さらに１時間還流した。加熱を止め反応溶液を室温に戻した後、メタノール３リットル中へ、反応溶液を滴下してポリマーを再沈殿させた。ポリマーをろ別し、メタノール／ＴＨＦ＝３／２（重量比）の混合溶媒１００ｍｌで２回洗浄した後、乾燥して、化１２（なお、化１２は便宜的にブロック体として記載したものである）に示す、水酸基末端を有するモノマーユニットを含有する側鎖型液晶ポリマーを得た（収量１１．９ｇ，収率７９％，重量平均分子量４２００）。
【００５２】
【化１３】

窒素雰囲気下において、前記側鎖型液晶ポリマー（５．０ｇ，このうち水酸基末端を有するモノマーユニットに係わるモノマー１．３６ｇ（３．４ミリモル））、トリエチルアミン（２．３ｍｌ，１６．８ミリモル）、ジメチルアミノピリジン（触媒量）およびブチルヒドロキシトルエン（少量）を、乾燥クロロホルム２５０ｍｌ中で攪拌して溶解させた。そこへ塩化アクリロイル（０．５５ｍｌ，６．７ミリモル）をゆっくり滴下し、そのまま室温で３時間攪拌した。次いで、水１０ｍｌを加えて過剰の塩化アクリロイルを失活させた後、クロロホルム７００ｍｌを加え、さらに０．５Ｎ塩酸、飽和炭酸水素ナトリウム水溶液、飽和食塩水（各４００ｍｌ）で洗浄し、硫酸マグネシウムで乾燥した後、溶媒を減圧下で留去した。そこへ、ＴＨＦ８０ｍｌを加えてポリマーを溶解した溶液を、メタノール７００ｍｌ中へ滴下してポリマーを析出させた後、ろ別、乾燥を行い、化１３（なお、化１３は便宜的にブロック体として記載したものである）に示す、目的の側鎖型液晶ポリマーを得た（収量４．０４ｇ，収率７８％，重量平均分子量４３００）。
【００５３】
合成例２：末端にアクリロイル基を有する液晶性低分子化合物（Ｂ）の合成
【化１４】

４−（２−プロペノイルオキシエトキシ）安息香酸（１８．９ｇ，８０ミリモル）、ヒドロキノン（４．４ｇ，４０ミリモル）およびジメチルアミノピリジン（１．９５ｇ，１６ミリモル，式中ＤＭＡＰ）をジクロロメタン２００ｇに溶解した溶液に、氷浴中で、ジシクロヘキシルカルボジイミド（１９．８ｇ，９６ミリモル，式中ＤＣＣ）をジクロロメタン５０ｇに溶解した溶液を滴下した。氷浴を除去した後、２０時間反応させた。反応溶液から析出したＤＣウレアをろ別により除去した後、ろ液にジクロロメタンを加え８００ｍｌとした。さらに、０．５Ｎ塩酸、飽和食塩水、飽和炭酸水素ナトリウム水溶液、飽和食塩水（各８００ｍｌ）で洗浄し、硫酸マグネシウムで乾燥後溶媒を留去した。シリカゲル３８０ｇ、展開溶媒ジクロロメタン／ジエチルエーテル＝１００：３でカラムクロマトグラフィーを行ない、化１４に示す、両末端にアクリロイル基を有する液晶性低分子化合物を得た（収量１５．１ｇ，収率６９％，純度９９％）
実施例１
（１）液晶ポリマー組成物の調製
合成例１（３）で得られた側鎖型液晶ポリマー（化１３）１００重量部および合成例２で得られた両末端にアクリロイル基を有する液晶性低分子化合物１０重量部をテトラクロロエタンに溶解した液晶ポリマー組成物の溶液（１４重量％）を得た。
【００５４】
（２）傾斜配向位相差板の調製
ガラス基板上に、ポリビニルアルコール（日本合成化学（株）製，商品名：ＮＨ−１８）の５重量％水溶液を２０００ｒｐｍ、２０秒の条件でスピンコートし、１５０℃で３０分加熱した後、ラビングして配向膜を形成した。前記（１）で得られた液晶ポリマー組成物の溶液を、配向膜上にスピンコートし、１６０℃で５分加熱して、液晶ポリマー組成物を配向させたフィルムを得た。液晶ポリマー組成物を配向させたフィルムの膜厚は１．０μｍであった。
【００５５】
実施例２
実施例１（１）において、両末端にアクリロイル基を有する液晶性低分子化合物の使用量を２０重量部にした以外は実施例１（１）と同様にして液晶ポリマー組成物を調製し、また実施例１（２）と同様にして液晶ポリマー組成物を配向させたフィルムを得た。
【００５６】
実施例３
実施例１（１）において、両末端にアクリロイル基を有する液晶性低分子化合物の使用量を３０重量部にした以外は実施例１（１）と同様にして液晶ポリマー組成物を調製し、また実施例１（２）と同様にして液晶ポリマー組成物を配向させたフィルムを得た。
【００５７】
合成例３
（１）：（ｅ）末端に水酸基を有するモノマーの合成
【化１５】

スリーワンモータ一を備えた１リットル容の３口フラスコに、ヒドロキノン（１３６．８ｇ，１．２４モル）、水酸化カリウムアルコール性水溶液（１７０ｇ，３．０３モル窒素バブリングしたエタノール４００ｍｌ、蒸留水１００ｍｌ）および触媒量のヨウ化カリウムを仕込んだ後、窒素バブリングしながら還流加熱条件でエチレンクロロヒドリン（１００ｇ，１．２４ミリモル）を３０分かけて滴下した。約１５時間還流をした後、減圧下でエタノールを留去すると光沢のある沈殿が析出した。この沈殿をろ別し、ろ液をジエチルエーテル５００ｍｌで２回洗浄した後、４Ｎの塩酸を５００ｍｌ加えて酸性にした。この酸性水溶液をジエチルエーテル５００ｍｌで４回抽出し、集めた有機相を飽和炭酸水素ナトリウム水溶液、飽和食塩水（各３００ｍｌで２回ずつ）で洗浄した後、無水硫酸マグネシウムで乾燥し、溶媒を留去して粗生成物を得た。粗生成物をシリカゲルカラムクロマトグラフィー（展開溶媒：酢酸エチル／ヘキサン＝２／１（重量比））で精製し、ヒドロキノンの片方の水酸基だけをエーテル化したエチレングリコール−（４−ヒドロキシフェニル）エーテルを得た（収量５０．０ｇ，収率２６％，純度９９％以上）
次いで、３リットル容のナスフラスコに、エチレングリコール−（４−ヒドロキシフェニル）エーテル（５０．０ｇ，３２４ミリモル）、４−（２−プロペノイルオキシエトキシ）安息香酸（８０．４ｇ，３４０ミリモル）、ジメチルアミノピリジン（１．３ｇ，１１ミリモル、式中ＤＭＡＰ）、少量の重合禁止剤ブチルヒドロキシトルエンおよび塩化メチレン１．５リットルを仕込んで溶液とした後、塩化メチレン５０ｍｌで希釈したジシクロヘキシルカルボジイミド（７３．６ｇ，３５７ミリモル，式中ＤＣＣ）を少量ずつ加え室温で終夜攪拌した。析出したＤＣウレアをろ別し、ろ液に塩化メチレンを加えて全量を４リットルにした後、０．５Ｎ塩酸、飽和炭酸水素ナトリウム水溶液、飽和食塩水（それぞれ１リットルで２回ずつ）で洗浄し、無水硫酸マグネシウムで乾燥し、溶媒を留去した。粗生成物をカラムクトマトグラフィー（展開溶媒：塩化メチレン／エーテル＝１０／１（重量比））により精製した後、減圧濃縮した。得られた白色沈殿を塩化メチレン３００ｍｌに溶解させ不溶物をろ別し、ヘキサン１リットルを加えて析出した白色沈殿を乾燥して、化１５に示す、目的とする末端フェニルエタノール型モノマーを得た（収量８０．８ｇ，収率６７％、純度９９％以上）。
【００５８】
（２）：側鎖型液晶ポリマー（Ａ）の合成
【化１６】

