JP4934899B2

JP4934899B2 - Liquid crystal composition and liquid crystal display element

Info

Publication number: JP4934899B2
Application number: JP2001099772A
Authority: JP
Inventors: 邦彦小谷; 浩二後藤
Original assignee: DIC Corp
Current assignee: DIC Corp
Priority date: 2001-03-30
Filing date: 2001-03-30
Publication date: 2012-05-23
Anticipated expiration: 2021-03-30
Also published as: JP2002294238A

Description

【０００１】
【発明の属する技術分野】
本発明は電気光学的液晶表示材料として有用なネマチック液晶組成物及び、これを用いた液晶表示素子に関する。
【０００２】
【従来の技術】
液晶表示装置(LCD)は、電卓のディスプレイとして登場して以来、コンピューターの開発と歩みを同じくして、TN-LCD(捻れネマチック液晶表示装置)から、STN-LCDへと表示容量の拡大に対応してきた。STN-LCDは、シェファー(Scheffer)等［SID '85 Digest, 120頁(1985年)］、あるいは衣川等［SID '86 Digest, 122頁(1986年)］によって開発され、ワードプロセッサ、パーソナルコンピュータなどの高情報処理用の表示に広く普及しはじめている。最近、STN-LCDでの応答特性を改善する目的でアクティブ・アドレッシング駆動方式が提案されている。(Proc.12th International Display Research Conference p.503 1992年)また、携帯用端末表示(Personal Digital Assistance)ではより広い温度域で良好な表示特性が要求されている。この様な液晶材料として粘性が低く、駆動電圧が低くなおかつ広い温度範囲に対して一定値を保持することや、あるいは種々の時分割に対応した周波数範囲で駆動電圧が変動しないことが要求されている。しかし、表示素子に組み込んだときの応答速度やコントラストなどはまだ十分とは言えず、現在も新しい液晶化合物あるいは液晶組成物の提案がなされている。
【０００３】
LCDの急速な用途拡大に伴い、コンピューターの携帯端末ディスプレイなど室内で使用されるだけでなく、携帯電話や車載用計器、屋外使用計測機のディスプレイのように、温度条件の過酷な屋外で使用されることが増加してきた。そのため、LCDが置かれる環境の温度変化による表示コントラストの低下、低温における応答速度の低下による表示品位の悪化が問題になってきている。また、屋外での使用では高い信頼性も求められるようになってきた。
【０００４】
周囲の温度変化によるLCD表示品位の低下の原因は、様々な要因が上げられるが、ネマチック液晶の弾性定数や誘電率などの温度変化と添加したカイラル物質の固有ピッチの温度変化に起因する閾値電圧Vthの温度変化を抑えるため、カイラル物質の固有ピッチの温度変化を制御することにより閾値電圧の温度依存性を改善する提案(特開昭55-38869号公報)は既に知られており、母体液晶とカイラル物質の組み合わせによりその効果が変化する事や、カイラル量を増やすことによりレスポンス等の表示特性に悪影響を及ぼすことが問題になっていた。
【０００５】
【発明が解決しようとする課題】
本発明が解決しようとする課題は、閾値電圧を上昇させることなく、急峻性γ及び閾値電圧の温度依存性を改善し、室温及び低温における応答速度の速い液晶組成物を提供することにあり、又、この組成物を使用した応答速度の速い液晶表示素子を提供することにある。
【０００６】
【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、種々の液晶化合物を用いた液晶組成物を検討した結果下記の液晶組成物を見いだした。
【０００７】
第一成分として一般式(I)
【０００８】
【化１１】

【０００９】
(式中、n及びrはそれぞれ独立して0〜10を表す。) から選ばれる化合物を1種もしくは2種以上を含有し、第二成分として一般式(II)
【００１０】
【化１２】

【００１１】
(式中、R³、R⁴はそれぞれ独立的にフッ素置換されていても良い炭素原子数1〜16のアルキル基又はアルコキシル基又は炭素原子数3〜16のアルケニル基を表す。但し、R³、R⁴がアルケニル基である場合、そのR³、R⁴中に存在する二重結合はベンゼン環から必ず1つ以上の炭素原子を隔てている。)から選ばれる化合物を1種もしくは2種以上を含有し、なお且つネマチック相−等方性液体相転移温度が75〜130℃であり、スメクチック相又は固体相-ネマチック相転移温度が-60〜-10℃であり、屈折率の異方性(Δn)が0.10〜0.30の範囲であることを特徴とする液晶組成物。
【００１２】
更に、第三成分として一般式(III)
【００１３】
【化１３】

【００１４】
(式中、R¹、R²はそれぞれ独立的にフッ素置換されていても良い炭素原子数1〜16のアルキル基又はアルコキシル基又は炭素原子数3〜16のアルケニル基を表す。但し、アルケニル基である場合、二重結合はベンゼン環から必ず１つ以上の炭素原子を隔てている。Bは、水素原子又はフッ素原子を表す。Aは単結合又は-CH₂CH₂-又は-COO-を表す。kは0又は1を表す。)から選ばれる化合物を1種もしくは2種以上を含有することを特徴とし、ネマチック相−等方性液体相転移温度が75〜130℃であり、スメクチック相又は固体相-ネマチック相転移温度が-60〜-10℃であり、屈折率の異方性(Δn)が0.10〜0.30の範囲であることを特徴とする液晶組成物。
【００１５】
一般式(I)及び(III)を含有する液晶組成物は、特開平5-311172号公報で明らかにされている。又、一般式(II)及び一般式(III)を含有する液晶組成物は、特開平10-77475号公報で明らかにされている。しかしながらこれらの組成物では、現在求められている高速応答には到達できていない。一般式(I)及び(II)を含有する組成物を用いた液晶素子で初めて、閾値電圧を上昇させることなく、急峻性γ及び閾値電圧の温度依存性を改善し、室温及び低温における応答速度を改善することができる。更に一般式(I)及び(II)及び(III)を同時に含有する組成物を用いた液晶表示素子では著しく応答速度の改善が図られるようになった。
【００１６】
【発明の実施の形態】
以下に本発明の例について説明する。
【００１７】
第一成分として一般式(I)から選ばれる化合物を1種もしくは2種以上を含有する。式中アルケニル基として式(a)〜(e)が特に好ましい。
【００１８】
【化１４】

