JP3630179B2 - Nematic liquid crystal composition and liquid crystal display device using the same - Google Patents

Description

【０００９】
（式中、Ｒ^７１は直鎖状アルキル基を表わし、式（ｂ）はシクロヘキサン環を表わし、該シクロヘキサン環に存在する重水素原子は、天然に存在する質量数１の水素原子に対する存在比に相当した確率で含有することを表わす。以下、式（ｂ）をこの意味で用いる。）
しかしながらこれらの化合物を用いても、広い温度範囲においてネマチック液晶性を保持することと、アクティブ・マトリクス方式に要求されるしきい値電圧及び飽和電圧を充分に低減させることとを両立させるには問題があった。特に、飽和電圧はコントラストを向上させる目的で、従来行われてきた透過率が１０％となる電圧より更に厳しい評価方法として、透過率が１％となる電圧が重視されている。以下、飽和電圧Ｖ_ｓａｔをこの意味で用いる。
【００１０】
更に加えて、均一で高いコントラストの液晶表示特性を得るために、液晶パネルの液晶層の厚みｄと液晶材料の複屈折率△ｎとの積△ｎ・ｄを０．３５〜０．５５（以下このことをファーストミニマムと呼称する）とするのが好ましいとされている。現在の液晶パネルの作製工程で行われている厚みｄは約４．５μｍ以上であることから、液晶材料の複屈折率△ｎを０．０７〜０．１０とすることが要求されている。しかし、より小さい複屈折率とより低い駆動電圧の特性は、相反する傾向のため両者を満足させることが困難であった。
【００１１】
本発明が解決しようとする課題は、上記の問題に応えることにあり、広い温度範囲で液晶性を示し、駆動電圧特に飽和電圧Ｖ_ｓａｔが低くしかも充分に高い電圧保持率を有し、装置に設定条件に適した複屈折率Δｎを有する液晶組成物を提供し、更にこの液晶組成物を用い、フリッカが発生せずコントラストに優れた液晶表示装置を提供することにある。
【００１２】
【課題を解決するための手段】
本発明は上記課題を解決するために、以下に示すネマチック液晶組成物を提供する。
【００１３】
即ち、本発明の第一の液晶組成物として、一般式（Ｉ−１）〜（Ｉ−４）、
【００１４】
【化１３】

【００１５】
（式中、Ｒ^１１〜Ｒ^１４はそれぞれ独立的に炭素原子数２〜５の直鎖状アルキル基を表わし、Ｙ^１１はフッ素原子又は塩素原子を表わし、Ｙ^１２及びＹ^１３はそれぞれ独立的に水素原子又はフッ素原子を表わす。）で表わされる第１の化合物群から選ばれる化合物を、少なくとも１つ以上含有することを特徴とするネマチック液晶組成物を提供する。
【００１６】
また、前記記載の一般式（Ｉ−１）〜（Ｉ−４）で表わされる化合物群は、１個又はそれ以上の水素原子が重水素原子に置換されたシクロヘキサン環を１個又は２個有していてもよい。
【００１７】
更に上記液晶組成物に一般式（ＩＩ）〜（ＩＶ）
【００１８】
【化１４】

【００１９】
（式中、Ｒ^２１及びＲ^２２はそれぞれ独立的に炭素原子数２〜５の直鎖状アルケニル基を表わし、Ｒ^２３は炭素原子数２〜５の直鎖状アルキル基を表わし、各化合物における２つの１，４−シクロヘキシレン基の少なくとも１個の水素原子（Ｈ）は重水素原子（Ｄ）で置換されていてもよい。）で表わされる第２の化合物群および一般式（Ｖ）〜（ＶＩＩＩ）
【００２０】
【化１５】

【００２１】
（式中、Ｒ^３１〜Ｒ^３４はそれぞれ独立的に炭素原子数２〜７の直鎖状アルキル基を表わし、各化合物における２つの１，４−シクロヘキシレン基の少なくとも１個の水素原子（Ｈ）は重水素原子（Ｄ）で置換されていてもよい。）で表わされる第３の化合物群から選ばれる１種又はそれ以上の化合物を含有することを特徴とするネマチック液晶組成物を提供する。
【００２２】
上記の一般式（Ｉ−１）〜（ＶＩＩＩ）で表わされる化合物において水素原子を重水素原子に置換したシクロヘキサン環を有する化合物には以下のものを使用することができる。一般式（Ｉ−１）において１個又はそれ以上の水素原子が重水素原子で置換されたシクロヘキサン環を有する化合物が、一般式（Ｉー１−１）
【００２３】
【化１６】

【００２４】
（式中、Ｒ^１１、Ｙ^１１、は前記と同じ意味であり、Ｘ^１〜Ｘ^３はそれぞれ独立して水素原子（Ｈ）又は重水素原子（Ｄ）を表わすが、少なくとも１個は重水素原子（Ｄ）を表わす。）で表わされる化合物であり、一般式（Ｉ−２）において１個又はそれ以上の水素原子が重水素原子で置換されたシクロヘキサン環を有する化合物が、一般式（Ｉー２−１）
【００２５】
【化１７】

【００２６】
（式中、Ｒ^１２、及びＸ^１〜Ｘ^３は前記と同じ意味である。）で表わされる化合物であり、一般式（Ｉ−３）において１個又はそれ以上の水素原子が重水素原子で置換されたシクロヘキサン環を有する化合物が、一般式（Ｉー３−１）
【００２７】
【化１８】

【００２８】
（式中、Ｒ^１３、Ｙ^１２、及びＸ^１〜Ｘ^３は前記と同じ意味である。）で表わされる化合物であり、一般式（Ｉ−４）において１個又はそれ以上の水素原子が重水素原子で置換されたシクロヘキサン環を有する化合物が、一般式（Ｉー４−１）
【００２９】
【化１９】

【００３０】
（式中、Ｒ^１４、Ｙ^１３、及びＸ^１〜Ｘ^３は前記と同じ意味である。）で表わされる化合物であり、一般式（ＩＩ）において１個又はそれ以上の水素原子が重水素原子で置換されたシクロヘキサン環を有する化合物が、一般式（ＩＩ−１）
【００３１】
【化２０】

【００３２】
（式中、Ｒ^２１及びＸ^４〜Ｘ^７は前記と同じ意味である。）で表わされる化合物であり、一般式（ＩＩＩ）において１個又はそれ以上の水素原子が重水素原子で置換されたシクロヘキサン環を有する化合物が、一般式（ＩＩＩー１）
【００３３】
【化２１】

【００３４】
（式中、Ｒ^２２及びＸ^４〜Ｘ^７は前記と同じ意味である。）で表わされる化合物であり、一般式（ＩＶ）において１個又はそれ以上の水素原子が重水素原子で置換されたシクロヘキサン環を有する化合物が、一般式（ＩＶー１）、（ＩＶー２）
【００３５】
【化２２】

【００３６】
（式中、Ｒ^２３及びＸ^１〜Ｘ^３、Ｘ^４〜Ｘ^７は前記と同じ意味である。）で表わされる化合物であり、一般式（Ｖ）において１個又はそれ以上の水素原子が重水素原子で置換されたシクロヘキサン環を有する化合物が、一般式（Ｖー１）
【００３７】
【化２３】

【００３８】
（式中、Ｒ^３１及びＸ^４〜Ｘ^７は前記と同じ意味である。）で表わされる化合物であり、一般式（ＶＩ）において１個又はそれ以上の水素原子が重水素原子で置換されたシクロヘキサン環を有する化合物が、一般式（ＶＩー１）
【００３９】
【化２４】

【００４０】
（式中、Ｒ^３２及びＸ^４〜Ｘ^７は前記と同じ意味である。）で表わされる化合物であり、一般式（ＶＩＩ）において１個又はそれ以上の水素原子が重水素原子で置換されたシクロヘキサン環を有する化合物が、一般式（ＶＩＩー１）
【００４１】
【化２５】

【００４２】
（式中、Ｒ^３３及びＸ^４〜Ｘ^７は前記と同じ意味である。）で表わされる化合物であり、一般式（ＶＩＩＩ）において１個又はそれ以上の水素原子が重水素原子で置換されたシクロヘキサン環を有する化合物が、一般式（ＶＩＩＩー１）
【００４３】
【化２６】

【００４４】
（式中、Ｒ^３４及びＸ^４〜Ｘ^７は前記と同じ意味である。）で表わされる化合物であり、これらのいずれかを用いたネマチック液晶組成物を提供する。
本発明は、上記の液晶組成物に一般式（ＩＸ）〜（ＸＩ）
【００４５】
【化２７】

【００４６】
（式中、Ｒ^４１〜Ｒ^４３はそれぞれ独立的に炭素原子数２〜５の直鎖状アルキル基を表わし、Ｙ^４１〜Ｙ^４３は水素原子又はフッ素原子を表わし、２つの１，４−シクロヘキシレン基の少なくとも１個の水素原子（Ｈ）は重水素原子（Ｄ）で置換されていてもよい。）で表わされる化合物群から選ばれる１種またはそれ以上の化合物、およびまたは一般式（ＸＩＩ）〜（ＸＩＶ）
【００４７】
【化２８】

【００４８】
（式中、Ｒ^５１〜Ｒ^５３はそれぞれ独立的に炭素原子数３〜７の直鎖状アルキル基を表わし、Ｙ^５１〜Ｙ^５４はそれぞれ独立的に水素原子又はフッ素原子を表わし、１個又はそれ以上の水素原子が重水素原子に置換されたシクロヘキサン環を有していてもよい。）で表わされる化合物群から選ばれる１種またはそれ以上の化合物、およびまたは一般式（ＸＶ）〜（ＸＩＸ）
【００４９】
【化２９】

【００５０】
（式中、Ｒ^６１〜Ｒ^６４はそれぞれ独立的に炭素原子数２〜５の直鎖状アルキル基またはアルケニル基を表わし、Ｒ^６７〜Ｒ^６９はそれぞれ独立的に炭素原子数１〜５の直鎖状アルキル基、アルコキシ基または炭素原子数２〜５の直鎖状アルケニル基を表わし、Ｒ^６５は炭素原子数２〜５の直鎖状アルキル基を表わし、ｒはそれぞれ独立的に０または１を表わし、Ｙ^６１及びＹ^６２はそれぞれ独立的に水素原子又はフッ素原子を表わし、一般式（ＸＶ）、（ＸＶＩ）における少なくとも１個の水素原子（Ｈ）が重水素原子（Ｄ）で置換されていてもよい。）で表わされる化合物群から選ばれる１種またはそれ以上の化合物を含有することができる。
【００５１】
更に本発明は上記のネマチック液晶組成物を用いたアクティブ・マトリクス液晶表示装置、ツイスティッド・ネマチックまたはスーパー・ツイスティッド・ネマチック液晶表示装置を提供する。
【００５２】
以下、本発明を詳述するにあたり、一般式（Ｉ−１）〜（Ｉ−４）、（ＩＩ）〜（ＸＩＶ）、、（ＸＶＩＩＩ）及び（ＸＩＸ）の化合物が有する全てのシクロヘキサン環が前述した式（ｂ）で表わされたシクロヘキサン環である化合物を下記に示した一般式（Ｉ−１ー０）〜（Ｉ−４−０）、（ＩＩ−０）〜（ＸＩＩＩ−０）、（ＸＶＩＩー０）及び（ＸＶＩＩＩー０）で表わす。（式中、Ｒ^０１１〜Ｒ^０５３、Ｒ^０６４及びＲ^０６５、Ｙ^０１１〜Ｙ^０６２は、それぞれ独立的に前記したＲ^１１〜Ｒ^５３、Ｒ^６４及びＲ^６５、Ｙ^１１〜Ｙ^６２と同じ意味である。）
【００５３】
【化３０】

