JP4788014B2

JP4788014B2 - Liquid crystal media

Info

Publication number: JP4788014B2
Application number: JP36960299A
Authority: JP
Inventors: 真治小川; 博之大西; 直枝加藤; 清文竹内; 晴義高津
Original assignee: DIC Corp
Current assignee: DIC Corp
Priority date: 1999-12-27
Filing date: 1999-12-27
Publication date: 2011-10-05
Anticipated expiration: 2019-12-27
Also published as: JP2001181637A

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媒体及び、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。特に、各画素に薄膜トランジスタをつけたアクティブマトリクス液晶表示素子(AM-LCD)は、CRTにも代替できる高画質を備え、フラット化、省エネルギー化の後押しを受けて、もっとも将来性のあるディスプレイとして期待されている。
【０００３】
AM-LCDではコントラストを上げるために、各画素に薄膜トランジスタやダイオードのスイッチング素子をつけて、画素に電圧を供給する。
AM-LCDはTN、STNのパッシブ駆動方式とは異なり、スイッチング素子を通して、各画素に数十msec毎に電荷を供給することにより駆動する。このため、電荷が供給されてから数十msec後の次の書き込み時間までの間は、与えられた電荷を完全に保持できないと、表示の悪化をきたすことになる。電荷が逃げると電極間の電位が下がり、透過光強度が変化してコントラストが低下してしまう。このため、AM-LCDでは、高い電圧保持特性が求められる。高い電圧保持特性を得るため、AM-LCD用液晶組成物は、高比抵抗を維持しやすい材料を取捨選択して使用する必要がある。
【０００４】
近年携帯を目的としたノート型コンピューターの需要が高まり、屋外での使用を可能とする広い使用温度範囲や長時間のバッテリー駆動を可能とする低消費電力の要請が強まっている。低消費電力には低電圧で駆動できる閾値電圧の低い液晶組成物が求められている。閾値電圧を低くするためには、誘電率異方性Δεを大きくする材料が必要であるが、誘電率異方性が大きい系では、粘性が増大し、レスポンスが悪化することに加え、周囲の汚染の影響を受けやすくなるため、高抵抗を維持することが難しくなるという問題があった。このため、TN、STN、AM-LCD等の液晶表示素子用液晶組成物には、
(1) 屋外でも使用できる広い液晶温度範囲
(2) 高温条件でも使用できる安定性
(3) 低い閾値電圧
(4) 高い電圧保持率
(5) 色づきを防ぎ、広い視角で最適なコントラストを得るために調節可能なΔｎが求められている。
【０００５】
従来の液晶組成物は、これらの要請に必ずしも応えることができず、高温での電圧保持率の低下によるコントラスト低下、低温での結晶析出やスメクチック相の発現が見られた。また、屋外の高温やUV光・太陽光暴露下に放置されると、保持率低下や表示不良がみられた。
【０００６】
すなわち、高いネマチック-アイソトロピック転移温度、低いクリスタル(若しくはスメクチック)転移温度、低電圧駆動可能な低い閾値電圧、高速応答を可能とする低粘性、かつ高温での高い保持率を同時に満足する液晶組成物及び液晶表示素子はなかった。
たとえば、WO9403558号には、トリフルオロ化合物とジフルオロ化合物とを用いた液晶組成物の例が開示されているが、液晶温度範囲が狭かったり、閾値電圧が高い等多くの問題点を抱えているのが現状である。
【０００７】
【発明が解決しようとする課題】
本発明の目的は、電気光学表示素子、特に上記の液晶表示素子に求められる種々の特性を満足し、かつ、閾値電圧が低く、広いネマティック温度範囲、低い粘性を有し、高速応答性が優れ、高い保持率を高温度まで維持できる液晶組成物及びこれを使用した液晶表示素子を提供する、若しくは従来より上記の欠点を改善した液晶組成物及び液晶表示素子(TN、STN、AM-LCD)を提供することにある。
【０００８】
【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見いだした。
【０００９】
発明1 正の誘電異方性を有する極性化合物の混合物を基礎とする液晶媒体であって、一般式(I)
【００１０】
【化１３】

【００１１】
（式中Ｒ^１は、炭素数１〜１５のアルキル基または炭素数２〜１５のアルケニル基で有り、
環Ａ及び環Ｂはトランス−１，４−シクロへキシレン基であり、
Ｌ ^１及びＬ ^２はそれぞれ独立して、−ＣＨ _２Ｏ−、−ＯＣＨ_２−、−ＣＨ_２ＣＨ_２−、−ＣＨ＝ＣＨ−、−Ｃ≡Ｃ−、−（ＣＨ_２）_４−、−ＣＨ＝ＣＨ−ＣＨ_２ＣＨ_２−、−ＣＨ_２ＣＨ_２−ＣＨ＝ＣＨ−、または単結合であり、
Ｘ ^１及びＸ ^２はＦであり、ｍは０から１であり、Ｙ^１は、−Ｆ、−ＣＦ_３、−ＯＣＦ_３、−ＯＣＨＦ_２、又は−ＯＣＨ _２Ｆである。）から選ばれる化合物を１種もしくは２種以上を含有し、さらに一般式（ＩＩ）
【００１２】
【化１４】

【００１３】
（式中Ｒ^２は互いに独立して式（Ｉ）でのＲ^１の定義と同じであり、環Ｃ及び環Ｄはそれぞれ相互に独立して、
（ｄ）トランス−１，４−シクロへキシレン基
（ｅ）１，４−フェニレン基
からなる群より選ばれる基であり、上記の基（ｅ）はハロゲンで置換されていても良い。
Ｌ^３、Ｌ^４はそれぞれ相互に独立して式（Ｉ）でのＬ^１、Ｌ^２と同じ定義である。
Ｘ^５、Ｘ^６はそれぞれ独立してＨもしくはＦであり、
ｎは、０、１もしくは２であり、
Ｙ^３は、Ｆであり、
Ｑ^２は、単結合、−ＣＦ_２−、−ＯＣＦ_２−または−ＯＣＨＦ−である。）
の１種または２種以上の化合物を含有し、さらに一般式（ＩＩＩ）
【化１４Ａ】

（式中、Ｒ ^３、Ｒ ^４はそれぞれ独立的に炭素原子数１〜１６のアルキル基もしくはアルコキシル基、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、もしくは炭素原子数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Ｆ、環Ｇ及び環Ｈはそれぞれ独立的にフッ素原子により置換されていてもよい１，４−フェニレン基、２−メチル−１，４−フェニレン基、３−メチル−１，４−フェニレン基もしくはトランス−１，４−シクロヘキシレン基を表し、ｏは０もしくは１を表し、Ｌ ^７及びＬ ^８はそれぞれ独立的に単結合、−ＣＨ _２ＣＨ _２ −、−（ＣＨ _２） _４ −、−ＯＣＨ _２ −、−ＣＨ _２Ｏ−もしくは−Ｃ≡Ｃ−を表す。）から選んだ、少なくとも１種の化合物を含むことを特徴とする液晶媒体。
【００１４】
発明2 少なくとも2種以上の一般式(I)の化合物を含むことを特徴とする発明1記載の液晶媒体。
発明3 一般式(I)の化合物の含有率が5〜40質量%の範囲あることを特徴とする発明1もしくは2記載の液晶媒体。
発明4 少なくとも2種以上の一般式(II)の化合物を含むことを特徴とする発明1、2もしくは3記載の液晶媒体。
発明5 一般式(II)の化合物として、一般式(II-a)
【００１５】
【化１５】

【００１６】
(式中、R²は一般式(II)におけると同じ意味を表し、L⁵、L⁶はそれぞれ独立して、-CH₂CH₂-、-CH=CH-、-C≡C-、-(CH₂)₄-もしくは単結合を表し、環Dは1,4-フェニレン基もしくはトランス-1,4-シクロヘキシレン基を表し、X⁶はHもしくはFを表し、nは0もしくは1を表し、Y⁴はF、-CF₃、-OCF₃もしくは-OCHF₂を表す。)の化合物を含むことを特徴とする発明1〜4記載の液晶媒体。
【００１７】
発明6 一般式(II)の化合物として、一般式(II-b)
【００１８】
【化１６】