【００１９】
(構造式は右端で環に連結しているものとする。)中でも特に((c)n=1,r=1)、((d)n=0,r=1)が特に好ましい。第二成分として一般式(II)から選ばれる化合物を1種もしくは2種以上を含有するが、1種もしくは2種が好ましい。又、式中R³、R⁴は炭素原子数1〜16のアルキル基、炭素原子数3〜16のアルケニル基を表すが、アルケニル基がより好ましく、式(a)、(b)の構造が更に好ましく、式(b)が特に好ましい。又、R³、R⁴は共にアルケニル基であることが更に好ましく、特に式(b)であることが好ましい。第三成分として一般式(III)から選ばれる化合物を1種もしくは2種以上を含有する。又、式中R¹、R²は炭素原子数1〜16のアルキル基、炭素原子数3〜16のアルケニル基を表すが、少なくとも一方はアルケニル基が好ましく、式(a)、(b)の構造がより好ましく、式(b)が特に好ましい。又、R¹、R²は共にアルケニル基であることが更に好ましく、特に式(b)であることが好ましい。又、kは0の方が粘度が低く、ネマチック相−等方性液体相転移温度を上げる目的でkが1の化合物を使用する場合、最小限に押さえ含有させることが望ましい。この液晶組成物はネマチック相上限温度が75℃〜130℃であることを特徴とするが、80℃〜110℃が好ましく、85℃〜105℃が特に好ましい。又、スメクチック相又は固体相-ネマチック相転移温度は-60℃〜-10℃であるが、-60℃〜-25℃が好ましく、-55℃〜-30℃がさらに好ましい。Δnは0.10〜0.30であることを特徴とするが、0.13〜0.22が好ましい。
第四成分として一般式(IV)、(V)
【００２０】
【化１５】

【００２１】
(式中、R⁶、R⁷及びR⁸はそれぞれ独立的にフッ素置換されていても良い炭素原子数1〜16のアルキル基又はアルコキシル基、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、又は炭素原子数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A、環B、環C、環D及び環E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-ジイル基又はピリダジン-2,5-ジイル基を表し、l及びmはそれぞれ独立的に0、1もしくは2を表し、Z¹、Z²、Z³及びZ⁴はそれぞれ独立的に単結合、-CH₂CH₂-、-(CH₂)₄-、-OCH₂-、-CH₂O-、-CH=CH-、-COO-又は-C≡C-を表し、X²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'又は-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、X¹、X³は水素原子、フッ素原子又は塩素原子を表す。)からなる群より選ばれる化合物を1種もしくは2種以上を含有することが好ましい。
R⁶、R⁷、R⁸はそれぞれ独立的にフッ素置換されていても良い炭素原子数1〜16のアルキル基又はアルコキシル基、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、又は炭素原子数1〜10のアルコキシル基で置換された炭素原子数1〜12のアルキル基を表すが、炭素原子数1〜16のアルキル基、炭素原子数2〜16のアルケニル基が好ましく、炭素原子数1〜8のアルキル基、炭素原子数2〜8のアルケニル基がより好ましく、炭素原子数1〜5のアルキル基もしくはアルケニル基として式(a)〜(e)が特に好ましい。環A、環B、環C、環D及び環E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-ジイル基又はピリダジン-2,5-ジイル基を表すが、1,4-フェニレン基、トランス-1,4-シクロヘキシレン基が好ましく、環A、環B、環D、環Eにおいてはトランス-1,4-シクロヘキシレン基がより好ましく、環Cにおいては1,4-フェニレン基がより好ましい。l、mはそれぞれ独立的に0、1もしくは2を表すが、0もしくは1が好ましい。Z¹、Z²、Z³、Z⁴はそれぞれ独立的に単結合、-CH₂CH₂-、-(CH₂)₄-、-OCH₂-、-CH₂O-、-COO-、-CH=CH-又は-C≡C-表すが、Z¹、Z²においては単結合、-C≡C-、-CH₂CH₂-が好ましく、単結合がより好ましい。Z³、Z⁴においては単結合、-COO-、-C≡C-が好ましく、単結合がより好ましい。X²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'又は-OR'を表し、R'は炭素原子数1〜12の直鎖状アルキル基又は、2〜12の直鎖状アルケニル基を表すが、シアノ基、フッ素原子、トリフルオロメトキシ基、ジフルオロメトキシ基が好ましく、フッ素原子、トリフルオロメトキシ基、ジフルオロメトキシ基がより好ましく、フッ素原子が特に好ましい。X¹、X³は水素原子、フッ素原子または塩素原子を表すが、水素原子、フッ素原子が好ましく、フッ素原子が特に好ましい。
本発明の組成物を構成するにあたっては、一般式(I)、(II)、(III) から選ばれる化合物をそれぞれ1種もしくは2種以上を含有し、その含有率がそれぞれ一般式(I)は5〜60質量%で、なお且つ一般式(II)は5〜30質量%で、更に一般式(III)は5〜50質量%であることが好ましい。
この際、一般式(I)は20〜50質量%で、なお且つ一般式(II)は10〜25質量%で、更に一般式(III)は20〜40質量%であることがより好ましい。
【００２２】
一般式(IV)の化合物として、環Aおよび環Bがトランス-1,4-シクロヘキシレン基であり、Z¹、Z²が単結合の一般式(IV-a)
【００２３】
【化１６】