【００５４】
【化３１】

【００５５】
本発明に係わる一般式（Ｉ−１）〜（ＶＩＩＩ）で表わされる代表的な化合物例（１−１−１）〜（１−１−４）および（１−２）〜（１−８）とその相転移温度を下記第１表に示す。下記表中、ｍ．ｐ．は結晶相から液晶相又は等方性液体相に相転移する温度を、ｃ．ｐ．は液晶相から等方性液体相に相転移する温度をそれぞれ表わす。また、各液晶化合物は、蒸留、カラム精製、再結晶等の方法を用いて不純物を除去し、充分精製したものを使用した。
【００５６】
【表１】

【００５７】
本発明の液晶組成物の特徴は、必須成分として前述の一般式（Ｉ−１）〜（Ｉ−４）で表わされる第１の化合物群から選ばれる化合物を含有し、更に一般式（ＩＩ）〜（ＩＶ）で表わされる第２の化合物群から選ばれた化合物及び又は、一般式（Ｖ）〜（ＶＩＩＩ）で表わされる第３の化合物群から選ばれた化合物と組み合わせて得られる液晶組成物を見い出したことにある。この様にして得られた液晶組成物は、駆動電圧特に飽和電圧Ｖ_ｓａｔを低減する効果があり、また複屈折率Δｎが小さい特性をもつ。
【００５８】
一般式（Ｉ−１）、（Ｉ−２）で表わされる化合物は、２，６−ジフルオロフェニル基と、３，４，５−トリフルオロフェニル基あるいは３，４−ジフルオロ−５−クロロフェニル基を−Ｃ_２Ｈ_４−で連結した構造を有している。この化合物は、しきい値電圧および飽和電圧が低いので、本発明に係わる他の化合物と組合わせることにより、電圧保持率を低下することなく駆動電圧の低い液晶材料を得ることができる。
【００５９】
一般式（Ｉ−３）、（Ｉ−４）で表わされる化合物は、５−置換２，３−ジフルオロフェニル基と、３，４−ジフルオロフェニル基または３，４，５−トリフルオロフェニル基を、−Ｏ−ＣＨ_２−基で連結した構造を有している。この化合物は駆動電圧特に飽和電圧が低く、本発明に係わる他の化合物と組み合わせることにより、電圧保持率を低下させることなく駆動電圧の低い液晶量を得ることができる。また、この材料は複屈折率Δｎを低減する効果が大きいので、用途に応じた複屈折率のネマチック液晶組成物を調製することができる。
一般式（ＩＩ）で表わされる化合物は、直鎖状のアルケニル基と３，４，５−トリフルオロフェニル基を有しているものである。この化合物は、本発明に係わる他の化合物と組み合わせた時、長期の低温保存において結晶の析出がみられる問題があるが、低温側においてネマチック相を誘起拡大させる相溶性を示し、電圧保持率を低下させることなく駆動電圧を維持あるいは低減させる効果がある。
【００６０】
一般式（ＩＩＩ）、（ＩＶ）で表わされる化合物は、３，４−ジフルオロフェニル基を有し、上述した相溶性に特徴を有している。また、一般式（ＩＩＩ）の化合物は複屈折率△ｎが一般式（ＩＩ）、（ＩＶ）〜（ＶＩＩＩ）の化合物に比べ大きいので、用途に応じた複屈折率のネマチック液晶組成物を調整するのに有用あり、一般式（ＩＶ）で表わされる化合物はしきい値電圧が比較的低く、この調整に有用である。
【００６１】
一般式（ＩＩ）、（ＩＩＩ）で表わされる化合物は、表示特性に重要な役割を果たす弾性定数比（Ｋ_３３／Ｋ_１１）が一般式（ＩＶ）〜（Ｖ）に比べて大きいあるいは小さい。従って、用途に応じた弾性定数比を示すネマチック液晶組成物を調製することができるものである。更に、一般式（ＩＩ）、（ＩＩＩ）の化合物は、ネマチック液晶組成物の粘性を低下させることもできるので、一般式（ＩＶ）〜（ＸＶ）の化合物と組み合わせることによって広い温度範囲で高速応答性を有する液晶材料を容易に得ることができる。一般式（ＩＩ）、（ＩＩＩ）で表わされる化合物のＲ^２１及びＲ^２２は特に下記のものが優れている。
【００６２】
【化３２】

【００６３】
一般式（Ｖ）〜（ＶＩＩＩ）で表わされる化合物は、−Ｃ_２Ｈ_４−、−Ｃ_４Ｈ_８−の連結基を有しており、３，４−ジフルオロフェニル基、３，４，５−トリフルオロフェニル基を有しているものである。これらの化合物は、複屈折率△ｎが一般式（ＩＩ）〜（ＩＶ）の化合物に比べ小さいので、用途に応じた複屈折率のネマチック液晶組成物を調整することができ、また電圧保持率を低下させることなく駆動電圧を維持あるいは低減させる効果を有していることを見いだした。
【００６４】
しかしながら、一般式（Ｖ）（ＶＩ）及び（ＶＩＩＩ）の化合物はスメクチック相を示し易く、これらの化合物のみからなる組成物では、スメクチック相の存在に依ってネマチック相が非常に狭く、特に室温から低温で駆動可能なネマチック液晶組成物を調製することは困難であった。
【００６５】
本発明者等は、上述した一般式（ＩＩ）〜（ＶＩＩＩ）で表わされる化合物について、Ｒ^２１をアルキル基とした化合物との詳細な比較も含め、種々の組み合わせを検討した。その技術を特願平６−２０２０３６号で明らかにしており、一般式（ＩＩ）〜（ＩＶ）で表わされる化合物群から選ばれる化合物と、一般式（Ｖ−１）〜（ＶＩＩＩ）で表わされる化合物群から選ばれる化合物を組み合わせて用いることにより、それぞれの化合物が有している優れた特性を損なうことなく、広い温度範囲で使用できるネマチック液晶組成物を調製できることを見出している。また一般式（ＩＩ）及び（ＶＩ）〜（ＶＩＩＩ）で表わされる化合物は３，４，５−トリフルオロフェニル基を有しているが低温での相溶性に優れ、３，４−ジフルオロフェニル基を有する一般式（ＩＩＩ）（ＩＶ）（Ｖ）で表わされる化合物との混合比を１：１以上にさせても、あるいは総含有量で５０％以上含有させても、特段の第三の手段を用いず広温度範囲で使用可能な液晶組成物を調製できるので、しきい値電圧の低減手段としての優位性は大きい。
【００６６】
今回本発明者らは、上述した一般式（Ｉ−１）〜（Ｉ−４）で表わされる化合物群から選ばれる化合物を、一般式（ＩＩ）〜（ＩＶ）で表わされる化合物群から選ばれた化合物及び又は、一般式（Ｖ）〜（ＶＩＩＩ）で表わされる化合物群から選ばれた化合物を含有する液晶組成物に組み合わせて用いることにより、更に駆動電圧を、特に飽和電圧を低減し、加えてΔｎが小さく、広い温度範囲で駆動可能な液晶組成物が調製できることを見いだした。
【００６７】
これについて以下詳述する。一般式（ＩＩ）〜（ＩＶ）で表わされる化合物と、一般式（Ｖ）〜（ＶＩＩＩ）で表わされる化合物からなる液晶材料において、しきい値電圧Ｖ_ｔｈ、飽和電圧Ｖ_ｓａｔ、及び複屈折率Δｎが小さい混合液晶（ｃ−１）を得た。この混合液晶（ｃ−１）に一般式（Ｉ−１）、（Ｉ−３）で表わされる代表的な化合物（ｄ）、（ｅ）を添加し、本発明液晶組成物（ｃー２）、（ｃ−３）を作製した。
【００６８】
【化３３】

【００６９】
これらの混合物について、ネマチック相−等方性液体相転移温度Ｔ_Ｎ−Ｉ、セル厚５μｍのしきい値電圧Ｖ_ｔｈ、飽和電圧Ｖ_ｓａｔ、複屈折率Δｎの測定を行った。この結果を下記第２表に示す。
【００７０】
【表２】