合成例３（１）で得られた末端フェニルエタノール型モノマー（１１．２ｇ，３０．０ミリモル）と合成例１（２）で得られたネマチック液晶性を有するモノマー（１８．６ｇ，４５．０ミリモル）をＴＨＦ６８０ｍｌに加え、窒素気流下で還流攪拌してモノマーをＴＨＦに完全に溶解した。そこへ、少量のＴＨＦ１０ｍｌに溶解したアゾビスイソブチロニトリル（１．２７ｇ，７．７ミリモル，式中ＡＩＢＮ）を滴下した。４時間還流した後、加熱を止め反応液を室温に戻した後、メタノール２．２リットル中へ、反応溶液を滴下してポリマーを再沈殿させた。ポリマーをろ別し、メタノール／ＴＨＦ＝３／２（重量比）の混合溶媒で洗浄した後、乾燥して、化１６（なお、化１６は便宜的にブロック体として記載したものである）に示す、水酸基末端を有するモノマーユニットを含有する側鎖型液晶ポリマーを得た（収量１６．５ｇ，収率５５％，重量平均分子量３８００）。
【００５９】
【化１７】

窒素雰囲気下において、前記側鎖型液晶ポリマー（１０．０ｇ，このうち水酸基末端を有するモノマーユニットに係わるモノマー３．５ｇ（９．３ミリモル））、トリエチルアミン（６．５ｍｌ，４６．７ミリモル）、ジメチルアミノピリジン（触媒量）およびブチルヒドロキシトルエン（少量）を、乾燥ＴＨＦ５００ｍｌ中で攪拌して溶解させた。そこへ塩化アクリロイル（１．５ｍｌ，１８．７ミリモル）をゆっくり滴下し、そのまま室温で３時間攪拌した。次いで、水１０ｍｌを加えて過剰の塩化アクリロイルを失活させ析出したアンモニウム塩をろ別した後、クロロホルム２リットルを加え、さらに０．５Ｎ塩酸、飽和炭酸水素ナトリウム水溶液、飽和食塩水（各５００ｍｌ）で洗浄し、硫酸マグネシウムで乾燥した後、溶媒を減圧下で留去した。そこへ、ＴＨＦ８０ｍｌを加えてポリマーを溶解した溶液を、メタノール８００ｍｌ中へ滴下してポリマーを析出させた後、ろ別、乾燥を行い、化１７（なお、化１７は便宜的にブロック体として記載したものである）に示す、目的の側鎖型液晶ポリマーを得た（収量８．５０ｇ，収率８１％，重量平均分子量４４００）。
【００６０】
実施例４
（１）液晶ポリマー組成物の調製
合成例３（２）で得られた側鎖型液晶ポリマー（化１７）１００重量部および合成例２で得られた両末端にアクリロイル基を有する液晶性低分子化合物１０重量部をテトラクロロエタンに溶解した液晶ポリマー組成物の溶液（１２重量％）を得た。
【００６１】
（２）傾斜配向位相差板の調製
ガラス基板上に、ポリビニルアルコール（日本合成化学（株）製，商品名：ＮＨ−１８）の５％水溶液を２０００ｒｐｍ、２０秒の条件でスピンコートし、１５０℃で３０分加熱した後、ラビングして配向膜を形成した。前記（１）で得られた液晶ポリマー組成物の溶液を、配向膜上にスピンコートし、１６０℃で５分加熱して、液晶ポリマー組成物を配向させたフィルムを得た。液晶ポリマー組成物を配向させたフィルムの膜厚は０．９μｍであった。
【００６２】
実施例５
実施例４（１）において、両末端にアクリロイル基を有する液晶性低分子化合物の使用量を３０重量部にした以外は実施例４（１）と同様にして液晶ポリマー組成物を調製し、また実施例４（２）と同様にして液晶ポリマー組成物を配向させたフィルムを得た。
【００６３】
比較例１
実施例１（１）において、両末端にアクリロイル基を有する液晶性低分子化合物を添加しないこと以外は実施例１（１）と同様にして液晶ポリマー組成物を調製し、また実施例１（２）と同様にして液晶ポリマー組成物を配向させたフィルムを得た。
【００６４】
比較例２
実施例４（１）において、両末端にアクリロイル基を有する液晶性低分子化合物を添加しないこと以外は実施例４（１）と同様にして液晶ポリマー組成物を調製し、また実施例４（２）と同様にして液晶ポリマー組成物を配向させたフィルムを得た。
【００６５】
比較例３
実施例１（１）において、合成例１（３）で得られた側鎖型液晶ポリマーの代わりに、合成例１（２）で得られた末端にシアノ基を有するモノマーを重合して得たホモポリマーを用い、合成例２で得られた両末端にアクリロイル基を有する液晶性低分子化合物の使用量を３０重量部にした以外は実施例１（１）と同様にして液晶ポリマー組成物を調製し、また実施例１（２）と同様にして液晶ポリマー組成物を配向させたフィルムを得た。
【００６６】
試験例（位相差測定）
実施例および比較例で得られた液晶ポリマー組成物を配向させたフィルムの位相差の視角依存性を評価した。評価は、液晶ポリマー組成物の傾斜度を下記式で算出し、傾斜度合いの指標とした。評価結果を表１に示す。なお、正面の位相差を△ｎｄ（０）、遅相軸方向に±３０°傾斜したときの位相差をそれぞれ△ｎｄ（＋３０）、△ｎｄ（−３０）とした。
【００６７】
傾斜度＝（△ｎｄ（−３０）−△ｎｄ（＋３０））／△ｎｄ（０）
傾斜していない水平配向のとき、傾斜度＝０となる。
【００６８】
【表１】

