JP4956861B2

JP4956861B2 - Liquid crystal display element

Info

Publication number: JP4956861B2
Application number: JP2001082626A
Authority: JP
Inventors: 真治小川; 博之大西; 小谷邦彦; 川上正太郎; 晴義高津
Original assignee: DIC Corp
Current assignee: DIC Corp
Priority date: 2000-04-19
Filing date: 2001-03-22
Publication date: 2012-06-20
Anticipated expiration: 2021-03-22
Also published as: JP2002003846A

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、現在も新しい液晶組成物の提案がなされている。
【０００３】
【発明が解決しようとする課題】
上述のようにTN-LCDやSTN-LCDの重要な特性改善課題の一つにコントラストの向上がある。また、LCDの急速な用途拡大に伴い、室内で使用されるだけでなく、コンピューターの携帯端末ディスプレイ、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おり、電流値もまた表示品位に影響を与えることが知られている。また、屋外での使用では高い化学的安定性に代表される高い信頼性も求められるようになってきた。
【０００４】
コントラスト及びコントラストの角度依存性の改善には、電気光学的特性曲線の急峻性が求められる。STNディスプレイにおいて、急峻な電気光学的特性を達成するために、液晶組成物は比較的高いK33/K11値及び比較的小さなΔε/ε⊥値が必要となる。しかし、従来の液晶組成物は急峻性と低閾値電圧が共に優れた組成物は得にくいのが現状であり。さらに、これらの特性に加えて応答速度の短い組成物を得ることは極めて困難であり、高マルチプレックス化が求められる現状では、これらの特性の最適化が強く求められていた。
【０００５】
本発明が解決しようとする課題は、閾値電圧、レスポンス(応答速度)、特性曲線の急峻性、広域な使用温度等の液晶諸特性を改善あるいは低下させることなく、信頼性の高い液晶組成物を提供することにあり、この液晶組成物を使用した表示品位の高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以下の液晶組成物を用いた液晶表示素子を見いだした。
【０００７】
本発明の液晶表示素子は、第一成分として一般式（Ｉ）
【化１５】

（式中、Ｒ^１は炭素原子数１〜１０のアルキル基もしくは水素原子を表す。）から選ばれる化合物を１種もしくは２種以上を含有し、
なおかつ一般式（ＩＩ−ｃ）
【０００８】
【化１６】

（式中、Ｒ^２ａ、Ｒ^３ａはそれぞれ独立的に炭素原子数１〜８のアルキル基または炭素原子数２〜８のアルケニル基を表す。）から選ばれる１種もしくは２種以上の化合物を含有し、さらに／もしくは一般式（ＩＩ−ｄ）
【化１７】

（式中、Ｒ^２ａ、Ｒ^３ａはそれぞれ独立的に炭素原子数１〜８のアルキル基または炭素原子数２〜８のアルケニル基を表す。）から選ばれる1種もしくは2種以上の化合物を含有し、
なおかつ一般式（ＩＩＩ）
【化１８】

（式中、Ｒ^２ｂ、Ｒ^３ｂ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のアルキル基またはアルコキシル基、炭素原子数２〜１６のアルケニル基、炭素原子数３〜１６のアルケニルオキシ基、または炭素原子数１〜１０のアルコキシル基で置換された炭素原子数１〜１２のアルキル基を表し、環Ａ'、環Ｂ'、環Ｃ'はそれぞれ独立的にフッ素原子により置換されていてもよい１，４−フェニレン基、２−メチル−１，４−フェニレン基、３−メチル−１，４−フェニレン基、ナフタレン−２,６−ジイル基、フェナントレン−２，７−ジイル基、フルオレン−２，７−ジイル基、トランス−１，４−シクロヘキシレン基、１，２，３，４−テトラヒドロナフタレン−２，６−ジイル基、デカヒドロナフタレン−２，６−ジイル基、トランス−１，３−ジオキサン−２，５−ジイル基、ピリジン−２，５−ジイル基、ピリミジン−２，５−ジイル基、ピラジン−２，５−ジイル基またはピリダジン−２，５−ジイル基を表し、ｌは０、１もしくは２を表し、Ｚ^２はそれぞれ独立的に単結合、−ＣＨ_２ＣＨ_２−、−（ＣＨ_２）_４−、−ＣＯ_２−、−ＯＣＯ−、−ＯＣＨ_２−、−ＣＨ_２Ｏ−もしくは−Ｃ≡Ｃ−を表す。)）から選ばれる１種もしくは２種以上の化合物を含有し、
なおかつ一般式（ＩＶ）
【化１９】

（式中、Ｒ^４はフッ素置換されていても良い炭素原子数１〜１６のアルキル基またはアルコキシル基、炭素原子数２〜１６のアルケニル基、炭素原子数３〜１６のアルケニルオキシ基、または炭素原子数１〜１０のアルコキシル基で置換された炭素原子数１〜１２のアルキル基を表し、環Ｄ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−ジイル基またはピリダジン−２，５−ジイル基を表し、ｍは０、１もしくは２を表し、Ｚ^３、Ｚ^４は単結合、−ＣＨ_２ＣＨ_２−、−（ＣＨ_２）_４−、−ＣＯ_２−、−ＯＣＯ−、−ＯＣＨ_２−、−ＣＨ_２Ｏ−もしくは−Ｃ≡Ｃ−を表し、Ｘ^２はシアノ基、フッ素原子、塩素原子、トリフルオロメトキシ基、トリフルオロメチル基、ジフルオロメトキシ基、水素原子、３，３，３−トリフルオロエトキシ基、Ｒ'または−ＯＲ'を表し、Ｒ'は炭素原子数１〜１２の直鎖状アルキル基または、２〜１２の直鎖状アルケニル基を表し、Ｘ^１、Ｘ^３は水素原子、フッ素原子または塩素原子を表す。）から選ばれる１種もしくは２種以上の化合物を含有し、なおかつネマチック相上限温度が６０℃以上であり、屈折率の異方性（Δｎ）が０．０６〜０．３の範囲であり、
一般式（ＩＶ）として一般式（ＩＶ−ｃ）
【化２０】

