JP4792623B2

JP4792623B2 - Liquid crystal composition

Info

Publication number: JP4792623B2
Application number: JP2000238303A
Authority: JP
Inventors: 清文竹内; 芳典岩下; 眞治小川; 晴義高津
Original assignee: DIC Corp
Current assignee: DIC Corp
Priority date: 2000-08-07
Filing date: 2000-08-07
Publication date: 2011-10-12
Anticipated expiration: 2020-08-07
Also published as: JP2002053861A

Description

【０００１】
【発明の属する技術分野】
本発明は電気光学的液晶表示材料として有用なネマチック液晶組成物及び、これを用いた液晶表示素子に関する。
【０００２】
【従来の技術】
液晶表示装置(LCD)は、電卓のディスプレイとして登場して以来、コンピューターの開発と歩みを同じくして、TN-LCD(捻れネマチック液晶表示装置)から、STN-LCDへと表示容量の拡大に対応してきた。STN-LCDは、シェファー(Scheffer)等［SID '85 Digest, 120頁(1985年)］、あるいは衣川等［SID '86 Digest, 122頁(1986年)］によって、開発され、ワードプロセッサ、パーソナルコンピュータなどの高情報処理用の表示に広く普及しはじめている。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しきい値電圧の低い液晶組成物が求められている。しきい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相温度範囲
(2) 高温条件でも使用できる安定性
(3) 低いしきい値電圧
(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しきい値電圧、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、しきい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、しきい値電圧が低く、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。
【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組成物であって、一般式(I)及び一般式(II)
【化８】

(式中R¹及びR²はそれぞれ独立的に、炭素数1〜15のアルキル基もしくはアルコキシル基または炭素数2〜15のアルケニル基を表し、X¹、X²、X³、X⁴及びX⁵はそれぞれ独立的に水素原子もしくはフッ素原子を表し、m及びnは0もしくは1を表し、Y¹及びY²はそれぞれ独立的に-F、-CF₃、-OCF₃、-OCHF₂、-OCH₂F、R¹と同じ意味を表す。)から、それぞれの1種または2種以上の化合物を含有し、屈折率異方性(Δn)が0.05〜0.3であることを特徴とする液晶組成物。
【００１１】
発明2 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記載の液晶組成物。
【００１２】
発明3 一般式(I)及び一般式(II)の化合物の含有率が10〜90質量%の範囲あることを特徴とする発明1〜2の何れかに記載の液晶組成物。
【００１３】
発明4 一般式(I)及び一般式(II)に加えて一般式(III)
【化９】

(式中、R³及びR⁴はそれぞれ独立的に、炭素数1〜15のアルキル基もしくはアルコキシル基または炭素数2〜15のアルケニル基を表し、環B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。)の化合物を含有することを特徴とする発明1〜3の何れかに記載の液晶組成物。
【００１４】
発明5 一般式(III)の化合物を、少なくとも1種以上含むことを特徴とする発明1〜4の何れかに記載の液晶組成物。
【００１５】
発明6 一般式(III)の化合物の含有率が5〜70質量%の範囲あることを特徴とする発明1〜5の何れかに記載の液晶組成物。
【００１６】
発明7 一般式(I)、一般式(II)及び一般式(III)に加えて一般式(IV)
【化１０】

(式中、R⁵は炭素数1〜15のアルキル基もしくはアルコキシル基または炭素数2〜15のアルケニル基を表し、pは0〜2を表し、Lは-CH₂CH₂-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、X⁷及びX⁸はそれぞれ独立してHもしくはFを表し、Y³はF、-CF₃、-OCF₃もしくは-OCHF₂を表す。また、L、環Cが複数存在する場合、同じでも異なっていても良い。)の化合物を含有することを特徴とする発明1〜6の何れかに記載の液晶組成物。
【００１７】
発明8 一般式(IV)の化合物を、少なくとも1種以上含むことを特徴とする発明1〜7の何れかに記載の液晶組成物。
【００１８】
発明9 一般式(IV)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1〜8の何れかに記載の液晶組成物。
【００１９】
発明10 一般式(I)及び一般式(II)の含有率が30〜70質量%の範囲で、なおかつ一般式(III)、一般式(IV)の含有率が20〜70質量%の範囲であることを特徴とする発明1〜9の何れかに記載の液晶組成物。
【００２０】
発明11 一般式(I)の化合物として、下記の式(Ia)〜(Ib)から選んだ、少なくとも1種の化合物を含み、一般式(II)の化合物として、下記の式(IIa)〜(IIb)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記載の液晶組成物。
【化１１】