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal polymer composition having a tilt alignment property, a retardation plate composed of a film formed from the liquid crystal polymer composition, and an elliptically polarizing plate using the same.
[0002]
[Prior art]
With the improvement of display performance, liquid crystal displays have expanded the range of application products from small monochrome displays such as calculators and watches to large color displays such as notebook computers, televisions and monitors. Recently, some characteristics, for example, those exceeding the CRT in terms of definition have appeared.
[0003]
However, the liquid crystal display has a disadvantage that the viewing angle is narrower than that of the CRT. For this reason, several methods have been proposed so far for widening the viewing angle of liquid crystal displays. For example, a method of dividing pixels such as an alignment division method and a halftone method into a plurality of regions having different alignment directions of liquid crystal molecules and averaging, a method of improving a liquid crystal operation mode such as IPS, MVA, and OCB, a condensing lens, and a diffusion lens A method using a lens, a method using a retardation plate serving as a viewing angle compensation film, and the like have been proposed.
[0004]
Among these methods, a method for improving the liquid crystal operation mode and a method using a retardation plate have been put into practical use. In particular, the method using a retardation plate allows a wide viewing angle to be achieved by simply attaching a polarizing plate and a retardation plate to the liquid crystal panel without changing the liquid crystal panel. Therefore, it is not necessary to change the production line, and the cost is lower than the method of improving the liquid crystal mode.
[0005]
As such a phase difference plate, those in which a discotic liquid crystal is tilted or those in which a rod-like nematic liquid crystal is tilted are known, and in any case, a liquid crystal polymer is tilted and aligned. Regarding the retardation plate made of a tilted liquid crystal polymer, various liquid crystal polymers are disclosed in JP-A-8-5838, JP-A-7-20434, etc., and the former mainly includes side chain type liquid crystal. A polymer is disclosed, and the latter mainly discloses a main chain type liquid crystal polymer.
[0006]
[Problems to be solved by the invention]
On the other hand, the method of improving the viewing angle using a retardation plate in which a liquid crystal polymer is tilted and aligned is accompanied by a change in the viewing angle of the liquid crystal cell due to a phase difference characteristic asymmetric to the plate surface due to the tilted alignment of the retardation plate. The viewing angle is improved by compensating for an asymmetric change in visibility. Therefore, in controlling the asymmetric phase difference characteristics of the phase difference plate three-dimensionally, a technique for controlling the angle of the tilted orientation is important.
[0007]
However, including the above-mentioned publications, there has been no technology to adjust the angle of tilted alignment by adjusting the components of the liquid crystal polymer composition.
[0008]
Accordingly, an object of the present invention is to provide a liquid crystal polymer composition capable of controlling the angle of tilt alignment when producing a tilt aligned liquid crystal film, a retardation plate comprising a film formed from the liquid crystal polymer composition, and The object is to provide an elliptically polarizing plate using the same.
[0009]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have found that a liquid crystal having an acryloyl group at the terminal in a side chain type liquid crystal polymer (A) containing a monomer unit having an acryloyl group at the terminal of the liquid crystalline side chain. The present invention has been completed by finding that a retardation plate meeting the above-mentioned purpose can be obtained by a liquid crystal polymer composition containing a low molecular weight compound (B).
[0010]
That is, the liquid crystal polymer composition of the present invention comprises a side chain type liquid crystal polymer (A) containing a monomer unit having an acryloyl group at the end of a liquid crystalline side chain, and Both ends Have an acryloyl group With a molecular weight of 662 or less It contains a liquid crystalline low molecular weight compound (B). Here, the liquid crystalline low molecular weight compound includes not only the compound exhibiting liquid crystallinity but also the compound exhibiting liquid crystallinity when mixed with the side chain type liquid crystal polymer (A).
[0011]
In the above, it is preferable that the monomer unit having the acryloyl group is a monomer unit represented by the following general formula (a1).
[0012]
Moreover, it is preferable that the said liquid crystalline low molecular compound (B) is a compound represented by the following general formula (B1).
[0013]
On the other hand, the retardation plate of the present invention is a film made of any one of the liquid crystal polymer compositions described above, wherein a film in which the orientation direction of the liquid crystal polymer composition is inclined with respect to the film surface of the film is used. It was.
[0014]
On the other hand, the elliptically polarizing plate of the present invention is formed by laminating and integrating the above retardation plate with a polarizing plate.
[0015]
[Function and effect]
As the results of Examples show, the liquid crystal polymer composition of the present invention has tilt alignment properties, and the tilt degree can be controlled by the addition amount of the liquid crystalline low molecular compound to be added. Therefore, by using such a liquid crystal polymer composition, it is possible to obtain a retardation plate and an elliptically polarizing plate having an inclined optical axis, which is effective for viewing angle compensation. The details of the reason why the inclination degree changes depending on the addition amount of the liquid crystalline low molecular weight compound are not clear, but are presumed as follows. In other words, it is considered that the terminal acryloyl group of the liquid crystalline side chain is localized at the air side interface during film formation, and tilted orientation occurs. At that time, the terminal acryloyl group of the liquid crystalline low molecular weight compound is also localized at the air side interface. Therefore, it is considered that as the amount of the liquid crystalline low-molecular compound increases due to the interaction between the two, the angle of the tilted alignment increases.
[0016]
When the monomer unit having an acryloyl group is a monomer unit represented by the following general formula (a1), the side-chain liquid crystal polymer tends to exhibit tilt alignment, and the tilt by the liquid crystalline low molecular compound (B) The orientation can be easily controlled.
[0017]
Further, when the liquid crystalline low molecular weight compound (B) is a compound represented by the following general formula (B1), since it has an appropriate spacer portion and a liquid crystal segment in the middle of the acryloyl groups at both ends, the side chain By adding to the liquid crystal polymer (A), it is possible to obtain the effects as described above more reliably.
[0018]
On the other hand, since the retardation plate of the present invention is composed of the liquid crystal polymer composition as described above, the angle of tilt alignment can be controlled, so that the retardation plate is effective for viewing angle compensation and has a suitably inclined optical axis. Can do.
[0019]
On the other hand, according to the elliptically polarizing plate of the present invention, since the retardation plate is laminated on the polarizing plate, the viewing angle can be suitably compensated as described above only by being attached to the liquid crystal panel.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
The side chain type liquid crystal polymer (A) of the present invention can be used without particular limitation as long as it is a side chain type liquid crystal polymer containing a monomer unit having an acryloyl group at the end of the liquid crystalline side chain.
[0021]
As the monomer unit, for example, general formula (a1):
[Chemical 3]