【００２４】
(式中、R⁹、R¹⁰はR⁶、R⁷と同じ意味を表し、環Fは1,4-フェニレン基又はトランス-1,4-シクロヘキシレン基を表し、nは0もしくは1を表す。)から選ばれる化合物を1種もしくは2種以上を含有することが応答速度の改善効果の観点からは好ましい。更にR⁹、R¹⁰が同時に又は一方がアルケニルであることが急峻性及び応答速度の観点から好ましい。
一般式(IV-a)の含有率が5〜50質量%であるが、5〜40質量%が好ましく、5〜30質量%がより好ましい。
一般式(IV)の化合物として一般式(IV-b)
【００２５】
【化１７】

【００２６】
(式中、R¹²、R¹³はそれぞれ独立的にフッ素置換されていても良い炭素原子数1〜8のアルキル基又は炭素原子数2〜8のアルケニル基を表す。)が、応答速度を改善するには有効であり、その含有率は5〜40質量%が好ましい。
一般式(IV)の化合物として、一般式(IV-c)
【００２７】
【化１８】

【００２８】
(式中、R¹⁴、R¹⁵はそれぞれ独立的フッ素置換されていても良い炭素原子数1〜8のアルキル基又は炭素原子数2〜8のアルケニル基を表す。)も応答速度の改善及び幅広い液晶温度範囲の拡大の点から好ましい。
この際に、一般式(IV-b)から選ばれる化合物を1種もしくは2種以上を含有し、その含有率が5〜40質量%であるが、5〜35質量%が好ましく、5〜30質量%がより好ましい。一般式(IV-c)から選ばれる化合物を1種もしくは2種以上を含有し、その含有率が5〜40質量%であるが、5〜35質量%が好ましく、5〜30質量%がより好ましい。式中R¹²、R¹³、R¹⁴、R¹⁵はそれぞれ独立的フッ素置換されていても良い炭素原子数1〜8のアルキル基又は炭素原子数2〜8のアルケニル基を表すが、炭素原子数1〜5のアルキル基もしくはアルケニル基として式(a)〜(e)が応答速度改善、急峻性改善の観点から特に好ましい。
一般式(V)の化合物として、環Dがトランス-1,4-シクロヘキシレン基であり、Z³、Z⁴が単結合であり、m=1の一般式(V-a)
【００２９】
【化１９】

【００３０】
(式中、R¹¹は炭素原子数1〜8のアルキル基又は、炭素原子数2〜8のアルケニル基を表し、環Gは1,4-フェニレン基又はトランス-1,4-シクロヘキシレン基を表し、X⁵はシアノ基、フッ素原子、トリフルオロメトキシ基、ジフルオロメトキシ基を表し、X⁴、X⁶はそれぞれ独立的に水素原子又はフッ素原子を表す。)から選ばれる化合物を1種もしくは2種以上を含有することが、閾値電圧の温度依存性を更に改善する観点から好ましい。一般式(V-a)の含有率はその効果を最も享受するためには、5〜50質量%が好ましいが、5〜40質量%が好ましく、5〜30質量%がより好ましい。
一般式(V)もしくは(V-a)として一般式(V-b)
【００３１】
【化２０】

【００３２】
(式中、R¹⁶は炭素原子数1〜16のアルキル基又は炭素原子数2〜8のアルケニル基を表す。)から選ばれる化合物を1種もしくは2種以上を含有し、その含有率が5〜40質量%であることが好ましく、より効果的にするには、5〜30質量%が好ましく、更に5〜20質量%がより好ましい。
また、一般式(V)もしくは(V-a)として一般式(V-c)
【００３３】
【化２１】

【００３４】
(式中、R¹⁷は炭素原子数1〜16のアルキル基又は炭素原子数2〜8のアルケニル基を表す。)から選ばれる化合物を1種もしくは2種以上を含有し、その含有率が5〜40質量%であるが、閾値電圧の温度依存性改善の観点から5〜30質量%が好ましく、5〜20質量%がより好ましい。
また、最も発明の効果を得ることができる液晶組成物の一つとしては、
一般式(I)として式(I-a)
【００３５】
【化２２】

【００３６】
又は式(III-b)
【００３７】
【化２３】

【００３８】
を含有し、その含有率が20〜50質量%であり、なお且つ一般式(II-a)として
【００３９】
【化２４】

【００４０】
を含有し、その含有率が10〜25質量%であり、なお且つ一般式(III)として式(III-a)
【００４１】
【化２５】

【００４２】
を含有し、その含有率が20〜40質量%であり、なお且つ一般式(IV)として式(IV-b)
【００４３】
【化２６】

【００４４】
(式中、R¹²、R¹³はそれぞれ独立的にフッ素置換されていても良い炭素原子数1〜8のアルキル基又は炭素原子数2〜8のアルケニル基を表す。)から選ばれる化合物を1種もしくは2種以上を含有し、その含有率が5〜30質量%であり、更に一般式(IV-c)
【００４５】
【化２７】