(式中、R¹、R²、X¹、X²、X⁴、Y¹及びY²は一般式(I)、一般式(II)におけると同じ意味を表す。)
【００２１】
発明12 一般式(III)の化合物として一般式(IIIa)
【化１２】

原子数2〜8のアルケニル基を表す。)及び/もしくは一般式(IIIb)
【化１３】

(式中、R^3b、R^4b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。)を含有することを特徴とする発明4〜11の何れかに記載の液晶組成物。
【００２２】
発明13 一般式(IV)として一般式(IVa)
【００２３】
【化１４】

(式中、R^5a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し、X^7a及びX^8aはそれぞれ独立してHもしくはFを表し、Y^3aはFもしくは-OCF₃を表す。)を含有することを特徴とする発明7〜12の何れかに記載の液晶組成物。
【００２４】
発明14 発明1〜13の何れかに記載の液晶組成物を用いた液晶表示素子。
【００２５】
発明15 発明1〜13の何れかに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。
【００２６】
発明16 発明1〜13の何れかに記載の液晶組成物を用いたアクティブマトリックス(AM)液晶表示素子。
【００２７】
発明17 発明1〜13の何れかに記載の液晶組成物を用いた反射型液晶表示素子。
【００２８】
発明18 Δnが0.06〜0.08であることを特徴とする発明17に記載の液晶組成物を用いた反射型液晶表示素子。
【００２９】
【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。
【００３０】
発明1において、R¹及びR²はそれぞれ独立して、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。
【００３１】
【化１５】