(Wherein R ¹ Is a hydrogen atom or a methyl group, X ¹ Is a —COO— group or a —OCO— group, m and n are each independently an integer of 1-6, p and q are each independently 1 or 2 (provided that p + q ≦ 3 Satisfied. ), R represents 0 or 1. ) Monomer units. Examples of the monomer unit represented by the general formula (a1) include R ¹ Is a hydrogen atom, X ¹ Are —COO— groups, m is an integer of 2 to 6, n is 1 or 2, p is 1, q is 2, and r is 0 or 1.
The proportion of the monomer unit having an acryloyl group at the terminal in the side chain type liquid crystal polymer (A) of the present invention is not particularly limited, but usually a monomer having a liquid crystal side chain constituting the side chain type liquid crystal polymer (A). It is preferable to set it to 1 mol% or more and 50 mol% or less of a unit. Further, when the proportion of the monomer unit having an acryloyl group at the terminal decreases, the side chain type liquid crystal polymer (A) tends to be difficult to take an inclined orientation. Therefore, the proportion of the monomer unit having an acryloyl group at the terminal is 10 mol. % Or more is more preferable. On the other hand, if the proportion of the monomer unit having an acryloyl group at the terminal increases, the orientation of the side chain type liquid crystal polymer (A) tends to be lowered and the uniformity cannot be maintained. The ratio is more preferably 40 mol% or less.
[0022]
The monomer unit having a liquid crystalline side chain that constitutes the side chain type liquid crystal polymer (A) together with the monomer unit is not particularly limited, but the side chain type liquid crystal polymer (A) of the present invention has a positive dielectric anisotropy. Since it is preferable to exhibit nematic liquid crystallinity having, the monomer unit exhibiting nematic liquid crystallinity is particularly preferably a monomer unit (b) having a cyano group at the terminal. In addition, (b) monomer units exhibiting nematic liquid crystal properties other than the monomer unit having a cyano group at the terminal include (c) a monomer unit having an optically active group and (d) a monomer unit having a terminal crosslinking group, These monomer units are preferably monomer units of the side chain type liquid crystal polymer (A) as necessary.
[0023]
Examples of the monomer unit (b) having a cyano group at its terminal include, for example, the general formula (b1):
[Formula 4]

(Wherein R ² Is a hydrogen atom or a methyl group, X ² Is a —COO— group or a —OCO— group, j is a positive integer of 1 to 6, and s and t are each independently 1 or 2 (provided that s + t ≦ 3 is satisfied). Monomer units.
[0024]
Examples of the monomer unit (c) having an optically active group include, for example, the general formula (c1):
[Chemical formula 5]

(Wherein R ^Three Represents a hydrogen atom or a methyl group, R ^Four Is
[Chemical 6]

(Wherein R ^Five Is
[Chemical 7]

X) ^Three Represents a —COO— group or —OCO— group, and k represents an integer of 1 to 6).
[0025]
Examples of the monomer unit (d) having a terminal crosslinking group include those having a crosslinking group other than an acryloyl group, for example, an unsaturated double bond such as a cyclohexene ring, at the end of the side chain of the monomer unit.
[0026]
The side chain type liquid crystal polymer (A) is prepared by using various acrylic or methacrylic liquid crystal monomers corresponding to the respective monomer units (hereinafter simply referred to as (meth) acrylic liquid crystal monomers), for example, radical polymerization, cation A monomer unit having an acryloyl group at the terminal, or (d) a terminal cross-linking group, can be carried out by copolymerization according to a usual polymerization method of a (meth) acrylic liquid crystal monomer such as a polymerization method or an anionic polymerization method. When the corresponding (meth) acrylic monomer is polymerized, the terminal acryloyl group and the crosslinking group are also polymerized at the same time. For example, the general formula (e):
[Chemical 8]

(Wherein R ¹ , X ¹ , M, n, p, q, r are the same as above. And (e) a copolymer obtained by copolymerizing a monomer unit having a hydroxyl group at the terminal, and then reacting acryloyl chloride or the like with the hydroxyl group to form a monomer unit having an acryloyl group at the terminal or (d It is preferable to introduce a monomer unit having a terminal crosslinking group into the side chain type liquid crystal polymer (A). In that case, the side chain type liquid crystal polymer (A) may contain a monomer unit having a hydroxyl group at the remaining (e) terminal.
[0027]
In addition, when it is necessary to protect the terminal hydroxyl group at the stage of preparation of the (meth) acrylic liquid crystal monomer corresponding to the monomer unit having a hydroxyl group at the terminal (e), the (meth) acrylic type in which the hydroxyl group is protected A monomer unit having a hydroxyl group at the terminal (e) can be introduced into the side chain liquid crystal polymer by removing the protective group after copolymerizing the liquid crystal monomer to produce the side chain liquid crystal polymer. .
[0028]
When applying the radical polymerization method, various polymerization initiators can be used. Among them, decomposition temperatures such as azobisisobutyronitrile and benzoyl peroxide are not high and are not low. Those are preferred.
[0029]
The molecular weight of the side chain type liquid crystal polymer (A) is usually about 2,000 to 100,000 based on the weight average molecular weight. In addition, if the weight average molecular weight is too small, the film-forming property of the film made of the liquid crystal polymer composition formed on the substrate when preparing the retardation plate becomes poor, so the weight average molecular weight is 2.5 thousand or more. It is preferable to do this. On the other hand, if the weight average molecular weight is excessive, the alignment property as a liquid crystal, particularly monodomain formation via a rubbing alignment film, etc., is poor and it becomes difficult to form a uniform alignment state, so the weight average molecular weight is 50,000 or less. Is preferred.
[0030]
Mixed in the side chain type liquid crystal polymer (A), Both ends Have an acryloyl group With a molecular weight of 662 or less The liquid crystalline low molecular compound (B) has liquid crystallinity and has a molecular end ( Both ends ) Is not particularly limited as long as it is a low molecular weight compound having an acryloyl group, but it does not disturb the orientation of the side chain liquid crystal polymer (A) when mixed with the side chain liquid crystal polymer (A). A skeleton is desirable.
[0031]
As this liquid crystalline low molecular weight compound (B), for example, general formula (B1):
[Chemical 9]

