JP4888676B2

JP4888676B2 - Liquid crystal composition

Info

Publication number: JP4888676B2
Application number: JP2000005915A
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: 2000-01-07
Filing date: 2000-01-07
Publication date: 2012-02-29
Anticipated expiration: 2020-01-07
Also published as: JP2001192660A

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。
【０００４】
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。
【０００５】
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。
【０００６】
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。
【０００７】
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、かつ高温での高い電圧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。
【０００８】
【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、高い電圧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。
【０００９】
【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。
【００１０】
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)
【００１１】
【化１４】

【００１２】
(式中R¹は、炭素数1〜15のアルキル基もしくは炭素数2〜15のアルケニル基で有りこの基を非置換であるか、あるいは置換基として少なくとも1個のハロゲンを有しており、そしてこれらの基中に存在する1個もしくは2個以上のCH₂基はそれぞれ独立してO原子が相互に直接結合しないものとして -O-、-S-、-CO-、-COO-、-OCO-、-OCO-O-により置き換えられても良い。Y¹は、-F、-Cl、-CF₃、-OCF₃、-OCHF₂、-OCH₂F、-CN、R¹と同じ定義もしくは式(I-1)
【化１５】

(式中X³及びX⁴はそれぞれ独立してH、FもしくはClであり、Q¹は-OCH₂-、-OCF₂-、-OCHF-、-CF₂-もしくは単結合であり、Y²はF、ClもしくはCNである。)である。環A及び環Bはそれぞれ独立して、
(a) トランス-1,4-シクロへキシレン基(この基中に存在する1個のCH₂基もしくは隣接していない2個以上のCH₂基は -O- 及びもしくは -S- に置き換えられてもよい)
(b) 1,4-フェニレン基(この基中に存在する1個のCH₂基もしくは隣接していない2個以上のCH₂基は -N- に置き換えられてもよい)
(c) 1,4-シクロヘキセニレン、1,4-ビシクロ(2.2.2)オクチレン、ピペリジン-1,4-ジイル、ナフタレン-2,6-ジイル、デカヒドロナフタレン-2,6-ジイル及び1,2,3,4-テトラヒドロナフタレン-2,6-ジイル
(d) 単結合
からなる群より選ばれる基であり、上記の基(a)、基(b)、基(c)はCNもしくはハロゲンで置換されていても良いが、環Bが単結合を表す場合、Y¹は式(I-1)を表す。
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り、X¹、X²はHまたはFであるが、X¹とX²は異なり、mは0から2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)
【００１３】
【化１６】

【００１４】
(式中R²は互いに独立して式(I)でのR¹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(この基中に存在する1個のCH₂基もしくは隣接していない2個以上のCH₂基は -O- 及びもしくは -S- に置き換えられてもよい)
(e) 1,4-フェニレン基(この基中に存在する1個のCH₂基もしくは隣接していない2個以上のCH₂基は -N- に置き換えられてもよい)
(f) 1,4-シクロヘキセニレン、1,4-ビシクロ(2.2.2)オクチレン、ピペリジン-1,4-ジイル、ナフタレン-2,6-ジイル、1,2,3,4-テトラヒドロナフタレン-2,6-ジイル及びデカヒドロナフタレン-2,6-ジイル
からなる群より選ばれる基であり、上記の基(d)、基(e)、基(f)はCNもしくはハロゲンで置換されていても良いが、1,2,3,4-テトラヒドロナフタレン-2,6-ジイルを表す場合、無置換であるか、少なくとも2つ以上のハロゲンによって置換されており、
L³、L⁴はそれぞれ相互に独立して式(1)でのL¹、L²と同じ定義であり、
X⁵、X⁶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、
Y³は、-F、-Clもしくは-CNであり、
Q²は、単結合、-CF₂-、-OCF₂- もしくは -OCHF- である。)
の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液晶媒体。
【００１５】
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1〜3記載の液晶媒体。
【００１６】
発明5 一般式(II)の化合物として、一般式(II-a)
【００１７】
【化１７】

【００１８】
(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、-Cl、-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。
【００１９】
発明6 一般式(II)の化合物として、一般式(II-b)
【００２０】
【化１８】

【００２１】
(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、-COO-、-OCO-、-CH₂O-、-OCH₂-、-CH₂CH₂-、-CH=CH-、-C≡C-、-(CH₂)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、X⁵、X⁶はそれぞれ独立してHもしくはFを表し、Y⁴はF、-Cl、-CF₃、-OCF₃、-CN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1〜5記載の液晶媒体。
【００２２】
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1〜6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1〜7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1〜8記載の液晶組成物。
【００２３】
発明10 一般式(I)、一般式(II)に加え一般式(III)
【００２４】
【化１９】