(構造式は右端で環に連結しているものとする。)mは0もしくは1を表すが、0もしくは1が好ましい。nは0もしくは1を表すが、0もしくは1が好ましく、0がより好ましい。Y¹は、-F、-CF₃、-OCF₃、-OCHF₂、-OCH₂F、R¹と同じ定義を表すが、-OCF₃、Fが好ましい。Y²は、-F、-CF₃、-OCF₃、-OCHF₂、-OCH₂F、R²と同じ定義を表すが、-OCF₃、Fが好ましく、Fがより好ましい。また、一般式(I)及び一般式(II)からそれぞれ選ばれる1種もしくは2種以上の化合物を含有するが、1種〜8種が好ましく、1種〜5種がより好ましく、1種〜3種が特に好ましい。液晶組成物の屈折率異方性(Δn)は0.05〜0.3であるが、0.06〜0.2が好ましく、0.06〜0.16がより好ましい。また、反射型の液晶表示素子においてはΔnは0.05〜0.1が好ましく、0.06〜0.08がより好ましい。
【００３２】
発明3において、一般式(I)及び一般式(II)の含有率は10〜90質量%の範囲あるが、10〜80質量%が好ましく、10〜70質量%がより好ましく、10〜60質量%が特に好ましい。
【００３３】
発明4において、少なくとも1種以上の一般式(III)の化合物を含むが、2種〜10種が好ましく、2種〜8種がより好ましく、2種〜6種が特に好ましい。R³及びR⁴はそれぞれ独立して、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、アルケニル基では式(a)〜(e)の構造がさらに好ましい。環B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すが、1,4-フェニレン基が好ましい。oは0もしくは1を表すが、0もしくは1が好ましく、1の場合環Bは1,4-フェニレン基であることが好ましい。
【００３４】
発明6において、一般式(III)の含有率は5〜70質量%の範囲あるが、10〜60質量%が好ましく、20〜50質量%がより好ましい。
【００３５】
発明7において、少なくとも1種以上の一般式(IV)の化合物を含むが、1種〜10種が好ましく、1種〜6種がより好ましく、2種〜5種が特に好ましい。R⁵は炭素数1〜15のアルキル基もしくはアルコキシル基または炭素数2〜15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、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、アルケニル基では式(a)〜(e)の構造がさらに好ましい。pは0〜2を表すが、1〜2が好ましく、2がより好ましい。Lは-CH₂CH₂-もしくは単結合を表すが、Lが複数存在する場合一つが-CH₂CH₂-であることが好ましい。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すが、環Cはトランス-1,4-シクロヘキシレン基が好ましく、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が好ましく、トランス-1,4-シクロヘキシレン基がより好ましい。Y³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。X⁷及びX⁸はそれぞれ独立してHもしくはFを表すが、X⁷及びX⁸の少なくとも一つがFであることが好ましく、一方がF、もう一方がHであることがより好ましい。
【００３６】
発明9において、一般式(IV)の含有率は5〜40質量%の範囲あるが、5〜30質量%が好ましく、10〜20質量%がより好ましい。
【００３７】
発明10において、一般式(I)及び一般式(II)の含有率が30〜70質量%の範囲で、なおかつ一般式(III)、一般式(IV)の含有率が20〜70質量%の範囲であるが、一般式(I)及び一般式(II)の含有率が30〜60質量%で、なおかつ一般式(III)、一般式(IV)の含有率が30〜70質量%が好ましく、一般式(I)及び一般式(II)の含有率が30〜60質量%で、なおかつ一般式(III)の含有率が20〜50質量%で、なおかつ一般式(IV)の含有率が10〜20質量%がより好ましい。
【００３８】
発明11において好ましい対応は発明1と同じ。
【００３９】
発明12において、R^3a、R^4a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が、炭素数1〜5のアルキル基もしくは炭素数2〜5のアルケニル基が好ましく、アルケニル基では式(a)〜(e)の構造がさらに好ましく、さらにR^3a、R^4aの少なくとも一つがアルケニル基であることが好ましい。R^3b、R^4b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が、炭素数1〜5のアルキル基もしくは炭素数2〜5のアルケニル基が好ましく、アルケニル基では式(a)〜(e)の構造がさらに好ましく、さらにR^3b、R^4bの少なくとも一つがアルケニル基であることが好ましい。
【００４０】
発明13において、R^5a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1〜5のアルキル基もしくは炭素数2〜5のアルケニル基が好ましく、アルケニル基では式(a)〜(e)の構造がさらに好ましい。X^7a及びX^8aはそれぞれ独立してHもしくはFを表すが、少なくとも一つがFであることが好ましく、一方がF、もう一方がHであることがより好ましい。Y^3aはFもしくは-OCF₃を表すが、Fが好ましい。
【００４１】
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。本発明の液晶組成物は、上記の化合物以外に、通常のネマチック液晶、スメクチック液晶、コレステリック液晶などを含有していてもよい。
【００４２】
【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%』を意味し、液晶相温度範囲(ネマチック液晶相温度範囲)とは特に指定がない限り、固体相又はスメクチック相−ネマチック相転移温度からネマチック相−等方性液体相転移温度までを意味する。
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を構成した時のしきい値電圧(V)
Δε ：誘電異方性
Δn ：屈折率異方性
τr=τd ：応答速度 (msec)
(実施例1、比較例1、比較例2)
ネマチック液晶組成物No.1
【化１６】

