JP5078203B2 - Liquid crystal display element and manufacturing method thereof - Google Patents

Description

（式中、ｍは１〜１５の整数を表す）で表されるような液晶性ジアクリレートや類縁化合物（２）〜（４）
【化２】

（式中、ｍは１〜１２の整数を表す）で表されるような液晶性ジアクリレートを含有していてもよい。
【００２２】
また、ＵＳＰ５５６７３４９号公報に開示されている化合物（５）
【化３】

（式中、ｍは４〜１２の整数を、ｐは２〜１２の整数を表す）で表される液晶性テトラアクリレート、
また、ＵＳＰ５５９３６１７号公報に開示されている化合物（６）
【化４】

（式中、ｍは４〜１１の整数を表す）で表される液晶性トリアクリレート、
また、特開平１０−３１０６１２号公報に開示されている化合物（７）
【化５】

で表される液晶性ジアクリレート等の液晶骨格を２つ以上有するような重合性官能基を有する液晶性化合物を含有していてもよい。
【００２３】
また、一つの重合性官能基を有する液晶性化合物としては一般式（Ｉ）
【化６】

（式中、Ｘ¹ は水素原子又はメチル基を表し、ｎは０または１の整数を表し、６員環Ａ、環Ｂ、環Ｃはそれぞれ独立的に、１，４−フェニレン基、隣接しないCH基が窒素で置換された１，４−フェニレン基、１，４−シクロヘキシレン基、１つまたは隣接しない２つのCH₂ 基が酸素原子又は硫黄原子で置換された１，４−シクロヘキシレン基、１，４−シクロヘキセニレン基を表し、これらの６員環Ａ、環Ｂ、環Ｃは、さらに炭素原子数１〜７のアルキル基、アルコキシル基、アルカノイル基、又はシアノ基、ハロゲン原子で一つ以上置換されていてもよく、Ｙ¹ 、Ｙ² はそれぞれ独立的に単結合、-CH₂CH₂-、-CH₂O-、-OCH₂-、-COO- 、-OCO- 、-C≡C-、-CH=CH- 、-CF=CF- 、-(CH₂)₄-、-CH₂CH₂CH₂O-、-OCH₂CH₂CH₂-、-CH=CH-CH₂CH₂-、-CH₂CH₂-CH=CH-、-CH=CH-COO- 、-OCO-CH=CH- を表し、Ｙ³ は単結合、-O- 、-OCO- 、-COO- 、-CH=CH-COO- を表し、Ｚ¹ は水素原子、ハロゲン原子、シアノ基、炭素原子１〜２０の炭化水素基を表す。）で表される化合物を含有することは好ましい。
【００２４】
一般式（Ｉ）で表されるような液晶性化合物を含有する重合性液晶組成物は、二つ以上の重合性官能基を有する液晶性化合物を含有する重合性液晶組成物より粘度が低く、また液晶下限温度を低くすることができる傾向がある。一般式（Ｉ）で表される化合物の具体的な例として化合物（８）〜（３２）を示す。しかしながら、本発明の液晶組成物において使用することができる化合物はこれらに限定されるものではない。（式中、シクロヘキサン環はトランスシクロヘキサン環を表し、数字は相転移温度を表し、Ｃは結晶相、Ｎはネマチック相、Ｓはスメクチック相、Ｉは等方性液体相をそれぞれ表す。）
【００２５】
【化７】

【化８】

【化９】

【００２６】
このような化合物の中でも、化合物（１１）、（１９）、（２０）のトラン化合物は、複屈折率が大きく、かつ液晶性を示す温度が５０〜６０℃付近と低く有用な化合物である。また、化合物（８）のフェニルシクロヘキサン化合物は、液晶性を示す温度が３０℃付近と非常に低いため、特に有用である。化合物（１１）と化合物（８）を等量混合した場合には、２５℃においてネマチック相を示すため、特に有用である。
【００２７】
本発明の重合性液晶組成物には、重合性官能基を有していない液晶性化合物が含有されていてもよい。重合性官能基を有していない液晶性化合物としては、一般式（II）、（III)
【化１０】