【００４６】
(式中、R¹⁴、R¹⁵はそれぞれ独立的にフッ素置換されていても良い炭素原子数1〜8のアルキル基又は炭素原子数2〜8のアルケニル基を表す。)から選ばれる化合物を1種もしくは2種以上を含有し、その含有率が5〜30質量%であることが最も好ましい。
【００４７】
上記の液晶組成物を用いた液晶表示素子は、応答速度が改善され有用である。
上記の液晶組成物を用いた捩れ角が180°〜270°であることを特徴とする超捩れネマチック(STN)液晶表示素子は、応答速度及びコントラストに優れ有用である。
【００４８】
上記ネマチック液晶組成物はTN-LCDやSTN-LCDに有用であるが、STN-LCDに特に有用であり、例えば、1/64Duty〜1/160Dutyの動画対応カラーSTN-LCDへの応用に適している。又、透過型あるいは反射型の液晶表示素子に用いることができる。本発明の液晶組成物は、上記の化合物以外に、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いてもよい。
【００４９】
【実施例】
以下、実施例を挙げて本発明を更に詳述するが、本発明はこれらの実施例に限定されるものではない。また、以下の実施例及び比較例の組成物における「%」は『質量%』を意味する。
【００５０】
実施例中、測定した特性は以下の通りである。
T_N-I ：ネマチック相−等方性液体相転移温度(℃)
T→_N ：固体相又はスメクチック相−ネマチック相転移温度(℃)
Vth ：240°ツイストセルを構成した時の輝度90%での印加電圧(V)
Vsat ：240°ツイストセルを構成した時の輝度10%での印加電圧(V)
γ ：240°ツイストセルにて測定したVsatとVthの印加電圧の比で
表される急峻性γ=Vsat/Vth
Δn ：複屈折率
η ：20℃での粘度(mPa・s)
τ₂₅ _℃ ：25℃におけるレスポンス(msec)
(立ち上がり時間と立ち下がり時間の平均値)
dV／dT ：温度範囲t¹(-20℃)における閾値電圧（Vth^-20）からt²(25℃)
における閾値電圧（Vth²⁵）の温度依存性(mV/℃)であり、
次式で表される。
dV／dT = (Vth^-20−Vth²⁵) ／ (t¹−t²)
この値が0に近いほど、閾値電圧の温度変化が少ないということ
であり、好ましい特性である。
dF :低温(-20℃)における閾値電圧の周波数依存性であり、
1kHz矩形波を印加したときの閾値電圧をVth^kとし、
64Hz矩形波を印加したときの閾値電圧をVth⁶⁴とすると、
次式で表される。
dF = Vth^K / Vth⁶⁴
この値が1に近いほど周波数変化による閾値電圧の変化が少ない
ということであり、好ましい特性である。
【００５１】
STN-LCD表示素子の作成は以下のように行った。ネマチック液晶組成物にカイラル物質「S-811」(メルク社製)を添加して混合液晶を調製し、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たツイスト角240°のSTN-LCD表示用セルに注入した。なお、カイラル物質はカイラル物質の添加による混合液晶の固有らせんピッチPと表示用セルのセル厚dが、Δn・d=0.90、d/P=0.50となるように添加した。
【００５２】
化合物の記載に下記の略号を使用する。

【００５３】
【化２８】

【００５４】
例えば、以下に示すように略号を用いる。
【００５５】
【化２９】

【００５６】
(実施例1、比較例1)
ネマチック液晶組成物No.1を調製し、この組成物の諸特性を測定した結果を比較例1と共に表1に示す。
【００５７】
【表１】

【００５８】
比較例１は、一般式(II)及び(III)を使用した組成物である。応答速度を速くすべく組成比を検討すると、どうしても急峻性が悪くなってしまう傾向にあった。しかし、実施例１は、一般式(I)及び(II)及び(III)を使用したことにより、応答速度を非常に速くできた。しかも驚くべくことは、同時に急峻性も改善されたことである。又、閾値電圧の温度依存性dV／dT(-20〜25℃)も0.67mV/℃から-0.04mV/℃へと改善された。更に閾値電圧の周波数依存性も大きく改善された。
【００５９】
【発明の効果】
本発明の液晶材料の組み合わせによって、閾値電圧を上昇させることなく、急峻性γ及び閾値電圧の温度依存性を改善し、室温及び低温における応答速度の高速化が達成された。又、この組成物を液晶表示素子として用いた場合、駆動電圧を維持したまま、コントラストが改善され、広い温度範囲での高速応答が実現された。この液晶ディスプレイはSTNおよびTN-LCDとして非常に有用である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a nematic liquid crystal composition useful as an electro-optical liquid crystal display material and a liquid crystal display element using the same.
[0002]
[Prior art]
The liquid crystal display (LCD) has been used as a calculator display, and it has been the same as the development of computers to support the expansion of display capacity from TN-LCD (twisted nematic liquid crystal display) to STN-LCD. I have done it. STN-LCD was developed by Scheffer et al. [SID '85 Digest, 120 (1985)] or Kinugawa et al. [SID '86 Digest, 122 (1986)]. Widely used in displays for high information processing. Recently, an active addressing drive system has been proposed for the purpose of improving the response characteristics of STN-LCD. (Proc. 12th International Display Research Conference p.503 1992) In addition, in portable terminal display (Personal Digital Assistance), good display characteristics are required in a wider temperature range. As such a liquid crystal material, it is required that the viscosity is low, the driving voltage is low and a constant value is maintained over a wide temperature range, or that the driving voltage does not fluctuate in a frequency range corresponding to various time divisions. Yes. However, the response speed and contrast when incorporated in a display element are still not sufficient, and new liquid crystal compounds or liquid crystal compositions have been proposed.
[0003]
Along with the rapid expansion of LCD applications, it is used not only indoors, such as computer mobile terminal displays, but also outdoors, where temperature conditions are severe, such as displays for mobile phones, in-vehicle instruments, and outdoor measuring instruments. Has increased. For this reason, display contrast deterioration due to temperature changes in the environment where the LCD is placed, and display quality deterioration due to low response speed at low temperatures, are becoming problems. In addition, high reliability has been required for outdoor use.
[0004]
There are various causes for the deterioration of the LCD display quality due to ambient temperature changes, but the threshold voltage is caused by the temperature change of the nematic liquid crystal, such as the elastic constant and dielectric constant, and the inherent pitch of the added chiral substance. In order to suppress the temperature change of Vth, a proposal for improving the temperature dependence of the threshold voltage by controlling the temperature change of the natural pitch of the chiral substance (Japanese Patent Laid-Open No. 55-38869) is already known, and the matrix liquid crystal It has been a problem that the effect changes depending on the combination of the chiral substance and that the display characteristics such as response are adversely affected by increasing the amount of chiral substance.
[0005]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to provide a liquid crystal composition that improves the temperature dependence of the steepness γ and the threshold voltage without increasing the threshold voltage, and has a high response speed at room temperature and low temperature. Another object of the present invention is to provide a liquid crystal display device having a high response speed using the composition.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention has studied the liquid crystal compositions using various liquid crystal compounds and found the following liquid crystal compositions.
[0007]
General formula (I) as the first component
[0008]
Embedded image