【００４３】
を調製した。また、比較例1の液晶組成物
【化１７】

【００４４】
及び比較例2
【化１８】

を調整し共に諸特性を測定した結果を表1に示す。
【表１】

【００４５】
まず、実施例1の液晶組成物と比較例1の組成物を比較する。液晶相上限温度と屈折率異方性をほぼ同等に調整した二つの組成物の場合、比較例1は低温の安定性で劣るため、実施例1の組成物が液晶相温度範囲では10℃近くも広く、閾値電圧も大幅に低いことが解る。次に、実施例1の液晶組成物と比較例2の組成物を比較する。液晶相上限温度と閾値電圧をほぼ同等に調整した二つの組成物の場合、比較例2では屈折率異方性が十分下がりきらず、実施例1に比べ液晶相温度範囲では10℃近くも狭いことが解る。また、この液晶組成物は99.5%の電圧保持率を示した。
【００４６】
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。
(実施例2、比較例3)
ネマチック液晶組成物No.2
【化１９】

【００４７】
を調製した。また、比較例3の液晶組成物
【化２０】

を調整し共に諸特性を測定した結果を表2に示す。
【００４８】
【表２】

【００４９】
表2に示すように、比較例3の液晶組成物は実施例2の液晶組成物に比べ、液晶相上限温度がやや高いが、低温安定性に劣るため液晶相温度範囲では15℃も低いことが解る。また、屈折率異方性と応答速度はほぼ同程度であるが、実施例2の組成物が、比較例3の組成物に比べて0.5Vも低い閾値電圧を有することが解る。この液晶組成物もまた99.5%の電圧保持率を示した。
【００５０】
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。
【００５１】
【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、液晶相温度範囲が広く、屈折率異方性が低く、閾値電圧が低く、低い粘性を有し、高速応答性が優れた液晶組成物が得られた。また、この組成物を液晶表示素子として用いた場合、コントラスト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 composition useful as an electro-optical liquid crystal display material and a liquid crystal display element using the same.
[0002]
[Prior art]
The liquid crystal display (LCD) has been used as a calculator display, and it has been the same as the development of computers to support the expansion of display capacity from TN-LCD (twisted nematic liquid crystal display) to STN-LCD. I have done it. STN-LCD was developed by Scheffer et al. [SID '85 Digest, 120 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 surrounding contamination. For this reason, liquid crystal compositions for liquid crystal display elements such as TN, STN, AM-LCD, etc.
(1) Wide liquid crystal phase 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, high nematic-isotropic transition temperature, low crystal (or smectic) transition temperature, low threshold voltage that can be driven at low voltage, low viscosity that enables high-speed response, and high retention at high temperature. There were no liquid crystal composition and liquid crystal display element.
For example, WO9403558 discloses an example of a liquid crystal composition using a trifluoro compound and a difluoro compound, but has many problems such as a narrow liquid crystal temperature range and a high threshold voltage. The current situation is.
[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 a high-speed response. Provide a liquid crystal composition that can maintain a high retention rate 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).
[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 composition based on a mixture of polar compounds having a positive dielectric anisotropy, comprising a general formula (I) and a general formula (II)
[Chemical 8]

(Wherein R ¹ and R ² each independently represents an alkyl group or an alkoxyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, and X ¹ , X ² , X ³ , X ⁴ and X ⁵ each independently represents a hydrogen atom or a fluorine atom, m and n each represents 0 or 1, Y ¹ and Y ² each independently represent -F, -CF ₃ , -OCF ₃ , -OCHF ₂ ,- OCH ₂ F represents the same meaning as R ¹ ), and each of them contains one or more compounds, and the refractive index anisotropy (Δn) is 0.05 to 0.3. object.
[0011]
Invention 2 The liquid crystal composition according to invention 1, comprising at least two compounds of the general formula (II).
[0012]
Invention 3 The liquid crystal composition according to any one of inventions 1 and 2, wherein the content of the compounds of the general formula (I) and the general formula (II) is in the range of 10 to 90% by mass.
[0013]
Invention 4 In addition to general formula (I) and general formula (II), general formula (III)
[Chemical 9]