（式中、Ｒ¹ 、Ｒ² 、Ｒ³ はそれぞれ独立的にフッ素置換されていてもよい炭素原子数１〜１６のアルキル基またはアルコキシル基、炭素原子数２〜１６のアルケニル基、炭素原子数３〜１６のアルケニルオキシ基、または炭素原子数１〜１０のアルコキシル基で置換された炭素原子数１〜１２のアルキル基を表し、環Ｄ、環Ｅ、環Ｆ、環Ｇ及び環Ｈはそれぞれ独立的にフッ素原子により置換されていてもよい１，４−フェニレン基、２−メチル−１，４−フェニレン基、３−メチル−１，４−フェニレン基、ナフタレン−２，６−ジイル基、フェナントレン−２，７−ジイル基、フルオレン−２，７−ジイル基、トランス−１，４−シクロヘキシレン基、１，２，３，４−テトラヒドロナフタレン−２，６−ジイル基、デカヒドロナフタレン−２，６−ジイル基、トランス−１，３−ジオキサン−２，５−ジイル基、ピリジン−２，５−ジイル基、ピリミジン−２，５−ジイル基、ピラジン−２，５−ジイル基またはピリダジン−２，５−ジイル基を表し、ｌ₂ 、ｍ₂ はそれぞれ独立的に０、１または２を表し、Ｚ² 、Ｚ³ 、Ｚ⁴ 、Ｚ⁵ はそれぞれ独立的に単結合、-CH₂CH₂-、-(CH₂)₄-、-OCH₂-、-CH₂O- 、-COO- 、-OCO- 、-C=C- または-C≡C-を表し、Ｘ³ はシアノ基、フッ素原子、塩素原子、トリフルオロメトキシ基、トリフルオロメチル基、ジフルオロメトキシ基、水素原子、３，３，３−トリフルオロエトキシ基、Ｒ' または−ＯＲ' を表し、Ｒ' は炭素原子数１〜１２の直鎖状アルキル基または、２〜１２の直鎖状アルケニル基を表し、Ｘ² 、Ｘ⁴ は水素原子、フッ素原子または塩素原子を表す。）から選ばれる化合物を１種または２種以上を含有するのが好ましい。
【００２８】
このような化合物の中において、Ｒ¹ 、Ｒ² 、Ｒ³ としては、それぞれ独立的にフッ素置換されていてもよく、不斉炭素原子を有していてもよい炭素原子数２〜８のアルキル基またはアルコキシル基、炭素原子数２〜８のアルケニル基、炭素原子数３〜８のアルケニルオキシ基、または炭素原子数１〜５のアルコキシル基で置換された炭素原子数２〜８のアルキル基が好ましく、環Ｄ、環Ｅ、環Ｆ、環Ｇ及び環Ｈとしては、それぞれ独立的にフッ素原子で置換されていてもよい１，４−フェニレン基または、トランス−１，４−シクロヘキシレン基が好ましく、Ｚ² 、Ｚ³ 、Ｚ⁴ 、Ｚ⁵ としてはそれぞれ独立的に単結合、-COO- 、-OCO- 、-C=C- または-C≡C-が好ましく、単結合、-COO- 、-OCO- がさらに好ましい。また、Ｘ² 、Ｘ³ 、Ｘ⁴ のうち２つがフッ素原子であり、他の１つが水素原子であることや、Ｘ³ がシアノ基であることが好ましい。
【００２９】
本発明の重合性液晶組成物中の重合性官能基を有していない液晶性化合物の含有量は、５〜９９質量％が好ましく、４０〜９８質量％がさらに好ましく、８０〜９８質量％が特に好ましい。重合性官能基を有していない液晶性化合物は特に制限がなく、この技術分野において液晶性化合物と認識されるものであれば使用することができるが、極性基としてシアノ基やフッ素原子等のハロゲン原子を有する液晶性化合物は、電界の印加によって配向を制御しやすいので、このような化合物を用いることが好ましい。特に極性基としてフッ素原子等のハロゲン原子のみを有するように重合性液晶組成物を設計すると、ＴＦＴ（薄膜トランジスタ）やＴＦＤ（薄膜ダイオード）等の能動素子による駆動に適した高い保持率を示す重合性液晶組成物が得られるので特に好ましい。
【００３０】
さらに、本発明の重合性液晶組成物には、液晶骨格の螺旋構造を内部に有する高分子を得ることを目的として、キラル化合物を添加することもできる。そのような目的で使用するキラル化合物は、それ自体が液晶性を示す必要はなく、また重合性官能基を有していても、有していなくてもよい。また、その螺旋の向きは、重合体の使用用途によって適宜選択できる。そのようなキラル化合物としては、例えば、キラル基としてコレステリル基を有するペラルゴン酸コレステロール、ステアリン酸コレステロール、キラル基として2-メチルブチル基を有するビーディーエイチ社（ＢＤＨ社；イギリス国）製の「ＣＢ−１５」、「Ｃ−１５」、メルク社（ドイツ国）製の「Ｓ−１０８２」、チッソ社製の「ＣＭ−１９」、「ＣＭ−２０」、「ＣＭ」；キラル基として１−メチルヘプチル基を有するメルク社製の「Ｓ−８１１」、チッソ社製の「ＣＭ−２１」、「ＣＭ−２２」などを挙げることができる。キラル化合物を添加する場合の好ましい添加量は、液晶組成物の用途によるが、重合して得られる重合体の厚み（ｄ）を重合体中での螺旋ピッチ（Ｐ）で除した値（ｄ／Ｐ）が０．１〜１００の範囲となる量が好ましく、０．１〜２０の範囲となる量がさらに好ましい。
【００３１】
本発明の重合性液晶組成物は、液晶性を示す温度範囲が下記条件を満たすことが好ましい。まず、液晶下限温度が３５℃以下であることが好ましく、３０℃以下であることがさらに好ましく、２５℃以下であることが特に好ましい。液晶下限温度が２５℃以下である場合、室温において液晶状態を安定に得ることができるため、配向処理等の製造プロセスにおいても特に加熱する必要がなくなり、望ましくない熱重合を回避するのが容易になる。液晶上限温度は、３０℃以上であるのが好ましく、３５℃以上がさらに好ましく、４０℃以上が特に好ましい。また、本発明の重合性液晶組成物を等方性液体相の状態で、液晶セルへの注入や基板への塗布等を行う必要がある場合に、熱重合の誘起を避けるため、液晶上限温度を１２０℃以下にするのが好ましく、８０℃以下がさらに好ましく、６０℃以下が特に好ましい。
また、本発明の重合性液晶組成物の複屈折率は、０．０４〜０．４５の範囲が好ましく、０．０５〜０．３５の範囲がさらに好ましく、０．０８〜０．２４の範囲が特に好ましい。
【００３２】
重合性液晶組成物に望まれる液晶相の種類は用途によって異なるが、ネマチック相、キラルネマチック相、スメクチックＡ相、スメクチックＣ相、キラルスメクチックＣ相、キラルスメクチックＣ_A 相を示すことが好ましく、キラルスメクチックＣ相（強誘電相）、キラルスメクチックＣ_A 相（反強誘電相）がさらに好ましい。
【００３３】
重合性液晶組成物が強誘電相または反強誘電相を示す場合は、重合性官能基を有する液晶性化合物または重合性官能基を有していない液晶性化合物のうちいずれか一方、特に重合性官能基を有していない液晶性化合物が強誘電性液晶または反強誘電性液晶であることが好ましい。
このとき、本発明の重合性液晶組成物中に含有される強誘電性液晶または反強誘電性液晶は、重合性液晶組成物の４０〜９８質量％であることが好ましく、８０〜９８質量％であることがさらに好ましい。
重合性液晶組成物が強誘電性液晶または反強誘電性液晶である場合は、強誘電相または反強誘電相を示す状態で紫外線を照射することにより、高速応答性を有し、コントラスト比が高く、中間調表示が可能な液晶表示素子が得られる。
このとき、液晶表示素子のセルギャップは２μｍ以下であることが好ましく、１．７μｍ以下がさらに好ましい。セルギャップを小さくすることで、強誘電相または反強誘電相の配向状態を安定化させることができる。
また、本発明の重合性液晶組成物の２５℃における粘度は、４００〜７６０ｍＰａ・ｓの範囲においても問題ない。
次に、本発明の液晶表示素子の製造方法について説明する。
【００３４】
本発明の液晶表示素子は、少なくとも一方が透明な一対の電極付き基板より形成されるセルギャップが６μｍ以下のセル内に、少なくとも１つの重合性官能基を有する液晶性化合物とアシルフォスフィンオキサイド化合物とを含有する重合性液晶組成物を、セル内に真空注入し、紫外線を照射することを特徴としている。必要な場合は、重合性液晶組成物はさらに重合性官能基を有していない液晶性化合物を含んでいてもよい。以下、本発明の液晶表示素子の製造方法のフローチャートを図１に示し、フローチャートに沿って各工程を詳しく説明する。