(In the formula, A and D are each independently 1,4-phenylene group or 1,4-cyclohexylene group, B is 1,4-phenylene group, 1,4-cyclohexylene group, 4,4 ′ − A biphenylene group or a 4,4′-bicyclohexylene group, ^Four And X ^Five Are each independently a —COO— group, —OCO— group or —O— group, and g and h are each independently an integer of 2 to 6). As the compound represented by the general formula (B1), A, B and D are all 1,4-phenylene groups, X ^Four -COO- group, X ^Five Are preferably —OCO— groups, and g and h are both 2 compounds.
[0032]
The liquid crystal polymer composition of the present invention comprises a side chain liquid crystal polymer (A) and a liquid crystal low molecular compound (B), and is mixed with the side chain liquid crystal polymer (A) (B ), The degree of tilted orientation (average tilt angle) of the film made of the liquid crystal polymer composition can be continuously controlled.
[0033]
The addition amount of the liquid crystalline low molecular weight compound (B) mixed with the side chain type liquid crystal polymer (A) is not particularly limited, but is usually 5 parts by weight or more with respect to 100 parts by weight of the side chain type liquid crystal polymer (A). 50 parts by weight or less is desirable. When the addition amount of the liquid crystalline low molecular compound (B) is small, the film made of the liquid crystal polymer composition of the present invention is difficult to take a sufficient tilted orientation. Therefore, the addition amount of the liquid crystalline low molecular compound (B) is 10 parts by weight. More preferably. On the other hand, when the addition amount of the liquid crystalline low molecular compound (B) is increased, the orientation of the film made of the liquid crystal polymer composition of the present invention is lowered and the uniformity is poor. Therefore, the addition amount of the liquid crystalline low molecular compound (B) is More preferably, it is 40 parts by weight or less.
[0034]
As a method for forming a film in which the alignment direction of the liquid crystal polymer composition is inclined with respect to the obtained film surface from the liquid crystal polymer composition of the present invention, a method according to a conventional alignment treatment can be employed.
[0035]
As such a method, for example, after forming an alignment film made of polyimide, polyvinyl alcohol or the like on a substrate and rubbing it with a rayon cloth or the like, a liquid crystal polymer composition is developed thereon, and then a liquid crystal polymer composition The liquid crystal polymer composition is heated to a temperature equal to or higher than the glass transition temperature and lower than the isotropic phase transition temperature to cause the molecules of the liquid crystal polymer composition to be tilted and aligned, and then cooled to a glass transition temperature below the glass transition temperature in the tilted and aligned state. Examples thereof include a method of forming a film by fixing the orientation of the composition. In such a method, the alignment treatment temperature is preferably 30 to 70 ° C., particularly about 50 ° C. higher than the glass transition temperature of the liquid crystal polymer composition, from the viewpoint of the alignment treatment efficiency.
[0036]
As the substrate, an inorganic material such as a glass plate or a polymer material such as a plastic film can be used. As the plastic substrate, triacetylcellulose, polycarbonate, polysulfone, polyethersulfone, polyethylene terephthalate and the like are preferable.
[0037]
Further, as an alignment treatment method of the liquid crystal polymer composition, instead of rubbing the alignment film, a method using a stretched film as an alignment film, or a polymer or polyimide having cinnamate or azobenzene is irradiated with polarized ultraviolet rays for alignment. A method used as a film can also be adopted.
[0038]
The liquid crystal polymer composition may be spread on the substrate by a heat melting method, or may be spread as a solution dissolved in a solvent. As the solvent, for example, methylene chloride, cyclohexanone, trichloroethylene, tetrachloroethane, N-methylpyrrolidone, tetrahydrofuran, dimethylformamide and the like can be appropriately selected and used. In development, a coating machine such as a Noor coater, a spinner, or a roll coater can be appropriately used.
[0039]
In addition, after the liquid crystal polymer composition is formed into a film and then oriented, if necessary, the terminal acryloyl group of the monomer unit having an acryloyl group at the terminal, (d) the terminal cross-linking group of the monomer unit having a terminal cross-linking group, The terminal acryloyl group of the liquid crystalline low molecular compound (B) can be crosslinked to further fix the alignment of the liquid crystal polymer composition. For crosslinking, electromagnetic waves such as UV and electron beams can be used. In particular, crosslinking by electron beam irradiation is advantageous because it does not require an initiator that tends to cause a decrease in the orientation of the liquid crystal polymer composition.
[0040]
The thickness of the film made of the liquid crystal polymer composition formed on the substrate may be appropriately adjusted depending on the characteristics of the liquid crystal cell to be compensated, but is usually about 0.1 to 10 μm, and preferably 0.2 to 3 μm. .
[0041]
The film made of the liquid crystal polymer composition formed on the substrate by the alignment treatment as described above has a phase difference for compensating the viewing angle of the liquid crystal cell because the alignment direction of the liquid crystal polymer composition is inclined with respect to the film surface. Used as a board. The phase difference plate is disposed on one side or both sides of the liquid crystal cell. Further, a structure in which a plurality of retardation plates are stacked may be used, and in that case, the retardation phase of the plate surface may be shifted and stacked (for example, two retardation plates are orthogonalized).
[0042]
Such a retardation plate can be applied alone to a liquid crystal cell, but can also be used as an elliptically polarizing plate formed by laminating a polarizing plate and a laminate. The arrangement position of the elliptically polarizing plate with respect to the liquid crystal cell is not particularly limited, but is generally arranged so that the retardation plate is located between the polarizing plate and the liquid crystal cell.
[0043]
As the polarizing plate, one having a polarizing function can be used without any particular limitation. Specifically, a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene / vinyl acetate copolymer partially saponified film was absorbed by iodine or a dichroic dye and stretched. And a polyene oriented film such as a dehydrated product of polyvinyl alcohol or a dehydrochlorinated product of polyvinyl chloride, and the like, which are provided with a protective film layer such as triacetyl cellulose, can be appropriately selected and used. The thickness of the polarizing plate is not particularly limited, but is usually preferably about 100 to 250 μm.
[0044]
In general, when the birefringence is generated in the alignment film on which the retardation plate is formed, the retardation plate and the polarizing plate are bonded together by transfer. On the other hand, when the alignment film on which the phase difference plate is formed is a base material having a small birefringence such as triacetyl cellulose, the film formed on the base material is used as it is as a phase difference plate and attached to a polarizing plate. You can also. A substrate such as triacetyl cellulose bonded to the polarizing plate together with the retardation plate is used as a protective film for the polarizing plate. It should be noted that the bonding angle between the polarizing plate and the retardation plate in producing the elliptically polarizing plate can be arbitrarily selected. Moreover, an adhesive agent can be used as needed for bonding of a phase difference plate and a polarizing plate.
[0045]
The elliptically polarizing plate can also be produced by directly forming a retardation plate (an inclined oriented film) on the polarizing plate.
[0046]
【Example】
Hereinafter, the present invention will be described in detail with reference to synthesis examples and examples, but the present invention is not limited to these examples.
[0047]
Synthesis example 1
(1): (e) Synthesis of a monomer having a hydroxyl group at the terminal
[Chemical Formula 10]