【００７１】
この結果より、一般式（Ｉ−１）及び（Ｉ−３）で表わされる化合物（ｄ）及び（ｅ）を含有するネマチック液晶組成物（ｃー２）及び（ｃー３）は、混合液晶（ｃー１）と比較すると、ともにしきい値電圧（Ｖ_ｔｈ）、飽和電圧（Ｖ_ｓａｔ）の低減が認められ、更に加えて複屈折率（Δｎ）の低減が見られた。このことより、一般式（Ｉ−１）〜（Ｉ−４）で表わされる化合物は、駆動電圧の低減および複屈折率（Δｎ）の低減に有用であることが認められた。
【００７２】
本発明の液晶組成物の第２の特徴は、一般式（Ｉ−１）〜（ＶＩＩＩ）で表わされる化合物から選ばれた１種又はそれ以上の化合物において、１個又はそれ以上の水素原子を重水素原子に置換したシクロヘキサン環を１個又は２個有する化合物を用いる点にある。この様にして得られた液晶組成物は、低温でのネマチック相を安定化させる性質があり、特に低温に保存してもネマチック液晶性をより長期に保持できるものである。本発明者らは、重水素原子に置換したシクロヘキサン環を有する化合物を用いたこの様な効果を特願平５ー１０４１４４、１８２７３４等で明らかにしたが、本発明は更にこの効果を優れたものとしている。即ち、本発明の第２の特徴により、例えば、本発明の液晶組成物は、後述の実施例で詳述するが、ー２５℃あるいはー４０℃に保存してもネマチック性を長時間有することができるものである。
【００７３】
また、第３の特徴は、重水素原子に置換したシクロヘキサン環を有した一般式（Ｉ−１）〜（ＶＩＩＩ）で表わされる化合物は、重水素原子に置換されていないシクロヘキサン環を有した一般式（Ｉー１−０）〜（ＶＩＩＩー０）で表わされる化合物と比較して、有為さのある弾性定数及びそれらの比、あるいは有利なしきい値電圧を示しており、用途に応じた電気光学特性に調製できるものである。
【００７４】
本発明のネマチック液晶組成物に用いる一般式（ＩＸ）〜（ＸＩＸ）で表わされる化合物は上述の特性及びＴＮ−ＬＣＤ、ＳＴＮ−ＬＣＤ、ＴＦＴ−ＬＣＤ等に要求される特性を維持向上する効果を有する。
【００７５】
詳しくは、一般式（ＩＸ）、（ＸＩＩＩ）で表わされる化合物は、液晶組成物の複屈折率（△ｎ）を０．０８〜０．１０に最適化して、液晶表示装置の視角特性の向上、コントラスト比の増加等を行うことができる。また、組成物のネマチック相温度範囲を高温側及び低温側に拡大させる効果を有し、液晶表示装置の駆動可能な温度範囲を拡大することができる。
【００７６】
一般式（ＸＩＩ）（ＸＩＩＩ）における−（ＣＨ_２）_２−あるいは−（ＣＨ_２）_４−の連結基を有する各化合物は、一般式（Ｉ−１）〜（ＶＩＩＩ）の化合物からなる液晶組成物との相溶性にも優れている。更に、これらの化合物は蒸気圧温度特性にも優れており、本発明の液晶組成物に多用しても、液晶表示パネルの作製工程における液晶注入条件を緩和することができ、大型液晶パネルの作製工程における注入ムラを低減させるという特徴も有する。一般式（ＸＩＩＩ）の化合物は、しきい値電圧の低減に有用であり、低い駆動電圧を必要とする携帯用途に適した液晶組成物を提供することができる。
【００７７】
一般式（ＸＶ）（ＸＶＩ）の化合物は、一般式（Ｉ−１）〜（ＶＩＩＩ）の化合物からなる液晶組成物に添加して用いることにより、複屈折率（△ｎ）の低減あるいは粘性の低減に有用である。
【００７８】
本発明のネマチック液晶組成物は、一般式（ＸＶＩＩ）〜（ＸＩＸ）で表わされる化合物からなる群から選ばれる化合物を含有させることができる。この一般式（ＸＶＩＩ）〜（ＸＩＸ）で表わされる化合物は、上記液晶組成物のネマチック相の温度範囲を高温域及び又は低温域に拡大し得るものである。一般式（ＸＶＩＩ）の化合物は、ネマチック液晶組成物の粘性を低下させることができるので、広い温度範囲で高速応答性を有する液晶材料を得ることができる。一般式（ＸＶＩＩＩ）、（ＸＩＸ）で表わされる化合物は、液晶組成物の複屈折率（△ｎ）を０．０７〜０．０９に最適化して、液晶表示装置の視角特性の向上、コントラスト比の増加等を行うことができる。一般式（ＸＩＸ）は、しきい値電圧及び飽和電圧の低減に有用であり、低い駆動電圧を必要とする携帯用途や駆動回路の省力化に適した液晶組成物を提供することができる。
【００７９】
更に、本発明の液晶組成物は、一般式（Ｉ−１）〜（ＸＩＸ）の化合物に加えて、液晶組成物の他の特性を改善するために、液晶化合物として認識される通常のネマチック液晶、スメクチック液晶、コレステリック液晶などを含有してもよい。
【００８０】
本発明の液晶組成物における各化合物の含有量は、一般式（Ｉ−１）で表わされる化合物を０〜１０重量％、一般式（Ｉ−２）で表わされる化合物を０〜１０重量％、一般式（Ｉ−３）で表わされる化合物を０〜１０重量％の範囲で含有することが好ましく、一般式（Ｉ−４）で表わされる化合物を０〜１５重量％の範囲で含有することが好ましい。また、一般式（ＩＩ）で表わされる化合物を０〜２５重量％、一般式（ＩＩＩ）で表わされる化合物を０〜２５重量％、一般式（ＩＶ）で表わされる化合物を０〜２０重量％の範囲で含有することが好ましい。一般式（Ｖ）で表わされる化合物を０〜２０重量％、一般式（ＶＩ）で表わされる化合物を０〜３０重量％、一般式（ＶＩＩ）で表わされる化合物を０〜３０重量％、一般式（ＶＩＩＩ）で表わされる化合物を０〜３０重量％の範囲で含有することが好ましい。
【００８１】
また、液晶組成物における各化合物の総含有量は、一般式（Ｉ−１）で表わされる化合物を０〜２０重量％、一般式（Ｉ−２）で表わされる化合物を０〜１５重量％、一般式（Ｉ−３）で表わされる化合物を０〜２０重量％の範囲で含有することが好ましく、一般式（Ｉ−４）で表わされる化合物を０〜１５重量％の範囲で含有することが好ましい。また、一般式（ＩＩ）で表わされる化合物を０〜５０重量％、一般式（ＩＩＩ）で表わされる化合物を０〜５０重量％、一般式（ＩＶ）の化合物群を０〜４０重量％の範囲で含有することが好ましく、一般式（Ｖ）の化合物群を０〜３５重量％、一般式（ＶＩ）の化合物群を０〜４０重量％、一般式（ＶＩＩ）の化合物群を０〜４０重量％、一般式（ＶＩＩＩ）の化合物群を０〜４０重量％の範囲で含有することが好ましい。
【００８２】
更に、各化合物群の総含有量は、一般式（ＩＩ）〜（ＩＶ）の第２の化合物群を１０〜８０重量％範囲で含有することが好ましく、一般式（Ｖ）〜（ＶＩＩＩ）の第３の化合物群を５〜５０重量％範囲で含有することが好ましい。
【００８３】
一般式（ＩＸ）〜（ＸＩＶ）で表わされる化合物はそれぞれ０〜２５重量％の範囲で含有することが好ましく、一般式（ＸＶ）〜（ＸＶＩＩ）で表わされる化合物はそれぞれ０〜２０重量％の範囲で含有することが好ましく、一般式（ＸＶＩＩＩ）で表わされる化合物はそれぞれ０〜２０重量％の範囲で含有することが好ましく、一般式（ＸＩＸ）で表わされる化合物はそれぞれ０〜１０重量％の範囲で含有することが好ましい。
【００８４】
本発明に係わる各化合物は、液晶組成物あるいは液晶表示特性に要求される目的に応じて以下のように組み合わせることができる。液晶組成物の結晶相またはスメクチック相ーネマチック相転移温度Ｔ→_Ｎを低くする目的には、（Ｉ−１）〜（Ｉ−４）＋（ＩＩ）＋（ＩＩＩ）＋（ＶＩ）＋（ＶＩＩ）＋（ＶＩＩＩ）の組み合わせが好ましく、更に（ＩＸ）〜（ＸＩ）を組み合わせることが好ましく、または（ＸＩＸ）を組み合わせることが特に好ましい。液晶組成物のネマチック相−等方性液体相転移温度Ｔ_Ｎ−Ｉを高くし、結晶相またはスメクチック相ーネマチック相転移温度Ｔ→_Ｎを低くする目的には、（Ｉ−１）〜（Ｉ−４）＋（ＩＩ）＋（ＩＩＩ）＋（ＶＩ）〜（ＶＩＩＩ）の組み合わせが好ましく、更に（ＩＸ）〜（ＸＩＩ）または（ＸＶＩＩ）と組み合わせることが好ましい。液晶表示のしきい値電圧Ｖ_ｔｈおよび飽和電圧Ｖ_ｓａｔを低くする目的には、（Ｉ−１）〜（Ｉ−４）＋（ＩＩ）＋（ＶＩ）〜（ＶＩＩＩ）の組み合わせが好ましく、更に（ＩＸ）〜（ＸＩＩ）、（ＸＶＩ）、（ＸＶＩＩ）を組み合わせることが好ましい。液晶表示の応答特性を速くする目的には、（Ｉ−１）〜（Ｉ−４）＋（ＩＩ）＋（ＩＩＩ）＋（ＶＩＩＩ）の組み合わせが好ましく、更に（ＶＩ）（ＶＩＩ）、（ＸＩＩ）〜（ＸＶＩ）を組み合わせることが好ましい。液晶組成物の複屈折率△ｎを０．０７〜０．０８とする目的には、（Ｉ−１）〜（Ｉ−４）＋（ＩＶ）＋（Ｖ）〜（ＶＩＩＩ）の組み合わせが好ましく、液晶組成物の複屈折率△ｎを０．０８〜０．１０とする目的には、（Ｉ−１）〜（Ｉ−４）＋（ＩＩ）＋（ＩＩＩ）＋（Ｖ）の組み合わせが好ましく、更に（ＩＸ）、（Ｘ）、（ＸＶＩＩＩ）を組み合わせることが好ましい。
【００８５】
この様にして得られた本発明の液晶組成物は、後述の実施例に示したように、８０〜９０℃のネマチック相−等方性液体相転移温度（Ｔ_Ｎ−Ｉ）のものでは１．１〜１．３Ｖのしきい値電圧（Ｖ_ｔｈ）、２．２〜３．１Ｖの飽和電圧（Ｖ_ｓａｔ）、０．０７１〜０．０８８の複屈折率△ｎの特性で、９０〜１００℃のネマチック相−等方性液体相転移温度（Ｔ_Ｎ−Ｉ）のものでは１．２〜１．４Ｖのしきい値電圧（Ｖ_ｔｈ）、２．５〜３．０Ｖの飽和電圧（Ｖ_ｓａｔ）、０．０７５〜０．０８８の複屈折率△ｎの特性、ー３０℃以下の結晶相またはスメクチック相ーネマチック相転移温度（Ｔ→_Ｎ）、９〜１１の誘電異方性（△ε）の特性を得ることができた。
【００８６】
また、本発明のネマチック液晶組成物は、後述の実施例に示した加熱促進テスト、紫外線照射促進テストを行ったところ、各促進テスト後も９８％以上の高い電圧保持率を有することや化学的にも非常に安定で高い抵抗値を有することが確認された。
【００８７】
このように、本発明のネマチック液晶組成物は、広い温度範囲で液晶性を示し、しきい値電圧および飽和電圧が低く、複屈折率が小さくしかも充分に高い電圧保持率を有する液晶組成物であり、フリッカが発生せず、コントラストに優れた液晶表示装置を提供することが可能となった。また、アクティブ・マトリクス液晶表示装置を作製したところ、フリッカが発生せずコントラストに優れた液晶表示装置を作製することができた。更に、ＴＮ−ＬＣＤやＳＴＮ−ＬＣＤ液晶表示パネルを作製したところ、広範な駆動周波数で表示可能であることが確認された。
【００８８】
【実施例】
以下、実施例を挙げて本発明を詳述するが、本発明はこれらの実施例に限定されるものではない。実施例中、測定した特性の各記号の意味は以下の通りである。
【００８９】
Ｔ_Ｎ−Ｉ ： ネマチック相−等方性液体相転移温度（℃）
Ｖ_ｔｈ ： パネル液晶層の厚みをｄとしファーストミニマム△ｎ・ｄ＝０．５のＴＮ−ＬＣＤを構成した時のしきい値電圧（Ｖ）
Ｖ_ｓａｔ ： パネル液晶層の厚みをｄとしファーストミニマム△ｎ・ｄ＝０．５のＴＮ−ＬＣＤを構成し、光透過率１％となる飽和電圧（Ｖ）
△ε ： 誘電異方性
△ｎ ： 複屈折率
又、組成物の促進テストは、液晶組成物２ｇをアンプル管に入れ、真空脱気後、窒素置換の処理をして封入し、１８０℃、１時間の加熱促進テスト、及び１０時間の紫外線照射促進テスト「ＳＵＮＴＥＳＴ」（オリジナルハナウ社製）で行った。液晶組成物の比抵抗と電圧保持率は促進テスト前後で測定した。
【００９０】
（実施例１）
【００９１】
【化３４】