（式中、Ｒ ^４は炭素原子数２〜８のアルケニル基を表し、Ｘ ^３は水素原子を表し、Ｚ ^４は単結合を表す。)から選ばれる１種もしくは２種以上の化合物を含有しその含有率が５〜４０質量％の範囲である液晶組成物を用いたことを特徴とする。
【０００９】
【発明の実施の形態】
以下に本発明の一例について説明する。
【００１０】
本発明の液晶組成物において、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種以上を含有するが、1種もしくは2種が好ましい。また、式中R¹は炭素原子数1〜10のアルキル基もしくは水素原子を表すが、炭素原子数1〜6のアルキル基が好ましく、炭素原子数1〜3のアルキル基がより好ましく、メチル基が特に好ましい。さらに、第二成分として一般式(II)、(III)から選ばれる化合物を1種もしくは2種以上を含有するが、3種以上が好ましく、3種〜20種がさらに好ましく、5種〜15種が特に好ましく、その中に一般式(II)の化合物を少なくとも2種以上含むことがより好ましい。この液晶組成物はネマチック相上限温度が60℃以上であることを特徴とするが、70℃以上が好ましく、75℃以上が特に好ましい。また、Δnは0.06〜0.3の範囲であることを特徴とするが、0.07〜0.22が好ましい。R^2a、R^3a、R^2b、R^3b、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のアルキル基またはアルコキシル基、炭素原子数2〜16のアルケニル基、炭素原子数3〜16のアルケニルオキシ基、または炭素原子数1〜10のアルコキシル基で置換された炭素原子数1〜12のアルキル基を表すが、炭素原子数1〜10のアルキル基またはアルコキシル基、炭素原子数2〜10のアルケニル基が好ましく、炭素原子数1〜6のアルキル基またはアルコキシル基、炭素原子数2〜6のアルケニル基がより好ましく、アルケニル基として式(a)〜(e)
【００１１】
【化１７】

(構造式は右端で環に連結しているものとする。)が特に好ましい。環A、環B、環C、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-ジイル基またはピリダジン-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、B、D、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A'、環B'及び環Cにおいては1,4-フェニレン基より好ましい。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-、-CO₂-、-OCO-、-OCH₂-、-CH₂O-もしくは-C≡C-を表すが、Z¹、Z²においては単結合、-CH₂CH₂-、-CO₂-、-OCO-もしくは-C≡C-が好ましく、Z¹においては単結合もしくは-C≡C-がより好ましく、Z²においては単結合、-CO₂-もしくは-OCO-が好ましい。Z³、Z⁴においては単結合、-CO₂-、-OCO-もしくは-C≡C-が好ましく、単結合もしくは-CO₂-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'または-OR'を表し、R'は炭素原子数1〜12の直鎖状アルキル基または、2〜12の直鎖状アルケニル基を表すが、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、シアノ基もしくは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、水素原子もしくはフッ素原子が好ましい。
本発明の別の実施形態として、一般式(I)の含有率は5〜40質量%であるが、5〜25質量%が好ましく、5〜20質量%が特に好ましく、一般式(II)もしくは一般式(III)の含有率は5〜95質量%であるが、15〜85質量%が好ましく、25〜85質量%が特に好ましい。
【００１２】
本発明の別の実施形態として、一般式(II)の化合物として、一般式(II-a)
【化１８】

(式中、R^2a、R^3aは一般式(II)と同じ意味を表し、環B及び環Cはそれぞれ独立的に1,4-フェニレン基またはトランス-1,4-シクロヘキシレン基を表し、kは0もしくは1を表す。)から選ばれる化合物を含有することを特徴とするが、一般式(II-a)の好ましい対応は、一般式(II)と同様。
本発明の別の実施形態として、一般式(I)の化合物を1種もしくは2種以上を含有しその含有率が5〜40質量%の範囲で、なおかつ一般式(II-a)の化合物を1種もしくは2種以上を含有しその含有率が5〜95質量%の範囲であるが、一般式(I)の化合物を1種もしくは2種含有しその含有率が5〜25質量%が好ましく、5〜20質量%が特に好ましく、一般式(II-a)の化合物を2種以上含有しその含有率が5〜95質量%であることが好ましく、15〜85質量%が好ましく、25〜85質量%が特に好ましい。
【００１３】
本発明の別の実施形態として、一般式(III)の化合物として、一般式(III-a)
【化１９】