【００３５】
はじめに、セルを作製し、このセルに注入するための重合性液晶組成物を調製する。セルの作製方法は上述した通りである。また、本発明の製造方法において使用する重合性液晶組成物は、前述の重合性液晶組成物が好適である。
次に、真空注入装置内に、セルと容器に収容した重合性液晶組成物を置き、以下のようにして、重合性液晶組成物を空セル内に注入する。
重合性液晶組成物は、真空注入する前に脱気するのが好ましい。脱気は、重合性液晶組成物が等方性液体相となる温度に加温し、真空状態で行うのが好ましい。この際、真空度は１３．３Ｐａ以下であることが好ましい。脱気を長時間行うと重合性が損われる場合があるので、３時間以内とすることが好ましく、３０分以内とすることがさらに好ましい。
【００３６】
脱気した後、容器に収容した重合性液晶組成物とセルとを、真空下、好ましくは７０℃以上、さらに好ましくは８０℃以上に昇温し、重合性液晶組成物に空セルの注入孔を浸す。その後常圧に戻し、注入完了後、セルを室温まで徐冷する。このように真空注入法を用いて、セルギャップが６μｍ以下のセル内に注入しようとする場合、セル内を１３．３Ｐａ以下の真空度とすることが好ましく、さらには１．３３Ｐａ以下の真空度とすることが好ましい。真空度が足りないと、セル全体に重合性液晶組成物が入らない欠陥が発生する場合がある。
【００３７】
特に、重合性液晶組成物が強誘電性液晶または反強誘電性液晶である場合は粘度が高いため、セルギャップが６μｍ以下および／または基板が対角１０ｃｍ以上のセルに均一に注入するのは困難であるので、セル内を１３．３Ｐａ以下の真空度とし、セルと重合性液晶組成物とを７０℃以上に加温して、真空注入するのが好ましく、特には、セル内を１．３３Ｐａ以下とし、セルと重合性液晶組成物とを８０℃以上に加温して、真空注入するのが好ましい。
【００３８】
重合性液晶組成物を注入した後は、注入孔を封止する。注入孔を封止する方法は特に制限されないが、例えば以下のようにして行える。まず、基板間に狭持したセルを好ましくは７０℃以上、さらに好ましくは８０℃以上に加熱する（加熱工程）。安定後、基板の両面から加圧し（加圧工程）、封止材を注入孔に塗布した後（注入孔封止工程）、加圧を緩める（減圧工程）ことにより封止材を注入孔に注入し、硬化させて封止する方法が挙げられる。封止材は、紫外線硬化性樹脂または二液性硬化封止材が使用できるが、紫外線照射による重合性液晶組成物の硬化を避けるためには、二液性硬化封止材を使用するのが好ましい。
【００３９】
このようにして製造された液晶表示素子は、セル中の液晶を所望の配向に整えながらまたは整えた後に、紫外線を照射することが好ましい。
配向を整える前に、均一な配向を実現しやすくするため、液晶表示素子を重合性液晶組成物が等方性液体相となる温度に昇温し、その温度で約１０分〜２時間保持した後、徐冷することが好ましい。
液晶表示素子を所望の配向を示す温度まで冷却した後、紫外線を照射し光重合させることにより、配向に沿った高分子鎖を形成させ、液晶の配向を安定化することができる。
重合性液晶組成物がネマチック相またはキラルネマチック相である場合、広視野角や双安定性が良好な表示装置を実現できる。
【００４０】
また、重合性液晶組成物が強誘電性液晶または反強誘電性液晶である場合には、強誘電相または反強誘電相を示す状態に配向させながら、または配向した後に、紫外線照射により、対角サイズの大きなセルを用いて、安定で均一な配向を実現するこことが困難であった問題が解消される。
紫外線を照射する際は、直流電圧を印加して配向を整えることが好ましい。直流電圧を印加して配向を整えた後は、直流電圧を印加した状態で紫外線を照射してもよいが、重合性液晶組成物がメモリー性を有する場合には、直流電圧の印加を切った状態で紫外線を照射してもよい。
【００４１】
例えば、重合性液晶組成物が強誘電性液晶である場合には、強誘電相を示す温度で直流電圧を印加することにより、重合性官能基を有する液晶性化合物の骨格の配向方向を強誘電相の双安定状態のうち、どちらか一方の配向と一致させることができ、この状態で紫外線を照射して光硬化させれば、駆動電圧を印加していない状態の強誘電相の配向方向は、紫外線照射時の強誘電性液晶の配向方向とほぼ一致する。これは硬化物の液晶骨格の配向安定化効果によるものと考えられる。このとき、セルギャップは２μｍ以下とすることが好ましく、１．７μｍ以下がさらに好ましい。このようにして得られる高分子安定型強誘電性液晶表示素子は、駆動電圧を印加することにより、双安定状態の一方の配向方向からもう一方の配向方向まで連続的に制御できるので、中間調表示を達成できる。
このとき、紫外線の照射強度は、１〜３００ｍＷ／ｃｍ² の範囲が好ましく、１〜３ｍＷ／ｃｍ² の範囲がさらに好ましい。
【００４２】
また、重合性液晶組成物として反強誘電性液晶を用いる場合には、反強誘電相を示す温度で電圧無印加状態で紫外線を照射して光硬化させる。これにより３状態スイッチングをＶ字型スイッチングに変えることができ、中間調表示ができるようになる。
【００４３】
上述のようにして得られる高分子安定型強誘電性液晶表示素子または単安定型強誘電性液晶表示素子は、スタティック型のフルドット、または非フルドット表示素子において、同一表示単位で時間と共に異なる色を発色させるフィールドシーケンシャル方式で駆動を行う液晶表示装置に好適に使用される。
この方式の液晶表示装置は、照明手段が複数の発光色を持つ光源で、ＣＣＴあるいはＬＥＤからなる。上記光源を独立に制御し、表示部と同期させて点灯することで部分的に任意の着色を行う。
【００４４】
この方式の液晶表示装置においては、照明手段が複数の発光色を持つ光源を独立に制御でき、かつ、各光源の点滅を１フレームとしてそれを１秒間に５０フレーム以上切り替えられるものであること、および照明手段の光源の切り替えと駆動手段とが同期されていることが重要である。そして、ＣＣＴまたはＬＥＤ等からなるＲ、Ｇ、Ｂなどの複数の単色光源を有し、高速に切り替えられる照明手段を設け、表示部と同期させて点灯させることにより部分的に任意の着色を行うことができる。
【００４５】
照明手段の光源の切り替えと駆動手段との同期は次のように行う。フリッカーを感じない表示とするために、例えば１秒間に６０フレーム程度の信号を書き込むことを行う。この場合、１回のフレーム時間は１６．６ｍｓとなる。Ｒ、Ｇ、Ｂの３色バックライトをこの時間内に順次点灯させるとすると、１色あたりの点灯時間は約５．５ｍｓとなる。ここで、高分子安定型強誘電性液晶や単安定型強誘電性液晶や双安定型強誘電性液晶の場合の立ち上がり時間は２００μｓ、立ち下がり時間は３００μｓである。
したがって、液晶の立ち上げと同時にＲのバックライトを５．５ｍｓ点灯させ、液晶の立ち下げと同時にＲのバックライトを消灯する。順次、Ｇ、Ｂを同様に点灯または非点灯させればよい。これらの単色画像は、肉眼の残像現象によって混色されるので、高分子安定型強誘電性液晶や単安定型強誘電性液晶の場合、各色毎に電圧制御にて液晶の中間調表示を行えば、さらなる多色化も可能となる。
【００４６】
【実施例】
次に、実施例を挙げて本発明をさらに詳しく説明するが、本発明はこれらの実施例に限定されるものではない。
（例１）高分子安定型強誘電性液晶表示素子の作製
はじめに、空セルとそれに注入する重合性液晶組成物（Ｂ）を調製した。
＜重合性液晶組成物（Ｂ）の調製＞
式（８）で表される化合物５０質量部
【化１１】