[0009]
(Wherein n and r each independently represents 0 to 0), which contains one or more compounds selected from general formula (II) as the second component
[0010]
Embedded image

[0011]
(Wherein R ³ and R ⁴ each independently represents an alkyl group having 1 to 16 carbon atoms, an alkoxyl group, or an alkenyl group having ^{3 to} 16 carbon atoms, which may be optionally substituted with fluorine, provided that R ³ In the case where R ⁴ is an alkenyl group, the double bond present in R ³ and R ⁴ always has at least one carbon atom separated from the benzene ring.) One or two compounds selected from In addition, the nematic phase-isotropic liquid phase transition temperature is 75 to 130 ° C, the smectic phase or solid phase-nematic phase transition temperature is -60 to -10 ° C, and the refractive index is anisotropic. A liquid crystal composition having a property (Δn) in the range of 0.10 to 0.30.
[0012]
Further, as the third component, the general formula (III)
[0013]
Embedded image

[0014]
(In the formula, R ¹ and R ² each independently represents an alkyl group having 1 to 16 carbon atoms or an alkoxyl group, or an alkenyl group having 3 to 16 carbon atoms, which may be fluorine-substituted. The double bond must be at least one carbon atom away from the benzene ring, B represents a hydrogen atom or a fluorine atom, A represents a single bond or —CH ₂ CH ₂ — or —COO—. K represents 0 or 1), a nematic phase-isotropic liquid phase transition temperature is 75 to 130 ° C., and a smectic phase. Alternatively, a liquid crystal composition having a solid phase-nematic phase transition temperature of −60 to −10 ° C. and a refractive index anisotropy (Δn) in the range of 0.10 to 0.30.
[0015]
A liquid crystal composition containing the general formulas (I) and (III) is disclosed in JP-A-5-311172. A liquid crystal composition containing the general formula (II) and the general formula (III) is disclosed in JP-A-10-77475. However, these compositions have not yet achieved the high speed response currently required. For the first time in a liquid crystal device using a composition containing the general formulas (I) and (II), the temperature dependence of the steepness γ and the threshold voltage is improved without increasing the threshold voltage, and the response speed at room temperature and low temperature. Can be improved. Furthermore, the response speed of the liquid crystal display device using the composition containing the general formulas (I), (II) and (III) at the same time can be remarkably improved.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the present invention will be described below.
[0017]
As the first component, one or more compounds selected from general formula (I) are contained. In the formula, the formulas (a) to (e) are particularly preferred as the alkenyl group.
[0018]
Embedded image

[0019]
(The structural formula is assumed to be connected to the ring at the right end.) Among them, ((c) n = 1, r = 1) and ((d) n = 0, r = 1) are particularly preferable. As the second component, one or more compounds selected from general formula (II) are contained, but one or two compounds are preferred. In the formula, R ³ and R ⁴ represent an alkyl group having 1 to 16 carbon atoms and an alkenyl group having ^{3 to} 16 carbon atoms, more preferably an alkenyl group, and the structures of formulas (a) and (b) More preferred is formula (b). R ³ and R ⁴ are more preferably an alkenyl group, and particularly preferably the formula (b). The third component contains one or more compounds selected from general formula (III). In the formula, R ¹ and R ² represent an alkyl group having 1 to 16 carbon atoms and an alkenyl group having 3 to 16 carbon atoms. At least one of them is preferably an alkenyl group, and the compounds represented by formulas (a) and (b) The structure is more preferable, and the formula (b) is particularly preferable. R ¹ and R ² are more preferably both alkenyl groups, particularly preferably the formula (b). When k is 0, the viscosity is lower, and when a compound having k of 1 is used for the purpose of increasing the nematic phase-isotropic liquid phase transition temperature, it is desirable to keep it to a minimum. The liquid crystal composition has a nematic phase upper limit temperature of 75 ° C to 130 ° C, preferably 80 ° C to 110 ° C, particularly preferably 85 ° C to 105 ° C. The smectic phase or solid phase-nematic phase transition temperature is -60 ° C to -10 ° C, preferably -60 ° C to -25 ° C, more preferably -55 ° C to -30 ° C. Δn is characterized by being 0.10 to 0.30, preferably 0.13 to 0.22.
General formula (IV), (V) as the fourth component
[0020]
Embedded image