(Wherein R ³ and R ⁴ each independently represents an alkyl group or alkoxyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, and ring B is a 1,4-phenylene group or trans- 4. A liquid crystal composition according to any one of inventions 1 to 3, comprising a compound of 1,4-cyclohexylene group, wherein o represents 0 or 1.
[0014]
Invention 5 The liquid crystal composition according to any one of inventions 1 to 4, comprising at least one compound of the general formula (III).
[0015]
Invention 6 The liquid crystal composition according to any one of inventions 1 to 5, wherein the content of the compound of the general formula (III) is in the range of 5 to 70% by mass.
[0016]
Invention 7 In addition to general formula (I), general formula (II) and general formula (III), in addition to general formula (IV)
[Chemical Formula 10]

(In the formula, R ⁵ represents an alkyl or alkoxyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, p represents 0 to 2, and L represents —CH ₂ CH ₂ — or a single bond. Ring C and Ring D each independently represent a 1,4-phenylene group or trans-1,4-cyclohexylene group, X ⁷ and X ⁸ each independently represent H or F, and Y ³ represents F, —CF ₃ , —OCF ₃ or —OCHF _{2. In} addition, when a plurality of L and ring C are present, they may be the same or different. 7. The liquid crystal composition according to any one of 6.
[0017]
Invention 8 The liquid crystal composition according to any one of inventions 1 to 7, comprising at least one compound of the general formula (IV).
[0018]
Invention 9 The liquid crystal composition according to any one of inventions 1 to 8, wherein the content of the compound of the general formula (IV) is in the range of 5 to 40% by mass.
[0019]
Invention 10 The content of general formula (I) and general formula (II) is in the range of 30 to 70% by mass, and the content of general formula (III) and general formula (IV) is in the range of 20 to 70% by mass. The liquid crystal composition according to any one of inventions 1 to 9, wherein
[0020]
Invention 11 The compound of the general formula (I) includes at least one compound selected from the following formulas (Ia) to (Ib), and the compound of the general formula (II) includes the following formulas (IIa) to (II) The liquid crystal composition according to any one of inventions 1 to 10, comprising at least one compound selected from IIb).
Embedded image

(In the formula, R ¹ , R ² , X ¹ , X ² , X ⁴ , Y ¹ and Y ² represent the same meaning as in general formula (I) and general formula (II).)
[0021]
Invention 12: The compound of the general formula (IIIa) as the compound of the general formula (III)
Embedded image

An alkenyl group having 2 to 8 atoms is represented. ) And / or general formula (IIIb)
Embedded image

(Wherein R ^3b and R ^4b each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms). The liquid crystal composition according to any one of the above.
[0022]
Invention 13 General formula (IVa) as general formula (IV)
[0023]
Embedded image

(In the formula, R ^5a represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, X ^7a and X ^8a each independently represent H or F, and Y ^3a represents F or The liquid crystal composition according to any one of inventions 7 to 12, which contains -OCF ₃ ).
[0024]
Invention 14 A liquid crystal display device using the liquid crystal composition according to any one of inventions 1 to 13.
[0025]
Invention 15 A super twisted nematic (STN) liquid crystal display element using the liquid crystal composition according to any one of Inventions 1 to 13 and having a twist angle of 220 ° to 270 °.
[0026]
Invention 16 An active matrix (AM) liquid crystal display device using the liquid crystal composition according to any one of Inventions 1 to 13.
[0027]
Invention 17 A reflective liquid crystal display device using the liquid crystal composition according to any one of Inventions 1 to 13.
[0028]
Invention 18 A reflection-type liquid crystal display device using the liquid crystal composition according to Invention 17, wherein Δn is 0.06 to 0.08.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
An example of the present invention will be described below.
[0030]
In Invention 1, R ¹ and R ² are each independently preferably an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, an unsubstituted linear alkyl group having 1 to 8 carbon atoms or An alkenyl group having 2 to 8 carbon atoms is more preferable, and 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, the following formulas (a) to (e ) Is more preferable.
[0031]
Embedded image