In a 3 liter three-necked flask, 4,4′-biphenol (200 g, 1.08 mol) was dissolved in 2 liters of tetrahydrofuran (hereinafter referred to as THF) and stirred at room temperature. 10 drops were added. To this, 3,4-dihydro-2H-pyran (90.3 g, 1.08 mol, DHP in the formula) was added dropwise over 45 minutes and stirred overnight. Next, triethylamine was added to the reaction solution to adjust the pH to about 8, and then the solvent THF was distilled off by about 4/5, and then 2 liters of methylene chloride was added. Further, when 2 liters of 2N sodium hydroxide aqueous solution was added and stirred, a glossy white precipitate was formed. The precipitate was filtered off and dispersed again in methylene chloride, and 30 ml of acetic acid was added to neutralize the salt to pH 4. Methylene chloride and THF were further added so as to completely dissolve, and then washed with a saturated aqueous sodium hydrogen carbonate solution and saturated brine (1 liter each), and then dried over anhydrous magnesium sulfate. The solvent was distilled off to obtain a white powder of 4- (4′-hydroxybiphenyl) tetrahydropyranyl ether (wherein THP represents a tetrahydropyranyl group) (yield 290.4 g, yield 58%, purity 92). %).
[0048]
Subsequently, 4- (4′-hydroxybiphenyl) tetrahydropyranyl ether (170.7 g, 631 mmol), 4- (2-propenoyloxyethoxy) benzoic acid (158.1 g, 669 mmol) was added to a 3-liter eggplant flask. ), Dimethylaminopyridine (8.07 g, 66 mmol, DMAP in the formula), butylhydroxytoluene and 2.5 liters of methylene chloride as a small amount of a polymerization inhibitor to prepare a solution, and then dicyclohexylcarbodiimide diluted with 150 ml of methylene chloride (138.0 g, 669 mmol, DCC in the formula) was added in small portions and stirred overnight. After filtering the precipitated DC urea, methylene chloride was added to make the total volume to 1 liter, and the filtrate was washed with 0.5N hydrochloric acid, saturated aqueous sodium hydrogen carbonate solution and saturated brine, and dried over anhydrous magnesium sulfate. The solvent was distilled off. The crude product was dissolved in a heated mixed solvent consisting of 2.5 liters of isopropyl alcohol and 250 ml of toluene, filtered through Celite, and then recrystallized by cooling to room temperature, and the terminal hydroxyl group shown in Chemical formula 10 was protected with THP. Of the monomer obtained (yield 186.3 g, yield 57%, purity 96%)
(2): (b) Synthesis of a monomer having a cyano group at the terminal
Embedded image

4-hydroxybenzoic acid (276 g, 2 mol) and a catalytic amount of potassium iodide were dissolved in a potassium hydroxide alcoholic aqueous solution (potassium hydroxide 300 g, ethanol 700 ml, water 300 ml). Ethylene chlorohydrin (177 g, 2.2 mol) was slowly added while warming, and refluxed for about 15 hours. Potassium chloride precipitated with the reaction. After completion of the reaction, ethanol was distilled off and the reaction solution was added to 2 liters of water. After this reaction aqueous solution was washed twice with diethyl ether, the aqueous layer was acidified with 4N hydrochloric acid. The obtained precipitate was filtered, dried, and recrystallized with ethanol to obtain 4- (2-hydroxyethoxy) benzoic acid (yield 290 g, yield 82%, purity 98%).
[0049]
Subsequently, 4- (2-hydroxyethoxy) benzoic acid (182 g, 1 mol), hydroquinone (40 g), p-toluenesulfonic acid (40 g) and acrylic acid (600 ml) were mixed with a 1/1 mixed solvent of benzene / toluene (600 ml). ) Was refluxed (about 15 hours) using a Dean-Stark tube until the theoretical amount of water was separated. The reaction solution was put into 4 liters of diethyl ether and washed with warm water. Further, the extract was washed with saturated brine and dried over anhydrous sodium sulfate. The solvent was distilled off, and the obtained solid was recrystallized from acetone / hexane to obtain 4- (2-propenoyloxyethoxy) benzoic acid (yield 153 g, yield 65%, purity 97%).
[0050]
Subsequently, 4- (2-propenoyloxyethoxy) benzoic acid (23.6 g, 0.1 mol) was dissolved in 400 ml of acetone and further dissolved in trifluoroacetic anhydride (20.8 ml, 0.15 mol). Was added and stirred. 4-Cyano-4'-hydroxybiphenyl (19.5 g, 0.1 mol) was added to the reaction solution and reacted at room temperature for 6 hours. Acetone was distilled off from the reaction solution, and diethyl ether was added for dissolution, and the mixture was washed with water, a saturated aqueous solution of sodium hydrogencarbonate and saturated brine, and then dried over anhydrous sodium sulfate. The solvent was distilled off, and the obtained solid was recrystallized from 600 ml of acetonitrile to obtain a monomer having a cyano group at the end (yield 29.3 g, yield 71%, purity 99%) shown in Chemical formula 11.
[0051]
(3): Synthesis of side chain type liquid crystal polymer (A)
Embedded image

Monomer (5.20 g, 10.2 mmol) in which the terminal hydroxyl group obtained in Synthesis Example 1 (1) was protected with THP and a monomer having a cyano group at the terminal obtained in Synthesis Example 1 (2) (10.3 g) , 23.9 mmol) was added to 300 ml of THF, and the mixture was refluxed and stirred under a nitrogen stream to completely dissolve each monomer in THF. Azobisisobutyronitrile (0.584 g, AIBN in the formula) dissolved in a small amount of THF was added dropwise thereto. After refluxing for 4 hours, p-toluenesulfonic acid monohydrate (3.5 g, in the formula, p-TsOH) was added, and the mixture was further refluxed for 1 hour. After stopping the heating and returning the reaction solution to room temperature, the reaction solution was dropped into 3 liters of methanol to reprecipitate the polymer. The polymer was separated by filtration, washed twice with 100 ml of a mixed solvent of methanol / THF = 3/2 (weight ratio), and then dried to obtain a chemical formula 12 (note that chemical formula 12 is described as a block body for convenience. A side chain type liquid crystal polymer containing a monomer unit having a hydroxyl group terminal as shown in (A) is obtained (yield 11.9 g, yield 79%, weight average molecular weight 4200).
[0052]
Embedded image