および式（１１）で表される化合物５０質量部
【化１２】

からなる組成物を調製した。この組成物は、室温（２５℃）でネマチック相を呈した。ネマチック相−等方性液体相転移温度は４６．１℃であった。また、５８９ｎｍで測定したｎ_e （異常光の屈折率）は１．６６２で、ｎ_o （常光の屈折率）は１．５１０、複屈折率は０．１５２であった。
【００４７】
この組成物に対し、重合開始剤として式（３３）で表されるアシルフォスフィンオキサイド化合物である２，４，６−トリメチルベンゾイルジフェニルフォスフィンオキサイド（商品名：ルシリン−ＴＰＯ、ＢＡＳＦ社）の０．１質量％
【化１３】

および重合禁止剤として式（３４）で表されるニトロソ化合物であるアルミニウムＮ−ニトロソフェニルヒドロキシルアミン（商品名：Ｑ−１３０１、和光純薬製）の３００ｐｐｍ
【化１４】

を添加して、重合性液晶組成物（Ａ）を調製した。
この重合性液晶組成物（Ａ）の２質量％に、重合性官能基を有していない強誘電性液晶化合物（商品名：ＦＥＬＩＸ Ｍ４８５１／１００、クラリアント社製）の９８質量％を添加して重合性液晶組成物（Ｂ）を調製した。この重合性液晶組成物（Ｂ）の２５℃における粘度は、４６０ｍＰａ・ｓであった。
＜空セルの作製＞
パターニングしたＩＴＯ電極を有する対角１３ｃｍの２枚のガラス基板に、それぞれＩＴＯ側に配向膜（商品名：ＲＮ１２８６、日産化学製）を塗布し膜厚を約１５０Åとした。配向膜には弱いラビングを実施し、ギャップスペーサーは１．７μｍのシリカ熱固着ビーズを使用し、２枚の基板をラビング方向がパラレル配向となるように張り合わせ、注入孔を除く外周部をシールして、セルギャップ１．７μｍの空セルを作製した。
【００４８】
次に、調製した重合性液晶組成物（Ｂ）を、以下のようにして空セルに真空注入した。
まず、真空注入装置内に、容器に収容した重合性液晶組成物（Ｂ）と空セルを置いた。
次に、重合性液晶組成物（Ｂ）を脱気した。加温温度は重合性液晶組成物（Ｂ）が等方性液体相となる８０℃とし、約３０分間の真空状態とした。その後、重合性液晶組成物（Ｂ）の温度を室温に戻し、空セルを真空度１．３３Ｐａになるまで脱気した。脱気に要した時間は約２時間であった。
脱気後、重合性液晶組成物（Ｂ）と空セルを８０℃に加熱し、安定後、空セルの注入孔を重合性液晶組成物（Ｂ）に浸し、常圧に戻して注入を開始させた。注入時間は約２時間であった。
注入後、重合性液晶組成物（Ｂ）を基板間に狭持したセルを８０℃に加熱し、安定後、両面より約１．２ｋｇ／ｃｍ² で加圧して約４０分間静置した。その後、注入孔に２液性硬化封止剤を塗布し、塗布後に加圧条件を１．１ｋｇ／ｃｍ² に減圧して１０分間静置して硬化させた。その後、室温まで戻した後、セルを洗浄した。この高温加圧封止により対角サイズの大きなセルであっても、そのセルギャップが均一に保たれた。
【００４９】
次に、配向を安定化するために、得られたセルを再度８０℃まで上げて１時間保持した後、徐冷した。室温まで戻した後、セルの全面に直流電圧１５Ｖを印加した状態で、ガラス基板透過後の強度が２．４７ｍＷ／ｃｍ² となる条件で中心波長３６５ｎｍの紫外線を約６０秒間照射し、重合性液晶組成物を光硬化させ、高分子安定型強誘電性液晶表示素子を作製した。
得られた液晶表示素子を偏光顕微鏡で観察したところ、液晶層は強誘電相を示し、欠陥がない均一な一軸配向をしていることが認められた。
この液晶表示素子に一対の偏光板をクロスニコル状態で配置し、電圧が無印加状態で最も暗状態となるように配置した。電圧を印加した時の光学的な変化を図２に示す。また、図３にはコントラスト比を、図４には電圧を変化させた時の応答速度を示す。
図２〜４より、得られた液晶表示素子は、中間調表示が可能で、コントラスト比が高く、かつ、高速応答表示ができることが理解できる。
【００５０】
（例２）高分子安定型双安定ツイストネマチック液晶表示素子の作製
はじめに、空セルとそれに注入する重合性液晶組成物（Ｃ）を調製した。
＜重合性液晶組成物（Ｃ）の調製＞
例１で調製した重合性液晶組成物（Ａ）の４．３質量％に、重合性官能基を持たない室温ネマチック液晶化合物ＺＬＩ−５０４９−１００（メルク社製）の９４質量％とキラル剤Ｓ−８１１（メルク社製）の１．７％を添加して重合性液晶組成物（Ｃ）を調製した。このときのピッチは約５μｍとなった。この重合性液晶組成物（Ｃ）は、室温（２５℃）でネマチック液晶相を呈した。
【００５１】
＜空セルの作製＞
パターニングされたＩＴＯ電極を有する対角２０ｃｍの２枚のガラス基板に、それぞれＩＴＯ側に配向膜（商品名：ＳＥ−３５１０、日産化学製）を塗布し膜厚を約３００Åとした。配向膜にはラビング処理を施し、プレチルト角約４°を実現した。ギャップスペーサーは３．５μｍのシリカ熱固着ビーズを使用し、２枚の基板をラビング方向がアンチパラレル配向となるように張り合わせ、注入孔を除く外周部をシールして、セルギャップ３．５μｍの空セルを作製した。
【００５２】
次に、調製した重合性液晶組成物（Ｃ）を空セルに真空注入した。
まず、真空注入装置内に容器を収容した重合性液晶組成物（Ｂ）と空セルを置いた。
次に、重合性液晶組成物（Ｃ）を脱気した。加温温度は重合性液晶組成物（Ｃ）が等方性液体相となる８０℃とし、約３０分間の真空状態とした。その後、重合性液晶組成物（Ｃ）の温度を室温に戻し、空セルを真空度１．３３Ｐａになるまで脱気した。脱気に要した時間は約２時間であった。
脱気後、空セルの注入孔を重合性液晶組成物（Ｃ）に浸し、常圧に戻して注入を開始させた。注入時間は約３０分間であった。
注入後、重合性液晶組成物（Ｃ）を狭持したセルを、両面より約０．３ｋｇ／ｃｍ² で加圧して約１５分間静置した。静置後、注入孔に２液性硬化封止剤を塗布し、塗布後に加圧条件を０．２５ｋｇ／ｃｍ² に減圧して８時間静置して硬化させた。その後、セルを洗浄した。
次に、配向を安定化するために、得られたセルを再度８０℃まで加温し、１０分間保持した後、徐冷した。室温まで戻した後、セルの全面に２０Ｖの交流電場を印加した状態で、画素部をマスクし、中心波長３６０ｎｍで２ｍＷ／ｃｍ² の強度の紫外線を５分間、ほぼ画素間の領域に照射した。これによりメモリー状態が長時間安定した高分子安定型双安定ツイストネマチック液晶表示素子を作製できた。
【００５３】
（例３）
例２の重合開始剤の代わりに、式（３５）で表される２，２−ジメトキシ−１，２−ジフェニルエタン−１−オン（商品名：イルガキュア−６５１、チバスペシャリティケミカルズ社）
【化１５】