【００１９】
（式中、Ｒ^２は一般式（ＩＩ）におけると同じ意味を表し、Ｌ^５、Ｌ^６はそれぞれ独立して、−ＣＨ_２Ｏ−、−ＯＣＨ_２−、−ＣＨ_２ＣＨ_２−、−ＣＨ＝ＣＨ−、−Ｃ≡Ｃ−、−（ＣＨ_２）_４−もしくは単結合を表し、環Ｃ、環Ｄはそれぞれ独立して１，４−フェニレン基もしくはトランス−１，４−シクロヘキシレン基を表し、Ｘ^５、Ｘ^６はそれぞれ独立してＨもしくはＦを表し、ｎは１もしくは２を表し、Ｙ^４は−Ｆ、−ＣＦ_３、−ＯＣＦ_３もしくは−ＯＣＨＦ_２を表す。）の化合物を含むことを特徴とする発明１〜５記載の液晶媒体
【００２０】
発明７一般式（ＩＩ−ａ）の化合物を、少なくとも２種以上含むことを特徴とする発明５もしくは６記載の液晶媒体。
発明８一般式（ＩＩ−ｂ）の化合物を、少なくとも２種以上含むことを特徴とする発明６もしくは７記載の液晶媒体。
発明９一般式（Ｉ）の含有率が５〜４０質量％の範囲で、なおかつ一般式（ＩＩ）、一般式（ＩＩ−ａ）、一般式（ＩＩ−ｂ）の含有率が５〜９５質量％の範囲であることを特徴とする発明６〜８記載の液晶媒体。
【００２３】
発明１０一般式（ＩＩＩ）の化合物として、一般式（ＩＩＩ−ａ）
【００２４】
【化１８】

【００２５】
（式中、Ｒ^３、Ｒ^４は一般式（ＩＩＩ）と同じ意味を表し、環Ｈは１，４−フェニレン基もしくはトランス−１，４−シクロヘキシレン基を表し、ｏは０もしくは１を表す。）の化合物を含むことを特徴とする発明１〜９記載の液晶媒体。
【００２６】
発明１１一般式（Ｉ）の化合物として、下記の式（Ｉａ）又は（Ｉｂ）から選んだ、少なくとも１種の化合物を含むことを特徴とする発明１〜１０記載の液晶媒体。
【００２７】
【化１９】

（式中、Ｘ ^１及びＸ ^２はＦを表し、Ｙ ^１は、−Ｆ、−ＣＦ _３、−ＯＣＦ _３、又は−ＯＣＨＦ _２を表し、Ｒ ^１は炭素数１〜５のアルキル基又は炭素数２〜５のアルケニル基を表す。）
【００２８】
発明１２一般式（ＩＩＩ）もしくは一般式（ＩＩＩ−ａ）の化合物の含有率が５〜９５質量％の範囲であることを特徴とする発明１〜１２記載の液晶媒体。
発明１３一般式（ＩＩ）もしくは（ＩＩ−ａ）として一般式（ＩＩ−ｃ）
【００２９】
【化２０】

【００３０】
（式中、Ｒ^５は炭素原子数１〜１６のアルキル基もしくは炭素原子数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、その含有率が５〜４０質量％の範囲であることを特徴とする発明１〜１２記載の液晶媒体。
【００３１】
発明１４一般式（ＩＩ）もしくは（ＩＩ−ａ）として一般式（ＩＩ−ｄ）
【００３２】
【化２１】

【００３３】
（式中、Ｒ^５は炭素原子数１〜１６のアルキル基もしくは炭素原子数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その含有率が５〜４０質量％の範囲であることを特徴とする発明１〜１３記載の液晶媒体。
【００３４】
発明１５一般式（ＩＩＩ）もしくは一般式（ＩＩＩ−ａ）の化合物として一般式（ＩＩＩ−ｂ）
【００３５】
【化２２】

【００３６】
(式中、R⁶、R⁷はそれぞれ独立的に炭素原子数1〜8のアルキル基もしくは炭素原子数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、その含有率が5〜40質量%の範囲で、さらに一般式(III-c)
【００３７】
【化２３】

【００３８】
（式中、Ｒ^８、Ｒ^９はそれぞれ独立的に炭素原子数１〜８のアルキル基もしくは炭素原子数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その含有率が５〜６０質量％の範囲であることを特徴とする発明１〜１４記載の液晶媒体。
【００３９】
発明１６一般式（Ｉ）もしくは一般式（Ｉ−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５〜４０質量％の範囲で、なおかつ一般式（ＩＩ）、一般式（ＩＩ−ａ）もしくは一般式（ＩＩ−ｂ）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（ＩＩＩ）、一般式（ＩＩＩ−ａ）、一般式（ＩＩＩ−ｂ）もしくは一般式（ＩＩＩ−ｃ）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５〜６０質量％の範囲であることを特徴とする発明１〜１５記載の液晶媒体。
【００４０】
発明１７一般式（Ｉ−１）
【００４１】
【化２４】

【００４２】
（式中Ｒ^１は、炭素数１〜１０のアルキル基または炭素数２〜１０のアルケニル基を表し、環Ｂはトランス−１，４−シクロへキシレン基を表し、Ｌ^１は−ＣＨ_２ＣＨ_２−もしくは単結合を表し、Ｘ ^１、Ｘ ^２はＦを表し、ｍは０もしくは１を表し、Ｙ^１は、−Ｆ、−ＣＦ _３、−ＯＣＦ_３、−ＯＣＨＦ_２、−ＯＣＨ _２Ｆを表す。）で表される化合物。
【００４３】
一般式(I-1)は一般式(I-1a)
【００４４】
【化２５】

【００４５】
(式中、X^aは塩素、臭素等のハロゲンを表し、Y⁵は-F、-CF₃、-OCF₃、-OCHF₂、-OCH₂F、Hを表す。)から製造することができる。一般式(I-1a)に塩化アルミニウム等のルイス酸存在下エチレンガスを反応させることにより得られる式(I-1b)
【００４６】
【化２６】

【００４７】
(式中、Y⁵は一般式(I-1a)と同じ意味を表す。)を得る、これに一般式(I-1c)
【００４８】
【化２７】

【００４９】
(式中、R¹、L¹、mは一般式(I-1)と同じ意味を表し、Mはマグネシウム、リチウム、亜鉛、セリウム等の金属原子を表す。)を反応させた後、水酸基を脱水し、パラジウム等の金属触媒存在下に水素ガスを反応させる事によって一般式(I-1)(Y¹=CNを除く)を製造することができる。
Y¹=CNの場合、Y⁵=Hの一般式(I-1a)を用いて一般式(I-1)Y¹=Hの化合物を合成し、これをリチオ化した後炭酸ガスを反応させて一般式(I-1d)
【００５０】
【化２８】

【００５１】
(式中、R¹、L¹、mは一般式(I-1)と同じ意味を表す。)のカルボン酸とし、これを経由する方法で製造することができる。
【００５２】
発明１８式（Ｉ−１）
【化２８Ａ】

（式中Ｒ ^１は、炭素数１〜１０のアルキル基または炭素数２〜１０のアルケニル基を表し、環Ｂはトランス−１，４−シクロへキシレン基を表し、Ｌ ^１は−ＣＨ _２ＣＨ _２ −もしくは単結合を表し、Ｘ ^１、Ｘ ^２はＦを表し、ｍは０もしくは１を表し、Ｙ ^１は、−Ｆ、−ＣＦ _３、−ＯＣＦ _３、−ＯＣＨＦ _２、−ＯＣＨ _２Ｆを表す。）で表される化合物を含有することを特徴とする発明１〜１６記載の液晶媒体。
発明１９発明１〜１６及び発明１８記載の液晶媒体を用いた液晶表示素子。
発明２０発明１〜１６及び発明１８記載の液晶媒体を用いた、ねじれ角が２２０°〜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。
発明２１発明１〜１６及び発明１８記載の液晶媒体を用いたアクティブマトリックス（ＡＭ）液晶表示素子。
【００５３】
【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。
発明1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〜10種が好ましく、1種〜8種がより好ましく、1種〜5種が特に好ましい。また、R¹は、炭素数1〜10のアルキル基もしくは炭素数2〜10のアルケニル基が好ましく、非置換の直鎖状炭素数1〜8のアルキル基もしくは炭素数2〜8のアルケニル基がより好ましく、非置換の直鎖状炭素数1〜5のアルキル基もしくは炭素数2〜5のアルケニル基が特に好ましく、アルケニル基では以下式(a)〜(e)の構造がさらに好ましい。
【００５４】
【化２９】