【００２５】
(式中、R³、R⁴はそれぞれ独立的にフッ素置換されていても良い炭素原子数1〜16のアルキル基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、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-ジイル基もしくはピリダジン-2,5-ジイル基を表し、oは0、1もしくは2を表し、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。)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1〜9記載の液晶媒体。
【００２６】
発明11 一般式(III)の化合物として、一般式(III-a)
【００２７】
【化２０】

【００２８】
(式中、R³、R⁴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10記載の液晶媒体。
【００２９】
発明12 一般式(I)の化合物として、下記の式(Ia)〜(Ie)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1〜11記載の液晶媒体。
【００３０】
【化２１】

【００３１】
(式中、R¹、X¹、X²、X³、X⁴、Q¹及びY²は一般式(I)と同じ意味を表す。)
発明13 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10〜12記載の液晶媒体。
【００３２】
発明14 一般式(II)もしくは(II-a)として一般式(II-c)
【００３３】
【化２２】

【００３４】
(式中、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。)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。
【００３５】
発明15 一般式(II)もしくは(II-a)として一般式(II-d)
【００３６】
【化２３】

【００３７】
(式中、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。)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1〜14記載の液晶媒体。
【００３８】
発明16 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)
【００３９】
【化２４】

【００４０】
(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)
【００４１】
【化２５】

【００４２】
(式中、R⁸、R⁹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10〜15記載の液晶媒体。
【００４３】
発明17 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1〜16記載の液晶媒体。
【００４４】
発明18 一般式(I-1)
【００４５】
【化２６】

【００４６】
(式中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、環A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、L¹は-CH₂CH₂-もしくは単結合を表し、X¹、X²はHもしくはFを表すが、X¹とX²は異なり、X³及びX⁴はそれぞれ独立的にはHもしくはFを表し、mは0もしくは1を表し、Y⁵は、-F、-CF₃、-OCF₃、-OCHF₂、-OCH₂F、-CNを表す。)で表される化合物。
【００４７】
一般式(I-1)は一般式(I-1a)
【化２７】

【００４８】
(式中R¹、環A、L¹、mは一般式(I-1)と同じ意味を表す。)から製造することができる。一般式(I-1a)にMEC試薬、F-TEDA-BF4(1-クロロメチル-4-フルオロ-1,4-ジアゾニウムビシクロ[2,2,2]オクタンビス(テトラフルオロボレート)等のフッ素化剤を反応させて一般式(I-1b)及び一般式(I-1c)の混合物
【００４９】
【化２８】

【００５０】
(式中R¹、環A、L¹、mは一般式(I-1)と同じ意味を表す。)を得る。これらを単離し、トリフルオロメタンスルフォン酸エステル一般式(I-1d)
【００５１】
【化２９】

【００５２】
(式中R¹、環A、L¹、m、X¹、X²は一般式(I-1)と同じ意味を表す。)とした後、これに一般式(I-1e)
【化３０】

(X³、X⁴、Y⁵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、亜鉛等の金属原子を表す。)をパラジウム等の遷移金属触媒存在下に反応させる事によって一般式(I-1)を製造することができる。
【００５３】
発明19 式(I-1)を含有することを特徴とする発明1〜17記載の液晶媒体。
発明20 発明1〜17及び発明19記載の液晶媒体を用いた液晶表示素子。
発明21 発明1〜17及び発明19記載の液晶組成物を用いた、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22 発明1〜17及び発明19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。
【００５４】
【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。
【００５５】
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。
【００５６】
【化３１】

【００５７】
(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。X¹、X²はHまたはFであるが、X¹がF、X²がHを表すことが好ましい。Y¹は、-F、-CF₃、-OCF₃、-OCHF₂、-OCH₂F、-CN、R¹と同じ定義もしくは式(I-1)を表すが、式(I-1)が好ましい。式(I-1)に置いて、X³及びX⁴はそれぞれ独立してH、FもしくはClを表すが、HもしくはFが好ましく、X³もしくはX⁴の少なくとも一方がFを表すことが特に好ましい。Q¹は-OCH₂-、-OCF₂-、-OCHF-、-CF₂-もしくは単結合を表すが、-OCF₂-、-OCHF-、-CF₂-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、単結合がより好ましい。Y²はF、ClもしくはCN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。
【００５８】
【化３２】

【００５９】
(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。
【００６０】
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。
【００６１】
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。
【００６２】
【化３３】

【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、-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、-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。
【００６４】
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。
【００６５】
【化３４】

【００６６】
(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。
【００６７】
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。
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。
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。
【００６８】
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。
【００６９】
【化３５】

【００７０】
(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。
【００７１】
発明12において一般式(Ia)〜(Ie)の中でも、一般式(Ia)、(Ib)、(Ic)および(Ie)が好ましく、一般式(Ia)および(Ic)がより好ましく、以下の一般式(Ia-1)〜(Ia-8)および(Ic-1)〜(Ic-8)が特に好ましい。
【００７２】
【化３６】