[0021]
(In the formula, R ⁶ , R ⁷ and R ⁸ are each independently a fluorine-substituted alkyl group or alkoxyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, or the number of carbon atoms. Represents an alkyl group having 1 to 12 carbon atoms substituted with an alkenyloxy group having 3 to 16 carbon atoms or an alkoxyl group having 1 to 10 carbon atoms, and ring A, ring B, ring C, ring D and ring E are each 1,4-phenylene group, 2-methyl-1,4-phenylene group, 3-methyl-1,4-phenylene group, naphthalene-2,6-diyl group, which may be independently substituted with a fluorine atom, 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, trans-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, l and m each independently represent 0, 1 or 2, and Z ¹ , Z ² , Z ³ and Z ⁴ each independently represent A bond, —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —OCH ₂ —, —CH ₂ O—, —CH═CH—, —COO— or —C≡C—, wherein X ² is cyano Group, fluorine atom, chlorine atom, trifluoromethoxy group, trifluoromethyl group, difluoromethoxy group, hydrogen atom, 3,3,3-trifluoroethoxy group, R ′ or —OR ′, wherein R ′ is a carbon atom A compound selected from the group consisting of a linear alkyl group of 1 to 12 or a linear alkenyl group of 2 to 12, wherein X ¹ and X ³ represent a hydrogen atom, a fluorine atom or a chlorine atom. It is preferable to contain 1 type or 2 types or more.
R ⁶ , R ⁷ , and R ⁸ each independently may be fluorine-substituted alkyl group or alkoxyl group having 1 to 16 carbon atoms, alkenyl group having 2 to 16 carbon atoms, or 3 to 16 carbon atoms An alkenyloxy group or an alkyl group having 1 to 12 carbon atoms substituted with an alkoxyl group having 1 to 10 carbon atoms, but an alkyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms Preferred is an alkyl group having 1 to 8 carbon atoms and an alkenyl group having 2 to 8 carbon atoms, and the formula (a) to (e) is particularly preferred as an alkyl group or alkenyl group having 1 to 5 carbon atoms. . Ring A, Ring B, Ring C, Ring D and Ring E are each independently a 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, trans-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, preferably 1,4-phenylene group or trans-1,4-cyclohexylene group, ring A, ring B In Ring D and Ring E, a trans-1,4-cyclohexylene group is more preferable, and in Ring C, a 1,4-phenylene group is more preferable. l and m each independently represents 0, 1 or 2, with 0 or 1 being preferred. Z ¹ , Z ² , Z ³ and Z ⁴ are each independently a single bond, —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —OCH ₂ —, —CH ₂ O—, —COO—, — CH = CH— or —C≡C— is represented. In Z ¹ and Z ² , a single bond, —C≡C—, —CH ₂ CH ₂ — is preferable, and a single bond is more preferable. In Z ³ and Z ⁴ , a single bond, —COO—, —C≡C— is preferable, and a single bond is more preferable. X ² 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 ′, 'Represents a linear alkyl group having 1 to 12 carbon atoms or a linear alkenyl group having 2 to 12 carbon atoms, preferably a cyano group, a fluorine atom, a trifluoromethoxy group, or a difluoromethoxy group. A fluoromethoxy group and a difluoromethoxy group are more preferable, and a fluorine atom is particularly preferable. X ¹ and X ³ represent a hydrogen atom, a fluorine atom or a chlorine atom, preferably a hydrogen atom or a fluorine atom, and particularly preferably a fluorine atom.
In composing the composition of the present invention, each of the compounds selected from the general formulas (I), (II), and (III) contains one or more compounds, and the content of each of the compounds is represented by the general formula (I) Is preferably 5 to 60% by mass, the general formula (II) is preferably 5 to 30% by mass, and the general formula (III) is preferably 5 to 50% by mass.
At this time, it is more preferable that the general formula (I) is 20 to 50% by mass, the general formula (II) is 10 to 25% by mass, and the general formula (III) is 20 to 40% by mass.
[0022]
As a compound of general formula (IV), ring A and ring B are trans-1,4-cyclohexylene groups, and Z ¹ and Z ² are single bonds.
[0023]
Embedded image

[0024]
(Wherein R ⁹ and R ¹⁰ have the same meanings as R ⁶ and R ⁷ , ring F represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group, and n represents 0 or 1) From the viewpoint of the effect of improving the response speed, it is preferable to contain one or more compounds selected from. Furthermore, it is preferable from the viewpoint of steepness and response speed that R ⁹ and R ¹⁰ are simultaneously or one of them is alkenyl.
Although the content rate of general formula (IV-a) is 5-50 mass%, 5-40 mass% is preferable and 5-30 mass% is more preferable.
General formula (IV-b) as a compound of general formula (IV)
[0025]
Embedded image

[0026]
(In the formula, R ¹² and R ¹³ each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms which may be substituted with fluorine.) The content is preferably 5 to 40% by mass.
As a compound of general formula (IV), general formula (IV-c)
[0027]
Embedded image

[0028]
(Wherein R ¹⁴ and R ¹⁵ each independently represents an optionally substituted fluorine-substituted alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms). This is preferable from the viewpoint of expanding the liquid crystal temperature range.
At this time, one or more compounds selected from the general formula (IV-b) are contained, and the content thereof is 5 to 40% by mass, preferably 5 to 35% by mass, and 5 to 30%. The mass% is more preferable. Contains one or more compounds selected from general formula (IV-c), the content of which is 5-40% by mass, preferably 5-35% by mass, more preferably 5-30% by mass preferable. In the formula, each of R ¹² , R ¹³ , R ¹⁴ , and R ¹⁵ independently represents an optionally substituted fluorine-substituted alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms. As the alkyl group or alkenyl group of 1 to 5, the formulas (a) to (e) are particularly preferable from the viewpoint of improving response speed and steepness.
As a compound of general formula (V), ring D is a trans-1,4-cyclohexylene group, Z ³ and Z ⁴ are single bonds, and m = 1
[0029]
Embedded image

[0030]
(Wherein R ¹¹ represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, and ring G represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group. X ⁵ represents a cyano group, a fluorine atom, a trifluoromethoxy group, or a difluoromethoxy group, and X ⁴ and X ⁶ each independently represent a hydrogen atom or a fluorine atom.) From the viewpoint of further improving the temperature dependence of the threshold voltage, it is preferable to contain a seed or more. The content of the general formula (Va) is preferably 5 to 50% by mass, more preferably 5 to 40% by mass, and more preferably 5 to 30% by mass in order to enjoy the effect most.
General formula (Vb) as general formula (V) or (Va)
[0031]
Embedded image

[0032]
(In the formula, R ¹⁶ represents an alkyl group having 1 to ¹⁶ carbon atoms or an alkenyl group having 2 to 8 carbon atoms.) One or more compounds selected from It is preferably ˜40 mass%, and in order to be more effective, it is preferably 5 to 30 mass%, and more preferably 5 to 20 mass%.
In addition, general formula (Vc) as general formula (V) or (Va)
[0033]
Embedded image

[0034]
(In the formula, R ¹⁷ represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms). Although it is -40 mass%, 5-30 mass% is preferable from a viewpoint of the temperature dependence improvement of a threshold voltage, and 5-20 mass% is more preferable.
In addition, as one of the liquid crystal compositions that can obtain the most advantageous effects,
Formula (Ia) as general formula (I)
[0035]
Embedded image