【００５５】
(構造式は右端で環に連結しているものとする。)
環Aはトランス-1,4-シクロへキシレン基もしくは1,4-フェニレン基が好ましく、トランス-1,4-シクロへキシレン基がより好ましく、環Bはトランス-1,4-シクロへキシレン基、1,4-フェニレン基もしくは単結合が好ましく、1,4-フェニレン基もしくは単結合がより好ましく、単結合が特に好ましい。L¹及びL²はそれぞれ独立して、-COO-、-OCO-、-CH₂O-、-OCH₂-、-CH₂CH₂-、-CH=CH-、-C≡C-、-(CH₂)₄-、-CH=CH-CH₂CH₂-、-CH₂CH₂-CH=CH- もしくは単結合であるが、-COO-、-OCO-、-CH₂CH₂-、-C≡C-、-(CH₂)₄-もしくは単結合が好ましく、-CH₂CH₂-、-C≡C-もしくは単結合がより好ましく、-CH₂CH₂-もしくは単結合が特に好ましく、単結合がさらに好ましい。mは0から2であるが、0もしくは1が好ましく、0がより好ましい。Y¹は、-F、-Cl、-CF₃、-OCF₃、-OCHF₂、-OCH₂F、-CN、R¹と同じ定義を表すが、Fが好ましい。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〜20種が好ましく、1種〜15種がより好ましく、1種〜10種が特に好ましい。また、R²は、非置換の直鎖状炭素数1〜15のアルキル基もしくは炭素数2〜15のアルケニル基が好ましく、非置換の直鎖状炭素数1〜10のアルキル基もしくは炭素数2〜10のアルケニル基がより好ましく、非置換の直鎖状炭素数1〜8のアルキル基もしくは炭素数2〜6のアルケニル基が特に好ましく、アルケニル基では以下式(a)〜(e)の構造がさらに好ましい。
【００５６】
【化３０】

【００５７】
(構造式は右端で環に連結しているものとする。)
L³、L⁴は、-COO-、-OCO-、-CH₂CH₂-、-C≡C-、-(CH₂)₄-もしくは単結合が好ましく、-CH₂CH₂-、-C≡C-もしくは単結合がより好ましく、-CH₂CH₂-もしくは単結合が特に好ましい。X⁵、X⁶は、少なくとも一方がFであることが好ましい。nは、0もしくは1が好ましい。Q²は、単結合、-CF₂-、-OCF₂-もしくは-OCHF-を表すが、-CF₂-、-OCF₂-もしくは単結合が好ましく、-OCF₂-もしくは単結合がより好ましく、単結合が特に好ましい。Y³は、-F、-Clもしくは-CNを表すが、-Fもしくは-CNが好ましい。
【００５８】
発明2において、少なくとも2種以上の一般式(I)の化合物を含むが、2種〜10種が好ましく、2種〜5種がより好ましい。
発明3において、一般式(I)の化合物の含有率は5〜40質量%の範囲あるが5〜35質量%が好ましく、5〜30質量%がより好ましい。
発明4において、少なくとも2種以上の一般式(II)の化合物を含むが、2種〜20種が好ましく、2種〜15種がより好ましく、2種〜10種が特に好ましい。
発明5において、R²は、炭素数1〜15のアルキル基もしくは炭素数2〜15のアルケニル基が好ましく、炭素数1〜10のアルキル基もしくは炭素数2〜10のアルケニル基がより好ましく、炭素数1〜8のアルキル基もしくは炭素数2〜6のアルケニル基が特に好ましく、アルケニル基では以下式(a)〜(e)の構造がさらに好ましい。
【００５９】
【化３１】

【００６０】
(構造式は右端で環に連結しているものとする。)
L⁵、L⁶は-COO-、-OCO-、-CH₂CH₂-、-C≡C-、-(CH₂)₄-もしくは単結合が好ましく、-CH₂CH₂-、-C≡C-もしくは単結合がより好ましく、-CH₂CH₂-もしくは単結合が特に好ましい。Y⁴はF、-Cl、-CF₃、-OCF₃もしくは-OCHF₂を表すが、Fもしくは-OCF₃が好ましく、Fがより好ましい。
【００６１】
発明6においてR²は炭素数1〜15のアルキル基もしくは炭素数2〜15のアルケニル基が好ましく、炭素数1〜10のアルキル基もしくは炭素数2〜10のアルケニル基がより好ましく、炭素数1〜8のアルキル基もしくは炭素数2〜6のアルケニル基が特に好ましく、アルケニル基では以下式(a)〜(e)の構造がさらに好ましい。
【００６２】
【化３２】

【００６３】
(構造式は右端で環に連結しているものとする。)
L⁵、L⁶は-COO-、-OCO-、-CH₂CH₂-、-C≡C-、-(CH₂)₄-もしくは単結合が好ましく、-COO-、-CH₂CH₂-、-C≡C-もしくは単結合がより好ましく、-COO-、-CH₂CH₂-もしくは単結合が特に好ましい。Y⁴はF、-CF₃、-OCF₃、-CNもしくは-OCHF₂を表すが、CNが好ましい。X⁵、X⁶はそれぞれ独立してHもしくはFを表すが、少なくとも一方はFであることが好ましい。
【００６４】
発明7において一般式(II-a)の化合物を少なくとも2種以上含むが、2種〜20種が好ましく、2種〜15種がより好ましく、2種〜10種が特に好ましい。
【００６５】
発明8において一般式(II-b)の化合物を少なくとも2種以上含むが、2種〜20種が好ましく、2種〜15種がより好ましく、2種〜10種が特に好ましい。
【００６６】
発明9において一般式(I)の化合物の含有率は5〜40質量%の範囲あるが、5〜35質量%が好ましく、5〜30質量%がより好ましい、また、一般式(II)、一般式(II-a)、一般式(II-b)の含有率は5〜95質量%の範囲であるが、10〜70質量%が好ましく、10〜60質量%がより好ましい。
【００６７】
発明10において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のアルキル基もしくはアルコキシル基、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、もしくは炭素原子数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のアルキル基もしくは炭素原子数2〜16のアルケニル基が好ましく、炭素数1〜10のアルキル基もしくは炭素数2〜10のアルケニル基がより好ましく、炭素数1〜8のアルキル基もしくは炭素数2〜6のアルケニル基が特に好ましく、アルケニル基では以下式(a)〜(e)の構造がさらに好ましい。
【００６８】
【化３３】

【００６９】
(構造式は右端で環に連結しているものとする。)
環F、環G及び環Hはそれぞれ独立的に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い。oは0、1もしくは2を表すが、0もしくは1が好ましい。L⁷及びL⁸はそれぞれ独立的に単結合、-CH₂CH₂-、-(CH₂)₄-、-OCH₂-、-CH₂O-もしくは-C≡C-を表すが、単結合もしくは-CH₂CH₂-が好ましく、単結合がより好ましい。また、一般式(III)の化合物を少なくとも1種以上含むが、1種〜20種が好ましく、2種〜15種がより好ましく、2種〜10種が特に好ましい。
【００７０】
発明12において一般式(Ia)〜(Id)の中でも、一般式(Ia)および(Ib)がより好ましく、以下の一般式(Ia-1)〜(Ia-5)、(Ib-1)〜(Ib-5)及び(Ic-1)〜(Ic-15)
【００７１】
【化３４】

【００７２】
【化３５】

【００７３】
(式中、R^aは炭素数1〜5のアルキル基もしくは以下式(a)〜(e)の構造を表す)。
【００７４】
【化３６】

【００７５】
(構造式は右端で環に連結しているものとする。)がさらに好ましく、一般式(Ia-1)〜(Ia-5)及び(Ib-1)〜(Ib-5)が特に好ましい。
【００７６】
発明13において一般式(III)もしくは一般式(III-a)の化合物の含有率は5〜95質量%の範囲であるが、10〜70質量%が好ましく、10〜50質量%がより好ましい。
【００７７】
発明14及び15において、R⁵は炭素原子数1〜16のアルキル基もしくは炭素原子数2〜8のアルケニル基を表すが、炭素数1〜10のアルキル基もしくは炭素数2〜10のアルケニル基が好ましく、炭素数1〜8のアルキル基もしくは炭素数2〜8のアルケニル基がより好ましく、炭素数1〜6のアルキル基もしくは炭素数2〜6のアルケニル基が特に好ましく、アルケニル基では以下式(a)〜(e)の構造がさらに好ましい。
【００７８】
【化３７】