【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３７】

【００７５】
(構造式は右端で環に連結しているものとする。)
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。
【００７６】
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。
【００７７】
【化３８】

【００７８】
(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。
【００７９】
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。
【００８０】
【化３９】

【００８１】
(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。
【００８２】
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。
【００８３】
【化４０】

【００８４】
(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。X³及びX⁴はそれぞれ独立的にはHもしくはFを表すが、少なくとも一方はFを表すことが好ましい。Y⁵は、-F、-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-8)および(Ic-1)〜(Ic-8)が特に好ましい。
【００８５】
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。
【００８６】
【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。
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を構成した時の閾値電圧(V)
Δε ：誘電異方性
Δn ：複屈折率
τr=τd ：応答速度 (msec)
【００８７】
(実施例1、比較例1)
ネマチック液晶組成物No.1
【００８８】
【化４１】

【００８９】
を調製した。また、この組成物(No.1)の(Ia-2a)及び(Ic-2a)を(R-1)及び(R-2)
【００９０】
【化４２】

【００９１】
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。
【００９２】
【表１】

【００９３】
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13℃も高く、その上応答速度も8msecも速いことが解る。
ここで作製した組成物を用いて、電圧保持率を測定したところ80℃で99%と高い値を示し、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。
【００９４】
(実施例2) 式(Ia-2a)の合成
【００９５】
【化４３】

【００９６】
トランス-6-プロピル-5,6,7,8-テトラヒドロナフタレン-2-オール30g とトリフルオロメタンスルホン酸ナトリウム2.3g の塩化メチレン120ml 溶液に室温でビステトラフルオロホウ酸N,N’-ジフルオロ-2,2’-ジピリジニウム(MEC31、ダイキン工業(株)製)27gを加えた。室温で8時間撹拌した後、反応系を水に加え反応を停止し、10%塩酸水溶液を加えトルエンで抽出した。有機層を水洗した後、溶媒を溜去して得られた1フルオロ体と3フルオロ体の混合物である粗生成物をシリカゲルクロマトグラフィー(シリカゲル50倍、ヘキサン:酢酸エチル=9:1)にて精製して1-フルオロ-トランス-6-プロピル-5,6,7,8-テトラヒドロナフタレン-2-オール5.4gを得た。
MS：m/e=268(M⁺)
【００９７】
1-フルオロ-トランス-6-プロピル-5,6,7,8-テトラヒドロナフタレン-2-オール5gおよび無水トリフルオロメタンスルホン酸7.9g の塩化メチレン40ml 溶液にピリジン3mlを滴下した。1時間撹拌後10%塩酸水溶液を加えトルエンで抽出した。有機層を水洗した後、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)にて精製してトリフルオロメタンスルホン酸1-フルオロ-トランス-6-プロピル-5,6,7,8-テトラヒドロナフタレン-2-イル6.1gを得た。
【００９８】
窒素雰囲気下、トリフルオロメタンスルホン酸1-フルオロ-トランス-6-プロピル-5,6,7,8-テトラヒドロナフタレン-2-イル5gおよびジブロモビス(トリフェニルホスフィン)ニッケル(II)0.5gのTHF20ml 溶液に、3,4,5-トリフルオロブロモベンゼン4.2g およびマグネシウム0.49g から調整したグリニャール反応剤を滴下した。1時間撹拌後10%塩酸水溶液を加えトルエンで抽出した。有機層を水洗した後、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1-フルオロ-6-(トランス-4-プロピルシクロヘキシル)-2-(3,4,5-トリフルオロフェニル)-5,6,7,8-テトラヒドロナフタレン0.9gを得た。
MS：m/e=322(M⁺)
【００９９】
(実施例3)
汎用のp型ホスト液晶組成物(H)
【０１００】
【化４４】

【０１０１】
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(Ia-2a)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) 1.51V
誘電率異方性(Δε) 6.3
屈折率異方性(Δn) 0.092
【０１０２】
【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、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, 120 pages (1985)] or Kinukawa et al. 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.
[0004]
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.
[0005]
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.
[0006]
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.
[0007]
That is, a liquid crystal 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 voltage holding ratio at a high temperature. There were no compositions and liquid crystal display elements.
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.
[0008]
[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. The present invention provides a liquid crystal composition capable of maintaining a high voltage 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 ) To provide.
[0009]
[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.
[0010]
Invention 1 A liquid crystal medium based on a mixture of polar compounds having positive dielectric anisotropy, which has the general formula (I)
[0011]
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[0012]
(Wherein R ¹ is an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, and this group is unsubstituted or has at least one halogen as a substituent, One or two or more CH ₂ groups present in these groups are each independently defined as those in which O atoms are not directly bonded to each other, -O-, -S-, -CO-, -COO-,- O ^1- may be replaced by OCO-, -OCO-O- Y ¹ has the same definition as -F, -Cl, -CF ₃ , -OCF ₃ , -OCHF ₂ , -OCH ₂ F, -CN, R ¹ Or formula (I-1)
Embedded image

