JPS5829876A - Liquid crystal composition - Google Patents

Abstract

PURPOSE:To obtain a liquid crystal of which negative dielectric anisotropism is great and orientation can be controlled at a low voltage, by mixing three specified compounds. CONSTITUTION:A mixture of compounds having formulaeI-III (wherein R1 and R2 denote -CnH2n+1 in which n=1-8; R3 and R4 denote -CnH2n+1, -O- CnH2n+1 -O- CnH2n+1 in which n=1-8; R<5> denotes any one of formulae IV-VI and; X denotes -CN or -Cl, and , if necessary, a compound having formula VII (wherein R<7> and R<8> denote CnH2n+1 in which n=1-8), and a cholesteric liquid crystal or an optically active substance having an asymmetric carbon atom in the molecule are mixed. EFFECT:When this liquid crystal composition is used for a guest-host or the like, it can be driven at a low voltage, and a positive type display wherein a color display is possible against a clear background can be widely used in information apparatuses including a watch, a clock, etc.

Description

【発明の詳細な説明】 本発明は、負の誘電異方性が大きく、低電圧で配向制御
が可能な液晶組成物に関する。さらに詳しくは、極性の
小さいエステル系ペース液晶に極性基を有する添加物を
加え、負の誘電異方性が大きいが難溶性の成分を多量に
とかした、駆動電圧の低い液晶組成物に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal composition which has a large negative dielectric anisotropy and whose alignment can be controlled at low voltage. More specifically, the present invention relates to a liquid crystal composition with a low driving voltage, in which an additive having a polar group is added to an ester-based liquid crystal with a low polarity, and a large amount of a poorly soluble component with a large negative dielectric anisotropy is dissolved.

従来、誘電異方性Δεが負の液晶性物質としては、次式
に示す、エステル系化合物が代表的であるが、 Ｒ１−（ｑ、ｗＣＯ−０−＠−ＯＲ！　　　　　　、、
、　、、、　（１）Ｒｓ　−＠−００−ｏ−＠−ｏ　Ｒ
４−−（２）（但し　Ｒ１−Ｒ４はアルキル基を示す。Conventionally, as liquid crystalline substances with negative dielectric anisotropy Δε, ester compounds shown in the following formula are typical.
, ,,, (1) Rs -@-00-o-@-o R
4--(2) (However, R1-R4 represent an alkyl group.

）これら自身は誘電異方性は一１程度で、配向のスイッ
チングに必要な電圧は、６〜８ｖ程度と高い。そこで、
これらに、非液晶性物質も含めて、負のΔｔの大きい化
合物を多量に添加する事により、低電圧化が可能となっ
ている。表１に主な添加物を示すが、この中で、１ΔＣ
１が大きいのはの型の化合物である。) These themselves have a dielectric anisotropy of about 11, and the voltage required for switching the orientation is as high as about 6 to 8 V. Therefore,
By adding a large amount of compounds with a large negative Δt, including non-liquid crystal substances, to these, it is possible to lower the voltage. Table 1 shows the main additives, of which 1ΔC
Compounds with a large value of 1 are of the type .

しかし、極性の小さいエステル系の液晶には、これらは
室温でも数％程度しかとけないために、とても集用には
耐えなかった。However, these liquid crystals dissolve only a few percent even at room temperature, making them unsuitable for general use in ester-based liquid crystals, which have low polarity.

本発明の特徴は、この様に誘電的特性が優れている化合
物の溶解性を向上すべく、溶質と溶媒の中間的極性を有
する添加物を加えた点にある。以下実施例に基づき本発
明を説明する。A feature of the present invention is that an additive having a polarity intermediate between that of the solute and the solvent is added in order to improve the solubility of a compound having excellent dielectric properties. The present invention will be explained below based on Examples.

鮮度に対する添加剤の効果を示す、但し、ベース液晶の
組成は表３に示す。The effect of additives on freshness is shown in Table 3, where the composition of the base liquid crystal is shown.