【００７９】
(構造式は右端で環に連結しているものとする。)
また、一般式(II-c)もしくは一般式(II-d)の化合物の含有率は5〜40質量%の範囲であるが、10〜40質量%が好ましく、10〜30質量%がより好ましい。また、少なくとも1種以上の一般式(II-c)もしくは一般式(II-d)の化合物を含むが、1種〜10種が好ましく、1種〜8種がより好ましく、1種〜5種が特に好ましい。
【００８０】
発明16において、R⁶、R⁷、R⁸、R⁹は炭素原子数1〜8のアルキル基もしくは炭素原子数2〜8のアルケニル基を表すが、炭素数1〜6のアルキル基もしくは炭素数2〜6のアルケニル基が好ましく、アルケニル基では以下式(a)〜(e)の構造がより好ましい。
【００８１】
【化３８】

【００８２】
(構造式は右端で環に連結しているものとする。)
また、一般式(III-b)もしくは一般式(III-c)の化合物の含有率は5〜40質量%の範囲であるが、10〜40質量%が好ましく、10〜30質量%がより好ましい。また、少なくとも1種以上の一般式(III-b)もしくは一般式(III-c)の化合物を含むが、1種〜10種が好ましく、1種〜8種がより好ましく、1種〜5種が特に好ましい。
【００８３】
発明18においてR¹は、炭素数1〜10のアルキル基もしくは炭素数2〜10のアルケニル基を表しすが、炭素数1〜8のアルキル基もしくは炭素数2〜8のアルケニル基が好ましく、炭素数1〜5のアルキル基もしくは炭素数2〜5のアルケニル基が特に好ましく、アルケニル基では以下式(a)〜(e)の構造がさらに好ましい。
【００８４】
【化３９】

【００８５】
(構造式は右端で環に連結しているものとする。)
L¹は-CH₂CH₂-もしくは単結合を表すが、単結合が好ましい。X¹及びX²はそれぞれ独立的にはHもしくはFを表すが、両方Fを表すことが好ましい。Y¹は、-F、-Cl、-CF₃、-OCF₃、-OCHF₂、-OCH₂F、-CNを表すが、-F、-OCF₃、-OCHF₂、-CNが好ましく、Fがより好ましく、前述の一般式(Ia-1)〜(Ia-5)、(Ib-1)〜(Ib-5)及び(Ic-1)〜(Ic-15)がさらに好ましく、一般式(Ia-1)〜(Ia-5)及び(Ib-1)〜(Ib-5)が特に好ましい。
【００８６】
上記ネマチック液晶組成物はAM-LCDやSTN-LCDに有用であるがAM-LCDに特に有用であり、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。本発明の液晶媒体は、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。
【００８７】
【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。
実施例中、測定した特性は以下の通りである。

【００８８】
(実施例1、比較例1)
ネマチック液晶組成物No.1
【００８９】
【化４０】

【００９０】
を調製した。また、この組成物(No.1)の(Ia-1a)及び(Ib-1a)を(R-1)及び(R-2)
【００９１】
【化４１】

【００９２】
に換えた組成物(比較例1)と共に諸特性を測定した結果を表1に示す。
【００９３】
【表１】

【００９４】
表1に示すように、実施例1の液晶組成物は、比較例1の組成物に近い閾値電圧を有するにもかかわらず、液晶相上限温度は14℃も高いことが解る。
ここで作製した組成物を用いて、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。
【００９５】
(実施例2) 式(Ic-1)の合成
【００９６】
【化４２】

【００９７】
1-ヨウ化-4-プロピルベンゼン29.5gをTHF120mlに溶解し、-50℃に冷却した。窒素雰囲気下に、n-ブチルリチウム(1.69M、n-ヘキサン溶液)85mlを20分間で滴下し、同温度で1時間撹拌後、無水塩化セリウム35gを加え0℃で1時間撹拌した。これに5,6,7-トリフルオロ-3,4-ジヒドロ-1H-ナフタレン-2-オン20gのTHF60ml溶液を同温度で20分間で滴下し2時間撹拌した。水100mlを加えた後、室温にもどし、有機層を分離後、水層から酢酸エチルで抽出した。有機層を、水、次いで飽和食塩水で洗浄し、無水硫酸ナトリウムで乾燥した。得られた粗生成物をトルエン200mlに溶解して、硫酸水素カリウム500mgを加え、水を留去しながら2時間撹拌した。室温にもどし、水を加え溶媒を溜去し得られた粗生成物をシリカゲルカラムクロマトグラフィー(ヘキサン)で精製して6,7,8-トリフルオロ-3-(4-プロピルフェニル)-1,2-ジヒドロナフタレン18.1gを得た。
6,7,8-トリフルオロ-3-(4-プロピルフェニル)-1,2-ジヒドロナフタレン15gの酢酸エチル60ml 溶液に5%パラジウム炭素3gを加え、水素圧0.392MPaで3時間撹拌した。反応終了後、触媒を濾別し、溶媒を溜去して得られた粗生成物をシリカゲルクロマトグラフィー（シリカゲル10倍、ヘキサン）にて精製して5,6,7-トリフルオロ-2-(4-プロピルフェニル)-1,2,3,4-テトラヒドロナフタレン14.1gを得た。この化合物は室温で油状物である。
MS：m/e=304（M+）
【００９８】
(実施例3)
汎用のp型ホスト液晶組成物(H)
【００９９】
【化４３】

【０１００】
この(H)は116.7℃以下でネマチック相を示し、その融点は11.0℃である。(H)をセル厚6.0μmのTNセルに充填して液晶素子を作成し、20℃での電気光学特性は以下のとおりであった。
閾値電圧(Vth) 2.14V
誘電率異方性(Δε) 4.8
屈折率異方性(Δn) 0.090
次に、この(H)の80質量%と実施例2で得られた本発明の化合物(Ic-1)の20質量%からなる液晶組成物(H-1)を調製し、セル厚6.0μmのTNセルに充填して液晶素子を作成し、20℃でその電気光学特性を測定したところ、以下のとおりであった。
閾値電圧(Vth) 1.63V
誘電率異方性(Δε) 5.2
屈折率異方性(Δn) 0.085
【０１０１】
【発明の効果】
本発明の液晶材料及び液晶材料の組み合わせによって、広いネマティック温度範囲、低い粘性を有し、閾値電圧が低く、高速応答性が優れた液晶媒体が得られた。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AM-LCDとして非常に実用的である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a nematic liquid crystal medium 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, p. 120 (1985)] or Kinukawa et al. [SID '86 Digest, p. 122 (1986)]. Word processors, personal computers, etc. It has begun to spread widely in the display for high information processing. In particular, the active matrix liquid crystal display element (AM-LCD) with thin film transistors attached to each pixel has high image quality that can be substituted for CRT, and is expected to be the most promising display with flattening and energy saving boosts. Has been.
[0003]
In the AM-LCD, in order to increase the contrast, a switching element such as a thin film transistor or a diode is attached to each pixel to supply a voltage to the pixel.
Unlike the TN and STN passive drive systems, the AM-LCD is driven by supplying electric charge to each pixel every several tens of milliseconds through a switching element. For this reason, if the applied charge cannot be held completely until the next writing time after several tens of milliseconds after the charge is supplied, the display is deteriorated. When the electric charge escapes, the potential between the electrodes is lowered, the transmitted light intensity is changed, and the contrast is lowered. For this reason, AM-LCDs require high voltage holding characteristics. In order to obtain a high voltage holding characteristic, it is necessary to select and use a material that can easily maintain a high specific resistance for the liquid crystal composition for AM-LCD.
[0004]
In recent years, demand for notebook computers for portable purposes has increased, and there has been a growing demand for low power consumption that enables a wide operating temperature range that allows outdoor use and long-time battery operation. For low power consumption, a liquid crystal composition having a low threshold voltage that can be driven at a low voltage is required. In order to lower the threshold voltage, a material that increases the dielectric anisotropy Δε is necessary. However, in a system with a large dielectric anisotropy, the viscosity increases and the response deteriorates. There is a problem that it is difficult to maintain a high resistance because it is easily affected by contamination. For this reason, liquid crystal compositions for liquid crystal display elements such as TN, STN, AM-LCD, etc.
(1) Wide LCD temperature range that can be used outdoors
(2) Stability that can be used even at high temperatures
(3) Low threshold voltage
(4) High voltage holding ratio
(5) There is a need for an adjustable Δn in order to prevent coloring and to obtain an optimum contrast with a wide viewing angle.
[0005]
Conventional liquid crystal compositions are not always able to meet these requirements, and a decrease in contrast due to a decrease in voltage holding ratio at a high temperature, a crystal precipitation at a low temperature, and an appearance of a smectic phase were observed. In addition, when it was left outdoors under high temperature or UV light / sunlight exposure, the retention rate decreased and display was poor.
[0006]
That is, a liquid crystal composition that simultaneously satisfies a high nematic-isotropic transition temperature, a low crystal (or smectic) transition temperature, a low threshold voltage that can be driven at a low voltage, a low viscosity that enables a high-speed response, and a high retention at high temperatures. There was no thing and a liquid crystal display element.
For example, WO9403558 discloses an example of a liquid crystal composition using a trifluoro compound and a difluoro compound, but it has many problems such as a narrow liquid crystal temperature range and a high threshold voltage. Is the current situation.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to satisfy various characteristics required for an electro-optic display element, particularly the above-described liquid crystal display element, have a low threshold voltage, a wide nematic temperature range, a low viscosity, and an excellent high-speed response. , Providing a liquid crystal composition capable of maintaining a high holding ratio up to a high temperature and a liquid crystal display device using the same, or a liquid crystal composition and a liquid crystal display device (TN, STN, AM-LCD) in which the above-mentioned drawbacks have been improved Is to provide.
[0008]
[Means for Solving the Problems]
The present invention has found the following liquid crystal compositions as a result of studying liquid crystal compositions using various liquid crystal compounds in order to solve the above problems.
[0009]
Invention 1 A liquid crystal medium based on a mixture of polar compounds having positive dielectric anisotropy, which has the general formula (I)
[0010]
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[0011]
(Wherein R ¹ is an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms ,
Ring A and Ring B are trans -1,4-cyclohexylene groups ,
L ¹ and L ² are each independently —CH ₂ O— , —OCH ₂ —, —CH ₂ CH ₂ —, —CH═CH— , —C≡C—, — (CH ₂ ) ₄ —, — CH═CH—CH ₂ CH ₂ —, —CH ₂ CH ₂ —CH═CH—, or a single bond ,
X ¹ and X ² are F, m is 0 to 1 , and Y ¹ is —F, —CF ₃ , —OCF ₃ , —OCHF ₂ , or —OCH ₂ F. ) Containing one or more compounds selected from general formula (II)
[0012]
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[0013]
(Wherein R ² is independently the same as the definition of R ^{1 in} formula (I), and ring C and ring D are each independently of each other;
(D) trans-1,4-cyclohexylene group
(E) 1,4-phenylene group
And the above group (e) may be substituted with a halogen .
L ³ and L ⁴ are each independently the same definition as L ¹ and L ^{2 in} Formula (I).
X ⁵ and X ⁶ are each independently H or F;
n is 0, 1 or 2;
Y ³ is F ,
Q ² is a single bond, —CF ₂ —, —OCF ₂ — or —OCHF—. )
Or one or more compounds of the general formula (III)
Embedded image