(Wherein X ³ and X ⁴ are each independently H, F or Cl, Q ¹ is —OCH ₂ —, —OCF ₂ —, —OCHF—, —CF ₂ — or a single bond, Y ² Is F, Cl or CN.) Ring A and Ring B are each independently
(a) trans-1,4-cyclohexylene group (one CH ₂ group present in this group or two or more non-adjacent CH ₂ groups are replaced by -O- and / or -S- (May be)
(b) 1,4-phenylene group (one CH ₂ group present in this group or two or more non-adjacent CH ₂ groups may be replaced by -N-)
(c) 1,4-cyclohexenylene, 1,4-bicyclo (2.2.2) octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl and 1 , 2,3,4-Tetrahydronaphthalene-2,6-diyl
(d) is a group selected from the group consisting of a single bond, and the group (a), the group (b) and the group (c) may be substituted with CN or halogen, but the ring B has a single bond. In the case of expression, Y ¹ represents the formula (I-1).
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 -, - a CH _₂ CH ₂ -CH = CH- or a single bond, but X ^1, X ² is H or F, X ¹ and X ² is different and m is from 0 to 2. ) Containing one or more compounds selected from general formula (II)
[0013]
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[0014]
(Wherein R ² is independently the same as defined for R ^{1 in} formula (I), and ring C and ring D are each independently of each other,
(d) trans-1,4-cyclohexylene group (one CH ₂ group present in this group or two or more non-adjacent CH ₂ groups are replaced by -O- and / or -S- (May be)
(e) 1,4-phenylene group (one CH ₂ group present in this group or two or more non-adjacent CH ₂ groups may be replaced by -N-)
(f) 1,4-cyclohexenylene, 1,4-bicyclo (2.2.2) octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene- A group selected from the group consisting of 2,6-diyl and decahydronaphthalene-2,6-diyl, wherein the groups (d), (e) and (f) are substituted with CN or halogen. But when it represents 1,2,3,4-tetrahydronaphthalene-2,6-diyl, it is unsubstituted or substituted with at least two or more halogens,
L ³ and L ⁴ have the same definition as L ¹ and L ² in the formula (1) independently of each other,
X ⁵ and X ⁶ are each independently H or F;
n is 0, 1 or 2,
Y ³ is -F, -Cl or -CN;
Q ² is a single bond, -CF _2- , -OCF ₂ -or -OCHF-. )
A liquid crystal medium comprising one or more compounds of the above.
[0015]
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 any one of Inventions 1 to 3, comprising at least two compounds of the general formula (II).
[0016]
Invention 5 As a compound of the general formula (II), the general formula (II-a)
[0017]
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[0018]
(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, —Cl, —CF ₃ , —OCF _3, or —OCHF ₂ )).
[0019]
Invention 6 As a compound of the general formula (II), the general formula (II-b)
[0020]
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[0021]
(In the formula, R ² represents the same meaning as in general formula (II), and L ⁵ and L ⁶ are each independently -COO-, -OCO-, -CH ₂ O-, -OCH ₂ -,- CH ₂ CH _2- , -CH = CH-, -C≡C-,-(CH ₂ ) ₄ -or a single bond, ring C and ring D are each independently a 1,4-phenylene group or trans- 1,4-cyclohexylene group, X ⁵ and X ⁶ each independently represent H or F, Y ⁴ represents F, —Cl, —CF ₃ , —OCF ₃ , —CN or —OCHF ₂ The liquid crystal medium according to any one of inventions 1 to 5, which comprises a compound of.
[0022]
Invention 7 The liquid crystal medium according to any one of Inventions 1 to 6, comprising at least two compounds of the general formula (II-a).
Invention 8 The liquid crystal medium according to any one of Inventions 1 to 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%. The liquid crystal composition according to inventions 1 to 8, wherein the liquid crystal composition is in the range of%.
[0023]
Invention 10 General formula (III) in addition to general formula (I) and general formula (II)
[0024]
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[0025]
(In the formula, 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. Represents an alkyl group having 1 to 12 carbon atoms substituted with an alkoxyl group having 1 to 10 carbon atoms, and Ring F, Ring G and Ring H are each independently substituted with a fluorine atom. 1,4-phenylene group, 2-methyl-1,4-phenylene group, 3-methyl-1,4-phenylene group, naphthalene-2,6-diyl group, phenanthrene-2,7-diyl group, Fluorene-2,7-diyl group, trans-1,4-cyclohexylene group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, decahydronaphthalene-2,6-diyl group, trans- 1,3-dioxane-2,5-diyl group, pyridine-2,5-diyl group, pyrimidine-2,5-diyl group, pyrazine-2,5-dii Represents a group or a pyridazine-2,5-diyl group, o is 0, 1 or 2, L ⁷ and L ⁸ are each independently a single _{_{bond, -CH 2 CH 2 -, -}} (CH 2) 4 - -OCH _2- , -CH ₂ O- or -C≡C-). The liquid crystal medium according to any one of inventions 1 to 9, comprising at least one compound selected from the group consisting of:
[0026]
Invention 11 As a compound of general formula (III), general formula (III-a)
[0027]
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[0028]
(Wherein R ³ and R ⁴ represent the same meaning as in general formula (III), ring H represents a 1,4-phenylene group or trans-1,4-cyclohexylene group, and o represents 0 or 1) 11. A liquid crystal medium according to invention 10, comprising the compound of
[0029]
Invention 12 The liquid crystal medium according to any one of Inventions 1 to 11, comprising at least one compound selected from the following formulas (Ia) to (Ie) as the compound of the general formula (I).
[0030]
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[0031]
(In the formula, R ¹ , X ¹ , X ² , X ³ , X ⁴ , Q ¹ and Y ² represent the same meaning as in the general formula (I).)
Invention 13 The liquid crystal medium according to Inventions 10 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.
[0032]
Invention 14 General formula (II-c) as general formula (II) or (II-a)
[0033]
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[0034]
(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 or more. The liquid crystal medium according to any one of inventions 1 to 13, which is in the range of ˜40 mass%.
[0035]
Invention 15 General formula (II-d) as general formula (II) or (II-a)
[0036]
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[0037]
(Wherein 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 any one of inventions 1 to 14, which is in the range of 40% by mass.
[0038]
Invention 16 General formula (III-b) as a compound of general formula (III) or general formula (III-a)
[0039]
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[0040]
(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)
[0041]
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[0042]
(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 of invention 10-15 characterized by the above-mentioned.
[0043]
Invention 17 One or more compounds of general formula (I) or general formula (Ia) are contained, the content thereof is in the range of 5 to 40% by mass, and general formula (II), 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), and the content thereof is in the range of 5 to 60% by mass. The liquid crystal medium according to -16.
[0044]
Invention 18 General Formula (I-1)
[0045]
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[0046]
(Wherein R ¹ represents an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, ring A represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group, and L ¹ represents —CH ₂ CH ₂ — or a single bond, X ¹ and X ² represent H or F, but X ¹ and X ² are different, and X ³ and X ⁴ each independently represent H or F. M represents 0 or 1, and Y ⁵ represents -F, -CF ₃ , -OCF ₃ , -OCHF ₂ , -OCH ₂ F, or -CN.
[0047]
General formula (I-1) is general formula (I-1a)
Embedded image