(式中、R^2b、R^3bは一般式(I)と同じ意味を表し、環C'は1,4-フェニレン基またはトランス-1,4-シクロヘキシレン基を表し、lは0もしくは1を表し、X⁴及びX⁵はそれぞれ独立的に水素原子もしくはフッ素原子を表し、Z²は単結合、-CH₂CH₂-、-CO₂-もしくは-OCO-を表す。)から選ばれる1種もしくは2種以上の化合物を含有するが、R^2b、R^3b、Z²、環C'、lの好ましい対応は一般式(III)と同様であり、X⁴及びX⁵はそれぞれ独立的に水素原子もしくはフッ素原子を表すが、共に水素原子を表すか、X⁴もしくはX⁵のどちらかがフッ素原子を表し、もう一方が水素原子を表すことが好ましく、共に水素原子を表すことがより好ましい。
本発明の別の実施形態として、一般式(I)の化合物を1種もしくは2種以上を含有し、その含有率が5〜40質量%の範囲で、なおかつ第二成分として一般式(III-a)の化合物を1種もしくは2種以上を含有し、その含有率が5〜95質量%の範囲であるが、一般式(I)の化合物を1種もしくは2種含有しその含有率が5〜25質量%が好ましく、5〜15質量%が特に好ましく、一般式(III-a)の化合物を2種以上含有しその含有率が5〜95質量%であることが好ましく、15〜85質量%が好ましく、25〜85質量%が特に好ましい。
【００１４】
本発明の別の実施形態として、一般式(I)の化合物を1種もしくは2種以上を含有し、その含有率が5〜40質量%の範囲で、なおかつ一般式(II)から選ばれる1種もしくは2種以上の化合物を含有し、なおかつ一般式(III)から選ばれる1種もしくは2種以上の化合物を含有し、なおかつ一般式(IV)から選ばれる1種もしくは2種以上の化合物を含有する、また、一般式(I)の化合物を1種もしくは2種以上を含有し、その含有率が5〜40質量%の範囲で、なおかつ一般式(II)もしくは一般式(III)から選ばれる1種もしくは2種以上の化合物を含有し、なおかつ一般式(IV)から選ばれる1種もしくは2種以上の化合物を含有することを特徴とするが、一般式(I)の化合物を1種もしくは2種含有しその含有率が5〜25質量%が好ましく、5〜15質量%が特に好ましく、一般式(II)の化合物を2種以上含有しその含有率が5〜85質量%であることが好ましく、15〜65質量%が好ましく、25〜55質量%が特に好ましく、一般式(III)の化合物を2種以上含有しその含有率が5〜85質量%であることが好ましく、15〜65質量%が好ましく、25〜55質量%が特に好ましく、一般式(IV)の化合物を2種以上含有しその含有率が5〜85質量%であることが好ましく、15〜65質量%が好ましく、25〜55質量%が特に好ましい。
【００１５】
本発明の別の実施形態として、一般式(IV-a)
【化２０】

(式中、R⁴は炭素原子数1〜8のアルキル基または、2〜8のアルケニル基を表し、環Eは1,4-フェニレン基またはトランス-1,4-シクロヘキシレン基を表し、X²はフッ素原子、トリフルオロメトキシ基、ジフルオロメトキシ基を表し、X¹、X³はそれぞれ独立的に水素原子またはフッ素原子を表し、Z⁴は単結合、-CH₂CH₂-、-CO₂-もしくは-C≡C-を表し、mは0もしくは1を表す。)もしくは一般式(IV-b)
【００１６】
【化２１】

(式中、R⁴は炭素原子数1〜8のアルキル基または、2〜8のアルケニル基を表し、環Eは1,4-フェニレン基またはトランス-1,4-シクロヘキシレン基を表し、X¹、X³はそれぞれ独立的に水素原子またはフッ素原子を表し、Z⁴は単結合もしくは-CO₂-を表し、mは0もしくは1を表す。)もしくは一般式(IV-c)
【００１７】
【化２２】

(式中、R⁴は炭素原子数1〜16のアルキル基または炭素原子数2〜8のアルケニル基を表し、X³は水素原子またはフッ素原子を表し、Z⁴は単結合もしくは-CH₂CH₂-を表す。)もしくは一般式(IV-d)
【００１８】
【化２３】

(式中、R⁴は炭素原子数1〜16のアルキル基または炭素原子数2〜8のアルケニル基を表し、X³は水素原子またはフッ素原子を表す。)もしくは一般式(IV-e)
【００１９】
【化２４】

(式中、R⁴は炭素原子数1〜16のアルキル基または炭素原子数2〜8のアルケニル基を表し、X¹及びX³はそれぞれ独立的に水素原子またはフッ素原子を表し、環Eは1,4-フェニレン基またはトランス-1,4-シクロヘキシレン基を表す。)もしくは一般式(IV-f)
【００２０】
【化２５】

(式中、R⁴は炭素原子数1〜16のアルキル基または炭素原子数2〜8のアルケニル基を表し、X¹及びX³はそれぞれ独立的に水素原子またはフッ素原子を表し、環Eは1,4-フェニレン基またはトランス-1,4-シクロヘキシレン基を表す。)から選ばれる1種もしくは2種以上の化合物を含有する場合の化合物の具体的な好ましい対応は一般式(IV)と同様。
【００２１】
本発明の別の実施形態として、一般式(II-c)
【化２６】

(式中、R^2a、R^3aはそれぞれ独立的炭素原子数1〜8のアルキル基または炭素原子数2〜8のアルケニル基を表す。)もしくは一般式(II-d)
【００２２】
【化２７】