(Wherein R ³ and R ⁴ are each independently an alkyl or alkoxyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, an alkenyloxy group having 3 to 16 carbon atoms, or carbon. Represents an alkyl group having 1 to 12 carbon atoms substituted by an alkoxyl group having 1 to 10 atoms, and ring F, ring G and ring H may each independently be substituted with a fluorine atom. Represents a phenylene group, a 2-methyl-1,4-phenylene group, a 3-methyl-1,4-phenylene group or a trans-1,4-cyclohexylene group, o represents 0 or 1, L ⁷ and L ⁸ Each independently represents a single bond, —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —OCH ₂ —, —CH ₂ O— or —C≡C—). Compound of Liquid crystal medium, characterized in that it comprises.
[0014]
Invention 2 The liquid crystal medium according to Invention 1, comprising at least two compounds of the general formula (I).
Invention 3 The liquid crystal medium according to Invention 1 or 2, wherein the content of the compound of the general formula (I) is in the range of 5 to 40% by mass.
Invention 4 The liquid crystal medium according to Invention 1, 2 or 3, comprising at least two compounds of the general formula (II).
Invention 5 As a compound of the general formula (II), the general formula (II-a)
[0015]
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[0016]
(In the formula, R ² represents the same meaning as in general formula (II), and L ⁵ and L ⁶ are each independently —CH ₂ CH ₂ —, —CH═CH—, —C≡C—, — (CH ₂ ) ₄ — or a single bond, ring D represents a 1,4-phenylene group or trans-1,4-cyclohexylene group, X ⁶ represents H or F, and n represents 0 or 1 , Y ⁴ represents F, —CF ₃ , —OCF ₃ or —OCHF ₂ )).
[0017]
Invention 6 As a compound of the general formula (II), the general formula (II-b)
[0018]
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[0019]
(In the formula, R ² represents the same meaning as in formula (II), and L ⁵ and L ⁶ are each independently —CH ₂ O—, —OCH ₂ —, —CH ₂ CH ₂ —, —CH. ═CH—, —C≡C—, — (CH ₂ ) ₄ — or a single bond, wherein ring C and ring D each independently represent a 1,4-phenylene group or a trans-1,4-cyclohexylene group. And X ⁵ and X ⁶ each independently represent H or F, n represents 1 or 2, and Y ⁴ represents —F, —CF ₃ , —OCF ₃ or —OCHF ₂ ). The liquid crystal medium according to any one of inventions 1 to 5, characterized by comprising
Invention 7 The liquid crystal medium according to Invention 5 or 6, comprising at least two compounds of the general formula (II-a).
Invention 8 The liquid crystal medium according to Invention 6 or 7, comprising at least two compounds of the general formula (II-b).
Invention 9 The content of general formula (I) is in the range of 5 to 40 mass%, and the content of general formula (II), general formula (II-a), and general formula (II-b) is 5 to 95 mass%. % Of the liquid crystal medium according to the inventions 6 to 8.
[0023]
Invention 10 As a compound of general formula (III), general formula (III-a)
[0024]
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[0025]
(Wherein R ³ and R ⁴ represent the same meaning as in formula (III), ring H represents a 1,4-phenylene group or trans-1,4-cyclohexylene group, and o represents 0 or 1) The liquid crystal medium according to any one of inventions 1 to 9 , which comprises a compound of.
[0026]
Invention 11 The liquid crystal medium according to any one of Inventions 1 to 10 , comprising at least one compound selected from the following formula (Ia) or (Ib) as the compound of general formula (I):
[0027]
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(In the formula, X ¹ and X ² represent F, Y ¹ represents —F, —CF ₃ , —OCF ₃ , or —OCHF ₂ , and R ¹ represents an alkyl group having 1 to 5 carbon atoms or a carbon number. Represents 2 to 5 alkenyl groups.)
[0028]
Invention 12 The liquid crystal medium according to Invention 1 to 12, wherein the content of the compound of the general formula (III) or the general formula (III-a) is in the range of 5 to 95% by mass.
Invention 13: General formula (II-c) as general formula (II) or (II-a)
[0029]
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[0030]
(In the formula, R ⁵ represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms), and the content ratio thereof is 5 or more. The liquid crystal medium according to any one of inventions 1 to 12, which is in a range of ˜40 mass%.
[0031]
Invention 14 General formula (II-d) as general formula (II) or (II-a)
[0032]
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[0033]
(In the formula, R ⁵ represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms), and the content thereof is 5 to 5 14. The liquid crystal medium according to any one of inventions 1 to 13, which is in the range of 40% by mass.
[0034]
Invention 15 General formula (III-b) as a compound of general formula (III) or general formula (III-a)
[0035]
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[0036]
(In the formula, each of R ⁶ and R ⁷ independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.) Contains one or more compounds selected from And the content thereof is in the range of 5 to 40% by mass, further represented by the general formula (III-c)
[0037]
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[0038]
(In the formula, each of R ⁸ and R ⁹ independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.) Contains one or more compounds selected from the liquid crystal medium of the present invention 1-14, wherein the content of perilla is characterized in that in the range of 5 to 60 wt%.
[0039]
Invention 16 One or more compounds of the general formula (I) or general formula (Ia) are contained, and the content thereof is in the range of 5 to 40% by mass, and the general formula (II) and general formula The compound of (II-a) or general formula (II-b) contains 1 type or 2 types or more, The content rate is the range of 5-40 mass%, and also general formula (III) and general formula (III) -A), containing one or more compounds of general formula (III-b) or general formula (III-c), the content of which is in the range of 5 to 60% by mass The liquid crystal medium according to any one of Inventions 1 to 15 .
[0040]
Invention 17 General Formula (I-1)
[0041]
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[0042]
(Wherein R ¹ represents an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, ring B represents a trans-1,4-cyclohexylene group, and L ¹ represents —CH ₂ CH. _2- or a single bond, X ¹ , X ² represents F , m represents 0 or 1, Y ¹ represents —F ₃ , —CF ₃ , —OCF ₃ , —OCHF ₂ , —OCH ₂ F. A compound represented by:
[0043]
General formula (I-1) is general formula (I-1a)
[0044]
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[0045]
(Wherein X ^a represents a halogen such as chlorine or bromine, and Y ⁵ represents —F, —CF ₃ , —OCF ₃ , —OCHF ₂ , —OCH ₂ F, H). . Formula (I-1b) obtained by reacting general formula (I-1a) with ethylene gas in the presence of a Lewis acid such as aluminum chloride
[0046]
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[0047]
(Wherein Y ⁵ represents the same meaning as in general formula (I-1a)), and this includes general formula (I-1c)
[0048]
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[0049]
(Wherein R ¹ , L ¹ , m represent the same meaning as in general formula (I-1), M represents a metal atom such as magnesium, lithium, zinc, cerium, etc.) General formula (I-1) (excluding Y ¹ = CN) can be produced by dehydrating and reacting hydrogen gas in the presence of a metal catalyst such as palladium.
In the case of Y ¹ = CN, a compound of general formula (I-1) Y ¹ = H is synthesized using general formula (I-1a) of Y ⁵ = H, and this is lithiated and then reacted with carbon dioxide gas. General formula (I-1d)