[0048]
(Wherein R ¹ , ring A, L ¹ and m have the same meaning as in general formula (I-1)). Fluorinating agent such as MEC reagent, F-TEDA-BF4 (1-chloromethyl-4-fluoro-1,4-diazonium bicyclo [2,2,2] octanebis (tetrafluoroborate), etc., in general formula (I-1a) And a mixture of general formula (I-1b) and general formula (I-1c)
Embedded image

[0050]
(Wherein R ¹ , ring A, L ¹ and m have the same meaning as in general formula (I-1)). These were isolated from trifluoromethanesulfonate ester general formula (I-1d)
[0051]
Embedded image

[0052]
(Wherein R ¹ , ring A, L ¹ , m, X ¹ , and X ² represent the same meaning as in general formula (I-1)), and then to general formula (I-1e)
Embedded image

(X ³ , X ⁴ and Y ⁵ represent the same meaning as in the general formula (I-1), and M represents a metal atom such as magnesium, lithium and zinc) in the presence of a transition metal catalyst such as palladium. By this, general formula (I-1) can be produced.
[0053]
Invention 19 A liquid crystal medium according to any one of Inventions 1 to 17, which comprises the formula (I-1).
Invention 20 A liquid crystal display device using the liquid crystal medium according to Inventions 1 to 17 and Invention 19.
Invention 21 A super twisted nematic (STN) liquid crystal display element using the liquid crystal composition according to Invention 1 to 17 and Invention 19 and having a twist angle of 220 ° to 270 °.
Invention 22 An active matrix (AM) liquid crystal display element using the liquid crystal medium according to Inventions 1 to 17 and Invention 19.
[0054]
DETAILED DESCRIPTION OF THE INVENTION
An example of the present invention will be described below.
[0055]
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.
[0056]
Embedded image