重合禁止剤の代わりに、式（３６）で表される４−メトキシフェノール
【化１６】

を用いた場合には、途中で望ましくない熱重合が誘起されてしまい、所望の液晶表示素子を作製することができなかった。
したがって、本発明の重合性液晶組成物は、重合開始剤としてアシルフォスフィンオキサイド化合物、重合禁止剤としてニトロソ化合物を含有することにより、加熱減圧条件に対して耐性があることがわかる。
【００５４】
（例４）
次に、例１で作製した高分子安定型強誘電性液晶表示素子をスタティック駆動させ、裏面にレッドとシアンの発光が可能なＣＣＴバックライトを設置し、１サブフレーム目でレッドの発光、２サブフレーム目でシアンの発光をさせるように同期させた。赤を表示したいセグメントには１サブフレーム目でオンとし、２サブフレーム目でオフとなるような駆動を行い、白色を表示したいセグメントには１サブフレーム、２サブフレームともオンとなるような駆動を行った結果、カラーフィルターがないにもかかわらず、赤と白の表示ができた。また、視角も広く良好な視認性を示した。
【００５５】
上記と同じ液晶表示素子をスタティック駆動させ、裏面にＲ、Ｇ、Ｂの発光が可能なＬＥＤバックライトを設置し、１サブフレーム目でＲ、２サブフレーム目でＧ、３サブフレーム目でＢの発光をさせるように同期させた。赤を表示したいセグメントには１サブフレーム目でオンとし、２サブフレーム目と３サブフレーム目でオフとなるような駆動を行い、白色を表示したいセグメントには全サブフレームともオンとなるような駆動を行った結果、カラーフィルターがないにも関わらず、赤と白の表示ができた。また、視角も広く良好な視認性を示した。
【００５６】
例１で作製した高分子安定型強誘電性液晶表示素子を、フィールドシーケンシャル方式で駆動を行う液晶表示装置のセグメントパターンの一例を図５に示す。
図５中、白い部分が表示部であり、孤立している所が独立した表示部を示す。黒い部分は非表示部であり、遮光を目的としてブラックマスク処理されている。
【００５７】
【発明の効果】
本発明によれば、セルギャップ６μｍ以下の薄型のセル内に重合性液晶組成物を均一に狭持させた液晶表示素子が得られる。また、本発明の液晶表示素子は、重合性組成物を注入した後に、所望の配向状態で紫外線を照射することにより、液晶材料の配向を安定化することができる。特に、重合性液晶組成物として強誘電性液晶または反強誘電性液晶を用いる場合には、高速応答性を有し、コントラスト比が高く、中間調表示を可能とした液晶表示素子が得られるので、特に高速応答性が要求されるフィールドシーケンシャル方式で駆動を行う液晶表示装置に好適に使用でき、ＯＡ機器のディスプレイ等のハイインフォメーション表示体や、広告板、案内板、装飾表示板等の公衆表示、またはテレビ等に利用される。
【図面の簡単な説明】
【図１】 本発明の液晶表示装置の製造方法のフローチャートを示す図である。
【図２】 本発明の液晶表示素子に電圧を印加した時の光学的な変化を示す図である。
【図３】 本発明の液晶表示素子のコントラスト比を示す図である。
【図４】 本発明の液晶表示素子の電圧を変化させた時の応答速度を示す図である。
【図５】 本発明の液晶表示装置のセグメントパターンの一例を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thin liquid crystal display element, and is particularly suitable for a high information display body such as a display of an OA device that requires high-speed switching, a public display such as an advertising board, a guide board, a decorative display board, or a television. The present invention relates to a thin liquid crystal display element to be used.
[0002]
[Prior art]
In order to produce a liquid crystal display element with a small cell gap, it is common to inject liquid crystal in vacuum in order to improve uniformity. In order to shorten the injection time, it is generally known that the vacuum injection is performed in a high temperature state where the viscosity of the liquid crystal is low or in an isotropic liquid phase state.
A polymerizable liquid crystal composition composed of a liquid crystal compound having a polymerizable functional group and a liquid crystal compound having no polymerizable functional group is injected into the cell, and a desired alignment state is obtained by applying an electric field or a magnetic field. After preparing, irradiate with active energy rays such as ultraviolet rays. As a result, a polymer chain is formed in the polymerizable liquid crystal composition, and a polymer-stable liquid crystal display element in which the orientation of the liquid crystal material having no polymerizable functional group is stabilized by the polymer chain is prepared. Can do.
In this case, a polymerization initiator is added to the polymerizable liquid crystal composition so that the polymerization is initiated by ultraviolet rays or the like. When such a polymerizable liquid crystal composition is used for production, it is suitable under certain production conditions. It is very difficult to cure at the timing.
In particular, when a polymerizable liquid crystal composition is injected into a thin cell, it is exposed to a long-time vacuum in order to increase the degree of vacuum. In addition, the polymerization initiator may volatilize and the polymerization reaction may not occur by being kept at a high temperature for a long time in order to shorten the injection time. In addition, there is a problem that thermal polymerization occurs and cannot be cured at an appropriate timing, and thus desired characteristics cannot be obtained.
[0003]
Japanese Patent Application Laid-Open No. 11-21554 describes a method for manufacturing a liquid crystal display element, in which a liquid crystal acrylate monomer is contained in a ferroelectric liquid crystal and cured while applying a DC voltage. And although it is said that halftone display can be performed, the problem at the time of inject | pouring a polymeric liquid crystal composition uniformly into a thin cell is not recognized.
Japanese Patent No. 3055208 discloses a method for producing a liquid crystal display element by injecting a liquid crystal material and a photopolymerizable composition into a cell by a vacuum injection method. However, a liquid crystal property having a polymerizable functional group is described. There is no mention of using compounds.
[0004]
[Problems to be solved by the invention]
The object of the present invention is to inject a liquid crystal material containing a polymerizable liquid crystal composition into a thin cell, particularly a thin cell having a large diagonal size, It is intended to stably control an important polymerization reaction process. An object of the present invention is to produce a liquid crystal display device using a polymerizable liquid crystal composition that does not deteriorate the polymerization properties such as the polymerization properties are not impaired or the polymerization starts. In particular, an attempt is made to provide a thin liquid crystal display element capable of halftone display using a ferroelectric liquid crystal or an antiferroelectric liquid crystal as a polymerizable liquid crystal composition.
Another object of the present invention is to provide a liquid crystal display device that is driven by a field sequential method, which uses a thin liquid crystal display element to develop different colors over time in the same display unit.
[0005]
[Means for Solving the Problems]
As a result of intensive investigations on the method of injecting a polymerizable liquid crystal composition into a thin cell without altering the polymerization characteristics, the inventors have vacuum injected a polymerizable liquid crystal composition containing a specific polymerization initiator. Thus, the inventors have found that the polymerizable liquid crystal composition can be uniformly held in a thin cell without changing the polymerization characteristics of the entire liquid crystal material in the cell, and the present invention has been completed.
[0006]
That is, the present invention includes a pair of substrates with electrodes, at least one of which is transparent, has a cell gap of 6 μm or less, and contains a liquid crystalline compound having at least one polymerizable functional group and an acylphosphine oxide compound. Provided is a liquid crystal display device in which a polymerizable liquid crystal composition is vacuum-injected into a cell and the polymerizable liquid crystal composition is polymerized by ultraviolet irradiation.
[0007]
The present invention also provides the liquid crystal display element, wherein the substrate has a diagonal of 10 cm or more.
[0008]
Here, the polymerizable liquid crystal composition further includes a liquid crystal compound having no polymerizable functional group, and the liquid crystal compound having no polymerizable functional group is the polymerizable liquid crystal. It is preferable that it is 40-98 mass% of a composition.
[0009]
The polymerizable liquid crystal composition preferably further contains a nitroso compound, and the polymerizable liquid crystal composition preferably has a viscosity at 25 ° C. of 400 to 760 mPa · s.
[0010]
The present invention also includes a liquid crystalline compound having at least one polymerizable functional group and a polymerizable functional group in a cell having a cell gap of 6 μm or less formed from a pair of substrates with electrodes, at least one of which is transparent. Provided is a method for producing a liquid crystal display element, wherein a polymerizable liquid crystal composition containing a liquid crystal compound and an acylphosphine oxide compound that are not present is vacuum-injected and irradiated with ultraviolet rays.
[0011]
In the production method of the present invention, it is preferable that the inside of the cell has a vacuum of 13.3 Pa or less, the cell and the polymerizable composition are heated to 70 ° C. or higher, and vacuum injection is performed.
[0012]
The polymerizable liquid crystal composition is preferably a ferroelectric liquid crystal or an antiferroelectric liquid crystal, and is irradiated with ultraviolet rays while being aligned in a state showing a ferroelectric phase or an antiferroelectric phase, or after being aligned. It is preferable.
[0013]
Furthermore, the present invention provides a liquid crystal display device that is driven by a field sequential method using the liquid crystal display element.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The liquid crystal display element of the present invention comprises a pair of substrates with electrodes at least one of which is transparent, a cell gap of 6 μm or less, and a liquid crystalline compound having at least one polymerizable functional group and an acylphosphine oxide compound. The polymerizable liquid crystal composition is polymerized.
[0015]
The cell consists of a transparent electrode such as ITO (conductive oxide in which tin is doped in indium), a rubbing-treated polyimide film or SiO diagonal on the inner surface of a pair of transparent substrates such as glass, metal or plastic film. A liquid crystal alignment film such as a vapor deposition film is sequentially laminated, arranged so that the liquid crystal alignment films face each other, a granular spacer for realizing a predetermined cell gap is sandwiched, and the periphery of the substrate excluding the injection hole is sealed with It is formed by sealing with. A liquid crystal alignment film that has been subjected to a rubbing treatment is used. Alternatively, since the alignment can be stabilized by photocuring in a desired alignment state, the rubbing treatment does not have to be performed.
A cell gap is 0.7-6 micrometers, Preferably it is 4 micrometers or less, More preferably, it is 2 micrometers or less. The size of the cell is not particularly limited, but the substrate constituting the cell is preferably 10 cm or more, more preferably 13 cm or more, and particularly preferably 16 cm or more.
In the present invention, at least one of the substrates is transparent, and the light control layer sandwiched between the two substrates may be visible from the outside. However, complete transparency is not essential, and an opaque electrode may be disposed on a part of the substrate. In the case of the configuration of the reflective liquid crystal display element, a reflective electrode or a transparent electrode and a reflective film are provided on the back side.
[0016]
When the polymerizable liquid crystal composition is vacuum-injected into a thin cell having a cell gap of 6 μm or less, the degree of vacuum in the cell is preferably 13.3 Pa or less, and more preferably 1.33 Pa or less. Further, the temperature at the time of vacuum injection is preferably 70 ° C. or higher, and more preferably 80 ° C. or higher. In particular, it is preferable that both the degree of vacuum and the temperature satisfy the above conditions simultaneously. That is, vacuum injection is preferably performed at 13.3 Pa or lower and 70 ° C. or higher, and particularly preferably performed at 1.33 Pa or lower and 80 ° C. or higher. Under these conditions, the polymerizable liquid crystal composition can be uniformly injected into a cell having a cell gap of 6 μm or less and / or a substrate having a diagonal of 10 cm or more.
[0017]
Thus, when the polymerizable liquid crystal composition is injected into the thin cell, the polymerizable liquid crystal composition is exposed to a vacuum state or a high temperature state for a long time. However, since the polymerizable liquid crystal composition of the present invention contains an acyl phosphine oxide compound as a polymerization initiator, the polymerization characteristics do not deteriorate even under such conditions.
[0018]
The acyl phosphine oxide compound can impart excellent curability to the polymerizable liquid crystal composition when added in a small amount. The acyl phosphine oxide compound has a molecular weight of 280 or more for the purpose of achieving a low odor of a cured product of the polymerizable liquid crystal composition and ensuring low volatility when exposed to a reduced pressure heating process such as vacuum injection. More preferably, it is preferable to select a compound having a molecular weight of 300 or more, particularly preferably a molecular weight of 320 or more. Examples of such compounds include BASF's Lucillin TPO, Lucillin-TPO-L, and Ciba Specialty Chemicals Irgacure 819. The preferable density | concentration of such a polymerization initiator is 0.05-2 mass% with respect to the mass sum total of the liquid crystalline compound which has a polymerizable functional group contained in a polymeric liquid crystal composition. 0.07-1 mass% is further more preferable, and 0.1-0.5 mass% is especially preferable. If the amount of the acylphosphine oxide compound added is too large, the cured product of the polymerizable liquid crystal composition tends to be colored yellow, and if the amount added is too small, excellent curability tends not to be obtained.
[0019]
When an acylphosphine oxide compound is used as a polymerization initiator, excellent curability can be obtained with a small amount of addition, but polymerization is prohibited in order to improve storage stability and suppress the induction of undesirable thermal polymerization as a polymerizable liquid crystal composition. It is preferable to add an agent. Examples of such compounds include phenols such as hydroquinone and tertiary butyl catechol, thiophenols, nitroso compounds, β-naphthylamines, β-naphthols and the like, and nitroso compounds are particularly preferable.
Nitroso compounds are particularly effective in suppressing undesired thermal polymerization, and are used in combination with the acylphosphine oxide compound contained in the polymerizable liquid crystal composition of the present invention, and are adapted to the manufacturing process by adjusting the concentration of each. It has been clarified by examination of the inventors that appropriate curability can be obtained.
As the nitroso compound, a molecular weight of 280 or more is more preferable for the purpose of achieving a low odor of the cured product of the polymerizable liquid crystal composition and ensuring low volatility when exposed to a vacuum heating process such as vacuum injection. It is preferable to select a compound having a molecular weight of 300 or more, particularly preferably a molecular weight of 320 or more. An example of such a compound is Wako Pure Chemical Q-1301. The concentration of such a polymerization inhibitor is preferably 50 to 1,000 ppm, more preferably 70 to 700 ppm, particularly preferably 100 to 500 ppm based on the total mass of the polymerizable materials contained in the polymerizable liquid crystal composition. .
[0020]
When such a polymerization inhibitor is added, the order of addition to the polymerizable liquid crystal composition is important. First, a polymerization inhibitor is added to a polymerizable material containing a liquid crystalline compound having a polymerizable functional group, and after adding a polymerization initiator, a stable quality polymerizable liquid crystal composition is prepared. it can. In addition, when the polymerization initiator or polymerization inhibitor is difficult to be uniformly compatible with a polymerizable material containing a liquid crystalline compound having a polymerizable functional group, it is common to the polymerization initiator, polymerization inhibitor, and polymerizable material. A stable quality polymerizable liquid crystal composition is prepared by adding a solvent to make each component compatible, and then removing the solvent by natural drying or distillation under reduced pressure, distillation under reduced pressure, etc. it can.
[0021]
If the liquid crystalline compound having a polymerizable functional group contained in the polymerizable liquid crystal composition of the present invention exhibits liquid crystallinity as a whole composition, the compound itself may or may not exhibit liquid crystallinity. Good. The polymerizable functional group is preferably a functional group selected from radically polymerizable acrylate groups, methacrylate groups, epoxy groups, and vinyl ether groups. The number of polymerizable functional groups in one molecule is not particularly limited, and a plurality of types of functional groups may be used in combination. The chemical structure of the liquid crystalline compound having a polymerizable functional group is not particularly limited as long as it can be used as a polymerizable liquid crystalline compound in this technical field. For example, the formula (1) as disclosed in Japanese Patent Publication No. 8-3586
[Chemical 1]