(The structural formula is assumed to be linked to the ring at the right end.) M represents 0 or 1, with 0 or 1 being preferred. n represents 0 or 1, but 0 or 1 is preferable, and 0 is more preferable. Y ¹ represents the same definition as —F, —CF ₃ , —OCF ₃ , —OCHF ₂ , —OCH ₂ F, and R ¹ , but —OCF ₃ and F are preferred. Y ² represents the same definition as —F, —CF ₃ , —OCF ₃ , —OCHF ₂ , —OCH ₂ F, and R ² , but —OCF ₃ and F are preferred, and F is more preferred. Further, it contains one or more compounds each selected from general formula (I) and general formula (II), but preferably 1 to 8 types, more preferably 1 to 5 types, and more preferably 1 to 5 types. Three are particularly preferred. The refractive index anisotropy (Δn) of the liquid crystal composition is 0.05 to 0.3, preferably 0.06 to 0.2, and more preferably 0.06 to 0.16. In a reflective liquid crystal display element, Δn is preferably 0.05 to 0.1, and more preferably 0.06 to 0.08.
[0032]
In Invention 3, the content of general formula (I) and general formula (II) is in the range of 10 to 90% by mass, preferably 10 to 80% by mass, more preferably 10 to 70% by mass, and 10 to 60% by mass. % Is particularly preferred.
[0033]
In the invention 4, at least one compound of the general formula (III) is included, but 2 to 10 types are preferable, 2 to 8 types are more preferable, and 2 to 6 types are particularly preferable. R ³ and R ⁴ are each independently 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 2 to 2 carbon atoms. An alkenyl group having 8 is more preferable, and 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, the structures of formulas (a) to (e) are further added. preferable. Ring B represents a 1,4-phenylene group or a trans-1,4-cyclohexylene group, and a 1,4-phenylene group is preferred. o represents 0 or 1, but 0 or 1 is preferred, and in the case of 1, ring B is preferably a 1,4-phenylene group.
[0034]
In the invention 6, the content of the general formula (III) is in the range of 5 to 70% by mass, preferably 10 to 60% by mass, and more preferably 20 to 50% by mass.
[0035]
In Invention 7, at least one compound of the general formula (IV) is included, but 1 to 10 types are preferable, 1 to 6 types are more preferable, and 2 to 5 types are particularly preferable. R ⁵ represents an alkyl group or alkoxyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, preferably an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, and is unsubstituted. A linear alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms is more preferable, and an unsubstituted linear alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms is particularly preferable. Of the alkenyl groups, the structures of formulas (a) to (e) are more preferred. p represents 0-2, preferably 1-2, and more preferably 2. L represents —CH ₂ CH ₂ — or a single bond. When a plurality of L are present, one is preferably —CH ₂ CH ₂ —. Ring C and Ring D each independently represent a 1,4-phenylene group or a trans-1,4-cyclohexylene group, but Ring C is preferably a trans-1,4-cyclohexylene group, and Ring D is 1, A 4-phenylene group or a trans-1,4-cyclohexylene group is preferred, and a trans-1,4-cyclohexylene group is more preferred. Y ³ represents F, —CF ₃ , —OCF ₃ or —OCHF ₂ , preferably F or —OCF ₃ , and more preferably F. X ⁷ and X ⁸ each independently represent H or F, but at least one of X ⁷ and X ⁸ is preferably F, more preferably one is F and the other is H.
[0036]
In the invention 9, the content of the general formula (IV) is in the range of 5 to 40% by mass, preferably 5 to 30% by mass, and more preferably 10 to 20% by mass.
[0037]
In the invention 10, the content of the general formula (I) and the general formula (II) is in the range of 30 to 70% by mass, and the content of the general formula (III) and the general formula (IV) is 20 to 70% by mass. The content of the general formula (I) and the general formula (II) is 30 to 60% by mass, and the content of the general formula (III) and the general formula (IV) is preferably 30 to 70% by mass. The content of the general formula (I) and the general formula (II) is 30 to 60% by mass, the content of the general formula (III) is 20 to 50% by mass, and the content of the general formula (IV) is 10-20 mass% is more preferable.
[0038]
The preferable correspondence in the eleventh aspect is the same as that in the first aspect.
[0039]
In Invention 12, R ^3a and R ^4a each independently 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 5 carbon atoms or 2 to 2 carbon atoms The alkenyl group of 5 is preferable, and in the alkenyl group, the structures of formulas (a) to (e) are more preferable, and at least one of R ^3a and R ^4a is preferably an alkenyl group. R ^3b and R ^4b each independently 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 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms In the alkenyl group, the structures of the formulas (a) to (e) are more preferable, and at least one of R ^3b and R ^4b is preferably an alkenyl group.
[0040]
In Invention 13, R ^5a represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, preferably an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms, For alkenyl groups, structures of formulas (a) to (e) are more preferred. X ^7a and X ^8a each independently represent H or F, but preferably at least one is F, more preferably one is F and the other is H. Y ^3a represents F or —OCF ₃ , and F is preferred.
[0041]
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 composition of the present invention may contain a normal nematic liquid crystal, a smectic liquid crystal, a cholesteric liquid crystal and the like in addition to the above compounds.
[0042]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is further explained in full detail, this invention is not limited to these Examples. Further, “%” in the compositions of the following examples and comparative examples means “mass%”, and unless otherwise specified, the liquid crystal phase temperature range (nematic liquid crystal phase temperature range) is a solid phase or smectic phase − It means from the nematic phase transition temperature to the nematic phase-isotropic liquid phase transition temperature.
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: Refractive index anisotropy τr = τd: Response speed (msec)
(Example 1, Comparative Example 1, Comparative Example 2)
Nematic liquid crystal composition No.1
Embedded image