[0057]
(The structural formula is assumed to be linked to the ring at the right end.) Ring A is preferably a trans-1,4-cyclohexylene group or a 1,4-phenylene group, and a trans-1,4-cyclohexylene group. Ring B is preferably a trans-1,4-cyclohexylene group, a 1,4-phenylene group or a single bond, more preferably a 1,4-phenylene group or a single bond, and particularly preferably a single bond. 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. X ¹ and X ² are H or F, and it is preferable that X ¹ represents F and X ² represents H. Y ¹ represents the same definition or formula (I-1) as -F, -CF ₃ , -OCF ₃ , -OCHF ₂ , -OCH ₂ F, -CN, R ¹ , but the formula (I-1) is preferable. In the formula (I-1), X ³ and X ⁴ each independently represent H, F or Cl, but H or F is preferred, and it is particularly preferred that at least one of X ³ or X ⁴ represents F. preferable. Q ¹ is _{_{-OCH 2 -, - OCF 2 -}} , - OCHF -, - CF 2 - or represents a single _{bond, -OCF 2 -, - OCHF -} , - CF 2 - or a single bond are preferred, -OCF ₂ -Or a single bond is more preferable and a single bond is more preferable. Y ² represents F, Cl or CN, and 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.
[0058]
Embedded image

[0059]
(The structural formula is assumed to be linked to the ring at the right end.) L ³ and L ⁴ are —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 preferred. 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.
[0060]
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.
[0061]
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.
[0062]
Embedded image

[0063]
(The structural formula is assumed to be linked to the ring at the right end.) L ⁵ and L ⁶ are -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. Y ⁴ represents F, —CF ₃ , —OCF ₃ or —OCHF ₂ , preferably F or —OCF ₃ , more preferably F.
[0064]
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.
[0065]
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[0066]
(The structural formula is assumed to be linked to the ring at the right end.) L ⁵ and L ⁶ are -COO-, -OCO-, -CH ₂ CH _2- , -C≡C-,-(CH ₂ ) ₄ -Or a single bond is preferable, -COO-, -CH ₂ CH _2- , -C≡C- or a single bond is more preferable, -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.
[0067]
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.
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.
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.
[0068]
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.
[0069]
Embedded image

[0070]
(The structural formula is assumed to be linked 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.
[0071]
Among the general formulas (Ia) to (Ie) in the invention 12, the general formulas (Ia), (Ib), (Ic) and (Ie) are preferable, the general formulas (Ia) and (Ic) are more preferable, The general formulas (Ia-1) to (Ia-8) and (Ic-1) to (Ic-8) are particularly preferred.
[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 shall be connected to the ring at the right end.)
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.
[0076]
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).
[0077]
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[0078]
(The structural formula is assumed to be linked 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. 10 to 40% by mass is preferable, and 10 to 30% by mass is more preferable. 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.
[0079]
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.
[0080]
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[0081]
(The structural formula is assumed to be linked to the ring at the right end.) The content of the compound of general formula (III-b) or general formula (III-c) is in the range of 5 to 40% by mass. 10 to 40% by mass is preferable, and 10 to 30% by mass is more preferable. 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.
[0082]
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.
[0083]
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[0084]
(The structural formula is assumed to be linked to the ring at the right end.) L ¹ represents —CH ₂ CH ₂ — or a single bond, and preferably a single bond. X ³ and X ⁴ each independently represent H or F, but preferably at least one represents F. Y ⁵ represents -F, -CF ₃ , -OCF ₃ , -OCHF ₂ , -OCH ₂ F, -CN, preferably -F, -OCF ₃ , -OCHF ₂ , -CN, and more preferably F The aforementioned general formulas (Ia-1) to (Ia-8) and (Ic-1) to (Ic-8) are particularly preferable.
[0085]
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.
[0086]
【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.
TN-I: Nematic phase-isotropic liquid phase transition temperature (° C)
T → N: Solid phase or smectic phase-nematic phase transition temperature (° C)
Vth: Threshold voltage (V) when a TN-LCD with a cell thickness of 6μm is constructed
Δε: Dielectric anisotropy Δn: Birefringence index τr = τd: Response speed (msec)
[0087]
(Example 1, Comparative Example 1)
Nematic liquid crystal composition No.1
[0088]
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[0089]
Was prepared. In addition, (Ia-2a) and (Ic-2a) of this composition (No. 1) are (R-1) and (R-2)
[0090]
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[0091]
Table 1 shows the results of measurement of various properties together with the composition (Comparative Example 1).
[0092]
[Table 1]