(Wherein m represents an integer of 1 to 15) liquid crystalline diacrylates and related compounds (2) to (4)
[Chemical 2]

(Wherein m represents an integer of 1 to 12) may contain a liquid crystalline diacrylate.
[0022]
Further, compound (5) disclosed in US Pat. No. 5,567,349
[Chemical 3]

(Wherein, m represents an integer of 4 to 12, and p represents an integer of 2 to 12),
Further, the compound (6) disclosed in US Pat. No. 5,593,617
[Formula 4]

(Wherein m represents an integer of 4 to 11),
Further, compound (7) disclosed in JP-A-10-310612
[Chemical formula 5]

A liquid crystal compound having a polymerizable functional group having two or more liquid crystal skeletons such as liquid crystal diacrylate represented by formula (1) may be contained.
[0023]
Further, the liquid crystal compound having one polymerizable functional group may be represented by the general formula (I)
[Chemical 6]

(Where X ¹ Represents a hydrogen atom or a methyl group, n represents an integer of 0 or 1, 6-membered ring A, ring B, and ring C are each independently substituted with 1,4-phenylene group and non-adjacent CH group with nitrogen 1,4-phenylene group, 1,4-cyclohexylene group, one or two non-adjacent CH ₂ A 1,4-cyclohexylene group or a 1,4-cyclohexenylene group in which the group is substituted with an oxygen atom or a sulfur atom is represented, and these 6-membered ring A, ring B, and ring C further have 1 to 7 may be substituted with one or more alkyl group, alkoxyl group, alkanoyl group, cyano group or halogen atom, ¹ , Y ² Are each independently a single bond, -CH ₂ CH ₂ -, -CH ₂ O-, -OCH ₂ -, -COO-, -OCO-, -C≡C-, -CH = CH-, -CF = CF-,-(CH ₂ ) _Four -, -CH ₂ CH ₂ CH ₂ O-, -OCH ₂ CH ₂ CH ₂ -, -CH = CH-CH ₂ CH ₂ -, -CH ₂ CH ₂ -CH = CH-, -CH = CH-COO-, -OCO-CH = CH- ^Three Represents a single bond, —O—, —OCO—, —COO—, —CH═CH—COO—, and Z ¹ Represents a hydrogen atom, a halogen atom, a cyano group, or a hydrocarbon group having 1 to 20 carbon atoms. It is preferable to contain the compound represented by this.
[0024]
The polymerizable liquid crystal composition containing a liquid crystal compound represented by the general formula (I) has a lower viscosity than the polymerizable liquid crystal composition containing a liquid crystal compound having two or more polymerizable functional groups, Moreover, there exists a tendency which can make liquid crystal minimum temperature low. Specific examples of the compound represented by the general formula (I) include compounds (8) to (32). However, compounds that can be used in the liquid crystal composition of the present invention are not limited thereto. (In the formula, a cyclohexane ring represents a transcyclohexane ring, a number represents a phase transition temperature, C represents a crystalline phase, N represents a nematic phase, S represents a smectic phase, and I represents an isotropic liquid phase.)
[0025]
[Chemical 7]

[Chemical 8]

[Chemical 9]

[0026]
Among these compounds, the tolan compounds of the compounds (11), (19), and (20) are useful compounds having a high birefringence and a low liquid crystallinity temperature of around 50 to 60 ° C. In addition, the phenylcyclohexane compound of the compound (8) is particularly useful because the temperature showing liquid crystallinity is as low as around 30 ° C. When equal amounts of the compound (11) and the compound (8) are mixed, a nematic phase is exhibited at 25 ° C., which is particularly useful.
[0027]
The polymerizable liquid crystal composition of the present invention may contain a liquid crystal compound having no polymerizable functional group. Examples of the liquid crystal compound having no polymerizable functional group include those represented by the general formulas (II) and (III)
[Chemical Formula 10]