[0036]
Or formula (III-b)
[0037]
Embedded image

[0038]
And the content is 20 to 50% by mass, and as the general formula (II-a)
Embedded image

[0040]
The content thereof is 10 to 25% by mass, and the formula (III-a) as the general formula (III)
[0041]
Embedded image

[0042]
And the content thereof is 20 to 40% by mass, and the formula (IV-b) as the general formula (IV)
[0043]
Embedded image

[0044]
(Wherein R ¹² and R ¹³ each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms which may be optionally substituted with fluorine). Containing two or more species, the content of which is 5 to 30% by mass, and further represented by the general formula (IV-c)
[0045]
Embedded image

[0046]
(Wherein R ¹⁴ and R ¹⁵ each independently represents an optionally substituted fluorine-substituted alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms). Most preferably, it contains seeds or two or more kinds, and the content thereof is 5 to 30% by mass.
[0047]
A liquid crystal display device using the above liquid crystal composition is useful because the response speed is improved.
A super twisted nematic (STN) liquid crystal display device having a twist angle of 180 ° to 270 ° using the above liquid crystal composition is excellent in response speed and contrast and is useful.
[0048]
The above nematic liquid crystal composition is useful for TN-LCDs and STN-LCDs, but is particularly useful for STN-LCDs, for example, suitable for application to color STN-LCDs that support moving images from 1/64 Duty to 1/160 Duty. Yes. Further, it can be used for a transmissive or reflective liquid crystal display element. The liquid crystal composition of the present invention may contain a normal nematic liquid crystal, a smectic liquid crystal, a cholesteric liquid crystal and the like in addition to the above compounds.
[0049]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is further explained in full detail, this invention is not limited to these Examples. Further, “%” in the compositions of the following examples and comparative examples means “mass%”.
[0050]
In the examples, the measured characteristics are as follows.
T _NI : Nematic phase-isotropic liquid phase transition temperature (° C)
T → _N : Solid phase or smectic phase-nematic phase transition temperature (° C)
Vth: Applied voltage (V) at a luminance of 90% when a 240 ° twist cell is configured
Vsat: Applied voltage (V) at a luminance of 10% when a 240 ° twist cell is configured
γ: Steepness expressed by the ratio of applied voltage of Vsat and Vth measured with 240 ° twist cell γ = Vsat / Vth
Δn: Birefringence index η: Viscosity at 20 ° C (mPa · s)
τ ₂₅ _{° C} : Response at 25 ° C (msec)
(Average of rise time and fall time)
dV / dT: From the threshold voltage (Vth ^-20 ) in the temperature range t ¹ (-20 ° C) to t ² (25 ° C)
Is the temperature dependence (mV / ° C) of the threshold voltage (Vth ²⁵ ) at
It is expressed by the following formula.
dV / dT = (Vth ^-20 −Vth ²⁵ ) / (t ¹ −t ² )
The closer this value is to 0, the less the temperature change of the threshold voltage, which is a preferable characteristic.
dF: Frequency dependence of threshold voltage at low temperature (-20 ° C)
The threshold voltage when a 1 kHz rectangular wave is applied is Vth ^k ,
When the threshold voltage when applying a ⁶⁴ Hz rectangular wave is Vth ⁶⁴ ,
It is expressed by the following formula.
dF = Vth ^K / Vth ⁶⁴
The closer this value is to 1, the less the threshold voltage changes due to the frequency change, which is a preferable characteristic.
[0051]
The STN-LCD display element was created as follows. A chiral substance `` S-811 '' (Merck) was added to the nematic liquid crystal composition to prepare a mixed liquid crystal, and an organic film of `` San Ever 150 '' (Nissan Chemical) was rubbed on the opposing flat transparent electrode. Then, it was injected into an STN-LCD display cell having a twist angle of 240 ° on which an alignment film was formed. The chiral material was added so that the intrinsic helical pitch P of the mixed liquid crystal and the cell thickness d of the display cell were Δn · d = 0.90 and d / P = 0.50.
[0052]
The following abbreviations are used in the description of compounds.

[0053]
Embedded image

[0054]
For example, abbreviations are used as shown below.
[0055]
Embedded image

[0056]
(Example 1, Comparative Example 1)
A nematic liquid crystal composition No. 1 was prepared, and various characteristics of this composition were measured.
[0057]
[Table 1]

[0058]
Comparative Example 1 is a composition using the general formulas (II) and (III). When the composition ratio was examined in order to increase the response speed, the steepness inevitably tended to deteriorate. However, in Example 1, the response speed could be greatly increased by using the general formulas (I) and (II) and (III). What is surprising is that the steepness is improved at the same time. Also, the temperature dependence dV / dT (-20 to 25 ° C.) of the threshold voltage was improved from 0.67 mV / ° C. to −0.04 mV / ° C. Furthermore, the frequency dependence of the threshold voltage is greatly improved.
[0059]
【Effect of the invention】
By combining the liquid crystal materials of the present invention, the temperature dependence of the steepness γ and the threshold voltage is improved without increasing the threshold voltage, and the response speed is increased at room temperature and low temperature. Further, when this composition was used as a liquid crystal display device, the contrast was improved while maintaining the driving voltage, and a high-speed response in a wide temperature range was realized. This liquid crystal display is very useful as STN and TN-LCD.

Claims

General formula (I) as the first component

(Wherein n and r each independently represents 0 to 0), containing one or more compounds selected from general formula (II) as the second component

(Wherein R ³ and R ⁴ each independently represents an alkyl group having 1 to 16 carbon atoms, an alkoxyl group, or an alkenyl group having ^{3 to} 16 carbon atoms, which may be optionally substituted with fluorine, provided that R ³ In the case where R ⁴ is an alkenyl group, the double bond present in R ³ and R ⁴ always has at least one carbon atom separated from the benzene ring.) One or two compounds selected from In addition, the nematic phase-isotropic liquid phase transition temperature is 75 to 130 ° C, the smectic phase or solid phase-nematic phase transition temperature is -60 to -10 ° C, and the refractive index is anisotropic. A liquid crystal composition having a property (Δn) in the range of 0.10 to 0.30.