(式中、R^2a、R^3aはそれぞれ独立的に炭素原子数1〜8のアルキル基または炭素原子数2〜8のアルケニル基を表す。)から選ばれる1種もしくは2種以上の化合物を含有する場合の具体的な好ましい対応は一般式(II)と同様。
【００２３】
本発明の別の実施形態として、一般式(III-b)
【化２８】

(式中、R^2b、R^3bはそれぞれ独立的に炭素原子数1〜8のアルキル基または炭素原子数2〜8のアルケニル基を表す。)もしくは一般式(III-c)
【００２４】
【化２９】

(式中、R^2b、R^3bはそれぞれ独立的に炭素原子数1〜8のアルキル基または炭素原子数2〜8のアルケニル基を表し、Z²は単結合、-CH₂CH₂-、-OCO-もしくは-CO₂-を表す。)から選ばれる1種もしくは2種以上の化合物を含有する場合の具体的な好ましい対応は一般式(III)と同様。
【００２５】
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に特に有用である。また、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く、光学活性物質を含有していても良い。
【００２６】
【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。
【００２７】
実施例中、測定した特性は以下の通りである。
TN-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：セル厚6μmのTN-LCDを構成した時のしきい値電圧(V)
Δε：誘電異方性
Δn：複屈折率
η：20℃での粘度(mPa・s)
Ir：240°ツイストのSTN-LCDに液晶組成物を真空注入し80℃、
100時間加熱後の電流値(μA/cm²)
γ：急峻性
τr=τd：応答時間(ms)
CR：240°ツイストのSTN-LCDに組成物を真空注入し、1/200デューティ、
1/16バイアスの駆動波形で駆動したときのコントラスト。
【００２８】
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610」(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度の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=0.85、d/P=0.50となるように添加した。
【００２９】
(実施例1、比較例1)
ネマチック液晶組成物No.1(実施例1)
【化３０】

【００３０】
ネマチック液晶組成物No.2(比較例1)
【化３１】

を調製し、この組成物の諸特性を測定した結果を表1に示す。
【００３１】
【表１】

表1に示すように、実施例1の液晶組成物は、比較例1の組成物に比べ急峻性(γ)を大幅に改善しコントラストも向上している。また、液晶相温度範囲もかなり改善している。
【００３２】
ここで作製した液晶組成物を用いて、優れた表示特性を示す液晶表示装置を作成することができた。
【００３３】
(実施例2、比較例2)
ネマチック液晶組成物No.3(実施例2)
【化３２】

【００３４】
ネマチック液晶組成物No.4(比較例2)
【化３３】

を調製し、この組成物の諸特性を測定した結果を表2に示す。
【００３５】
【表２】

表2に示すように、実施例2の液晶組成物もまた、比較例2の組成物に比べ急峻性を改善しコントラストも向上している。また、応答速度も改善している。
【００３６】
(実施例3、比較例3)
ネマチック液晶組成物No.5(実施例3)
【化３４】

ネマチック液晶組成物No.6(比較例3)
【００３７】
【化３５】

を調製し、この組成物の諸特性を測定した結果を表1に示す。
【００３８】
【表３】

表3に示すように、実施例3の液晶組成物は、比較例3の組成物に比べ応答速度を大幅に改善しコントラストも向上している。
【００３９】
【発明の効果】
本発明の液晶材料の組み合わせによって、液晶相温度範囲、急峻性の優れた液晶組成物が得られた。また、この組成物を液晶表示素子として用いた場合、コントラスト、応答速度及び信頼性が高く優れたものであった。この液晶ディスプレイはSTNおよびTN-LCDとして非常に実用的である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display element using a nematic liquid crystal composition useful as an electro-optical liquid crystal display material.
[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 pages (1985)] or Kinukawa et al. It has begun to spread widely in the display 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 a new liquid crystal composition has been proposed at present.
[0003]
[Problems to be solved by the invention]
As described above, one of the important characteristics improvement issues of TN-LCD and STN-LCD is the improvement of contrast. In addition to the rapid expansion of LCD applications, it is not only used indoors, but also used outdoors where the temperature conditions are severe, such as computer portable terminal displays, in-vehicle instruments, and displays used outdoors. Things have increased. For this reason, the deterioration of display contrast due to temperature changes in the environment where the LCD is placed and the deterioration of display quality due to the decrease in response speed at low temperatures are becoming problems, and the current value is also known to affect the display quality. Yes. In addition, high reliability represented by high chemical stability has been required for outdoor use.
[0004]
In order to improve the contrast and the angle dependency of the contrast, the steepness of the electro-optical characteristic curve is required. In STN displays, the liquid crystal composition requires a relatively high K33 / K11 value and a relatively small Δε / ε⊥ value in order to achieve steep electro-optical properties. However, it is difficult to obtain a conventional liquid crystal composition that is excellent in both steepness and low threshold voltage. Furthermore, in addition to these characteristics, it is extremely difficult to obtain a composition with a short response speed, and in the present situation where high multiplexing is required, optimization of these characteristics has been strongly demanded.
[0005]
The problem to be solved by the present invention is to provide a highly reliable liquid crystal composition without improving or degrading liquid crystal characteristics such as threshold voltage, response (response speed), steepness of characteristic curve, and wide use temperature. The object of the present invention is to provide a liquid crystal display element having high display quality using the liquid crystal composition.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention has studied liquid crystal compositions using various liquid crystal compounds, and as a result, has found liquid crystal display elements using the following liquid crystal compositions.
[0007]
The liquid crystal display element of the present invention has the general formula (I) as the first component.
Embedded image