【００９２】
からなるネマチック液晶組成物（３ー１）を調製し、この組成物の諸特性を測定した。結果は以下の通りであった。
Ｔ_Ｎ−Ｉ ： ８２．３ ℃
Ｖ_ｔｈ ： １．２３ Ｖ
Ｖ_ｓａｔ ： ２．９９ Ｖ
△ε ： ８．７
△ｎ ： ０．０７１
テスト前の比抵抗 ： ６．７×１０^１３Ω ｃｍ
加熱促進テスト後比抵抗 ： ５．９×１０^１３Ω ｃｍ
紫外線照射促進テスト後比抵抗： ３．０×１０^１３Ω ｃｍ
テスト前の電圧保持率 ： ９９．３％（測定温度８０℃）
加熱促進テスト後電圧保持率 ： ９８．２％（測定温度８０℃）
紫外線照射促進テスト後電圧保持率： ９８．０％（測定温度８０℃）
このネマチック液晶組成物（３ー１）を構成材料とするアクティブ・マトリクス液晶表示装置を作製したところ、漏れ電流が小さくフリッカの発生しない優れたものであることが確認できた。
【００９３】
またこのネマチック液晶組成物（３ー１）にカイラル物質「Ｓ−８１１」（メルク社製）を添加して混合液晶を調製した。一方、対向する平面透明電極上に「サンエバー１５０」（日産化学社製）の有機膜をラビングして配向膜を形成し、ツイスト角２２０度のＳＴＮ−ＬＣＤ表示用セルを作製した。上記の混合液晶をこのセルに注入して液晶表示装置を構成し、表示特性を測定した。その結果、しきい値電圧が低く、高時分割特性に優れ、表示画面のちらつきやクロストーク現象が改善されたＳＴＮ−ＬＣＤ表示特性を示す液晶表示装置が得られた。
【００９４】
（実施例２）
【００９５】
【化３５】

【００９６】
からなるネマチック液晶組成物（３ー２）を調製し、この組成物の諸特性を測定した。結果は以下の通りであった。
Ｔ_Ｎ−Ｉ ： ８９．８ ℃
Ｖ_ｔｈ ： １．１８ Ｖ
Ｖ_ｓａｔ ： ２．９０ Ｖ
△ε ： ９．９
△ｎ ： ０．０７６
【００９７】
このネマチック液晶組成物（３ー２）にカイラル物質「Ｓ−８１１」（メルク社製）を添加して混合液晶を調製した。一方、対向する平面透明電極上に「サンエバー１５０」（日産化学社製）の有機膜をラビングして配向膜を形成し、ツイスト角２２０度のＳＴＮ−ＬＣＤ表示用セルを作製した。上記の混合液晶をこのセルに注入して液晶表示装置を構成し、表示特性を測定した。その結果、しきい値電圧が低く、高時分割特性に優れ、表示画面のちらつきやクロストーク現象が改善されたＳＴＮ−ＬＣＤ表示特性を示す液晶表示装置が得られた。
【００９８】
（実施例３）
【００９９】
【化３６】

【０１００】
からなるネマチック液晶組成物（３ー３）を調製し、この組成物の諸特性を測定した。結果は以下の通りであった。
Ｔ_Ｎ−Ｉ ： ８３．５ ℃
Ｖ_ｔｈ ： １．１９ Ｖ
Ｖ_ｓａｔ ： ２．５３ Ｖ
△ε ： ９．６
△ｎ ： ０．０７９
【０１０１】
【０１０２】
（実施例４）
【０１０３】
【化３７】

【０１０４】
【化３８】

【０１０５】
からなるネマチック液晶組成物（３ー４）を調製し、この組成物の諸特性を測定した。結果は以下の通りであった。
Ｔ_Ｎ−Ｉ ： ９１．６ ℃
Ｖ_ｔｈ ： １．１６ Ｖ
Ｖ_ｓａｔ ： ２．５５ Ｖ
△ε ： １１．１
△ｎ ： ０．０８７
【０１０６】
（実施例５）
【０１０７】
【化３９】

【０１０８】
【化４０】

【０１０９】
からなるネマチック液晶組成物（３ー５）を調製し、この組成物の諸特性を測定した。結果は以下の通りであった。
Ｔ_Ｎ−Ｉ ： ８０．０ ℃
Ｖ_ｔｈ ： １．０８ Ｖ
Ｖ_ｓａｔ ： ２．２０ Ｖ
△ε ： １１．６
△ｎ ： ０．０８８
【０１１０】
（実施例６）
【０１１１】
【化４１】

【０１１２】
からなるネマチック液晶組成物（３ー６）を調製し、この組成物の諸特性を測定した。結果は以下の通りであった。
Ｔ_Ｎ−Ｉ ： １００．３ ℃
Ｖ_ｔｈ ： １．３９ Ｖ
Ｖ_ｓａｔ ： ２．９０ Ｖ
△ε ： ８．５
△ｎ ： ０．０７５
【０１１３】
このネマチック液晶組成物（３ー６）にカイラル物質「Ｓ−８１１」（メルク社製）を添加して混合液晶を調製した。一方、対向する平面透明電極上に「サンエバー１５０」（日産化学社製）の有機膜をラビングして配向膜を形成し、ツイスト角２２０度のＳＴＮ−ＬＣＤ表示用セルを作製した。上記の混合液晶をこのセルに注入して液晶表示装置を構成し、表示特性を測定した。その結果、しきい値電圧が低く、高時分割特性に優れ、表示画面のちらつきやクロストーク現象が改善されたＳＴＮ−ＬＣＤ表示特性を示す液晶表示装置が得られた。
【０１１４】
（実施例７）
【０１１５】
【化４２】

【０１１６】
からなるネマチック液晶組成物（３ー７）を調製し、この組成物の諸特性を測定した。結果は以下の通りであった。
Ｔ_Ｎ−Ｉ ： ９６．３ ℃
Ｖ_ｔｈ ： １．３０ Ｖ
Ｖ_ｓａｔ ： ２．７２ Ｖ
△ε ： ９．６
△ｎ ： ０．０８８
テスト前の比抵抗 ： ７．４×１０^１３Ω ｃｍ
加熱促進テスト後比抵抗 ： ５．８×１０^１３Ω ｃｍ
紫外線照射促進テスト後比抵抗： ２．５×１０^１３Ω ｃｍ
テスト前の電圧保持率 ： ９９．５％
加熱促進テスト後電圧保持率 ： ９８．４％
紫外線照射促進テスト後電圧保持率： ９８．１％
このネマチック液晶組成物（３ー７）を構成材料とするアクティブ・マトリクス液晶表示装置を作製したところ、漏れ電流が小さくフリッカの発生しない優れたものであることが確認できた。
【０１１７】
（実施例８）
【０１１８】
【化４３】

【０１１９】
からなるネマチック液晶組成物（３ー８）を調製し、この組成物の諸特性を測定した。結果は以下の通りであった。
Ｔ_Ｎ−Ｉ ： ８３．５ ℃
Ｖ_ｔｈ ： １．３８ Ｖ
Ｖ_ｓａｔ ： ２．７５ Ｖ
△ε ： ７．７
△ｎ ： ０．０７５
【０１２０】
（実施例９）
【０１２１】
【化４４】

【０１２２】
からなるネマチック液晶組成物（３ー９）を調製し、この組成物の諸特性を測定した。結果は以下の通りであった。
Ｔ_Ｎ−Ｉ ： ９６．３ ℃
Ｖ_ｔｈ ： １．３６ Ｖ
Ｖ_ｓａｔ ： ２．９９ Ｖ
△ε ： ９．３
△ｎ ： ０．０７９
テスト前の比抵抗 ： ８．２×１０^１３Ω ｃｍ
加熱促進テスト後比抵抗 ： ５．８×１０^１３Ω ｃｍ
紫外線照射促進テスト後比抵抗： ２．７×１０^１３Ω ｃｍ
テスト前の電圧保持率 ： ９９．４％
加熱促進テスト後電圧保持率 ： ９８．６％
紫外線照射促進テスト後電圧保持率： ９８．２％
このネマチック液晶組成物（３ー９）を構成材料 とするアクティブ・マトリクス液晶表示装置を作製したところ、漏れ電流が小さくフリッカの発生しない優れたものであることが確認できた。
【０１２３】
（比較例１）
比較例として、
【０１２４】
【化４５】

【０１２５】
からなるネマチック液晶組成物（ａ）を調製し、この組成物の諸特性を測定した。結果は以下の通りであった。
Ｔ_Ｎ−Ｉ ： ５９．１ ℃
Ｖ_ｔｈ ： １．０７ Ｖ
Ｖ_ｓａｔ ： ２．５５ Ｖ
△ε ： ８．１
△ｎ ： ０．０６７
（実施例１０）
比較例（１）に一般式（Ｉ）で表わされる化合物を組み合わせた液晶組成物
【０１２６】
【化４６】

【０１２７】
からなるネマチック液晶組成物（３ー１０）を調製し、この組成物の諸特性を測定した。結果は以下の通りであった。
Ｔ_Ｎ−Ｉ ： ５０．７ ℃
Ｖ_ｔｈ ： ０．９７ Ｖ
Ｖ_ｓａｔ ： ２．１５ Ｖ
△ε ： ８．７
△ｎ ： ０．０６５
テスト前の比抵抗 ： ８．２×１０^１３Ω ｃｍ
加熱促進テスト後比抵抗 ： ５．８×１０^１３Ω ｃｍ
紫外線照射促進テスト後比抵抗： ２．７×１０^１３Ω ｃｍ
テスト前の電圧保持率 ： ９９．４％
加熱促進テスト後電圧保持率 ： ９８．６％
紫外線照射促進テスト後電圧保持率： ９８．２％
このネマチック液晶組成物（３ー１０）を構成材料 とするアクティブ・マトリクス液晶表示装置を作製したところ、漏れ電流が小さくフリッカの発生しない優れたものであることが確認できた。
【０１２８】
上記の結果より、本発明の組み合わせにより、更にしきい値電圧及び飽和電圧を低減させ、低い複屈折率を持つ液晶組成物が得られることが明らかとなった。
【０１２９】
【発明の効果】
本発明のネマチック液晶組成物は、広い温度範囲でネマチック相を示し、しきい値電圧および飽和電圧が低く、更に複屈折率が小さく、高い電圧保持率を有す。しかも化学的安定性が高い。従って、これを用いた本発明の液晶表示装置は、均一で高いコントラストが得られ、表示画面のちらつき、クロストーク現象を改善することができ、情報量の多いＴＮ−ＬＣＤ、ＳＴＮ−ＬＣＤあるいはアクティブ・マトリクス方式において良好な駆動特性及び表示特性が得られる。[0001]
[Industrial application fields]
The present invention relates to a nematic liquid crystal composition useful as an electro-optical display material and a liquid crystal display device using the same.
[0002]
[Prior art]
A typical liquid crystal display element is a TN-LCD (twisted nematic liquid crystal display element), which is used in a clock, a calculator, an electronic notebook, a pocket computer, a word processor, a personal computer, and the like. On the other hand, with the increase in processing information of OA devices, the amount of information displayed on one screen has increased, and Scheffer et al. [SID '85 Digest, page 120 (1985)], or Kinugawa et al. [SID '86 Digest, p. 122 (1986)], an STN-LCD (super twisted nematic liquid crystal display element) has been developed, and is beginning to be widely used in displays for high information processing such as word processors and personal computers.
[0003]
Furthermore, because of its excellent display quality, active matrix type liquid crystal display devices have been put on the market as being promising in application fields of displays such as liquid crystal televisions, projector displays, and computers. In the active matrix display system, a switching element such as a TFT (thin film transistor) or MIM (metal insulator metal) is used for each pixel. This system has a small leakage current, that is, a high voltage holding ratio. It is important. (Hereinafter, these active matrix display type liquid crystal display elements are collectively referred to as TFT-LCDs.) Accordingly, in order to cope with such display elements, new liquid crystal compounds or liquid crystal compositions are still proposed. ing.
[0004]
[Problems to be solved by the invention]
TN-LCD and STN-LCD have problems such as chemical stability of liquid crystal materials, low-voltage drivability and response characteristics of liquid crystal display devices.
[0005]
For example, a liquid crystal with a large dielectric anisotropy having a CN group is necessary for STN-LCDs with a large amount of information, such as word processors and personal computers, which require high drive characteristics with a high number of time divisions, because the drive voltage needs to be reduced. Material is used. However, such a liquid crystal material makes it difficult to obtain a good response characteristic due to an increase in viscosity, or causes a crosstalk phenomenon by narrowing a display frequency range that can be displayed by increasing a capacitance component for each pixel. Have problems such as.
[0006]
Also, in the case of conventional liquid crystal materials that can be driven at a low voltage, the resistance value after the initial test or accelerated test is often low, which causes display flickering or a decrease in contrast due to an increase in the number of time divisions. When used in STN-LCDs using a backlight for the purpose of supplementing dark image quality, chemical stability such as heat resistance and light resistance is newly required.
[0007]
In addition to these required characteristics, particularly in the active matrix system, it is important to have a small leakage current and a high voltage holding ratio in order to obtain uniform and high contrast. In order to obtain such characteristics, for example, the following compound (a) has been used.
[0008]
Embedded image