General formula (III) as the third component

(In the formula, R ¹ and R ² each independently represents an alkyl group having 1 to 16 carbon atoms or an alkoxyl group, or an alkenyl group having 3 to 16 carbon atoms, which may be fluorine-substituted. The double bond must be at least one carbon atom away from the benzene ring, B represents a hydrogen atom or a fluorine atom, A represents a single bond or —CH ₂ CH ₂ — or —COO—. 2. The liquid crystal composition according to claim 1, wherein k represents 1 or 2).

One or two or more compounds each selected from general formula (I), each containing 5 to 60% by mass, and one or two compounds selected from general formula (II) 2. The liquid crystal composition according to claim 1, wherein the liquid crystal composition comprises 5 to 30% by mass.

4. The liquid crystal composition according to claim 2, comprising one or more compounds selected from the general formula (III), the content of which is 5 to 50% by mass.

General formula (IV), (V) as the fourth component

(In the formula, R ⁶ , R ⁷ and R ⁸ are each independently a fluorine-substituted alkyl group or alkoxyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, or the number of carbon atoms. Represents an alkyl group having 1 to 12 carbon atoms substituted with an alkenyloxy group having 3 to 16 carbon atoms or an alkoxyl group having 1 to 10 carbon atoms, and ring A, ring B, ring C, ring D and ring E are each 1,4-phenylene group, 2-methyl-1,4-phenylene group, 3-methyl-1,4-phenylene group, naphthalene-2,6-diyl group, which may be independently substituted with a fluorine atom, 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, trans-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, l and m each independently represent 0, 1 or 2, and Z ¹ , Z ² , Z ³ and Z ⁴ each independently represent A bond, —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —OCH ₂ —, —CH ₂ O—, —CH═CH—, —COO— or —C≡C—, wherein X ² is cyano Group, fluorine atom, chlorine atom, trifluoromethoxy group, trifluoromethyl group, difluoromethoxy group, hydrogen atom, 3,3,3-trifluoroethoxy group, R ′ or —OR ′, wherein R ′ is a carbon atom A compound selected from the group consisting of a linear alkyl group of 1 to 12 or a linear alkenyl group of 2 to 12, wherein X ¹ and X ³ represent a hydrogen atom, a fluorine atom or a chlorine atom. 5. The liquid crystal composition according to claim 1, which contains one or more kinds.

6. The liquid crystal according to claim 5 , wherein the liquid crystal composition contains one or more compounds selected from the group consisting of general formulas (IV) and (V), and the content thereof is 5 to 50% by mass. Composition.

As a compound of general formula (IV), ring A and ring B are trans-1,4-cyclohexylene groups, and Z ¹ and Z ² are single bonds.

(Wherein R ⁹ and R ¹⁰ have the same meanings as R ⁶ and R ⁷ , ring F represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group, and n represents 0 or 1) 7. The liquid crystal composition according to claim 5 or 6 , wherein the liquid crystal composition comprises one or more compounds selected from.

One or two or more compounds each selected from general formula (I), each containing 5 to 60% by mass, and one or two compounds selected from general formula (II) The content is 5 to 30% by mass, and the compound selected from the general formula (III) is one or two or more, the content is 5 to 50% by mass, The liquid crystal composition according to claim 7 , wherein the fourth component contains one or more compounds selected from general formula (IV-a), and the content thereof is 5 to 50% by mass. object.

As a compound of general formula (V), ring D is a trans-1,4-cyclohexylene group, Z ³ and Z ⁴ are single bonds, and m = 1

(Wherein R ¹¹ represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, ring G represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group, and ⁵ represents a cyano group, a fluorine atom, a trifluoromethoxy group, or a difluoromethoxy group, and X ⁴ and X ⁶ each independently represent a hydrogen atom or a fluorine atom.) The liquid crystal composition according to claim 5 , wherein the liquid crystal composition is contained.

One or two or more compounds each selected from general formula (I), each containing 5 to 60% by mass, and one or two compounds selected from general formula (II) The content is 5 to 30% by mass, and the compound selected from the general formula (III) is one or two or more, the content is 5 to 50% by mass, The liquid crystal composition according to claim 9 , wherein the fourth component contains one or more compounds selected from general formula (Va), and the content thereof is 5 to 50% by mass.

One or two or more compounds each selected from general formula (I), each containing 5 to 60% by mass, and one or two compounds selected from general formula (II) The content is 5 to 30% by mass, and the compound selected from the general formula (III) is one or two or more, the content is 5 to 50% by mass, General formula (IV-b) as a compound of general formula (IV)

(Wherein R ¹² and R ¹³ each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms which may be optionally substituted with fluorine). Containing two or more species, the content of which is 5-40% by mass, and further represented by general formula (IV-c)

(Wherein R ¹⁴ and R ¹⁵ each independently represents an optionally substituted fluorine-substituted alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms). Or it contains 2 or more types, The content rate is 5-40 mass%, The liquid-crystal composition in any one of Claims 5-10 characterized by the above-mentioned.

General formula (Vb) as general formula (V) or (Va)

(In the formula, R ¹⁶ represents an alkyl group having 1 to ¹⁶ carbon atoms or an alkenyl group having 2 to 8 carbon atoms.) One or more compounds selected from The liquid crystal composition according to claim 5 , wherein the liquid crystal composition is ˜40 mass%.

General formula (Vc) as general formula (V) or (Va)

(In the formula, R ¹⁷ represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms). The liquid crystal composition according to claim 5 , wherein the liquid crystal composition is ˜40 mass%.

A liquid crystal display device using the liquid crystal composition according to claim 1.

14. A super twisted nematic (STN) liquid crystal display element having a twist angle of 180 ° to 270 ° using the liquid crystal composition according to claim 1.