(Wherein R ¹ represents an alkyl group having 1 to 10 carbon atoms or a hydrogen atom), and contains one or more compounds selected from
And general formula (II-c)
[0008]
Embedded image

(In the formula, each of R ^2a and R ^3a independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms). And / or general formula (II-d)
Embedded image

(In the formula, R ^2a and R ^3a each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms), containing one or more compounds selected from And
Furthermore, the general formula (III)
Embedded image

(In the formula, R ^2b and R ^3b are each independently an alkyl or alkoxyl group having 1 to 16 carbon atoms which may be fluorine-substituted, an alkenyl group having 2 to 16 carbon atoms, or 3 to 16 carbon atoms. Or an alkyl group having 1 to 12 carbon atoms substituted with an alkoxyl group having 1 to 10 carbon atoms, and ring A ′, ring B ′ and ring C ′ are each independently a fluorine atom. Optionally substituted 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-di Yl 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 - represents a diyl group, l is 0, 1 or 2, ^{Z 2} are each independently a single _{_{_{_{bond, -CH 2 CH 2 -, -}}}} (CH 2) 4 -, - CO 2 -, - OCO-, -Represents OCH _2- , -CH ₂ O- or -C≡C-))).
Furthermore, the general formula (IV)
Embedded image

(In the formula, R ⁴ is an optionally substituted fluorine-substituted alkyl group or alkoxyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, an alkenyloxy group having 3 to 16 carbon atoms, or carbon. An alkyl group having 1 to 12 carbon atoms substituted with an alkoxyl group having 1 to 10 atoms, wherein ring D and ring E are each independently a 1,4-phenylene group optionally substituted by a fluorine atom; 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-dioxy group Sun-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, m is 0 1 or 2 and Z ³ and Z ⁴ are a single bond, —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —CO ₂ —, —OCO—, —OCH ₂ —, —CH ₂ O—. Or -C≡C-, X ² is a cyano group, fluorine atom, chlorine atom, trifluoromethoxy group, trifluoromethyl group, difluoromethoxy group, hydrogen atom, 3,3,3-trifluoroethoxy group, R 'Or -OR', R 'represents a linear alkyl group having 1 to 12 carbon atoms or a linear alkenyl group having 2 to 12 carbon atoms, and X ¹ and X ³ represent a hydrogen atom, a fluorine atom or chlorine. 1 or 2 selected from atoms) Containing more compounds are in yet a nematic phase upper limit temperature of 60 ° C. or higher, Ri range der anisotropy ([Delta] n) is 0.06 to 0.3 in refractive index,
General formula (IV-c) as general formula (IV)
Embedded image

(Wherein R ⁴ represents an alkenyl group having 2 to 8 carbon atoms, X ³ represents a hydrogen atom, and Z ⁴ represents a single bond). its content is characterized by using a liquid crystal composition area by der of 5 to 40 mass%.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An example of the present invention will be described below.
[0010]
The liquid crystal composition of the present invention contains one or more compounds selected from general formula (I) as the first component, but one or two are preferable. In the formula, R ¹ represents an alkyl group having 1 to 10 carbon atoms or a hydrogen atom, preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and a methyl group. Is particularly preferred. Furthermore, it contains one or more compounds selected from general formulas (II) and (III) as the second component, preferably 3 or more, more preferably 3 to 20 and more preferably 5 to 15 Species are particularly preferred, and it is more preferred that at least two kinds of compounds of the general formula (II) are contained therein. The liquid crystal composition has a nematic phase upper limit temperature of 60 ° C. or higher, preferably 70 ° C. or higher, particularly preferably 75 ° C. or higher. Further, Δn is characterized by being in the range of 0.06 to 0.3, preferably 0.07 to 0.22. R ^2a , R ^3a , R ^2b , R ^3b and R ⁴ 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, carbon An alkenyloxy group having 3 to 16 atoms, or an alkyl group having 1 to 12 carbon atoms substituted with an alkoxyl group having 1 to 10 carbon atoms, and an alkyl or alkoxyl group having 1 to 10 carbon atoms, An alkenyl group having 2 to 10 carbon atoms is preferable, an alkyl group having 1 to 6 carbon atoms or an alkoxyl group, and more preferably an alkenyl group having 2 to 6 carbon atoms, and the alkenyl groups represented by the formulas (a) to (e)
[0011]
Embedded image

(The structural formula is assumed to be linked to the ring at the right end). Ring A, Ring B, Ring C, Ring A ′, Ring B ′, Ring C ′, Ring D and Ring E are each independently a 1,4-phenylene group optionally substituted with a fluorine atom, 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, pyrimidine-2,5-diyl, pyrazine-2,5-diyl or pyridazine-2,5-diyl represents 1,4-phenylene, trans-1,4 -Cyclohexylene group is preferred, trans-1,4-cyclohexylene group is more preferred in rings A, B, D and E, and 1,4-phenylene group is more preferred in ring A ′, ring B ′ and ring C . 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 —, —CO ₂ —, —OCO—, —OCH ₂ —, —CH ₂ O- or represents a -C≡C-, Z ^1, single bond in ^{_{_{Z 2, -CH 2 CH 2 -}}} , - CO 2 -, - OCO- or -C≡C- are preferred, in Z ¹ Is more preferably a single bond or —C≡C—, and Z ² is preferably a single bond, —CO ₂ — or —OCO—. In Z ³ and Z ⁴ , a single bond, —CO ₂ —, —OCO— or —C≡C— is preferable, and a single bond or —CO ₂ — 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 ′, and R 'Represents a linear alkyl group having 1 to 12 carbon atoms or a linear alkenyl group having 2 to 12 carbon atoms, and is 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 cyano group or a fluorine atom is particularly preferable. X ¹ and X ^{3 each} represents a hydrogen atom, a fluorine atom or a chlorine atom, preferably a hydrogen atom or a fluorine atom.
As another embodiment of the present invention, the content of the general formula (I) is 5 to 40% by mass, preferably 5 to 25% by mass, particularly preferably 5 to 20% by mass, the general formula (II) or The content of the general formula (III) is 5 to 95% by mass, preferably 15 to 85% by mass, particularly preferably 25 to 85% by mass.
[0012]
As another embodiment of the present invention, the compound of the general formula (II) is represented by the general formula (II-a)
Embedded image