[0043]
Was prepared. In addition, the liquid crystal composition of Comparative Example 1

[0044]
And Comparative Example 2
Embedded image

Table 1 shows the results obtained by adjusting the values and measuring various properties.
[Table 1]

[0045]
First, the liquid crystal composition of Example 1 and the composition of Comparative Example 1 are compared. In the case of two compositions in which the upper limit temperature of the liquid crystal phase and the refractive index anisotropy are adjusted to be approximately the same, Comparative Example 1 is inferior in stability at low temperatures, so the composition of Example 1 is nearly 10 ° C. in the liquid crystal phase temperature range. It can be seen that the threshold voltage is significantly low. Next, the liquid crystal composition of Example 1 and the composition of Comparative Example 2 are compared. In the case of two compositions in which the upper limit temperature of the liquid crystal phase and the threshold voltage are adjusted to be approximately the same, the refractive index anisotropy is not sufficiently lowered in Comparative Example 2, and the liquid crystal phase temperature range is narrower by nearly 10 ° C than in Example 1. I understand. Further, this liquid crystal composition showed a voltage holding ratio of 99.5%.
[0046]
Using the composition produced here, a liquid crystal display device having excellent display characteristics could be produced.
(Example 2, Comparative Example 3)
Nematic liquid crystal composition No.2
Embedded image

[0047]
Was prepared. In addition, the liquid crystal composition of Comparative Example 3

Table 2 shows the results of adjusting the values and measuring various properties.
[0048]
[Table 2]

[0049]
As shown in Table 2, the liquid crystal composition of Comparative Example 3 has a slightly higher liquid crystal phase upper limit temperature than the liquid crystal composition of Example 2, but it is inferior in low-temperature stability, and is as low as 15 ° C in the liquid crystal phase temperature range. I understand. Further, it is understood that the refractive index anisotropy and the response speed are substantially the same, but the composition of Example 2 has a threshold voltage as low as 0.5 V compared to the composition of Comparative Example 3. This liquid crystal composition also showed a voltage holding ratio of 99.5%.
[0050]
Using the composition produced here, a liquid crystal display device having excellent display characteristics could be produced.
[0051]
【The invention's effect】
By the combination of the liquid crystal material and the liquid crystal material of the present invention, a liquid crystal composition having a wide liquid crystal phase temperature range, low refractive index anisotropy, low threshold voltage, low viscosity, and excellent high-speed response can be obtained. It was. 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 composition based on a mixture of polar compounds having a positive dielectric anisotropy, having the general formula (I) and the general formula (II)