[0050]
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[0051]
(Wherein R ¹ , L ¹ and m have the same meaning as in general formula (I-1)), and can be produced by a method via this.
[0052]
Invention 18 Formula (I-1)
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(Wherein R ¹ represents an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, ring B represents a trans-1,4-cyclohexylene group, and L ¹ represents —CH ₂ CH. _2- represents a single bond, X ¹ , X ² represents F, m represents 0 or 1, Y ¹ represents —F, —CF ₃ , —OCF ₃ , —OCHF ₂ , —OCH ₂ F. The liquid crystal medium according to any one of inventions 1 to 16 , which comprises a compound represented by:
Invention 19 Inventions 1 to 16 and Invention 18 A liquid crystal display device using the liquid crystal medium.
Invention 20 A super twisted nematic (STN) liquid crystal display element using the liquid crystal medium according to Inventions 1 to 16 and Invention 18 , wherein the twist angle is 220 ° to 270 °.
Invention 21 Inventions 1 to 16 and Invention 18 An active matrix (AM) liquid crystal display device using the liquid crystal medium.
[0053]
DETAILED DESCRIPTION OF THE INVENTION
An example of the present invention will be described below.
In invention 1, the compound selected from general formula (I) as the first component contains one or more compounds, preferably 1 to 10 compounds, more preferably 1 to 8 compounds, and more preferably 1 to 5 compounds. Species are particularly preferred. R ¹ is preferably an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, and an unsubstituted linear alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms. More preferably, an unsubstituted linear alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms is particularly preferable. In the alkenyl group, structures of the following formulas (a) to (e) are further preferable.
[0054]
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[0055]
(The structural formula shall be connected to the ring at the right end.)
Ring A is preferably a trans-1,4-cyclohexylene group or 1,4-phenylene group, more preferably a trans-1,4-cyclohexylene group, and ring B is a trans-1,4-cyclohexylene group. 1,4-phenylene group or single bond is preferable, 1,4-phenylene group or single bond is more preferable, and single bond is particularly preferable. L ¹ and L ² are each independently -COO-, -OCO-, -CH ₂ O-, -OCH _2- , -CH ₂ CH _2- , -CH = CH-, -C≡C-,- _{_{(CH 2) 4 -, -}} CH = CH-CH 2 CH 2 -, - CH 2 CH 2 -CH = CH- or is a single bond, -COO -, - OCO -, - CH 2 CH 2 -, —C≡C—, — (CH ₂ ) ₄ — or a single bond is preferable, —CH ₂ CH ₂ —, —C≡C— or a single bond is more preferable, —CH ₂ CH ₂ — or a single bond is particularly preferable. A single bond is more preferable. m is 0 to 2, preferably 0 or 1, and more preferably 0. Y ¹ represents the same definition as —F, —Cl, —CF ₃ , —OCF ₃ , —OCHF ₂ , —OCH ₂ F, —CN, R ¹ , but F is preferred. As the second component, one or more compounds selected from the general formula (II) are contained, preferably 1 to 20 types, more preferably 1 to 15 types, and particularly preferably 1 to 10 types. . R ² is preferably an unsubstituted linear alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, and an unsubstituted linear alkyl group having 1 to 10 carbon atoms or 2 carbon atoms. Is more preferably an unsubstituted linear alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 6 carbon atoms, and the alkenyl group has the following structures (a) to (e): Is more preferable.
[0056]
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[0057]
(The structural formula shall be connected to the ring at the right end.)
L ³ and L ⁴ are preferably —COO—, —OCO—, —CH ₂ CH ₂ —, —C≡C—, — (CH ₂ ) ₄ — or a single bond, —CH ₂ CH ₂ —, —C ≡C— or a single bond is more preferable, and —CH ₂ CH ₂ — or a single bond is particularly preferable. At least one of X ⁵ and X ⁶ is preferably F. n is preferably 0 or 1. Q ² is a single _{_{bond, -CF 2 -, - OCF 2}} - or represents a _{-OCHF-, -CF 2 -, - OCF} 2 - or a single bond are preferred, -OCF ₂ - or a single bond is more preferable, A single bond is particularly preferred. Y ³ represents -F, -Cl or -CN, preferably -F or -CN.
[0058]
In invention 2, at least 2 or more types of compounds of general formula (I) are included, but 2 to 10 types are preferable, and 2 to 5 types are more preferable.
In Invention 3, the content of the compound of general formula (I) is in the range of 5 to 40% by mass, preferably 5 to 35% by mass, and more preferably 5 to 30% by mass.
In invention 4, at least 2 or more types of compounds of general formula (II) are included, but 2 to 20 types are preferable, 2 to 15 types are more preferable, and 2 to 10 types are particularly preferable.
In Invention 5, R ² is preferably an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, An alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 6 carbon atoms is particularly preferable. In the alkenyl group, structures of the following formulas (a) to (e) are more preferable.
[0059]
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[0060]
(The structural formula shall be connected to the ring at the right end.)
L ^5, L ⁶ is -COO -, - OCO -, - CH 2 CH 2 -, - C≡C -, - (CH 2) 4 - or a single bond are _{_{preferred, -CH 2 CH 2 -, -}} C≡ C- or a single bond is more preferable, -CH ₂ CH ₂ -or a single bond is particularly preferable. Y ⁴ represents F, —Cl, —CF ₃ , —OCF ₃ or —OCHF ₂ , preferably F or —OCF ₃ , and more preferably F.
[0061]
In Invention 6, R ² is preferably an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, more preferably an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, and 1 carbon atom. An alkyl group of ˜8 or an alkenyl group of 2 to 6 carbon atoms is particularly preferred, and the structure of the following formulas (a) to (e) is more preferred for the alkenyl group.
[0062]
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[0063]
(The structural formula shall be connected to the ring at the right end.)
L ⁵ and L ⁶ are preferably —COO—, —OCO—, —CH ₂ CH ₂ —, —C≡C—, — (CH ₂ ) ₄ — or a single bond, —COO—, —CH ₂ CH ₂ — , —C≡C— or a single bond is more preferable, and —COO—, —CH ₂ CH ₂ — or a single bond is particularly preferable. Y ⁴ represents F, —CF ₃ , —OCF ₃ , —CN or —OCHF ₂ , preferably CN. X ⁵ and X ⁶ each independently represent H or F, but at least one is preferably F.
[0064]
In the invention 7, the compound of the general formula (II-a) is contained in at least two kinds, preferably 2 to 20 kinds, more preferably 2 to 15 kinds, particularly preferably 2 to 10 kinds.
[0065]
In the invention 8, the compound of the general formula (II-b) is contained in at least two kinds, preferably 2 to 20 kinds, more preferably 2 to 15 kinds, particularly preferably 2 to 10 kinds.
[0066]
In the invention 9, the content of the compound of the general formula (I) is in the range of 5 to 40% by mass, preferably 5 to 35% by mass, more preferably 5 to 30% by mass, and the general formula (II) The content of the formula (II-a) and the general formula (II-b) is in the range of 5 to 95% by mass, preferably 10 to 70% by mass, and more preferably 10 to 60% by mass.
[0067]
In Invention 10, R ³ and R ⁴ 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 or an alkenyl group having 2 to 16 carbon atoms Is more preferable, an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms is more preferable, an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 6 carbon atoms is particularly preferable. The structures (a) to (e) are more preferable.
[0068]
Embedded image