[0009]
(Wherein R ⁷¹ Represents a linear alkyl group, formula (b) represents a cyclohexane ring, and the deuterium atom present in the cyclohexane ring is contained with a probability corresponding to the abundance ratio with respect to a naturally occurring hydrogen atom having a mass number of 1. Represents. Hereinafter, formula (b) is used in this sense. )
However, even if these compounds are used, there is a problem in maintaining both nematic liquid crystal properties over a wide temperature range and sufficiently reducing the threshold voltage and saturation voltage required for the active matrix method. was there. In particular, the saturation voltage emphasizes the voltage at which the transmittance is 1% as a stricter evaluation method than the conventional voltage at which the transmittance is 10% for the purpose of improving the contrast. Hereinafter, saturation voltage V _sat Is used in this sense.
[0010]
In addition, in order to obtain uniform and high contrast liquid crystal display characteristics, the product Δn · d of the thickness d of the liquid crystal layer of the liquid crystal panel and the birefringence Δn of the liquid crystal material is set to 0.35 to 0.55 ( This is hereinafter referred to as the first minimum). Since the thickness d currently performed in the manufacturing process of the liquid crystal panel is about 4.5 μm or more, the birefringence Δn of the liquid crystal material is required to be 0.07 to 0.10. However, the characteristics of smaller birefringence and lower drive voltage tend to conflict with each other, making it difficult to satisfy both.
[0011]
The problem to be solved by the present invention is to meet the above-mentioned problem, exhibiting liquid crystal properties in a wide temperature range, and driving voltage, particularly saturation voltage V. _sat Provides a liquid crystal composition having a low and yet sufficiently high voltage holding ratio and having a birefringence index Δn suitable for the setting conditions in the apparatus, and further, using this liquid crystal composition, flicker is not generated and excellent in contrast. The object is to provide a liquid crystal display device.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides the following nematic liquid crystal composition.
[0013]
That is, as the first liquid crystal composition of the present invention, general formulas (I-1) to (I-4),
[0014]
Embedded image

[0015]
(Wherein R ¹¹ ~ R ¹⁴ Each independently represents a linear alkyl group having 2 to 5 carbon atoms; ¹¹ Represents a fluorine atom or a chlorine atom, Y ¹² And Y ¹³ Each independently represents a hydrogen atom or a fluorine atom. And a nematic liquid crystal composition comprising at least one compound selected from the first group of compounds represented by formula (1).
[0016]
The compound groups represented by the general formulas (I-1) to (I-4) described above have one or two cyclohexane rings in which one or more hydrogen atoms are substituted with deuterium atoms. You may do it.
[0017]
Further, the liquid crystal composition may have the general formulas (II) to (IV).
[0018]
Embedded image

[0019]
(Wherein R ²¹ And R ²² Each independently represents a linear alkenyl group having 2 to 5 carbon atoms; ²³ Represents a linear alkyl group having 2 to 5 carbon atoms, and at least one hydrogen atom (H) of two 1,4-cyclohexylene groups in each compound is substituted with a deuterium atom (D). Also good. And a second group of compounds represented by general formulas (V) to (VIII)
[0020]
Embedded image

[0021]
(Wherein R ³¹ ~ R ³⁴ Each independently represents a linear alkyl group having 2 to 7 carbon atoms, and at least one hydrogen atom (H) of two 1,4-cyclohexylene groups in each compound is a deuterium atom (D). May be substituted. And a nematic liquid crystal composition comprising one or more compounds selected from the third group of compounds represented by formula (1):
[0022]
In the compounds represented by the general formulas (I-1) to (VIII), compounds having a cyclohexane ring in which a hydrogen atom is substituted with a deuterium atom can be used as follows. A compound having a cyclohexane ring in which one or more hydrogen atoms in general formula (I-1) are substituted with deuterium atoms is represented by general formula (I-1-1)
[0023]
Embedded image

[0024]
(Wherein R ¹¹ , Y ¹¹ , Has the same meaning as above, and X ¹ ~ X ³ Each independently represents a hydrogen atom (H) or a deuterium atom (D), but at least one represents a deuterium atom (D). And a compound having a cyclohexane ring in which one or more hydrogen atoms in the general formula (I-2) are substituted with deuterium atoms is represented by the general formula (I-2-1)
[0025]
Embedded image

[0026]
(Wherein R ¹² And X ¹ ~ X ³ Is as defined above. And a compound having a cyclohexane ring in which one or more hydrogen atoms in the general formula (I-3) are substituted with deuterium atoms is represented by the general formula (I-3-1)
[0027]
Embedded image

[0028]
(Wherein R ¹³ , Y ¹² And X ¹ ~ X ³ Is as defined above. And a compound having a cyclohexane ring in which one or more hydrogen atoms in the general formula (I-4) are substituted with deuterium atoms is represented by the general formula (I-4-1)
[0029]
Embedded image

[0030]
(Wherein R ¹⁴ , Y ¹³ And X ¹ ~ X ³ Is as defined above. And a compound having a cyclohexane ring in which one or more hydrogen atoms in the general formula (II) are substituted with deuterium atoms is represented by the general formula (II-1)
[0031]
Embedded image

[0032]
(Wherein R ²¹ And X ⁴ ~ X ⁷ Is as defined above. And a compound having a cyclohexane ring in which one or more hydrogen atoms in the general formula (III) are substituted with deuterium atoms is represented by the general formula (III-1)
[0033]
Embedded image

[0034]
(Wherein R ²² And X ⁴ ~ X ⁷ Is as defined above. And a compound having a cyclohexane ring in which one or more hydrogen atoms in the general formula (IV) are substituted with deuterium atoms is represented by the general formulas (IV-1), (IV-2)
[0035]
Embedded image

[0036]
(Wherein R ²³ And X ¹ ~ X ³ , X ⁴ ~ X ⁷ Is as defined above. And a compound having a cyclohexane ring in which one or more hydrogen atoms in the general formula (V) are substituted with deuterium atoms is represented by the general formula (V-1)
[0037]
Embedded image

[0038]
(Wherein R ³¹ And X ⁴ ~ X ⁷ Is as defined above. And a compound having a cyclohexane ring in which one or more hydrogen atoms in the general formula (VI) are substituted with deuterium atoms is represented by the general formula (VI-1)
[0039]
Embedded image

[0040]
(Wherein R ³² And X ⁴ ~ X ⁷ Is as defined above. And a compound having a cyclohexane ring in which one or more hydrogen atoms in general formula (VII) are substituted with deuterium atoms is represented by general formula (VII-1)
[0041]
Embedded image

[0042]
(Wherein R ³³ And X ⁴ ~ X ⁷ Is as defined above. And a compound having a cyclohexane ring in which one or more hydrogen atoms in the general formula (VIII) are substituted with deuterium atoms is represented by the general formula (VIII-1)
[0043]
Embedded image

[0044]
(Wherein R ³⁴ And X ⁴ ~ X ⁷ Is as defined above. And a nematic liquid crystal composition using any one of these compounds.
In the present invention, the liquid crystal composition may have the general formulas (IX) to (XI)
[0045]
Embedded image

[0046]
(Wherein R ⁴¹ ~ R ⁴³ Each independently represents a linear alkyl group having 2 to 5 carbon atoms; ⁴¹ ~ Y ⁴³ Represents a hydrogen atom or a fluorine atom, and at least one hydrogen atom (H) of two 1,4-cyclohexylene groups may be substituted with a deuterium atom (D). And one or more compounds selected from the group of compounds represented by formula (XII) to (XIV)
[0047]
Embedded image

[0048]
(Wherein R ⁵¹ ~ R ⁵³ Each independently represents a linear alkyl group having 3 to 7 carbon atoms; ⁵¹ ~ Y ⁵⁴ Each independently represents a hydrogen atom or a fluorine atom, and may have a cyclohexane ring in which one or more hydrogen atoms are substituted with deuterium atoms. And one or more compounds selected from the group of compounds represented by formula (XV) to (XIX)
[0049]
Embedded image

[0050]
(Wherein R ⁶¹ ~ R ⁶⁴ Each independently represents a linear alkyl group or alkenyl group having 2 to 5 carbon atoms; ⁶⁷ ~ R ⁶⁹ Each independently represents a linear alkyl group having 1 to 5 carbon atoms, an alkoxy group or a linear alkenyl group having 2 to 5 carbon atoms; ⁶⁵ Represents a linear alkyl group having 2 to 5 carbon atoms, r independently represents 0 or 1, Y ⁶¹ And Y ⁶² Each independently represents a hydrogen atom or a fluorine atom, and at least one hydrogen atom (H) in the general formulas (XV) and (XVI) may be substituted with a deuterium atom (D). 1) or more compounds selected from the group of compounds represented by
[0051]
Furthermore, the present invention provides an active matrix liquid crystal display device, a twisted nematic or a super twisted nematic liquid crystal display device using the above nematic liquid crystal composition.
[0052]
Hereinafter, in detailing the present invention, all the cyclohexane rings which the compounds of the general formulas (I-1) to (I-4), (II) to (XIV), (XVIII) and (XIX) have are described above. The compounds of the formula (b) that are cyclohexane rings are represented by the following general formulas (I-1-0) to (I-4-0), (II-0) to (XIII-0), It is represented by (XVII-0) and (XVIII-0). (Wherein R ⁰¹¹ ~ R ⁰⁵³ , R ⁰⁶⁴ And R ⁰⁶⁵ , Y ⁰¹¹ ~ Y ⁰⁶² Are each independently R ¹¹ ~ R ⁵³ , R ⁶⁴ And R ⁶⁵ , Y ¹¹ ~ Y ⁶² Means the same. )
[0053]
Embedded image

[0054]
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[0055]
Representative compound examples (1-1-1) to (1-1-4) and (1-2) to (1-8) represented by the general formulas (I-1) to (VIII) according to the present invention. Table 1 below shows their phase transition temperatures. In the table below, m. p. Is the temperature at which the phase transition from the crystal phase to the liquid crystal phase or the isotropic liquid phase, p. Represents the temperature at which the liquid crystal phase transitions to the isotropic liquid phase. Moreover, each liquid crystal compound used what removed the impurity using methods, such as distillation, column purification, and recrystallization, and fully refined.
[0056]
[Table 1]