Under a nitrogen atmosphere, the side-chain liquid crystal polymer (5.0 g, of which 1.36 g (3.4 mmol) of monomer related to the monomer unit having a hydroxyl terminal), triethylamine (2.3 ml, 16.8 mmol), Dimethylaminopyridine (catalytic amount) and butylhydroxytoluene (small amount) were dissolved by stirring in 250 ml of dry chloroform. Acryloyl chloride (0.55 ml, 6.7 mmol) was slowly added dropwise thereto, and the mixture was stirred at room temperature for 3 hours. Next, 10 ml of water was added to inactivate excess acryloyl chloride, and then 700 ml of chloroform was added, followed by washing with 0.5N hydrochloric acid, saturated aqueous sodium hydrogen carbonate solution and saturated brine (each 400 ml), and drying over magnesium sulfate. After that, the solvent was distilled off under reduced pressure. Then, a solution in which 80 ml of THF was added and the polymer was dissolved was dropped into 700 ml of methanol to precipitate the polymer, followed by filtration and drying, and chemical formula 13 (note that chemical formula 13 is described as a block body for convenience). The target side chain type liquid crystal polymer was obtained (yield 4.04 g, yield 78%, weight average molecular weight 4300).
[0053]
Synthesis Example 2: Synthesis of liquid crystalline low molecular weight compound (B) having an acryloyl group at the terminal
Embedded image

4- (2-propenoyloxyethoxy) benzoic acid (18.9 g, 80 mmol), hydroquinone (4.4 g, 40 mmol) and dimethylaminopyridine (1.95 g, 16 mmol, in formula DMAP) in 200 g of dichloromethane. A solution of dicyclohexylcarbodiimide (19.8 g, 96 mmol, DCC in the formula) dissolved in 50 g of dichloromethane was added dropwise to the dissolved solution in an ice bath. After removing the ice bath, the reaction was allowed to proceed for 20 hours. After DC urea precipitated from the reaction solution was removed by filtration, dichloromethane was added to the filtrate to make 800 ml. Further, the mixture was washed with 0.5N hydrochloric acid, saturated brine, saturated aqueous sodium hydrogen carbonate solution and saturated brine (800 ml each), dried over magnesium sulfate, and the solvent was distilled off. Column chromatography was performed with 380 g of silica gel and developing solvent dichloromethane / diethyl ether = 100: 3 to obtain a liquid crystalline low molecular weight compound having acryloyl groups at both ends as shown in Chemical formula 14 (yield 15.1 g, yield 69%). , Purity 99%)
Example 1
(1) Preparation of liquid crystal polymer composition
100 parts by weight of the side chain type liquid crystal polymer (Chemical Formula 13) obtained in Synthesis Example 1 (3) and 10 parts by weight of the liquid crystalline low molecular weight compound having an acryloyl group at both ends obtained in Synthesis Example 2 are dissolved in tetrachloroethane. A solution (14% by weight) of the liquid crystal polymer composition obtained was obtained.
[0054]
(2) Preparation of tilted alignment phase difference plate
A glass substrate was spin-coated with a 5% by weight aqueous solution of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd., trade name: NH-18) at 2000 rpm for 20 seconds, heated at 150 ° C. for 30 minutes, and then rubbed. Thus, an alignment film was formed. The liquid crystal polymer composition solution obtained in the above (1) was spin-coated on the alignment film and heated at 160 ° C. for 5 minutes to obtain a film in which the liquid crystal polymer composition was aligned. The film thickness of the film on which the liquid crystal polymer composition was oriented was 1.0 μm.
[0055]
Example 2
In Example 1 (1), a liquid crystal polymer composition was prepared in the same manner as in Example 1 (1) except that the amount of the liquid crystalline low molecular compound having an acryloyl group at both ends was 20 parts by weight. A film in which the liquid crystal polymer composition was oriented was obtained in the same manner as in Example 1 (2).
[0056]
Example 3
In Example 1 (1), a liquid crystal polymer composition was prepared in the same manner as in Example 1 (1) except that the amount of the liquid crystalline low molecular compound having an acryloyl group at both ends was changed to 30 parts by weight. A film in which the liquid crystal polymer composition was oriented was obtained in the same manner as in Example 1 (2).
[0057]
Synthesis example 3
(1): (e) Synthesis of a monomer having a hydroxyl group at the terminal
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Hydroquinone (136.8 g, 1.24 mol), potassium hydroxide alcoholic solution (170 g, 3.03 mol nitrogen bubbled ethanol 400 ml, distilled water 100 ml) in a 1 liter 3-neck flask equipped with a three-one motor Then, after charging a catalytic amount of potassium iodide, ethylene chlorohydrin (100 g, 1.24 mmol) was added dropwise over 30 minutes under reflux heating conditions with nitrogen bubbling. After refluxing for about 15 hours, when ethanol was distilled off under reduced pressure, a glossy precipitate was deposited. The precipitate was filtered off, and the filtrate was washed twice with 500 ml of diethyl ether, and then acidified by adding 500 ml of 4N hydrochloric acid. This acidic aqueous solution was extracted four times with 500 ml of diethyl ether, and the collected organic phase was washed with a saturated aqueous sodium hydrogen carbonate solution and saturated brine (twice with 300 ml each), then dried over anhydrous magnesium sulfate, and the solvent was distilled off. To give the crude product. The crude product was purified by silica gel column chromatography (developing solvent: ethyl acetate / hexane = 2/1 (weight ratio)), and ethylene glycol- (4-hydroxyphenyl) ether obtained by etherifying only one hydroxyl group of hydroquinone was obtained. Obtained (yield 50.0 g, yield 26%, purity 99% or more)
Then, a 3-liter eggplant flask was charged with ethylene glycol- (4-hydroxyphenyl) ether (50.0 g, 324 mmol), 4- (2-propenoyloxyethoxy) benzoic acid (80.4 g, 340 mmol), Dimethylaminopyridine (1.3 g, 11 mmol, DMAP in the formula), a small amount of a polymerization inhibitor butylhydroxytoluene and 1.5 liters of methylene chloride were added to make a solution, and then dicyclohexylcarbodiimide (73.73) diluted with 50 ml of methylene chloride. 6 g, 357 mmol, DCC in the formula) was added in small portions and stirred at room temperature overnight. The precipitated DC urea was filtered off, and methylene chloride was added to the filtrate to make a total volume of 4 liters, followed by washing with 0.5N hydrochloric acid, saturated aqueous sodium hydrogen carbonate solution, and saturated brine (each twice in 1 liter). And dried over anhydrous magnesium sulfate, and the solvent was distilled off. The crude product was purified by column chromatography (developing solvent: methylene chloride / ether = 10/1 (weight ratio)) and then concentrated under reduced pressure. The obtained white precipitate was dissolved in 300 ml of methylene chloride, insoluble matter was filtered off, 1 liter of hexane was added to dry the precipitated white precipitate, and the target terminal phenylethanol type monomer shown in Chemical formula 15 was obtained. (Yield 80.8 g, yield 67%, purity 99% or more).
[0058]
(2): Synthesis of side chain type liquid crystal polymer (A)
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The terminal phenylethanol monomer (11.2 g, 30.0 mmol) obtained in Synthesis Example 3 (1) and the nematic liquid crystalline monomer (18.6 g, 45.0) obtained in Synthesis Example 1 (2). Mmol) was added to 680 ml of THF, and the mixture was stirred under reflux under a nitrogen stream to completely dissolve the monomer in THF. Azobisisobutyronitrile (1.27 g, 7.7 mmol, AIBN in the formula) dissolved in 10 ml of a small amount of THF was added dropwise thereto. After refluxing for 4 hours, heating was stopped and the reaction solution was returned to room temperature, and then the reaction solution was dropped into 2.2 liters of methanol to reprecipitate the polymer. The polymer was separated by filtration, washed with a mixed solvent of methanol / THF = 3/2 (weight ratio), and then dried to obtain chemical formula 16 (note that chemical formula 16 is described as a block for convenience). A side chain type liquid crystal polymer containing a monomer unit having a hydroxyl group terminal was obtained (yield 16.5 g, yield 55%, weight average molecular weight 3800).
[0059]
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Under a nitrogen atmosphere, the side-chain liquid crystal polymer (10.0 g, of which 3.5 g (9.3 mmol) of the monomer related to the monomer unit having a hydroxyl terminal), triethylamine (6.5 ml, 46.7 mmol), Dimethylaminopyridine (catalytic amount) and butylhydroxytoluene (small amount) were dissolved by stirring in 500 ml of dry THF. Acryloyl chloride (1.5 ml, 18.7 mmol) was slowly added dropwise thereto, and the mixture was stirred at room temperature for 3 hours. Next, 10 ml of water was added to deactivate excess acryloyl chloride, and the precipitated ammonium salt was filtered off. Then, 2 liters of chloroform was added, and 0.5 N hydrochloric acid, saturated aqueous sodium hydrogen carbonate solution, saturated brine (500 ml each) After washing with and drying over magnesium sulfate, the solvent was distilled off under reduced pressure. Then, a solution in which 80 ml of THF was added and the polymer was dissolved was dropped into 800 ml of methanol to precipitate the polymer, followed by filtration and drying, and chemical formula 17 (the chemical formula 17 is described as a block for convenience). The target side chain type liquid crystal polymer was obtained (yield 8.50 g, yield 81%, weight average molecular weight 4400).
[0060]
Example 4
(1) Preparation of liquid crystal polymer composition
100 parts by weight of the side chain type liquid crystal polymer (Chemical Formula 17) obtained in Synthesis Example 3 (2) and 10 parts by weight of the liquid crystalline low molecular weight compound having acryloyl groups at both ends obtained in Synthesis Example 2 are dissolved in tetrachloroethane. A liquid crystal polymer composition solution (12% by weight) was obtained.
[0061]
(2) Preparation of tilted alignment phase difference plate
A glass substrate was spin coated with a 5% aqueous solution of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Co., Ltd., trade name: NH-18) at 2000 rpm for 20 seconds, heated at 150 ° C. for 30 minutes, and then rubbed. Thus, an alignment film was formed. The liquid crystal polymer composition solution obtained in the above (1) was spin-coated on the alignment film and heated at 160 ° C. for 5 minutes to obtain a film in which the liquid crystal polymer composition was aligned. The film thickness of the film on which the liquid crystal polymer composition was oriented was 0.9 μm.
[0062]
Example 5
In Example 4 (1), a liquid crystal polymer composition was prepared in the same manner as in Example 4 (1) except that the amount of the liquid crystalline low molecular compound having an acryloyl group at both ends was changed to 30 parts by weight. A film in which the liquid crystal polymer composition was oriented was obtained in the same manner as in Example 4 (2).
[0063]
Comparative Example 1
In Example 1 (1), a liquid crystal polymer composition was prepared in the same manner as in Example 1 (1) except that a liquid crystalline low molecular compound having an acryloyl group at both ends was not added. ) To obtain a film in which the liquid crystal polymer composition was oriented.
[0064]
Comparative Example 2
In Example 4 (1), a liquid crystal polymer composition was prepared in the same manner as in Example 4 (1) except that a liquid crystalline low molecular compound having an acryloyl group at both ends was not added. ) To obtain a film in which the liquid crystal polymer composition was oriented.
[0065]
Comparative Example 3
In Example 1 (1), instead of the side chain type liquid crystal polymer obtained in Synthesis Example 1 (3), a monomer having a cyano group at the terminal obtained in Synthesis Example 1 (2) was polymerized. A liquid crystal polymer composition was prepared in the same manner as in Example 1 (1) except that the amount of the liquid crystalline low molecular weight compound having an acryloyl group at both ends obtained in Synthesis Example 2 was changed to 30 parts by weight using a homopolymer. The film which prepared and orientated the liquid crystal polymer composition like Example 1 (2) was obtained.
[0066]
Test example (phase difference measurement)
The viewing angle dependence of the retardation of the film in which the liquid crystal polymer compositions obtained in Examples and Comparative Examples were aligned was evaluated. In the evaluation, the inclination of the liquid crystal polymer composition was calculated by the following formula and used as an index of the inclination. The evaluation results are shown in Table 1. The front phase difference was Δnd (0), and the phase difference when tilted ± 30 ° in the slow axis direction was Δnd (+30) and Δnd (−30), respectively.
[0067]
Inclination = (Δnd (−30) −Δnd (+30)) / Δnd (0)
When the horizontal alignment is not inclined, the inclination is 0.
[0068]
[Table 1]