(Wherein R ^2a and R ^3a represent the same meaning as in general formula (II), ring B and ring C each independently represent a 1,4-phenylene group or a trans-1,4-cyclohexylene group, k represents 0 or 1), but a preferable correspondence of the general formula (II-a) is the same as that of the general formula (II).
As another embodiment of the present invention, the compound of the general formula (I) contains one or more compounds of the general formula (I), the content thereof is in the range of 5 to 40% by mass, and the compound of the general formula (II-a) It contains 1 or 2 or more types and its content is in the range of 5 to 95% by mass, but preferably contains 1 or 2 compounds of general formula (I) and the content is 5 to 25% by mass. 5 to 20% by mass is particularly preferable, containing two or more compounds of the general formula (II-a), the content of which is preferably 5 to 95% by mass, preferably 15 to 85% by mass, 85% by mass is particularly preferred.
[0013]
As another embodiment of the present invention, the compound of the general formula (III) is represented by the general formula (III-a)
Embedded image

(Wherein R ^2b and R ^3b represent the same meaning as in general formula (I), ring C ′ represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group, and l represents 0 or 1) X ⁴ and X ⁵ each independently represent a hydrogen atom or a fluorine atom, and Z ² represents a single bond, —CH ₂ CH ₂ —, —CO ₂ — or —OCO—. Alternatively, it contains two or more compounds, but the preferred correspondence of R ^2b , R ^3b , Z ² , ring C ′, l is the same as in general formula (III), and X ⁴ and X ⁵ are each independently hydrogen It represents an atom or a fluorine atom, and both represent a hydrogen atom, or either X ⁴ or X ⁵ represents a fluorine atom, and the other represents a hydrogen atom, more preferably a hydrogen atom.
As another embodiment of the present invention, one or more compounds of the general formula (I) are contained, the content thereof is in the range of 5 to 40% by mass, and the general formula (III- It contains one or more compounds of a) and the content thereof is in the range of 5 to 95% by mass, but contains one or two compounds of general formula (I) and the content thereof is 5 ~ 25% by mass is preferable, 5 to 15% by mass is particularly preferable, two or more compounds of the general formula (III-a) are contained, and the content is preferably 5 to 95% by mass, and 15 to 85% by mass. % Is preferable, and 25 to 85% by mass is particularly preferable.
[0014]
As another embodiment of the present invention, one or more compounds of the general formula (I) are contained, the content is in the range of 5 to 40% by mass, and is selected from the general formula (II) 1 One or two or more compounds selected from the general formula (IV) containing one or more compounds selected from the general formula (III) Containing one or more compounds of general formula (I), the content of which is in the range of 5-40% by mass, and selected from general formula (II) or general formula (III) One or more compounds selected from the general formula (IV) and one or more compounds selected from the general formula (IV). Alternatively, two types are contained, and the content is preferably 5 to 25% by mass, particularly preferably 5 to 15% by mass, and two or more compounds of the general formula (II) are contained. The content thereof is preferably 5 to 85% by mass, preferably 15 to 65% by mass, particularly preferably 25 to 55% by mass, and containing two or more compounds of the general formula (III) Is preferably 5 to 85 mass%, more preferably 15 to 65 mass%, particularly preferably 25 to 55 mass%, containing two or more compounds of the general formula (IV), and the content thereof is 5 to 85 mass% %, Preferably 15 to 65% by mass, particularly preferably 25 to 55% by mass.
[0015]
As another embodiment of the present invention, the general formula (IV-a)
Embedded image

(Wherein R ⁴ represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, ring E represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group, and X ² represents a fluorine atom, a trifluoromethoxy group, or a difluoromethoxy group, X ¹ and X ³ each independently represent a hydrogen atom or a fluorine atom, Z ⁴ represents a single bond, —CH ₂ CH ₂ —, —CO ₂ -Or-C≡C-, m represents 0 or 1) or general formula (IV-b)
[0016]
Embedded image

(Wherein R ⁴ represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, ring E represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group, and X ¹ and X ³ each independently represents a hydrogen atom or a fluorine atom, Z ⁴ represents a single bond or —CO ₂ —, and m represents 0 or 1.) or General Formula (IV-c)
[0017]
Embedded image

(In the formula, R ⁴ represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, X ³ represents a hydrogen atom or a fluorine atom, and Z ⁴ represents a single bond or —CH ₂ CH. ₂ represents-) or general formula (IV-d)
[0018]
Embedded image