[0057]
The liquid crystal composition of the present invention is characterized by containing, as an essential component, a compound selected from the first compound group represented by the aforementioned general formulas (I-1) to (I-4), and further the general formula (II). A liquid crystal composition obtained by combining with a compound selected from the second compound group represented by (IV) and / or a compound selected from the third compound group represented by the general formulas (V) to (VIII) It is in having found out. The liquid crystal composition thus obtained has a driving voltage, particularly a saturation voltage V _sat And has a characteristic that the birefringence Δn is small.
[0058]
The compounds represented by the general formulas (I-1) and (I-2) include a 2,6-difluorophenyl group and a 3,4,5-trifluorophenyl group or a 3,4-difluoro-5-chlorophenyl group. -C ₂ H ₄ It has the structure connected with-. Since this compound has a low threshold voltage and saturation voltage, a liquid crystal material having a low driving voltage can be obtained without reducing the voltage holding ratio by combining with another compound according to the present invention.
[0059]
The compounds represented by the general formulas (I-3) and (I-4) include a 5-substituted 2,3-difluorophenyl group and a 3,4-difluorophenyl group or a 3,4,5-trifluorophenyl group. , -O-CH ₂ -It has a structure connected by a group. This compound has a low driving voltage, particularly a saturation voltage, and when combined with another compound according to the present invention, a liquid crystal amount having a low driving voltage can be obtained without reducing the voltage holding ratio. Moreover, since this material has a great effect of reducing the birefringence Δn, it is possible to prepare a nematic liquid crystal composition having a birefringence according to the application.
The compound represented by the general formula (II) has a linear alkenyl group and a 3,4,5-trifluorophenyl group. When this compound is combined with other compounds according to the present invention, there is a problem that crystals are precipitated during long-term low-temperature storage, but it exhibits compatibility that induces and expands the nematic phase on the low-temperature side, and has a voltage holding ratio. There is an effect of maintaining or reducing the drive voltage without lowering.
[0060]
The compounds represented by the general formulas (III) and (IV) have a 3,4-difluorophenyl group and are characterized by the compatibility described above. Moreover, since the compound of general formula (III) has a large birefringence Δn compared to the compounds of general formulas (II) and (IV) to (VIII), a nematic liquid crystal composition having a birefringence according to the application is adjusted. The compound represented by the general formula (IV) has a relatively low threshold voltage and is useful for this adjustment.
[0061]
The compounds represented by the general formulas (II) and (III) have an elastic constant ratio (K) that plays an important role in display characteristics. ₃₃ / K ₁₁ ) Is larger or smaller than the general formulas (IV) to (V). Therefore, it is possible to prepare a nematic liquid crystal composition exhibiting an elastic constant ratio according to the application. Furthermore, since the compounds of the general formulas (II) and (III) can also reduce the viscosity of the nematic liquid crystal composition, a high-speed response in a wide temperature range by combining with the compounds of the general formulas (IV) to (XV). A liquid crystal material having properties can be easily obtained. R of the compounds represented by the general formulas (II) and (III) ²¹ And R ²² The following are particularly excellent.
[0062]
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[0063]
Compounds represented by the general formulas (V) to (VIII) are represented by -C ₂ H ₄ -, -C ₄ H ₈ And a 3,4-difluorophenyl group and a 3,4,5-trifluorophenyl group. Since these compounds have a small birefringence Δn compared to the compounds of the general formulas (II) to (IV), it is possible to adjust a nematic liquid crystal composition having a birefringence according to the application, and to maintain a voltage holding ratio. It has been found that it has the effect of maintaining or reducing the drive voltage without lowering the voltage.
[0064]
However, the compounds of the general formulas (V), (VI) and (VIII) tend to exhibit a smectic phase, and in a composition comprising only these compounds, the nematic phase is very narrow due to the presence of the smectic phase, particularly from room temperature. It has been difficult to prepare a nematic liquid crystal composition that can be driven at a low temperature.
[0065]
The inventors of the present invention have described R for the compounds represented by the general formulas (II) to (VIII). ²¹ Various combinations were studied, including detailed comparisons with compounds having an alkyl group. The technology is clarified in Japanese Patent Application No. 6-202036, which is represented by compounds selected from the group of compounds represented by general formulas (II) to (IV) and general formulas (V-1) to (VIII). It has been found that by using a combination of compounds selected from a group of compounds, a nematic liquid crystal composition that can be used in a wide temperature range can be prepared without impairing the excellent properties of each compound. Further, the compounds represented by the general formulas (II) and (VI) to (VIII) have a 3,4,5-trifluorophenyl group, but are excellent in compatibility at low temperatures, and have a 3,4-difluorophenyl group. Even if the mixing ratio with the compound represented by the general formulas (III), (IV) and (V) having a ratio of 1: 1 or more, or a total content of 50% or more, a special third means Since a liquid crystal composition that can be used in a wide temperature range can be prepared without using, the advantage as a means for reducing threshold voltage is great.
[0066]
The present inventors have selected compounds selected from the compound groups represented by the general formulas (I-1) to (I-4) described above from the compound groups represented by the general formulas (II) to (IV). In combination with a liquid crystal composition containing a compound selected from the group consisting of the compounds represented by formulas (V) to (VIII), a driving voltage, particularly a saturation voltage is further reduced. It was found that a liquid crystal composition having a small Δn and capable of being driven in a wide temperature range can be prepared.
[0067]
This will be described in detail below. In a liquid crystal material comprising a compound represented by general formulas (II) to (IV) and a compound represented by general formulas (V) to (VIII), threshold voltage V _th , Saturation voltage V _sat And a mixed liquid crystal (c-1) having a small birefringence Δn was obtained. Representative compounds (d) and (e) represented by the general formulas (I-1) and (I-3) are added to the mixed liquid crystal (c-1), and the liquid crystal composition (c-2) of the present invention. , (C-3) was produced.
[0068]
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[0069]
For these mixtures, the nematic phase-isotropic liquid phase transition temperature T _NI , Threshold voltage V of cell thickness 5 μm _th , Saturation voltage V _sat The birefringence Δn was measured. The results are shown in Table 2 below.
[0070]
[Table 2]