表　　１ 表　　２ 表　　３ 表２から明らかな如（、Ｎａ１．Ｎｎｌの極性の小さい
系では表３の屹５〜１０の化合物は大牛が析出してしま
うが、表２のＮａ３．８１４の如く、それ自身は液晶で
なく、又１Δ８１も小さいが分子内に極性基を有する化
合物を添加する事により、溶解性の著しい向上が見られ
る。この結果、大きな負のΔｅを有し、表示素子へ用い
る際のスイッチング電圧が通常用いられている正液晶並
みの３〜４．５ｖ駆動のものが得られた。又、この様な
効果は、他物質の存在によっても阻害されず、表２のｍ
２とＮ１４の比較から、ＰＯＨ−負の如く、極性が小さ
く低粘性のものをかなり添加でき、結果としては高速応
答化が可能である。Table 1 Table 2 Table 3 As is clear from Table 2 (in a system with low polarity of Na1.Nnl, compounds numbered 5 to 10 in Table 3 will precipitate heavily, but as in Na3.814 in Table 2) , itself is not a liquid crystal, and its 1Δ81 is small, but by adding a compound with a polar group in the molecule, a significant improvement in solubility can be seen.As a result, it has a large negative Δe, making it suitable for display elements. A device with a switching voltage of 3 to 4.5V, which is comparable to that of a normally used positive liquid crystal, was obtained.In addition, such an effect was not inhibited by the presence of other substances, and m
From a comparison of 2 and N14, it is possible to add a large amount of a material with low polarity and low viscosity, such as POH-negative, and as a result, a high-speed response is possible.

この様な負液晶の用途として一番有望なのは、表４に示
す様な棒状構造からなり、分子長軸方向と、ｌ短軸方向
とで吸収スペクトルの興なる二色性色素を溶解させて、
対向する電極間に挾持し、電圧の印加除去により表示を
行なうゲスト・ホストＣＧ−Ｈ）効果がある。第１図は
その表示セルの構成断面図を示す。対向する透明電極■
、■を有するガラス支持体■、■の内面は、有機クロム
錯体、等の垂直配向膜■、■で覆われている。このため
、電圧のかからない周辺部■では液晶分子は基板表面に
垂直な配向を、又電圧印加部０ではΔ６く０のため電界
によりトルクを受けて、基板表面に平行な配向構造をと
り、この両状態間の光吸収の差を用いて表示を行なう。The most promising use of such negative liquid crystals is that they have a rod-like structure as shown in Table 4, and dissolve dichroic dyes whose absorption spectra vary in the long axis direction and the short axis direction of the molecules.
There is a guest-host CG-H) effect in which display is performed by sandwiching between opposing electrodes and applying and removing voltage. FIG. 1 shows a sectional view of the structure of the display cell. Opposing transparent electrode■
The inner surfaces of the glass supports (2) and (2) having the glass supports (2) and (2) are covered with vertical alignment films (2) and (2) made of organic chromium complexes, etc. Therefore, in the peripheral area (2) where no voltage is applied, the liquid crystal molecules are aligned perpendicular to the substrate surface, and in the voltage applied area (0), due to the torque applied by the electric field, the liquid crystal molecules are aligned parallel to the substrate surface. Display is performed using the difference in light absorption between the two states.

表　　４ 第２図は、この様な表示セルの印加電圧（横軸）と、透
過率（縦軸）の関係を示す。透過率の高い状態Ｏから電
圧を上げていくと、明確な閾値ｖｔｈ　　を経て、着色
状態０へと遷移する。０の飽和は遅く、かなり電圧を上
げても完全ではない。Table 4 and FIG. 2 show the relationship between the applied voltage (horizontal axis) and transmittance (vertical axis) of such a display cell. When the voltage is increased from state O with high transmittance, the state passes through a clear threshold value vth and transitions to colored state 0. Saturation at 0 is slow and is not complete even if the voltage is increased considerably.

表示に必要な駆動電圧としては、ｖｔｈ　の２倍以上が
目処となる。The drive voltage required for display is expected to be at least twice vth.

表５は、本発明に基づく組成物の電圧、及び応答特性を
示す。又、実際用いる場合には、これらの液晶中に光学
活性物質やプレステリツク液晶を加え、電圧印加時にド
メインが現われない様にしている。光、学、活、性物質
等の添加は実質的には、電圧を下げる効果をもち、第２
図の破線−１３の如く１ｖｔｈ　が下がりはじめの立ち
下りも急激になる。Table 5 shows the voltage and response characteristics of compositions according to the invention. In actual use, optically active substances or presteric liquid crystals are added to these liquid crystals to prevent domains from appearing when voltage is applied. The addition of optical, chemical, active, and active substances has the effect of lowering the voltage and has the effect of lowering the voltage.
As shown by the broken line -13 in the figure, when 1vth begins to fall, the fall is also rapid.

第３図はこれら・の液晶へ光学活性を添加した際のｖｔ
ｈ　の変化を示す、横軸が添加量を示す。臨界濃度ａＯ
はこの状態では、コレステリックのねじれ力が強すぎて
、はじめから分子は垂直配向をとれない臨婬値である。Figure 3 shows the vt when optically active substances are added to these liquid crystals.
The horizontal axis shows the change in h and the amount added. Critical concentration aO
In this state, the cholesteric twisting force is so strong that the molecules cannot maintain vertical alignment from the beginning.

従って適当量の光学活性の添加により充分５ｖ駆動も可
能である。Therefore, sufficient 5V driving is possible by adding an appropriate amount of optical activity.