Claims (5)

Containing side chain type liquid crystal polymer (A), and both ends have a acryloyl group molecular weight 662 or less of the liquid crystalline low molecular compound (B) containing a monomer unit having a terminal acryloyl groups of the liquid crystalline side chain A liquid crystal polymer composition. The monomer unit having the acryloyl group has the general formula (a1):

(Wherein R ¹ represents a hydrogen atom or a methyl group, X ¹ represents a —COO— group or —OCO— group, m and n each independently represents an integer of 1 to 6, and p and q each independently represents 1; 2. The liquid crystal polymer composition according to claim 1, which is a monomer unit represented by 2 (provided that p + q ≦ 3 is satisfied), and r represents 0 or 1. The liquid crystalline low molecular compound (B) is represented by the general formula (B1):

(In the formula, A and D are each independently 1,4-phenylene group or 1,4-cyclohexylene group, B is 1,4-phenylene group, 1,4-cyclohexylene group, 4,4 ′ − A biphenylene group or a 4,4′-bicyclohexylene group, X ⁴ and X ⁵ each independently represent a —COO— group, —OCO— group or —O— group, and g and h each independently represents 2 to 2; The liquid crystal polymer composition according to claim 1, wherein the liquid crystal polymer composition is a compound represented by the formula: A retardation film using a film comprising the liquid crystal polymer composition according to claim 1, wherein the orientation direction of the liquid crystal polymer composition is inclined with respect to the film surface of the film. An elliptically polarizing plate formed by laminating and integrating the retardation plate according to claim 4 on a polarizing plate.