(Wherein R ¹ and R ² each independently represents an alkyl group or alkoxyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, and X ¹ , X ² , X ⁴ and X ⁵ are each Independently represents a hydrogen atom or a fluorine atom, X ³ represents a fluorine atom, m and n each represents 0 or 1, Y ¹ and Y ² each independently represent -F, -CF ₃ , -OCF ₃ , -OCHF ₂ , -OCH ₂ F, and R ¹ have the same meanings)), and each compound contains one or more compounds and has a refractive index anisotropy (Δn) of 0.05 to 0.3. A liquid crystal composition.

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

General formula (I) and the liquid crystal composition according to any one of claims 1 to 2 content and wherein in the range of 10 to 90 wt% of a compound of general formula (II).

In addition to general formula (I) and general formula (II), general formula (III)

(Wherein R ³ and R ⁴ each independently represents an alkyl group or alkoxyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, and ring B is a 1,4-phenylene group or trans- 1,4 cyclohexylene, o is 0 or liquid crystal composition according to any one of claims 1-3, characterized by containing a compound of the representative.) 1.

5. The liquid crystal composition according to claim 4, comprising at least one compound of the general formula (III).

6. The liquid crystal composition according to claim 4 , wherein the content of the compound of general formula (III) is in the range of 5 to 70% by mass.

In addition to general formula (I), general formula (II) and general formula (III), general formula (IV)

(In the formula, R ⁵ represents an alkyl or alkoxyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, p represents 0 to 2, and L represents —CH ₂ CH ₂ — or a single bond. Ring C and Ring D each independently represent a 1,4-phenylene group or trans-1,4-cyclohexylene group, X ⁷ and X ⁸ each independently represent H or F, and Y ³ represents F, -CF _3, represents a -OCF ₃ or -OCHF _2. also, L, according to claim 4 ring C may be plurality of, which is characterized by containing a compound of the may be the same or different.) The liquid crystal composition according to any one of -6 .

8. The liquid crystal composition according to claim 7, comprising at least one compound of the general formula (IV).

9. The liquid crystal composition according to claim 7 , wherein the content of the compound of the general formula (IV) is in the range of 5 to 40% by mass.

The content of general formula (I) and general formula (II) is in the range of 30 to 70% by mass, and the content of general formula (III) and general formula (IV) is in the range of 20 to 70% by mass. 10. The liquid crystal composition according to any one of claims 7 to 9, wherein:

The compound of the general formula (I) includes a compound represented by the following formula (Ib), and the compound of the general formula (II) is selected from the following formulas (IIa) to (IIb): the liquid crystal composition according to any one of claims 1 to 10, characterized in that it comprises a compound.

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

General formula (IIIa) as a compound of general formula (III)

(Wherein R ^3a and R ^4a each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms) and / or general formula (IIIb)

(Wherein R ^3b and R ^4b each independently represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms), The liquid crystal composition according to any one of the above.

General formula (IVa) as general formula (IV)

(In the formula, R ^5a represents an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms, X ^7a and X ^8a each independently represent H or F, and Y ^3a represents F or represents a -OCF _3.) the liquid crystal composition according to any one of claims 7 to 12, characterized in that it contains.

The liquid crystal display device using the liquid crystal composition according to any one of claims 1 to 13.

A super twisted nematic (STN) liquid crystal display element using the liquid crystal composition according to any one of claims 1 to 13 and having a twist angle of 220 ° to 270 °.

An active matrix (AM) liquid crystal display device using the liquid crystal composition according to any one of claims 1 to 13.

Reflection type liquid crystal display device using the liquid crystal composition according to any one of claims 1 to 13.

18. The reflective liquid crystal display element using the liquid crystal composition according to claim 17, wherein Δn is 0.06 to 0.08.