[0093]
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, the upper limit temperature of the liquid crystal phase is as high as 13 ° C., and the response speed is 8 msec. I understand that it is fast.
When the voltage holding ratio was measured using the composition produced here, a high value of 99% at 80 ° C. was obtained, and a liquid crystal display device exhibiting excellent display characteristics could be produced.
[0094]
Example 2 Synthesis of Formula (Ia-2a)
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[0096]
N, N'-Difluoro-2 bistetrafluoroborate at room temperature in 120 ml of methylene chloride containing 30 g of trans-6-propyl-5,6,7,8-tetrahydronaphthalen-2-ol and 2.3 g of sodium trifluoromethanesulfonate 2,2′-dipyridinium (MEC31, manufactured by Daikin Industries, Ltd.) 27 g was added. After stirring at room temperature for 8 hours, the reaction system was added to water to stop the reaction, 10% aqueous hydrochloric acid was added, and the mixture was extracted with toluene. After washing the organic layer with water, the crude product, which is a mixture of 1-fluoro and 3-fluoro forms obtained by distilling off the solvent, was purified by silica gel chromatography (silica gel 50 times, hexane: ethyl acetate = 9: 1). Purification gave 5.4 g of 1-fluoro-trans-6-propyl-5,6,7,8-tetrahydronaphthalen-2-ol.
MS: m / e = 268 (M ⁺ )
[0097]
To a solution of 5 g of 1-fluoro-trans-6-propyl-5,6,7,8-tetrahydronaphthalen-2-ol and 7.9 g of trifluoromethanesulfonic anhydride in 40 ml of methylene chloride was added dropwise 3 ml of pyridine. After stirring for 1 hour, a 10% aqueous hydrochloric acid solution was added, and the mixture was extracted with toluene. The organic layer was washed with water, and the crude product obtained by distilling off the solvent was purified by silica gel chromatography (silica gel 10 times, hexane) to give trifluoromethanesulfonic acid 1-fluoro-trans-6-propyl-5. Thus, 6.1 g of 6,7,8-tetrahydronaphthalen-2-yl was obtained.
[0098]
To a 20 ml THF solution of 1 g of trifluoromethanesulfonic acid 1-fluoro-trans-6-propyl-5,6,7,8-tetrahydronaphthalen-2-yl and 0.5 g of dibromobis (triphenylphosphine) nickel (II) under a nitrogen atmosphere A Grignard reagent prepared from 4.2 g of 3,4,5-trifluorobromobenzene and 0.49 g of magnesium was added dropwise. After stirring for 1 hour, a 10% aqueous hydrochloric acid solution was added, and the mixture was extracted with toluene. After washing the organic layer with water, the solvent was distilled off and the resulting crude product was purified by silica gel chromatography (silica gel 10 times, hexane) to give 1-fluoro-6- (trans-4-propylcyclohexyl)- 0.9 g of 2- (3,4,5-trifluorophenyl) -5,6,7,8-tetrahydronaphthalene was obtained.
MS: m / e = 322 (M ⁺ )
[0099]
(Example 3)
General-purpose p-type host liquid crystal composition (H)
[0100]
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[0101]
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 (Ia-2a) 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) 1.51V
Dielectric anisotropy (Δε) 6.3
Refractive index anisotropy (Δn) 0.092
[0102]
【Effect of the invention】
By the liquid crystal material and the combination of the liquid crystal materials of the present invention, a liquid crystal medium having a low threshold voltage, a wide nematic temperature range, a low viscosity, and excellent high-speed response was obtained. 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 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, and this group is unsubstituted or has at least one halogen as a substituent, One or two or more CH ₂ groups present in these groups are each independently defined as those in which O atoms are not directly bonded to each other, -O-, -S-, -CO-, -COO-,- It may be replaced by OCO-, -OCO-O-, where Y ¹ represents the formula (I-1)

(Wherein X ³ and X ⁴ are each independently H, F or Cl, Q ¹ is —OCH ₂ —, —OCF ₂ —, —OCHF—, —CF ₂ — or a single bond, Y ² Is F, Cl or CN.)
Ring A is
(a) trans-1,4-cyclohexylene group (one CH ₂ group present in this group or two or more CH ₂ groups not adjacent to each other may be replaced by -O-)
(b) 1,4-phenylene group (one CH ₂ group present in this group or two or more non-adjacent CH ₂ groups may be replaced by -N-)
A group selected from the group consisting of: and the group (b) may be substituted with CN or halogen,
Ring B is
(b) 1,4-phenylene group (one CH ₂ group present in this group or two or more non-adjacent CH ₂ groups may be replaced by -N-)
(d) is a group selected from the group consisting of a single bond, the group (b) may be substituted with CN or halogen,
L ¹ is —COO—, —OCO—, —CH ₂ O—, —OCH ₂ —, —CH ₂ CH ₂ —, —CH═CH—, —C≡C— or a single bond,
L ² is a single bond,
X ¹ and X ² are H or F, but X ¹ and X ² are different, and m is 0 or 1. ) Containing one or more compounds selected from general formula (II)