[0069]
(The structural formula shall be connected to the ring at the right end.)
Ring F, ring G and ring H are each independently preferably a 1,4-phenylene group or a trans-1,4-cyclohexylene group. o represents 0, 1 or 2, with 0 or 1 being preferred. L ⁷ and L ⁸ each independently represent a single bond, —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —OCH ₂ —, —CH ₂ O— or —C≡C—, or -CH ₂ CH ₂ - is more preferably a single bond. Moreover, although at least 1 or more types of compounds of general formula (III) are included, 1 type-20 types are preferable, 2 types-15 types are more preferable, 2 types-10 types are especially preferable.
[0070]
Among the general formulas (Ia) to (Id) in the invention 12, general formulas (Ia) and (Ib) are more preferable, and the following general formulas (Ia-1) to (Ia-5), (Ib-1) to (Ib-5) and (Ic-1) to (Ic-15)
[0071]
Embedded image

[0072]
Embedded image

[0073]
(Wherein, R ^a represents the structure of the alkyl group or the following formula of 1 to 5 carbon atoms (a) ~ (e)) .
[0074]
Embedded image

[0075]
(The structural formula is assumed to be linked to the ring at the right end), and general formulas (Ia-1) to (Ia-5) and (Ib-1) to (Ib-5) are particularly preferable.
[0076]
In invention 13, the content of the compound of general formula (III) or general formula (III-a) is in the range of 5 to 95% by mass, preferably 10 to 70% by mass, and more preferably 10 to 50% by mass.
[0077]
In Inventions 14 and 15, R ⁵ represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, and an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms is Preferably, an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms is more preferable, an alkyl group having 1 to 6 carbon atoms or an alkenyl group having 2 to 6 carbon atoms is particularly preferable. More preferred are the structures a) to (e).
[0078]
Embedded image

[0079]
(The structural formula shall be connected to the ring at the right end.)
The content of the compound of the general formula (II-c) or the general formula (II-d) is in the range of 5 to 40% by mass, preferably 10 to 40% by mass, more preferably 10 to 30% by mass. . Further, it contains at least one compound of the general formula (II-c) or general formula (II-d), preferably 1 to 10 types, more preferably 1 to 8 types, more preferably 1 to 5 types Is particularly preferred.
[0080]
In Invention 16, R ⁶ , R ⁷ , R ⁸ , R ⁹ represent an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, but an alkyl group having 1 to 6 carbon atoms or a carbon number The alkenyl group of 2-6 is preferable, and the structure of the following formula (a)-(e) is more preferable in an alkenyl group.
[0081]
Embedded image

[0082]
(The structural formula shall be connected to the ring at the right end.)
The content of the compound of the general formula (III-b) or the general formula (III-c) is in the range of 5 to 40% by mass, preferably 10 to 40% by mass, more preferably 10 to 30% by mass. . In addition, it contains at least one compound of the general formula (III-b) or general formula (III-c), preferably 1 to 10 types, more preferably 1 to 8 types, more preferably 1 to 5 types Is particularly preferred.
[0083]
In Invention 18, R ¹ represents an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, preferably an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, An alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms is particularly preferable. In the alkenyl group, structures of the following formulas (a) to (e) are more preferable.
[0084]
Embedded image

[0085]
(The structural formula shall be connected to the ring at the right end.)
L ¹ represents —CH ₂ CH ₂ — or a single bond, and preferably a single bond. X ¹ and X ² each independently represent H or F, but preferably both F. Y ¹ represents -F, -Cl, -CF ₃ , -OCF ₃ , -OCHF ₂ , -OCH ₂ F, -CN, preferably -F, -OCF ₃ , -OCHF ₂ , -CN, F Are more preferable, the above-mentioned general formulas (Ia-1) to (Ia-5), (Ib-1) to (Ib-5) and (Ic-1) to (Ic-15) are more preferable, and the general formula ( Ia-1) to (Ia-5) and (Ib-1) to (Ib-5) are particularly preferred.
[0086]
The nematic liquid crystal composition is useful for AM-LCDs and STN-LCDs, but is particularly useful for AM-LCDs, and can be used for transmissive or reflective liquid crystal display elements. The liquid crystal medium of the present invention may contain ordinary nematic liquid crystal, smectic liquid crystal, cholesteric liquid crystal and the like in addition to the above-mentioned compounds.
[0087]
【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 “% by mass”.
In the examples, the measured characteristics are as follows.

[0088]
(Example 1, Comparative Example 1)
Nematic liquid crystal composition No.1
[0089]
Embedded image

[0090]
Was prepared. Further, (Ia-1a) and (Ib-1a) of this composition (No. 1) were changed to (R-1) and (R-2)
[0091]
Embedded image

[0092]
Table 1 shows the results of measurement of various properties together with the composition (Comparative Example 1).
[0093]
[Table 1]

[0094]
As shown in Table 1, although the liquid crystal composition of Example 1 has a threshold voltage close to that of the composition of Comparative Example 1, it can be seen that the liquid crystal phase upper limit temperature is as high as 14 ° C.
Using the composition produced here, a liquid crystal display device having excellent display characteristics could be produced.
[0095]
Example 2 Synthesis of Formula (Ic-1)
Embedded image

[0097]
29.5 g of 1-iodo-4-propylbenzene was dissolved in 120 ml of THF and cooled to −50 ° C. Under a nitrogen atmosphere, 85 ml of n-butyllithium (1.69 M, n-hexane solution) was added dropwise over 20 minutes. After stirring at the same temperature for 1 hour, 35 g of anhydrous cerium chloride was added and stirred at 0 ° C. for 1 hour. A solution of 5,6,7-trifluoro-3,4-dihydro-1H-naphthalen-2-one (20 g) in THF (60 ml) was added dropwise thereto at the same temperature over 20 minutes, and the mixture was stirred for 2 hours. After adding 100 ml of water, the temperature was returned to room temperature, the organic layer was separated, and extracted from the aqueous layer with ethyl acetate. The organic layer was washed with water and then with saturated brine and dried over anhydrous sodium sulfate. The obtained crude product was dissolved in 200 ml of toluene, 500 mg of potassium hydrogen sulfate was added, and the mixture was stirred for 2 hours while distilling off water. The crude product obtained by returning to room temperature, adding water and distilling off the solvent was purified by silica gel column chromatography (hexane) to obtain 6,7,8-trifluoro-3- (4-propylphenyl) -1, 18.1 g of 2-dihydronaphthalene was obtained.
To a solution of 15 g of 6,7,8-trifluoro-3- (4-propylphenyl) -1,2-dihydronaphthalene in 60 ml of ethyl acetate was added 3 g of 5% palladium carbon, and the mixture was stirred at a hydrogen pressure of 0.392 MPa for 3 hours. After completion of the reaction, the catalyst was filtered off, the solvent was distilled off, and the resulting crude product was purified by silica gel chromatography (silica gel 10 times, hexane) to obtain 5,6,7-trifluoro-2- ( 14.1 g of 4-propylphenyl) -1,2,3,4-tetrahydronaphthalene was obtained. This compound is an oil at room temperature.
MS: m / e = 304 (M +)
[0098]
(Example 3)
General-purpose p-type host liquid crystal composition (H)
[0099]
Embedded image

[0100]
This (H) shows a nematic phase at 116.7 ° C. or lower, and its melting point is 11.0 ° C. A liquid crystal device was prepared by filling (H) into a TN cell having a cell thickness of 6.0 μm, and the electro-optical characteristics at 20 ° C. were as follows.
Threshold voltage (Vth) 2.14V
Dielectric Anisotropy (Δε) 4.8
Refractive index anisotropy (Δn) 0.090
Next, a liquid crystal composition (H-1) comprising 80% by mass of this (H) and 20% by mass of the compound (Ic-1) of the present invention obtained in Example 2 was prepared, and the cell thickness was 6.0 μm. A TN cell was filled to prepare a liquid crystal element, and its electro-optical characteristics were measured at 20 ° C., and the results were as follows.
Threshold voltage (Vth) 1.63V
Dielectric Anisotropy (Δε) 5.2
Refractive index anisotropy (Δn) 0.085
[0101]
【The invention's effect】
A liquid crystal medium having a wide nematic temperature range, a low viscosity, a low threshold voltage, and an excellent high-speed response was obtained by combining the liquid crystal material and the liquid crystal material of the present invention. Moreover, when this composition was used as a liquid crystal display element, it was excellent in contrast and reliability. This liquid crystal display is very practical as STN and AM-LCD.