[0071]
From this result, the nematic liquid crystal compositions (c-2) and (c-3) containing the compounds (d) and (e) represented by the general formulas (I-1) and (I-3) are mixed liquid crystals. Compared with (c-1), the threshold voltage (V _th ), Saturation voltage (V _sat ) Was observed, and in addition, a reduction in birefringence (Δn) was observed. From this, it was confirmed that the compounds represented by the general formulas (I-1) to (I-4) are useful for reducing driving voltage and birefringence (Δn).
[0072]
The second feature of the liquid crystal composition of the present invention is that one or more hydrogen atoms are selected from one or more compounds selected from the compounds represented by formulas (I-1) to (VIII). The point is to use a compound having one or two cyclohexane rings substituted with deuterium atoms. The liquid crystal composition thus obtained has the property of stabilizing the nematic phase at a low temperature, and can maintain the nematic liquid crystal properties for a long time even when stored at a low temperature. The present inventors have clarified such an effect by using a compound having a cyclohexane ring substituted with a deuterium atom in Japanese Patent Application Nos. Hei 5-104144, 182734, etc., but the present invention further improves this effect. It is said. That is, according to the second feature of the present invention, for example, the liquid crystal composition of the present invention will be described in detail in Examples below, but it has nematic properties for a long time even when stored at -25 ° C or -40 ° C. It is something that can be done.
[0073]
The third feature is that the compounds represented by the general formulas (I-1) to (VIII) having a cyclohexane ring substituted with a deuterium atom have a cyclohexane ring not substituted with a deuterium atom. Compared with the compounds represented by formulas (I-1-0) to (VIII-0), they show significant elastic constants and their ratios, or advantageous threshold voltages, depending on the application. It can be adjusted to electro-optical characteristics.
[0074]
The compounds represented by the general formulas (IX) to (XIX) used in the nematic liquid crystal composition of the present invention have the effect of maintaining and improving the above-mentioned characteristics and the characteristics required for TN-LCD, STN-LCD, TFT-LCD, etc. Have.
[0075]
Specifically, the compounds represented by the general formulas (IX) and (XIII) optimize the birefringence (Δn) of the liquid crystal composition to 0.08 to 0.10 to improve the viewing angle characteristics of the liquid crystal display device. The contrast ratio can be increased. Moreover, it has the effect of expanding the nematic phase temperature range of the composition to the high temperature side and the low temperature side, and the temperature range in which the liquid crystal display device can be driven can be expanded.
[0076]
— (CH in general formula (XII) (XIII) ₂ ) ₂ -Or- (CH ₂ ) ₄ Each compound having a-linking group is also excellent in compatibility with a liquid crystal composition comprising the compounds of general formulas (I-1) to (VIII). Furthermore, these compounds have excellent vapor pressure-temperature characteristics, and even if they are frequently used in the liquid crystal composition of the present invention, the liquid crystal injection conditions in the liquid crystal display panel manufacturing process can be relaxed, and a large liquid crystal panel can be manufactured. It also has a feature of reducing injection unevenness in the process. The compound of the general formula (XIII) is useful for reducing the threshold voltage, and can provide a liquid crystal composition suitable for portable use requiring a low driving voltage.
[0077]
The compound of the general formula (XV) (XVI) is used by adding to the liquid crystal composition comprising the compounds of the general formulas (I-1) to (VIII), thereby reducing the birefringence (Δn) or the viscosity. Useful for reduction.
[0078]
The nematic liquid crystal composition of the present invention can contain a compound selected from the group consisting of compounds represented by general formulas (XVII) to (XIX). The compounds represented by the general formulas (XVII) to (XIX) can expand the temperature range of the nematic phase of the liquid crystal composition to a high temperature range and / or a low temperature range. Since the compound of the general formula (XVII) can reduce the viscosity of the nematic liquid crystal composition, a liquid crystal material having high-speed response in a wide temperature range can be obtained. The compounds represented by the general formulas (XVIII) and (XIX) optimize the birefringence (Δn) of the liquid crystal composition to 0.07 to 0.09, improve the viewing angle characteristics of the liquid crystal display device, and contrast ratio Can be increased. The general formula (XIX) is useful for reducing the threshold voltage and the saturation voltage, and can provide a liquid crystal composition suitable for portable use requiring a low driving voltage and labor saving of a driving circuit.
[0079]
Furthermore, the liquid crystal composition of the present invention is an ordinary nematic liquid crystal that is recognized as a liquid crystal compound in order to improve other characteristics of the liquid crystal composition in addition to the compounds of the general formulas (I-1) to (XIX). , Smectic liquid crystal, cholesteric liquid crystal and the like may be contained.
[0080]
The content of each compound in the liquid crystal composition of the present invention is 0 to 10% by weight of the compound represented by the general formula (I-1), 0 to 10% by weight of the compound represented by the general formula (I-2), The compound represented by the general formula (I-3) is preferably contained in the range of 0 to 10% by weight, and the compound represented by the general formula (I-4) is preferably contained in the range of 0 to 15% by weight. preferable. Further, the compound represented by the general formula (II) is 0 to 25% by weight, the compound represented by the general formula (III) is 0 to 25% by weight, and the compound represented by the general formula (IV) is 0 to 20% by weight. It is preferable to contain in the range. 0 to 20% by weight of the compound represented by the general formula (V), 0 to 30% by weight of the compound represented by the general formula (VI), 0 to 30% by weight of the compound represented by the general formula (VII), It is preferable to contain the compound represented by (VIII) in the range of 0 to 30% by weight.
[0081]
The total content of each compound in the liquid crystal composition is 0 to 20% by weight of the compound represented by the general formula (I-1), 0 to 15% by weight of the compound represented by the general formula (I-2), The compound represented by the general formula (I-3) is preferably contained in the range of 0 to 20% by weight, and the compound represented by the general formula (I-4) is preferably contained in the range of 0 to 15% by weight. preferable. Moreover, the compound represented by general formula (II) is 0 to 50% by weight, the compound represented by general formula (III) is 0 to 50% by weight, and the compound group of general formula (IV) is in the range of 0 to 40% by weight. The compound group of general formula (V) is preferably 0 to 35% by weight, the compound group of general formula (VI) is 0 to 40% by weight, and the compound group of general formula (VII) is 0 to 40% by weight. %, And the compound group of the general formula (VIII) is preferably contained in the range of 0 to 40% by weight.
[0082]
Furthermore, the total content of each compound group preferably contains the second compound group of the general formulas (II) to (IV) in the range of 10 to 80% by weight, and the general formulas (V) to (VIII) It is preferable to contain the 3rd compound group in 5 to 50 weight% range.
[0083]
The compounds represented by the general formulas (IX) to (XIV) are preferably contained in the range of 0 to 25% by weight, respectively, and the compounds represented by the general formulas (XV) to (XVII) are each 0 to 20% by weight. The compound represented by the general formula (XVIII) is preferably contained in the range of 0 to 20% by weight, and the compound represented by the general formula (XIX) is preferably 0 to 10% by weight. It is preferable to contain in the range.
[0084]
Each compound concerning this invention can be combined as follows according to the objective requested | required of a liquid crystal composition or a liquid crystal display characteristic. Crystalline phase or smectic phase-nematic phase transition temperature T → of liquid crystal composition _N Is preferably a combination of (I-1) to (I-4) + (II) + (III) + (VI) + (VII) + (VIII), and more preferably (IX) to (XI ) Are preferred, or (XIX) is particularly preferred. Nematic phase-isotropic liquid phase transition temperature T of liquid crystal composition _NI The crystal phase or smectic phase-nematic phase transition temperature T → _N Is preferably a combination of (I-1) to (I-4) + (II) + (III) + (VI) to (VIII), and (IX) to (XII) or (XVII) ) In combination. Liquid crystal display threshold voltage V _th And saturation voltage V _sat For the purpose of lowering, a combination of (I-1) to (I-4) + (II) + (VI) to (VIII) is preferable, and (IX) to (XII), (XVI), (XVII) ) Are preferably combined. For the purpose of speeding up the response characteristics of the liquid crystal display, a combination of (I-1) to (I-4) + (II) + (III) + (VIII) is preferable, and (VI) (VII), (XII) ) To (XVI) are preferably combined. For the purpose of setting the birefringence Δn of the liquid crystal composition to 0.07 to 0.08, a combination of (I-1) to (I-4) + (IV) + (V) to (VIII) is preferable. For the purpose of setting the birefringence Δn of the liquid crystal composition to 0.08 to 0.10, a combination of (I-1) to (I-4) + (II) + (III) + (V) is used. It is preferable to further combine (IX), (X) and (XVIII).
[0085]
The liquid crystal composition of the present invention thus obtained has a nematic phase-isotropic liquid phase transition temperature (T) of 80 to 90 ° C., as shown in Examples described later. _NI ) Has a threshold voltage of 1.1 to 1.3 V (V _th ), 2.2-3.1V saturation voltage (V _sat ), A nematic phase-isotropic liquid phase transition temperature (T) of 90-100 ° C. with a birefringence Δn characteristic of 0.071-0.088. _NI ) Has a threshold voltage of 1.2 to 1.4 V (V _th ), 2.5-3.0V saturation voltage (V _sat ), Characteristics of birefringence Δn of 0.075 to 0.088, crystal phase or smectic phase of −30 ° C. or less—nematic phase transition temperature (T → _N ), 9 to 11 characteristics of dielectric anisotropy (Δε) were obtained.
[0086]
Further, the nematic liquid crystal composition of the present invention was subjected to a heating acceleration test and an ultraviolet irradiation acceleration test shown in the examples described later. As a result, the nematic liquid crystal composition had a high voltage holding ratio of 98% or more even after each acceleration test. It was also confirmed that it has a very stable and high resistance value.
[0087]
Thus, the nematic liquid crystal composition of the present invention is a liquid crystal composition that exhibits liquid crystallinity over a wide temperature range, has a low threshold voltage and saturation voltage, a small birefringence, and a sufficiently high voltage holding ratio. In addition, it is possible to provide a liquid crystal display device that does not generate flicker and has excellent contrast. Further, when an active matrix liquid crystal display device was manufactured, a liquid crystal display device having excellent contrast without flickering could be manufactured. Furthermore, when a TN-LCD or STN-LCD liquid crystal display panel was produced, it was confirmed that display was possible with a wide range of driving frequencies.
[0088]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is explained in full detail, this invention is not limited to these Examples. In the examples, the meaning of each symbol of the measured characteristic is as follows.
[0089]
T _NI : Nematic phase-isotropic liquid phase transition temperature (° C)
V _th : Threshold voltage (V) when a TN-LCD having a first minimum Δn · d = 0.5 with a panel liquid crystal layer thickness of d is constructed.
V _sat : Saturation voltage (V) at which the thickness of the panel liquid crystal layer is d and a TN-LCD having a first minimum Δn · d = 0.5 is formed and the light transmittance is 1%.
Δε: Dielectric anisotropy
Δn: birefringence
In addition, the composition acceleration test was carried out by placing 2 g of the liquid crystal composition into an ampule tube, vacuum degassing, nitrogen treatment and sealing, 180 ° C., 1 hour heating acceleration test, and 10 hours ultraviolet irradiation. The acceleration test “SUNTEST” (original Hanau) was used. The specific resistance and voltage holding ratio of the liquid crystal composition were measured before and after the accelerated test.
[0090]
(Example 1)
[0091]
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[0092]
A nematic liquid crystal composition (3-1) comprising the following was prepared, and various properties of the composition were measured. The results were as follows.
T _NI : 82.3 ° C
V _th : 1.23 V
V _sat : 2.99 V
Δε: 8.7
Δn: 0.071
Specific resistance before test: 6.7 × 10 ¹³ Ω cm
Specific resistance after heating acceleration test: 5.9 × 10 ¹³ Ω cm
Specific resistance after UV irradiation acceleration test: 3.0 × 10 ¹³ Ω cm
Voltage holding ratio before test: 99.3% (measurement temperature 80 ° C.)
Voltage retention after heating acceleration test: 98.2% (measuring temperature 80 ° C)
Voltage holding ratio after UV irradiation acceleration test: 98.0% (measurement temperature 80 ° C.)
When an active matrix liquid crystal display device comprising the nematic liquid crystal composition (3-1) as a constituent material was produced, it was confirmed that the liquid crystal display device was excellent and had a small leakage current and no flicker.
[0093]
Further, a chiral substance “S-811” (manufactured by Merck) was added to the nematic liquid crystal composition (3-1) to prepare a mixed liquid crystal. On the other hand, an organic film of “Sunever 150” (manufactured by Nissan Chemical Industries, Ltd.) was rubbed on the opposing planar transparent electrode to form an alignment film, and an STN-LCD display cell having a twist angle of 220 degrees was produced. The mixed liquid crystal was injected into this cell to constitute a liquid crystal display device, and the display characteristics were measured. As a result, a liquid crystal display device having STN-LCD display characteristics with a low threshold voltage, excellent high time division characteristics, and improved display screen flickering and crosstalk phenomenon was obtained.
[0094]
(Example 2)
[0095]
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[0096]
A nematic liquid crystal composition (3-2) was prepared and various properties of this composition were measured. The results were as follows.
T _NI : 89.8 ° C
V _th : 1.18 V
V _sat : 2.90 V
Δε: 9.9
Δn: 0.076
[0097]
A chiral substance “S-811” (manufactured by Merck) was added to the nematic liquid crystal composition (3-2) to prepare a mixed liquid crystal. On the other hand, an organic film of “Sunever 150” (manufactured by Nissan Chemical Industries, Ltd.) was rubbed on the opposing planar transparent electrode to form an alignment film, and an STN-LCD display cell having a twist angle of 220 degrees was produced. The mixed liquid crystal was injected into this cell to constitute a liquid crystal display device, and the display characteristics were measured. As a result, a liquid crystal display device having STN-LCD display characteristics with a low threshold voltage, excellent high time division characteristics, and improved display screen flickering and crosstalk phenomenon was obtained.
[0098]
(Example 3)
[0099]
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[0100]
A nematic liquid crystal composition (3-3) comprising the following was prepared, and various properties of this composition were measured. The results were as follows.
T _NI : 83.5 ° C
V _th : 1.19 V
V _sat : 2.53 V
Δε: 9.6
Δn: 0.079
[0101]
[0102]
(Example 4)
[0103]
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[0104]
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[0105]
A nematic liquid crystal composition (3-4) comprising the following was prepared, and various properties of this composition were measured. The results were as follows.
T _NI : 91.6 ° C
V _th : 1.16 V
V _sat : 2.55 V
Δε: 11.1
Δn: 0.087
[0106]
(Example 5)
[0107]
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[0108]
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[0109]
A nematic liquid crystal composition (3-5) was prepared and various properties of this composition were measured. The results were as follows.
T _NI : 80.0 ° C
V _th : 1.08 V
V _sat : 2.20 V
Δε: 11.6
Δn: 0.088
[0110]
(Example 6)
[0111]
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[0112]
A nematic liquid crystal composition (3-6) was prepared and various properties of this composition were measured. The results were as follows.
T _NI : 100.3 ° C
V _th : 1.39 V
V _sat : 2.90 V
Δε: 8.5
Δn: 0.075
[0113]
A chiral compound “S-811” (manufactured by Merck & Co., Inc.) was added to the nematic liquid crystal composition (3-6) to prepare a mixed liquid crystal. On the other hand, an organic film of “Sunever 150” (manufactured by Nissan Chemical Industries, Ltd.) was rubbed on the opposing planar transparent electrode to form an alignment film, and an STN-LCD display cell having a twist angle of 220 degrees was produced. The mixed liquid crystal was injected into this cell to constitute a liquid crystal display device, and the display characteristics were measured. As a result, a liquid crystal display device having STN-LCD display characteristics with a low threshold voltage, excellent high time division characteristics, and improved display screen flickering and crosstalk phenomenon was obtained.
[0114]
(Example 7)
[0115]
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[0116]
A nematic liquid crystal composition (3-7) was prepared, and various properties of this composition were measured. The results were as follows.
T _NI : 96.3 ° C
V _th : 1.30 V
V _sat : 2.72 V
Δε: 9.6
Δn: 0.088
Specific resistance before test: 7.4 × 10 ¹³ Ω cm
Specific resistance after heating acceleration test: 5.8 × 10 ¹³ Ω cm
Specific resistance after UV irradiation acceleration test: 2.5 × 10 ¹³ Ω cm
Voltage holding ratio before test: 99.5%
Voltage holding ratio after heating acceleration test: 98.4%
Voltage holding ratio after UV irradiation acceleration test: 98.1%
When an active matrix liquid crystal display device comprising the nematic liquid crystal composition (3-7) as a constituent material was produced, it was confirmed that the liquid crystal display device had excellent leakage current and no flicker.
[0117]
(Example 8)
[0118]
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[0119]
A nematic liquid crystal composition (3-8) was prepared and various properties of this composition were measured. The results were as follows.
T _NI : 83.5 ° C
V _th : 1.38 V
V _sat : 2.75 V
Δε: 7.7
Δn: 0.075
[0120]
Example 9
[0121]
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[0122]
A nematic liquid crystal composition (3-9) comprising the following was prepared, and various properties of this composition were measured. The results were as follows.
T _NI : 96.3 ° C
V _th : 1.36 V
V _sat : 2.99 V
Δε: 9.3
Δn: 0.079
Specific resistance before test: 8.2 × 10 ¹³ Ω cm
Specific resistance after heating acceleration test: 5.8 × 10 ¹³ Ω cm
Specific resistance after UV irradiation acceleration test: 2.7 × 10 ¹³ Ω cm
Voltage holding ratio before test: 99.4%
Voltage holding ratio after heating acceleration test: 98.6%
Voltage holding ratio after UV irradiation acceleration test: 98.2%
When an active matrix liquid crystal display device using the nematic liquid crystal composition (3-9) as a constituent material was produced, it was confirmed that the liquid crystal display device was excellent and had a small leakage current and no flicker.
[0123]
(Comparative Example 1)
As a comparative example,
[0124]
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[0125]
A nematic liquid crystal composition (a) comprising: was prepared, and various properties of this composition were measured. The results were as follows.
T _NI : 59.1 ° C
V _th : 1.07 V
V _sat : 2.55 V
Δε: 8.1
Δn: 0.067
(Example 10)
Liquid crystal composition in which the compound represented by the general formula (I) is combined with Comparative Example (1)
[0126]
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[0127]
A nematic liquid crystal composition (3-10) comprising: was prepared, and various properties of this composition were measured. The results were as follows.
T _NI : 50.7 ° C
V _th : 0.97 V
V _sat : 2.15 V
Δε: 8.7
Δn: 0.065
Specific resistance before test: 8.2 × 10 ¹³ Ω cm
Specific resistance after heating acceleration test: 5.8 × 10 ¹³ Ω cm
Specific resistance after UV irradiation acceleration test: 2.7 × 10 ¹³ Ω cm
Voltage holding ratio before test: 99.4%
Voltage holding ratio after heating acceleration test: 98.6%
Voltage holding ratio after UV irradiation acceleration test: 98.2%
When an active matrix liquid crystal display device comprising the nematic liquid crystal composition (3-10) as a constituent material was produced, it was confirmed that the liquid crystal display device was excellent and had a small leakage current and no flicker.
[0128]
From the above results, it was revealed that the liquid crystal composition having a low birefringence can be obtained by further reducing the threshold voltage and the saturation voltage by the combination of the present invention.
[0129]
【The invention's effect】
The nematic liquid crystal composition of the present invention exhibits a nematic phase over a wide temperature range, has a low threshold voltage and saturation voltage, a small birefringence, and a high voltage holding ratio. Moreover, it has high chemical stability. Therefore, the liquid crystal display device of the present invention using this can obtain uniform and high contrast, can improve the flickering of the display screen and the crosstalk phenomenon, and has a large amount of information such as TN-LCD, STN-LCD or active. -Good drive characteristics and display characteristics can be obtained in the matrix system.