(Wherein R ¹ , R ² , R ^Three Are each independently a fluorine-substituted alkyl or alkoxyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, an alkenyloxy group having 3 to 16 carbon atoms, or the number of carbon atoms Represents an alkyl group having 1 to 12 carbon atoms substituted with 1 to 10 alkoxyl groups, and each of Ring D, Ring E, Ring F, Ring G and Ring H may be independently substituted with a fluorine atom. 1,4-phenylene group, 2-methyl-1,4-phenylene group, 3-methyl-1,4-phenylene group, naphthalene-2,6-diyl group, phenanthrene-2,7-diyl group, fluorene-2 , 7-diyl group, trans-1,4-cyclohexylene group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, decahydronaphthalene-2,6-diyl group, 1,3-dioxane-2,5-diyl group, pyridine-2,5-diyl group, pyrimidine-2,5-diyl group, pyrazine-2,5-diyl group or pyridazine-2,5-diyl group Represents l ₂ , M ₂ Each independently represents 0, 1 or 2, Z ² , Z ^Three , Z ^Four , Z ^Five Are each independently a single bond, -CH ₂ CH ₂ -,-(CH ₂ ) _Four -, -OCH ₂ -, -CH ₂ O-, -COO-, -OCO-, -C = C- or -C≡C-, X ^Three Represents a cyano group, a fluorine atom, a chlorine atom, a trifluoromethoxy group, a trifluoromethyl group, a difluoromethoxy group, a hydrogen atom, a 3,3,3-trifluoroethoxy group, R ′ or —OR ′, and R ′ represents A linear alkyl group having 1 to 12 carbon atoms or a linear alkenyl group having 2 to 12 carbon atoms; ² , X ^Four Represents a hydrogen atom, a fluorine atom or a chlorine atom. It is preferable to contain one or more compounds selected from.
[0028]
Among such compounds, R ¹ , R ² , R ^Three As each independently substituted with fluorine and optionally having an asymmetric carbon atom, an alkyl or alkoxyl group having 2 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, carbon An alkenyloxy group having 3 to 8 atoms or an alkyl group having 2 to 8 carbon atoms substituted with an alkoxyl group having 1 to 5 carbon atoms is preferable, and ring D, ring E, ring F, ring G and ring H are preferred. Is preferably a 1,4-phenylene group or a trans-1,4-cyclohexylene group which may be independently substituted with a fluorine atom, ² , Z ^Three , Z ^Four , Z ^Five Are each independently preferably a single bond, —COO—, —OCO—, —C═C— or —C≡C—, and more preferably a single bond, —COO— or —OCO—. X ² , X ^Three , X ^Four Two of them are fluorine atoms and the other one is a hydrogen atom, ^Three Is preferably a cyano group.
[0029]
The content of the liquid crystal compound having no polymerizable functional group in the polymerizable liquid crystal composition of the present invention is preferably 5 to 99% by mass, more preferably 40 to 98% by mass, and 80 to 98% by mass. Particularly preferred. The liquid crystalline compound having no polymerizable functional group is not particularly limited and can be used as long as it is recognized as a liquid crystalline compound in this technical field. However, a polar group such as a cyano group or a fluorine atom can be used. Since the liquid crystalline compound having a halogen atom can be easily controlled in orientation by application of an electric field, such a compound is preferably used. In particular, when a polymerizable liquid crystal composition is designed to have only a halogen atom such as a fluorine atom as a polar group, the polymerizability exhibits a high retention rate suitable for driving by an active element such as a TFT (thin film transistor) or TFD (thin film diode). Since a liquid crystal composition is obtained, it is particularly preferable.
[0030]
Furthermore, a chiral compound can also be added to the polymerizable liquid crystal composition of the present invention for the purpose of obtaining a polymer having a helical structure of a liquid crystal skeleton inside. The chiral compound used for such a purpose does not need to exhibit liquid crystal properties per se, and may or may not have a polymerizable functional group. The direction of the spiral can be appropriately selected depending on the intended use of the polymer. As such a chiral compound, for example, “CB-” manufactured by BD H. Co. (BDH; UK) having cholesteryl group cholesteryl group as a chiral group and cholesterol stearate and 2-methylbutyl group as a chiral group. 15 ”,“ C-15 ”,“ S-1082 ”manufactured by Merck (Germany),“ CM-19 ”,“ CM-20 ”,“ CM ”manufactured by Chisso; 1-methylheptyl as a chiral group Examples thereof include “S-811” manufactured by Merck Co., which has a group, “CM-21” manufactured by Chisso Corporation, “CM-22”, and the like. A preferable addition amount in the case of adding a chiral compound depends on the use of the liquid crystal composition, but is a value obtained by dividing the thickness (d) of the polymer obtained by polymerization by the helical pitch (P) in the polymer (d / P) is preferably in the range of 0.1 to 100, more preferably in the range of 0.1 to 20.
[0031]
In the polymerizable liquid crystal composition of the present invention, the temperature range exhibiting liquid crystallinity preferably satisfies the following conditions. First, the liquid crystal lower limit temperature is preferably 35 ° C. or less, more preferably 30 ° C. or less, and particularly preferably 25 ° C. or less. When the lower limit temperature of the liquid crystal is 25 ° C. or lower, the liquid crystal state can be stably obtained at room temperature, so that it is not necessary to heat particularly in the manufacturing process such as alignment treatment, and it is easy to avoid undesirable thermal polymerization. Become. The upper limit temperature of the liquid crystal is preferably 30 ° C. or higher, more preferably 35 ° C. or higher, and particularly preferably 40 ° C. or higher. In addition, when it is necessary to inject the polymerizable liquid crystal composition of the present invention into an liquid crystal cell or apply it to a substrate in an isotropic liquid phase, the liquid crystal upper limit temperature is avoided in order to avoid induction of thermal polymerization. Is preferably 120 ° C. or lower, more preferably 80 ° C. or lower, and particularly preferably 60 ° C. or lower.
The birefringence of the polymerizable liquid crystal composition of the present invention is preferably in the range of 0.04 to 0.45, more preferably in the range of 0.05 to 0.35, and in the range of 0.08 to 0.24. Is particularly preferred.
[0032]
The type of liquid crystal phase desired for the polymerizable liquid crystal composition varies depending on the application, but nematic phase, chiral nematic phase, smectic A phase, smectic C phase, chiral smectic C phase, chiral smectic C phase. _A Preferably exhibit a phase, chiral smectic C phase (ferroelectric phase), chiral smectic C _A A phase (antiferroelectric phase) is more preferred.
[0033]
When the polymerizable liquid crystal composition exhibits a ferroelectric phase or an antiferroelectric phase, either a liquid crystalline compound having a polymerizable functional group or a liquid crystalline compound having no polymerizable functional group, particularly polymerizable. The liquid crystalline compound having no functional group is preferably a ferroelectric liquid crystal or an antiferroelectric liquid crystal.
At this time, the ferroelectric liquid crystal or antiferroelectric liquid crystal contained in the polymerizable liquid crystal composition of the present invention is preferably 40 to 98% by mass of the polymerizable liquid crystal composition, and 80 to 98% by mass. More preferably.
When the polymerizable liquid crystal composition is a ferroelectric liquid crystal or an anti-ferroelectric liquid crystal, it has high-speed response and a contrast ratio by irradiating ultraviolet rays in a state showing a ferroelectric phase or an anti-ferroelectric phase. A high liquid crystal display element capable of halftone display is obtained.
At this time, the cell gap of the liquid crystal display element is preferably 2 μm or less, more preferably 1.7 μm or less. By reducing the cell gap, the orientation state of the ferroelectric phase or the antiferroelectric phase can be stabilized.
Moreover, the viscosity at 25 ° C. of the polymerizable liquid crystal composition of the present invention is not problematic even in the range of 400 to 760 mPa · s.
Next, the manufacturing method of the liquid crystal display element of this invention is demonstrated.
[0034]
The liquid crystal display element of the present invention includes a liquid crystal compound having at least one polymerizable functional group and an acylphosphine oxide compound in a cell having a cell gap of 6 μm or less formed from a pair of substrates with electrodes at least one of which is transparent. A polymerizable liquid crystal composition containing the above is vacuum-injected into a cell and irradiated with ultraviolet rays. If necessary, the polymerizable liquid crystal composition may further contain a liquid crystal compound having no polymerizable functional group. Hereinafter, a flowchart of the method for producing a liquid crystal display element of the present invention is shown in FIG. 1, and each step will be described in detail along the flowchart.
[0035]
First, a cell is prepared, and a polymerizable liquid crystal composition to be injected into the cell is prepared. The method for manufacturing the cell is as described above. The polymerizable liquid crystal composition used in the production method of the present invention is preferably the polymerizable liquid crystal composition described above.
Next, the polymerizable liquid crystal composition contained in the cell and the container is placed in a vacuum injection apparatus, and the polymerizable liquid crystal composition is injected into the empty cell as follows.
The polymerizable liquid crystal composition is preferably deaerated before being vacuum-injected. Deaeration is preferably performed in a vacuum state by heating to a temperature at which the polymerizable liquid crystal composition becomes an isotropic liquid phase. At this time, the degree of vacuum is preferably 13.3 Pa or less. If deaeration is carried out for a long time, the polymerizability may be impaired. Therefore, it is preferably within 3 hours, and more preferably within 30 minutes.
[0036]
After degassing, the polymerizable liquid crystal composition and the cell contained in the container are heated to 70 ° C. or higher, more preferably 80 ° C. or higher under vacuum, and an empty cell injection hole is formed in the polymerizable liquid crystal composition. Soak. Thereafter, the pressure is returned to normal pressure, and after the injection is completed, the cell is gradually cooled to room temperature. Thus, when it is going to inject | pour into a cell whose cell gap is 6 micrometers or less using a vacuum injection method, it is preferable to make the inside of a cell into the vacuum degree of 13.3 Pa or less, Furthermore, the vacuum degree of 1.33 Pa or less It is preferable that If the degree of vacuum is insufficient, a defect may occur in which the polymerizable liquid crystal composition does not enter the entire cell.
[0037]
In particular, when the polymerizable liquid crystal composition is a ferroelectric liquid crystal or an anti-ferroelectric liquid crystal, the viscosity is high, so that the cell gap is 6 μm or less and / or the substrate is uniformly injected into a cell having a diagonal of 10 cm or more. Since it is difficult, it is preferable that the inside of the cell is set to a vacuum of 13.3 Pa or less, the cell and the polymerizable liquid crystal composition are heated to 70 ° C. or more, and vacuum injection is performed. It is preferable that the pressure is 33 Pa or less, the cell and the polymerizable liquid crystal composition are heated to 80 ° C. or more, and vacuum injection is performed.
[0038]
After injecting the polymerizable liquid crystal composition, the injection hole is sealed. The method for sealing the injection hole is not particularly limited, but can be performed as follows, for example. First, the cell sandwiched between the substrates is preferably heated to 70 ° C. or higher, more preferably 80 ° C. or higher (heating step). After stabilization, pressurize from both sides of the substrate (pressurization process), apply the sealing material to the injection hole (injection hole sealing process), and loosen the pressure (decompression process) to make the sealing material into the injection hole There is a method of injecting, curing and sealing. As the sealing material, an ultraviolet curable resin or a two-component cured sealing material can be used, but in order to avoid curing of the polymerizable liquid crystal composition by ultraviolet irradiation, a two-component cured sealing material is used. preferable.
[0039]
The liquid crystal display device thus manufactured is preferably irradiated with ultraviolet rays while or after adjusting the liquid crystal in the cell to a desired orientation.
Before the alignment is adjusted, the liquid crystal display element is heated to a temperature at which the polymerizable liquid crystal composition becomes an isotropic liquid phase in order to facilitate the uniform alignment, and is held at that temperature for about 10 minutes to 2 hours. Then, it is preferable to cool slowly.
After the liquid crystal display element is cooled to a temperature exhibiting a desired alignment, ultraviolet rays are irradiated and photopolymerized to form a polymer chain along the alignment, thereby stabilizing the alignment of the liquid crystal.
When the polymerizable liquid crystal composition is a nematic phase or a chiral nematic phase, a display device having a wide viewing angle and good bistability can be realized.
[0040]
Further, when the polymerizable liquid crystal composition is a ferroelectric liquid crystal or an antiferroelectric liquid crystal, it is irradiated with ultraviolet rays while orienting in a state showing a ferroelectric phase or an antiferroelectric phase. The problem that it was difficult to achieve stable and uniform orientation using cells having a large corner size is solved.
When irradiating with ultraviolet rays, it is preferable to adjust the orientation by applying a DC voltage. After adjusting the alignment by applying a DC voltage, UV irradiation may be performed with the DC voltage applied, but when the polymerizable liquid crystal composition has a memory property, the application of the DC voltage was turned off. You may irradiate with an ultraviolet-ray in a state.
[0041]
For example, when the polymerizable liquid crystal composition is a ferroelectric liquid crystal, the orientation direction of the skeleton of the liquid crystalline compound having a polymerizable functional group is made ferroelectric by applying a DC voltage at a temperature showing a ferroelectric phase. The orientation of the ferroelectric phase in the state where no drive voltage is applied can be obtained by irradiating with ultraviolet rays and photocuring in this state. This is almost the same as the alignment direction of the ferroelectric liquid crystal when irradiated with ultraviolet rays. This is considered to be due to the alignment stabilization effect of the liquid crystal skeleton of the cured product. At this time, the cell gap is preferably 2 μm or less, and more preferably 1.7 μm or less. The polymer stable ferroelectric liquid crystal display device thus obtained can be controlled continuously from one orientation direction of the bistable state to the other orientation direction by applying a driving voltage. Display can be achieved.
At this time, the irradiation intensity of ultraviolet rays is 1 to 300 mW / cm. ² The range of 1 to 3 mW / cm is preferable. ² The range of is more preferable.
[0042]
Further, when an antiferroelectric liquid crystal is used as the polymerizable liquid crystal composition, it is photocured by irradiating with ultraviolet rays at a temperature exhibiting an antiferroelectric phase and without applying a voltage. As a result, the three-state switching can be changed to V-shaped switching, and halftone display can be performed.
[0043]
The polymer-stable ferroelectric liquid crystal display element or monostable ferroelectric liquid crystal display element obtained as described above is different with time in the same display unit in static full-dot or non-full-dot display elements. It is preferably used in a liquid crystal display device that is driven by a field sequential method for generating colors.
In this type of liquid crystal display device, the illuminating means is a light source having a plurality of emission colors, and is composed of a CCT or LED. Arbitrary coloration is performed partially by controlling the light source independently and lighting in synchronization with the display unit.
[0044]
In this type of liquid crystal display device, the illumination means can independently control light sources having a plurality of emission colors, and each light source can be blinked as one frame and switched over 50 frames per second, It is important that the switching of the light source of the illumination means and the drive means are synchronized. Then, it has a plurality of monochromatic light sources such as R, G, B such as CCT or LED, is provided with illumination means that can be switched at high speed, and is turned on in synchronism with the display unit, so that it is partially colored arbitrarily be able to.
[0045]
The switching of the light source of the illumination means and the synchronization with the drive means are performed as follows. In order to display without feeling flicker, for example, a signal of about 60 frames is written per second. In this case, one frame time is 16.6 ms. If the three-color backlights of R, G, and B are sequentially turned on within this time, the lighting time per color is about 5.5 ms. Here, in the case of polymer stable ferroelectric liquid crystal, monostable ferroelectric liquid crystal, and bistable ferroelectric liquid crystal, the rise time is 200 μs and the fall time is 300 μs.
Therefore, the R backlight is turned on for 5.5 ms simultaneously with the start-up of the liquid crystal, and the R backlight is turned off simultaneously with the fall of the liquid crystal. Sequentially, G and B may be turned on or off in the same manner. Since these monochromatic images are mixed by the afterimage phenomenon of the naked eye, in the case of polymer-stable ferroelectric liquid crystals and monostable ferroelectric liquid crystals, halftone display of the liquid crystal is performed by voltage control for each color. Further, it is possible to increase the number of colors.
[0046]
【Example】
EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these Examples.
(Example 1) Production of polymer-stable ferroelectric liquid crystal display device
First, an empty cell and a polymerizable liquid crystal composition (B) injected therein were prepared.
<Preparation of polymerizable liquid crystal composition (B)>
50 parts by mass of the compound represented by formula (8)
Embedded image