(Wherein R ² is independently the same as defined for R ^{1 in} formula (I), and ring C and ring D are each independently of each other,
(d) trans-1,4-cyclohexylene group (one CH ₂ group present in this group or two or more non-adjacent CH ₂ groups are replaced by -O- and / or -S- (May be)
(e) 1,4-phenylene group (one CH ₂ group present in this group or two or more non-adjacent CH ₂ groups may be replaced by -N-)
(f) 1,4-cyclohexenylene, 1,4-bicyclo (2.2.2) octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene- A group selected from the group consisting of 2,6-diyl and decahydronaphthalene-2,6-diyl, wherein the groups (d), (e) and (f) are substituted with CN or halogen. But when it represents 1,2,3,4-tetrahydronaphthalene-2,6-diyl, it is unsubstituted or substituted with at least two or more halogens,
L ³ and L ⁴ are each independently the same definition as L ^{1 in} formula (I),
X ⁵ and X ⁶ are each independently H or F;
n is 0, 1 or 2,
Y ³ is -F, -Cl or -CN;
Q ² is a single bond, -CF _2- , -OCF ₂ -or -OCHF-. )
A liquid crystal medium comprising one or more compounds of the above.

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

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

4. The liquid crystal medium according to claim 1, comprising at least two kinds of compounds of the 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 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, —Cl, —CF ₃ , —OCF _3, or —OCHF ₂ ).) The liquid crystal medium according to claim 1,

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

(In the formula, R ² represents the same meaning as in general formula (II), and L ⁵ and L ⁶ are each independently -COO-, -OCO-, -CH ₂ O-, -OCH ₂ -,- CH ₂ CH _2- , -CH = CH-, -C≡C-,-(CH ₂ ) ₄ -or a single bond, ring C and ring D are each independently a 1,4-phenylene group or trans- 1,4-cyclohexylene group, X ⁵ and X ⁶ each independently represent H or F, n represents 0, 1 or 2, Y ⁴ represents F, -Cl, -CF ₃ ,- 6. The liquid crystal medium according to claim 1, comprising a compound of OCF ₃ , —CN or —OCHF ₂ ).

7. The liquid crystal medium according to any one of claims 1 to 6, comprising at least two kinds of the compound of the general formula (II-a).

8. The liquid crystal medium according to any one of claims 1 to 7, comprising at least two or more compounds 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 claim 1, wherein the liquid crystal medium is in a range.

General formula (III) in addition to general formula (I) and general formula (II)

(In the formula, 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. Represents an alkyl group having 1 to 12 carbon atoms substituted with an alkoxyl group having 1 to 10 carbon atoms, and Ring F, Ring G and Ring H are each independently substituted with a fluorine atom. 1,4-phenylene group, 2-methyl-1,4-phenylene group, 3-methyl-1,4-phenylene group, naphthalene-2,6-diyl group, phenanthrene-2,7-diyl group, Fluorene-2,7-diyl group, trans-1,4-cyclohexylene group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, decahydronaphthalene-2,6-diyl group, trans- 1,3-dioxane-2,5-diyl group, pyridine-2,5-diyl group, pyrimidine-2,5-diyl group, pyrazine-2,5-dii Represents a group or a pyridazine-2,5-diyl group, o is 0, 1 or 2, L ⁷ and L ⁸ are each independently a single _{_{bond, -CH 2 CH 2 -, -}} (CH 2) 4 - , -OCH _2- , -CH ₂ O- or -C≡C-)). The compound according to any one of claims 1 to 9, comprising at least one compound selected from the group consisting of Liquid crystal medium.

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

(Wherein R ³ and R ⁴ represent the same meaning as in general formula (III), ring H represents a 1,4-phenylene group or trans-1,4-cyclohexylene group, and o represents 0 or 1) 11. The liquid crystal medium according to claim 10, comprising a compound of

The liquid crystal medium according to any one of claims 1 to 11, comprising at least one compound selected from the following formulas (Ia) to (Ie) as the compound of the general formula (I): .

(In the formula, R ¹ , X ¹ , X ² , X ³ , X ⁴ , Q ¹ and Y ² represent the same meaning as in the general formula (I).)

13. The liquid crystal medium according to claim 10, 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.

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 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)

(Wherein 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 15. 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 And the content thereof is in the range of 5 to 40% by mass, further represented by 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 16. The liquid crystal medium according to claim 10, wherein the content thereof is in the range of 5 to 60% by mass.

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), 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), 10. The compound of general formula (III-b) or general formula (III-c) contains one or more compounds, and the content thereof is in the range of 5 to 60% by mass. The liquid crystal medium according to any one of 16.

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

A super twisted nematic (STN) liquid crystal display element using the liquid crystal medium according to any one of claims 1 to 17 and having a twist angle of 220 ° to 270 °.

An active matrix (AM) liquid crystal display element using the liquid crystal medium according to claim 1.