Claims (23)

(1) General formulas (I-1) to (I-4)

(Wherein R ^{11 to} R ¹⁴ each independently represents a linear alkyl group having 2 to 5 carbon atoms, Y ¹¹ represents a fluorine atom or a chlorine atom, and Y ¹² and Y ¹³ each independently represent A hydrogen atom or a fluorine atom.) Containing at least one compound selected from the first group consisting of compounds represented by (2) General formulas ( II ) to ( IV )

(Wherein R ²¹ and R ²² each independently represents a linear alkenyl group having 2 to 5 carbon atoms , R ²³ represents a linear alkyl group having 2 to 5 carbon atoms, At least one hydrogen atom (H) of two 1,4-cyclohexylene groups may be substituted with a deuterium atom (D)), and a compound selected from the second group consisting of compounds represented by: (3) General formula ( V )-( VIII )

(In the formula, each of R ^{31 to} R ³⁴ independently represents a linear alkyl group having 2 to 7 carbon atoms, and at least one hydrogen atom of two 1,4-cyclohexylene groups in each compound (H ) May be substituted with a deuterium atom (D).) A nematic liquid crystal composition comprising at least one compound selected from the third group consisting of the compound group represented by: In the first group represented by the general formulas (I-1) to (I-4), at least one hydrogen atom (H) of at least one 1,4-cyclohexylene group in each compound is a deuterium atom (D The nematic liquid crystal composition according to claim 1, comprising at least one compound substituted with General formula (I-1-1) to (I-4-1)

(Wherein R ^{11 to} R ¹⁴ each independently represents a linear alkyl group having 2 to 5 carbon atoms, Y ¹¹ represents a fluorine atom or a chlorine atom, and Y ¹² and Y ¹³ each independently represent A hydrogen atom or a fluorine atom, and X ^{1 to} X ³ each independently represents a hydrogen atom (H) or a deuterium atom (D), at least one of which represents a deuterium atom). The nematic liquid crystal composition according to claim 1, comprising a compound selected from the group consisting of: 4. A compound selected from the group consisting of compounds represented by formulas (1-4), (I-1-1) and (I-3-1): Nematic liquid crystal composition. Formulas (II-1) to (VIII-1)

(Wherein, R ²¹ and R ²² each independently represents a straight-chain alkenyl group having 2 to 5 carbon atoms, R ²³ represents a linear alkyl group having 2 to 5 carbon atoms, R ³¹ ~ R ³⁴ independently represents a linear alkyl group having 2 to 7 carbon atoms, and X ^{1 to} X ³ each independently represents a hydrogen atom (H) or a deuterium atom (D), but at least 1 Each represents a deuterium atom, and X ^{4 to} X ⁷ each independently represents a hydrogen atom (H) or a deuterium atom (D), but at least one represents a deuterium atom (D). nematic liquid crystal composition according to claim 1, characterized by containing a compound compound selected from the group consisting of. From the compounds represented by the general formulas (II), (II-1), (IV-1), (IV-2), (V-1), (VI-1), (VII-1), (VIII) The nematic liquid crystal composition according to claim 5, comprising a compound selected from the group consisting of: The nematic liquid crystal composition according to claim 4, 5 or 6 , wherein the compound selected from the first group is a general formula (I-3-1). The nematic liquid crystal composition according to claim 4, 5 or 6 , wherein the compound selected from the first group is represented by general formulas (I-1-1) and (I-3-1). 7. The nematic liquid crystal according to claim 4, 5 or 6 , wherein the compound selected from the first group is represented by the general formulas (I-1-1), (I-3-1) and (I-4). Composition. The nematic liquid crystal composition according to any one of claims 1 to 9, wherein the compound selected from the second group is represented by the general formula (II). The nematic liquid crystal composition according to any one of claims 1 to 9, wherein the compound selected from the second group is represented by the general formulas (II) and (IV). The nematic liquid crystal composition according to claim 4, 5, 6, 7, 8 or 12, wherein the compound selected from the third group is represented by the general formulas (V), (VI) and (VIII). The nematic liquid crystal composition according to any one of claims 1 to 9, wherein the compound selected from the third group is a general formula (VI). The nematic liquid crystal composition according to any one of claims 1 to 9, wherein the compound selected from the third group is represented by the general formulas (VI) and (VIII). The nematic liquid crystal composition according to any one of claims 1 to 9, wherein the compound selected from the third group is a general formula (VI) (VII) or (VIII). (4) General formulas (IX) to (XI)

(Wherein R ^{41 to} R ⁴³ each independently represents a linear alkyl group having 2 to 5 carbon atoms, Y ^{41 to} Y ⁴³ each independently represents a hydrogen atom or a fluorine atom, At least one hydrogen atom (H) of two 1,4-cyclohexylene groups may be substituted with a deuterium atom (D)), and at least a compound selected from the fourth group consisting of compounds represented by The nematic liquid crystal composition according to any one of claims 1 to 7, comprising one kind. General formula (XI-1)

(In the formula, R ⁴³ represents a linear alkyl group having 2 to 5 carbon atoms, Y ⁴³ represents a hydrogen atom or a fluorine atom, and X ^{4 to} X ⁷ each independently represents a hydrogen atom (H) or a heavy atom. The nematic liquid crystal composition according to claim 16, comprising a compound represented by the formula: a hydrogen atom (D), wherein at least one represents a deuterium atom. (5) General formulas (XII) to (XIV)

(Wherein, R ^{51 to} R ⁵³ each independently represents a linear alkyl group having 3 to 7 carbon atoms, Y ^{51 to} Y ⁵⁴ each independently represents a hydrogen atom or a fluorine atom, At least one hydrogen atom (H) of the 1,4-cyclohexylene group may be substituted with a deuterium atom (D).) At least one compound selected from the fifth group consisting of compounds represented by: The nematic liquid crystal composition according to claim 16 or 17, which is contained. General formula (XIV-1)

(In the formula, R ⁵³ represents a linear alkyl group having 3 to 7 carbon atoms, Y ⁵⁴ represents a hydrogen atom or a fluorine atom, and X ^{1 to} X ³ each independently represents a hydrogen atom (H) or a heavy atom. The nematic liquid crystal composition according to claim 18, comprising a compound represented by the formula: a hydrogen atom (D), wherein at least one represents a deuterium atom. (6) General formula (XV)-(XIX)

(Wherein R ^{61 to} R ⁶⁴ each independently represents a linear alkyl group or alkenyl group having 2 to 5 carbon atoms, and R ^{67 to} R ⁶⁹ are each independently a straight chain having 1 to 5 carbon atoms. A chain alkyl group, an alkoxy group or a linear alkenyl group having 2 to 5 carbon atoms; R ⁶⁵ represents a linear alkyl group having 2 to 5 carbon atoms; and r is independently 0 or 1 Y ⁶¹ and Y ⁶² each independently represent a hydrogen atom or a fluorine atom, and at least one hydrogen atom (H in the at least one 1,4-cyclohexylene group in the general formulas (XVIII) and (XIX)) 21 ) may be substituted with a deuterium atom (D), and contains one or more compounds selected from the sixth group consisting of compounds represented by: Nematic liquid crystal composition. General formula (XVIII-1), (XIX-1), (XIX-2)

(In the formula, R ⁶⁴ represents a linear alkyl group or alkenyl group having 2 to 5 carbon atoms, R ⁶⁵ represents a linear alkyl group having 2 to 5 carbon atoms, and Y ⁶¹ and Y ⁶² each represent Independently represents a hydrogen atom or a fluorine atom, X _{1 to} X ³ each independently represents a hydrogen atom (H) or a deuterium atom (D), but at least one represents a deuterium atom, and X ⁴ to X ⁷ each independently represents a hydrogen atom (H) or a deuterium atom (D), but at least one represents a deuterium atom), and contains at least one compound represented by The nematic liquid crystal composition according to claim 20 . Active matrix type liquid crystal display device using nematic liquid crystal composition according to claim 1 to 21 wherein. Twisted nematic or super twisted nematic liquid crystal display device using a nematic liquid crystal composition according to claim 1 to 21 wherein.