Claims

A liquid crystal medium based on a mixture of polar compounds having a positive dielectric anisotropy, having the general formula (I)

(Wherein R ¹ is an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms ,
Ring A and Ring B are trans -1,4-cyclohexylene groups ,
L ¹ and L ² are each independently —CH ₂ O— , —OCH ₂ —, —CH ₂ CH ₂ —, —CH═CH— , —C≡C—, — (CH ₂ ) ₄ —, — CH═CH—CH ₂ CH ₂ —, —CH ₂ CH ₂ —CH═CH—, or a single bond ,
X ¹ and X ² are F, m is 0 to 1 , and Y ¹ is —F, —CF ₃ , —OCF ₃ , —OCHF ₂ , or —OCH ₂ F. ) Containing one or more compounds selected from general formula (II)

(Wherein R ² is independently the same as the definition of R ^{1 in} formula (I), and ring C and ring D are each independently of each other;
(D) trans-1,4-cyclohexylene group
(E) 1,4-phenylene group
And the above group (e) may be substituted with a halogen .
L ³ and L ⁴ are each independently the same definition as L ¹ and L ^{2 in} Formula (I).
X ⁵ and X ⁶ are each independently H or F;
n is 0, 1 or 2;
Y ³ is F ,
Q ² is a single bond, —CF ₂ —, —OCF ₂ — or —OCHF—. )
Or one or more compounds of the general formula (III)

(Wherein R ³ and R ⁴ are each independently an alkyl or alkoxyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, an alkenyloxy group having 3 to 16 carbon atoms, or carbon. Represents an alkyl group having 1 to 12 carbon atoms substituted by an alkoxyl group having 1 to 10 atoms, and ring F, ring G and ring H may each independently be substituted with a fluorine atom. Represents a phenylene group, a 2-methyl-1,4-phenylene group, a 3-methyl-1,4-phenylene group or a trans-1,4-cyclohexylene group, o represents 0 or 1, L ⁷ and L ⁸ Each independently represents a single bond, —CH ₂ CH ₂ —, — (CH ₂ ) ₄ —, —OCH ₂ —, —CH ₂ O— or —C≡C—). Compound of Liquid crystal medium, characterized in that it comprises.

The liquid crystal medium according to claim 1, comprising at least two compounds of the general formula (I).

The liquid crystal medium according to claim 1 or 2, wherein the content of the compound of the general formula (I) is in the range of 5 to 40% by mass.

The liquid crystal medium according to any one of claims 1, 2 or 3, characterized in that it comprises at least two or more compounds of general formula (II).

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

(In the formula, R ² represents the same meaning as in formula (II), and L ⁵ and L ⁶ each independently represent —CH ₂ CH ₂ —, —CH═CH—, —C≡C—, — (CH ₂ ) ₄ — or a single bond, ring D represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group, X ⁶ represents H or F, and n represents 0 or 1. , ^{Y 4} are _-F, -CF 3, a liquid crystal medium according to claim 1, characterized in that it comprises a compound of representative.) the -OCF ₃ or -OCHF _2.

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

(In the formula, R ² represents the same meaning as in formula (II), and L ⁵ and L ⁶ are each independently —CH ₂ O—, —OCH ₂ —, —CH ₂ CH ₂ —, —CH. ═CH—, —C≡C—, — (CH ₂ ) ₄ — or a single bond, wherein ring C and ring D each independently represent a 1,4-phenylene group or a trans-1,4-cyclohexylene group. And X ⁵ and X ⁶ each independently represent H or F, n represents 1 or 2, and Y ⁴ represents —F, —CF ₃ , —OCF ₃ or —OCHF ₂ ). The liquid crystal medium according to claim 1, wherein the liquid crystal medium is contained.

The liquid crystal medium according to claim 5 or 6 , comprising at least two kinds of the compound of the general formula (II-a).

The liquid crystal medium according to claim 6 or 7 , comprising at least two kinds of the compound of the general formula (II-b).

The content of general formula (I) is in the range of 5 to 40% by mass, and the content of general formula (II), general formula (II-a), and general formula (II-b) is 5 to 95% by mass. the liquid crystal medium according to any one of claims 6-8, characterized in that the range.

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

(Wherein R ³ and R ⁴ represent the same meaning as in formula (III), ring H represents a 1,4-phenylene group or trans-1,4-cyclohexylene group, and o represents 0 or 1) The liquid crystal medium according to any one of claims 1 to 9, wherein the liquid crystal medium comprises a compound of.

The liquid crystal medium according to claim 1, comprising at least one compound selected from the following formula (Ia) or (Ib) as the compound of the general formula (I): .

(In the formula, X ¹ and X ² represent F, Y ¹ represents —F, —CF ₃ , —OCF ₃ , or —OCHF ₂ , and R ¹ represents an alkyl group having 1 to 5 carbon atoms or a carbon number. Represents 2 to 5 alkenyl groups.)

The liquid crystal medium according to any one of claims 1 to 11, wherein the content of the compound of the general formula (III) or the general formula (III-a) is in the range of 5 to 95 mass%.

General formula (II-c) as general formula (II) or (II-a)

(In the formula, R ⁵ represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms), and the content ratio thereof is 5 or more. The liquid crystal medium according to claim 1 , wherein the liquid crystal medium is in a range of ˜40 mass%.

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

(In the formula, R ⁵ represents an alkyl group having 1 to 16 carbon atoms or an alkenyl group having 2 to 8 carbon atoms), and the content thereof is 5 to 5 The liquid crystal medium according to claim 1 , wherein the liquid crystal medium is in a range of 40% by mass.

General formula (III-b) as a compound of general formula (III) or general formula (III-a)

(In the formula, each of R ⁶ and R ⁷ independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.) Contains one or more compounds selected from In the range of 5 to 40% by mass, further the general formula (III-c)

(In the formula, each of R ⁸ and R ⁹ independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms.) Contains one or more compounds selected from And the content rate is the range of 5-60 mass%, The liquid-crystal medium as described in any one of Claims 1-14 characterized by the above-mentioned.

1 type or 2 types or more of the compound of general formula (I) or general formula (Ia) is contained in the range of 5-40 mass%, and also general formula (II) and general formula (II) -A) or one or more compounds of the general formula (II-b), the content is in the range of 5 to 40% by mass, and the general formula (III), general formula (III-a) ), One or more compounds of general formula (III-b) or general formula (III-c), wherein the content is in the range of 5 to 60% by mass. The liquid crystal medium according to any one of 1 to 15 .

Formula (I-1)

(Wherein R ¹ represents an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, ring B represents a trans-1,4-cyclohexylene group, and L ¹ represents —CH ₂ CH. _2- or a single bond, X ¹ , X ² represents F , m represents 0 or 1, Y ¹ represents —F ₃ , —CF ₃ , —OCF ₃ , —OCHF ₂ , —OCH ₂ F. A compound represented by:

Formula (I-1)

(Wherein R ¹ represents an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, ring B represents a trans-1,4-cyclohexylene group, and L ¹ represents —CH ₂ CH. _2- represents a single bond, X ¹ , X ² represents F, m represents 0 or 1, Y ¹ represents —F, —CF ₃ , —OCF ₃ , —OCHF ₂ , —OCH ₂ F. represents. the liquid crystal media according to any one of claims 1 to 16, characterized by containing a compound represented by).

The liquid crystal display device using a liquid crystal medium according to any one of claims 1 to 16 and claim 18.

A super twisted nematic (STN) liquid crystal display element using the liquid crystal medium according to any one of claims 1 to 16 and claim 18 , wherein the twist angle is 220 ° to 270 °.

An active matrix (AM) liquid crystal display element using the liquid crystal medium according to any one of claims 1 to 16 and claim 18 .