And 50 parts by mass of the compound represented by formula (11)
Embedded image

A composition consisting of: This composition exhibited a nematic phase at room temperature (25 ° C.). The nematic phase-isotropic liquid phase transition temperature was 46.1 ° C. N measured at 589 nm _e (Refractive index of extraordinary light) is 1.661, n _o The refractive index of ordinary light was 1.510, and the birefringence was 0.152.
[0047]
For this composition, 0,2,4,6-trimethylbenzoyldiphenylphosphine oxide (trade name: Lucillin-TPO, BASF), which is an acylphosphine oxide compound represented by the formula (33) as a polymerization initiator. .1% by mass
Embedded image

300 ppm of aluminum N-nitrosophenylhydroxylamine (trade name: Q-1301, manufactured by Wako Pure Chemical Industries, Ltd.) which is a nitroso compound represented by the formula (34) as a polymerization inhibitor
Embedded image

Was added to prepare a polymerizable liquid crystal composition (A).
To 2% by mass of this polymerizable liquid crystal composition (A), 98% by mass of a ferroelectric liquid crystal compound having no polymerizable functional group (trade name: FELIX M4851 / 100, manufactured by Clariant) was added. A polymerizable liquid crystal composition (B) was prepared. The viscosity of this polymerizable liquid crystal composition (B) at 25 ° C. was 460 mPa · s.
<Preparation of empty cell>
An alignment film (trade name: RN1286, manufactured by Nissan Chemical Co., Ltd.) was applied to each of the two glass substrates having a diagonal of 13 cm having a patterned ITO electrode on the ITO side to a thickness of about 150 mm. Weak rubbing is applied to the alignment film, 1.7 μm silica heat-fixed beads are used as the gap spacer, and the two substrates are bonded together so that the rubbing direction is in parallel orientation, and the outer periphery excluding the injection hole is sealed. Thus, an empty cell having a cell gap of 1.7 μm was produced.
[0048]
Next, the prepared polymerizable liquid crystal composition (B) was vacuum-injected into an empty cell as follows.
First, the polymerizable liquid crystal composition (B) and an empty cell contained in a container were placed in a vacuum injection apparatus.
Next, the polymerizable liquid crystal composition (B) was deaerated. The heating temperature was 80 ° C. at which the polymerizable liquid crystal composition (B) became an isotropic liquid phase, and the vacuum state was about 30 minutes. Thereafter, the temperature of the polymerizable liquid crystal composition (B) was returned to room temperature, and the empty cell was deaerated until the degree of vacuum was 1.33 Pa. The time required for deaeration was about 2 hours.
After deaeration, the polymerizable liquid crystal composition (B) and the empty cell are heated to 80 ° C. After stabilization, the injection hole of the empty cell is immersed in the polymerizable liquid crystal composition (B), and the injection is started after returning to normal pressure. I let you. The injection time was about 2 hours.
After the injection, the cell holding the polymerizable liquid crystal composition (B) between the substrates was heated to 80 ° C., and after stabilization, about 1.2 kg / cm from both sides. ² And was allowed to stand for about 40 minutes. Thereafter, a two-component cured sealant is applied to the injection hole, and the pressure condition after application is 1.1 kg / cm. ² The mixture was allowed to stand for 10 minutes under reduced pressure and cured. Then, after returning to room temperature, the cell was washed. Even with a large diagonal cell, the cell gap was kept uniform by this high-temperature pressure sealing.
[0049]
Next, in order to stabilize the orientation, the obtained cell was again raised to 80 ° C. and held for 1 hour, and then slowly cooled. After returning to room temperature, the strength after passing through the glass substrate is 2.47 mW / cm with a DC voltage of 15 V applied to the entire surface of the cell. ² Under such conditions, ultraviolet light having a central wavelength of 365 nm was irradiated for about 60 seconds, and the polymerizable liquid crystal composition was photocured to produce a polymer-stable ferroelectric liquid crystal display device.
When the obtained liquid crystal display element was observed with a polarizing microscope, it was confirmed that the liquid crystal layer exhibited a ferroelectric phase and had a uniform uniaxial orientation with no defects.
A pair of polarizing plates was placed in this liquid crystal display element in a crossed Nicols state so that the darkest state was obtained when no voltage was applied. The optical change when a voltage is applied is shown in FIG. FIG. 3 shows the contrast ratio, and FIG. 4 shows the response speed when the voltage is changed.
2 to 4, it can be understood that the obtained liquid crystal display element can perform halftone display, has a high contrast ratio, and can perform high-speed response display.
[0050]
(Example 2) Production of polymer stable bistable twisted nematic liquid crystal display device
First, an empty cell and a polymerizable liquid crystal composition (C) injected therein were prepared.
<Preparation of polymerizable liquid crystal composition (C)>
In 43% by mass of the polymerizable liquid crystal composition (A) prepared in Example 1, 94% by mass of a room temperature nematic liquid crystal compound ZLI-5049-100 (manufactured by Merck & Co.) without a polymerizable functional group and a chiral agent S A polymerizable liquid crystal composition (C) was prepared by adding 1.7% of -811 (manufactured by Merck). The pitch at this time was about 5 μm. This polymerizable liquid crystal composition (C) exhibited a nematic liquid crystal phase at room temperature (25 ° C.).
[0051]
<Preparation of empty cell>
An alignment film (trade name: SE-3510, manufactured by Nissan Chemical Co., Ltd.) was applied on each ITO side to two 20 cm diagonal glass substrates having patterned ITO electrodes to make the film thickness about 300 mm. The alignment film was rubbed to achieve a pretilt angle of about 4 °. The gap spacer uses 3.5 μm silica heat-adhering beads, the two substrates are bonded together so that the rubbing direction is anti-parallel, and the outer periphery excluding the injection hole is sealed, and the cell gap is 3.5 μm. A cell was produced.
[0052]
Next, the prepared polymerizable liquid crystal composition (C) was vacuum-injected into an empty cell.
First, a polymerizable liquid crystal composition (B) containing a container and an empty cell were placed in a vacuum injection apparatus.
Next, the polymerizable liquid crystal composition (C) was degassed. The heating temperature was 80 ° C. at which the polymerizable liquid crystal composition (C) became an isotropic liquid phase, and the vacuum state was about 30 minutes. Thereafter, the temperature of the polymerizable liquid crystal composition (C) was returned to room temperature, and the empty cell was deaerated until the degree of vacuum was 1.33 Pa. The time required for deaeration was about 2 hours.
After deaeration, the injection hole of the empty cell was immersed in the polymerizable liquid crystal composition (C) and returned to normal pressure to start injection. The injection time was about 30 minutes.
After the injection, the cell sandwiching the polymerizable liquid crystal composition (C) was about 0.3 kg / cm from both sides. ² And was allowed to stand for about 15 minutes. After standing, a two-component cured sealant is applied to the injection hole, and the pressure condition is 0.25 kg / cm after application. ² The mixture was allowed to stand for 8 hours under reduced pressure and cured. Thereafter, the cell was washed.
Next, in order to stabilize the orientation, the obtained cell was heated again to 80 ° C., held for 10 minutes, and then gradually cooled. After returning to room temperature, the pixel portion is masked with a 20 V AC electric field applied to the entire surface of the cell, and 2 mW / cm at a center wavelength of 360 nm. ² The region between the pixels was irradiated with ultraviolet rays having the intensity of about 5 minutes. As a result, a polymer-stable bistable twisted nematic liquid crystal display element in which the memory state was stable for a long time could be fabricated.
[0053]
(Example 3)
In place of the polymerization initiator of Example 2, 2,2-dimethoxy-1,2-diphenylethane-1-one represented by formula (35) (trade name: Irgacure-651, Ciba Specialty Chemicals)
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4-methoxyphenol represented by the formula (36) instead of the polymerization inhibitor
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When was used, undesirable thermal polymerization was induced on the way, and a desired liquid crystal display element could not be produced.
Therefore, it can be seen that the polymerizable liquid crystal composition of the present invention is resistant to heating and decompression conditions by containing an acyl phosphine oxide compound as a polymerization initiator and a nitroso compound as a polymerization inhibitor.
[0054]
(Example 4)
Next, the polymer stable ferroelectric liquid crystal display device manufactured in Example 1 is statically driven, and a CCT backlight capable of emitting red and cyan is installed on the back surface, and red light is emitted in the first subframe. Synchronized to emit cyan in the subframe. Drive to turn on in the first subframe for the segment that wants to display red, and turn off in the second subframe, and drive to turn on in both the first and second subframes for the segment that wants to display white As a result, red and white were displayed even though there was no color filter. In addition, the viewing angle was wide and showed good visibility.
[0055]
The same liquid crystal display element as described above is statically driven, and an LED backlight capable of emitting R, G, and B is installed on the back surface, R in the first subframe, G in the second subframe, and B in the third subframe. Synchronized to emit light. The segment that wants to display red is turned on in the first subframe and turned off in the second and third subframes. The segment that wants to display white is turned on in all subframes. As a result of driving, red and white were displayed even though there was no color filter. In addition, the viewing angle was wide and showed good visibility.
[0056]
FIG. 5 shows an example of a segment pattern of a liquid crystal display device in which the polymer stable ferroelectric liquid crystal display element manufactured in Example 1 is driven by a field sequential method.
In FIG. 5, the white part is the display part, and the isolated part shows the independent display part. The black part is a non-display part and is black masked for the purpose of light shielding.
[0057]
【Effect of the invention】
According to the present invention, a liquid crystal display element in which a polymerizable liquid crystal composition is uniformly held in a thin cell having a cell gap of 6 μm or less can be obtained. The liquid crystal display element of the present invention can stabilize the alignment of the liquid crystal material by irradiating ultraviolet rays in a desired alignment state after injecting the polymerizable composition. In particular, when a ferroelectric liquid crystal or an antiferroelectric liquid crystal is used as the polymerizable liquid crystal composition, a liquid crystal display element having high-speed response, a high contrast ratio, and capable of halftone display is obtained. In particular, it can be suitably used for a liquid crystal display device that is driven by a field-sequential method that requires high-speed response, and is a high-information display such as a display for office automation equipment, or a public display such as an advertising board, a guide board, or a decorative display board. Or used for television.
[Brief description of the drawings]
FIG. 1 is a flowchart of a method for manufacturing a liquid crystal display device of the present invention.
FIG. 2 is a diagram showing an optical change when a voltage is applied to the liquid crystal display element of the present invention.
FIG. 3 is a diagram showing a contrast ratio of the liquid crystal display element of the present invention.
FIG. 4 is a diagram showing the response speed when the voltage of the liquid crystal display element of the present invention is changed.
FIG. 5 is a diagram showing an example of a segment pattern of the liquid crystal display device of the present invention.

Claims (10)

Polymerization comprising a pair of substrates with electrodes, at least one of which is transparent, a cell gap of 6 μm or less, and containing a liquid crystalline compound having at least one polymerizable functional group and an acyl phosphine oxide compound having a molecular weight of 280 or more A liquid crystal display element in which a liquid crystal composition is vacuum-injected into a cell and a polymerizable liquid crystal composition is polymerized by irradiation with ultraviolet rays.   The liquid crystal display element according to claim 1, wherein the substrate has a diagonal of 10 cm or more. The liquid crystal display element according to claim 1, wherein the polymerizable functional group is at least one functional group selected from an acrylate group, a methacrylate group, an epoxy group, and a vinyl ether group. The polymerizable liquid crystal composition further includes a liquid crystal compound having no polymerizable functional group, and the liquid crystal compound not having the polymerizable functional group is obtained from the polymerizable liquid crystal composition. The liquid crystal display element according to any one of claims 1 to 3, which is 40 to 98 mass%. The liquid crystal display element according to any one of claims 1 to 4, wherein the polymerizable liquid crystal composition further contains a nitroso compound. The liquid crystal display element according to claim 1, wherein the polymerizable liquid crystal composition has a viscosity at 25 ° C. of 400 to 760 mPa · s. A cell having a cell gap of 6 μm or less formed from a pair of substrates with electrodes, at least one of which is transparent, contains a liquid crystalline compound having at least one polymerizable functional group and an acyl phosphine oxide compound having a molecular weight of 280 or more. A method for producing a liquid crystal display element, comprising vacuum-injecting a polymerizable liquid crystal composition and irradiating with ultraviolet rays. 8. The liquid crystal display device according to claim 7 , wherein the inside of the cell is set to a vacuum degree of 13.3 Pa or less, the cell and the polymerizable composition are heated to 70 ° C. or more, and vacuum injection is performed. Method. The polymerizable liquid crystal composition is a ferroelectric liquid crystal or an antiferroelectric liquid crystal, and is irradiated with ultraviolet rays while or after being aligned in a state exhibiting a ferroelectric phase or an antiferroelectric phase. The manufacturing method of the liquid crystal display element of Claim 7 or 8 . A liquid crystal display device according to any one of claims 1 to 6, a liquid crystal display device driven by the field sequential method is performed.

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