(Wherein R ⁴ represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, and X ³ represents a hydrogen atom or a fluorine atom) or a general formula (IV-e)
[0019]
Embedded image

(Wherein R ⁴ represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, X ¹ and X ³ each independently represent a hydrogen atom or a fluorine atom, and ring E represents Represents a 1,4-phenylene group or trans-1,4-cyclohexylene group) or a general formula (IV-f)
[0020]
Embedded image

(Wherein R ⁴ represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, X ¹ and X ³ each independently represent a hydrogen atom or a fluorine atom, and ring E represents A specific preferred correspondence of the compound when it contains one or two or more compounds selected from 1,4-phenylene group or trans-1,4-cyclohexylene group is Same.
[0021]
As another embodiment of the present invention, the general formula (II-c)
Embedded image

(Wherein R ^2a and R ^3a each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms) or a general formula (II-d)
[0022]
Embedded image

(Wherein R ^2a and R ^3a each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms), containing one or more compounds selected from In this case, the specific preferable correspondence is the same as in the general formula (II).
[0023]
As another embodiment of the present invention, the general formula (III-b)
Embedded image

(Wherein R ^2b and R ^3b each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms) or the general formula (III-c)
[0024]
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(Wherein R ^2b and R ^3b each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, Z ² represents a single bond, —CH ₂ CH ₂ —, — OCO- or -CO ₂ -. a representative) specific preferred response when containing one or more compounds selected from the same as in the general formula (III).
[0025]
The nematic liquid crystal composition is useful for TN-LCD and STN-LCD, but is particularly useful for STN-LCD. 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, or the like, in addition to the above compound, and may contain an optically active substance.
[0026]
【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%”.
[0027]
In the examples, the measured characteristics are as follows.
TN-I: Nematic phase-isotropic liquid phase transition temperature (℃)
T → N: Solid phase or smectic phase-nematic phase transition temperature (℃)
Vth: Threshold voltage (V) when a TN-LCD with a cell thickness of 6μm is constructed
Δε: Dielectric anisotropy Δn: Birefringence η: Viscosity at 20 ° C (mPa · s)
Ir: Liquid crystal composition is vacuum injected into a 240 ° twisted STN-LCD at 80 ° C.
Current value after heating for 100 hours (μA / cm ² )
γ: Steepness τr = τd: Response time (ms)
CR: Vacuum injection of composition into STN-LCD with 240 ° twist, 1/200 duty,
Contrast when driven with 1/16 bias drive waveform.
[0028]
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 `` Sunever 610 '' (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 degrees on which an orientation 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 = 0.85 and d / P = 0.50.
[0029]
(Example 1, Comparative Example 1)
Nematic liquid crystal composition No. 1 (Example 1)
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[0030]
Nematic liquid crystal composition No. 2 (Comparative Example 1)
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Table 1 shows the results obtained by preparing various samples and measuring various properties of the composition.
[0031]
[Table 1]

As shown in Table 1, the liquid crystal composition of Example 1 significantly improved the steepness (γ) and the contrast as compared with the composition of Comparative Example 1. In addition, the liquid crystal phase temperature range is considerably improved.
[0032]
Using the liquid crystal composition produced here, a liquid crystal display device having excellent display characteristics could be produced.
[0033]
(Example 2, Comparative Example 2)
Nematic liquid crystal composition No. 3 (Example 2)
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[0034]
Nematic liquid crystal composition No. 4 (Comparative Example 2)
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Table 2 shows the results of measuring the various properties of this composition.
[0035]
[Table 2]

As shown in Table 2, the liquid crystal composition of Example 2 also has improved steepness and contrast as compared with the composition of Comparative Example 2. Response speed has also improved.
[0036]
(Example 3, Comparative Example 3)
Nematic liquid crystal composition No. 5 (Example 3)
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Nematic liquid crystal composition No. 6 (Comparative Example 3)
[0037]
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Table 1 shows the results obtained by preparing various samples and measuring various properties of the composition.
[0038]
[Table 3]

As shown in Table 3, the liquid crystal composition of Example 3 significantly improved the response speed and the contrast as compared with the composition of Comparative Example 3.
[0039]
【Effect of the invention】
By the combination of the liquid crystal materials of the present invention, a liquid crystal composition excellent in liquid crystal phase temperature range and steepness was obtained. Further, when this composition was used as a liquid crystal display device, it was excellent in contrast, response speed and reliability. This liquid crystal display is very practical as STN and TN-LCD.

Claims

General formula (I) as the first component

(Wherein R ¹ represents an alkyl group having 1 to 10 carbon atoms or a hydrogen atom), and contains one or more compounds selected from
And general formula (II-c)

(In the formula, each of R ^2a and R ^3a independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms). And / or general formula (II-d)

(In the formula, each of R ^2a and R ^3a independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms). And
Furthermore, the general formula (III)

(In the formula, R ^2b and R ^3b are each independently an alkyl or alkoxyl group having 1 to 16 carbon atoms which may be fluorine-substituted, an alkenyl group having 2 to 16 carbon atoms, or 3 to 16 carbon atoms. Or an alkyl group having 1 to 12 carbon atoms substituted with an alkoxyl group having 1 to 10 carbon atoms, and ring A ′, ring B ′ and ring C ′ are each independently a fluorine atom. Optionally substituted 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-di Yl 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 - represents a diyl group, l is 0, 1 or 2, ^{Z 2} are each independently a single _{_{_{_{bond, -CH 2 CH 2 -, -}}}} (CH 2) 4 -, - CO 2 -, - OCO-, -OCH _2- , -CH ₂ O- or -C≡C-).) Containing one or more compounds selected from
Furthermore, the general formula (IV)