表６に代表的光学活性種を例示する。（但し、Ｌ、Ｒは
、ネマチック液晶中に添加した際に、左旋性、右旋性の
ラセン構造をとる事を示す。）表　　５ 以上の実施例からも明らかな如く、本発明に基づく液晶
組成物は、ゲスト・ホスト等に用いられた場合、低電圧
駆動が可能で、これにより、明るい背景にスッキリした
カラー表示ができるｌジ聾表示を、ウォッチ、クロック
類をはじめ、小型情報機器に普及しうるちのである。Table 6 illustrates representative optically active species. (However, L and R indicate that when added to a nematic liquid crystal, it takes a levorotatory or dextrorotatory helical structure.) Table 5 As is clear from the above examples, the liquid crystal according to the present invention When used as a guest/host, the composition can be driven at a low voltage, making it possible to use digital deaf displays, which can display clear colors on a bright background, in watches, clocks, and other small information devices. It is popular.

表　　６Table 6

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は、Ｇ−Ｈ効果を用いた表示セルの構成を示す。 １．２・・・・・・透明電極 ３．４・・・・・・ガラス板 ５．６・・・・・・垂直配向膜 ７．８・・・…スペーサー ９・・・・・・・・・・・・周辺部 ・１０・・・・・・・・・点灯部 第２図は、ポジＩ！！（）１１セルの光透過率の電圧依
存性を示す。 １１・・・・・・非点灯状態 １２・・・・・・点灯状態 １３・・・・・・光学活性物質を添加した状態第３図は
、閾値電圧ｖｔｈ　の光学活性添加量依存性を示す。 以　　上 出願人　株式会社諏訪精工舎 代理人　弁理士　最上　　務FIG. 1 shows the configuration of a display cell using the GH effect. 1.2...Transparent electrode 3.4...Glass plate 5.6...Vertical alignment film 7.8...Spacer 9... ...Peripheral part 10......Lighting part Figure 2 is positive I! ! () shows the voltage dependence of the light transmittance of 11 cells. 11: Non-lighting state 12: Lighting state 13: Optically active substance added state FIG. 3 shows the dependence of the threshold voltage vth on the amount of optically active material added. . Applicant Suwa Seikosha Co., Ltd. Patent Attorney Tsutomu Mogami

Claims (1)

【特許請求の範囲】 １、一般式が各々 ａ）　　Ｒ１−４−００−０−ｏ−０−Ｒ２ｂ）Ｒ３−
００−０木０−Ｏｏ−Ｒ４ ｃ　）　　Ｒ６−０００ｆ　Ｒ＠ （但し、ｕｌ、Ｒｘ、ｕｓは算＝１〜８の一０ｒＬＨ２
ｎ＋１を、又Ｒ３，Ｒ４はｓ＝１〜８の一０ＷＨＩＫ＋
１　　、−０−０３Ｈ！Ｗ＋１　　、ぺ１）−ＯＴＬＨ
１ａ＋１、−０−ａ％Ｈｘｒ＆＋ｔ　　、−＠−＠−０
ｓＨｓｓ＋ｔを、又、Ｒｉ　はｏｓｕｔｓ＋ｔ＋　、　
　ａｓａｓｓ＋ｔ−＠−。 す。） で与えられる化合物を混合して得られる誘電異方性が負
の液晶組成物。 ２、一般式が Ｒγ−＠−＠−０・Ｒ１（但し、Ｒ７，Ｒ１はルー１〜
Ｂの０ｆＬＨ１ｆＬ＋１　を示す。）で与えられる化合
物を含む特許請求の範凹第１項記載の液晶組成物。 五　分子内に不整炭素を有する光学活性物質又はコレス
テリック液晶を含む、特許請求の範匪第１〜２項記載の
液晶組成物。[Claims] 1. Each of the general formulas a) R1-4-00-0-o-0-R2b) R3-
00-0 Tree 0-Oo-R4 c) R6-000f R@ (However, ul, Rx, us are calculations = 1 to 8, 10rLH2
n+1, and R3 and R4 are s=1 to 8 -WHIK+
1, -0-03H! W+1, Pe1)-OTLH
1a+1, -0-a%Hxr&+t, -@-@-0
sHss+t, and Ri is osuts+t+,
asass+t-@-. vinegar. ) A liquid crystal composition with negative dielectric anisotropy obtained by mixing the compounds given by 2. The general formula is Rγ-@-@-0・R1 (however, R7 and R1 are Ru1~
0fLH1fL+1 of B is shown. ) A liquid crystal composition according to claim 1, comprising a compound given by: 5. The liquid crystal composition according to claim 1 or 2, which contains an optically active substance or cholesteric liquid crystal having asymmetric carbon in its molecule.