(In the formula, R ⁴ is an optionally substituted fluorine-substituted alkyl group or alkoxyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, an alkenyloxy group having 3 to 16 carbon atoms, or carbon. An alkyl group having 1 to 12 carbon atoms substituted with an alkoxyl group having 1 to 10 atoms, wherein ring D and ring E are each independently a 1,4-phenylene group optionally substituted by a fluorine atom; 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-dioxy group Sun-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, m is 0 1 or 2 and Z ³ and Z ⁴ are a single bond, —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —CO ₂ —, —OCO—, —OCH ₂ —, —CH ₂ O—. Or -C≡C-, X ² is a cyano group, fluorine atom, chlorine atom, trifluoromethoxy group, trifluoromethyl group, difluoromethoxy group, hydrogen atom, 3,3,3-trifluoroethoxy group, R 'Or -OR', R 'represents a linear alkyl group having 1 to 12 carbon atoms or a linear alkenyl group having 2 to 12 carbon atoms, and X ¹ and X ³ represent a hydrogen atom, a fluorine atom or chlorine. 1 or 2 selected from atoms) Containing more compounds are in yet a nematic phase upper limit temperature of 60 ° C. or higher, Ri range der anisotropy ([Delta] n) is 0.06 to 0.3 in refractive index,
General formula (IV-c) as general formula (IV)

(Wherein R ⁴ represents an alkenyl group having 2 to 8 carbon atoms, X ³ represents a hydrogen atom, and Z ⁴ represents a single bond). the liquid crystal display device in which the content is characterized by using a liquid crystal composition is in the range of 5 to 40 mass%.

When the content of the compound of the general formula (I) is in the range of 5 to 40% by mass and the content of the general formula (II-c) is in the range of 5 to 40% by mass, and / or the general formula (II-d ) Is in the range of 5 to 60% by mass, the content of the general formula (III) is in the range of 5 to 40% by mass, and the content of the compound of the general formula (IV) is 5 to 40% by mass. The liquid crystal display element according to claim 1, wherein the liquid crystal display element is in the range.

As a compound of general formula (III), general formula (III-a)

(Wherein R ^2b and R ^3b represent the same meaning as in formula (I), ring C ′ represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group, and l represents 0 or 1) X ⁴ and X ⁵ each independently represent a hydrogen atom or a fluorine atom, and Z ² represents a single bond, —CH ₂ CH ₂ —, —CO ₂ — or —OCO—. Or the liquid crystal display element of Claim 1 or 2 containing 2 or more types of compounds.

As a compound of general formula (IV), general formula (IV-a)

(Wherein R ⁴ represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, ring E represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group, and X ² represents a fluorine atom, a trifluoromethoxy group, or a difluoromethoxy group, X ¹ and X ³ each independently represent a hydrogen atom or a fluorine atom, Z ⁴ represents a single bond, —CH ₂ CH ₂ —, —CO _2. 4 represents one or more compounds selected from the group consisting of-or -C≡C-, and m represents 0 or 1. Liquid crystal display element .

As a compound of general formula (IV), general formula (IV-b)

(Wherein R ⁴ represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, ring E represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group, and X ¹ and X ³ each independently represents a hydrogen atom or a fluorine atom, Z ⁴ represents a single bond or —CO ₂ —, and m represents 0 or 1). The liquid crystal display element according to claim 1, comprising:

1 type or 2 types or more of compounds of general formula (I) are contained, the content rate is the range of 5-40 mass%, and also general formula (III-b)

(In the formula, R ^2b and R ^3b each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms), containing one or more compounds selected from And the content thereof is in the range of 5 to 40% by mass, and / or the general formula (III-c)

(Wherein R ^2b and R ^3b each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, Z ² is a single bond, —CH ₂ CH ₂ —, — OCO- or -CO 2 _-. representing a) contain one or more compounds selected from any of claims 1 to 5, the content thereof is equal to or in the range of 5 to 60 wt% A liquid crystal display element according to claim 1 .

General formula (IV-d) as general formula (IV) or (IV-a)

(In the formula, R ⁴ represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, and X ³ represents a hydrogen atom or a fluorine atom.) The liquid crystal display element as described in any one of Claims 1-6 characterized by the above-mentioned, and the content rate being the range of 5-40 mass%.

General formula (IV-e) as general formula (IV) or (IV-b)

(In the formula, R ⁴ represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, X ¹ and X ³ each independently represent a hydrogen atom or a fluorine atom, and ring E represents 1 or 4-phenylene group or a trans-1,4-cyclohexylene group) is contained, and the content thereof is in the range of 5 to 40% by mass. Or general formula (IV-f)

(In the formula, R ⁴ represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, X ¹ and X ³ each independently represent a hydrogen atom or a fluorine atom, and ring E represents It represents one or two or more compounds selected from 1,4-phenylene group or trans-1,4-cyclohexylene group), and its content is in the range of 5 to 40% by mass. The liquid crystal display element according to any one of claims 1 to 7 .

Claim 1 using a liquid crystal display device according to any one of 8, supertwisted nematic (STN) liquid crystal display device twist angle is characterized by a 220 ° to 270 °.