JP2006273978A - Liquid crystal composition containing binaphthyl-containing compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal composition stable in bend state. <P>SOLUTION: The liquid crystal material is obtained by adding an optically active compound represented by the general formula to a nematic liquid crystal composition. Wherein, A and B are a linkage such as ether or ester; X is a hard structure called as core; C and D are an electron-withdrawing group or an electron donating group such as an alkyl, an alkoxy or a halogen; m and n are each independently an integer of ≥1; and, in the formula, absolute configuration of optically active binaphthyl having axial asymmetry may be R or S. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal composition containing a compound having an optically active binaphthyl group, and more particularly to a liquid crystal composition capable of accelerating a spray-bend transition in an OCB mode liquid crystal display.

  The problem with the current liquid crystal display is to improve the high-speed response that can withstand moving image display. Conventionally, there are mainly development of a drive mode (Non-Patent Document 1) and development of a liquid crystal material (Non-Patent Document 2) as an approach to such a problem. In the former mode development, an OCB mode has been developed, which has been demonstrated to be faster than the conventional TN mode.

Satoshi Nakamura "Liquid Crystal" 2001, 5, 253 Akihiro Kubo “Liquid Crystal” 2001, 5, 327

However, in order to drive the OCB mode, it is necessary to transfer the orientation of liquid crystal molecules from splay to bend. However, there is a problem that rapid transfer is difficult. For such problems,
・ High voltage applied,
・ Introduction of vertical alignment,
・ Introduction of twist by chiral liquid crystal material,
-Conventionally, a solution means such as formation of a twisted region by orientation control has been proposed. However, it has not led to rapid transition at low voltage.

  The problem to be solved by the present invention is that, except for the above-mentioned problems of the prior art, by adding a compound that induces a unique twisted structure to a nematic liquid crystal material, the bend state that has been difficult with the addition of a conventional chiral compound is stabilized. And providing a liquid crystal composition.

  The inventor of the present application has shown that a compound in which a liquid crystal forming group is linked to an optically active binaphthyl group exhibits a phase sequence called Iso-BP-SmA, which stabilizes a blue phase (BP), and further makes a nematic liquid crystal material. It was found to induce a short helical pitch. In considering this phase transition behavior, it was considered that this compound induced two twists consisting of a binaphthyl group and a mesogenic moiety, and as a result, the blue phase was stabilized. Based on the above studies, when a compound having a binaphthyl group was added to a nematic liquid crystal, a spray-bend transition was accelerated and a liquid crystal composition in which the bend state was stabilized was obtained, leading to the present invention. That is, the invention claimed in the present application, or at least the disclosed invention, as means for solving the above-described problems is as follows.

（式中、Ａ、Ｂはエーテル、エステルなどの結合基。Ｘはコアとよばれる堅い構造をもち、たとえば、ベンゼン、ピリミジン、シクロヘキサンなどからなり、その水素の一部がフッ素等のハロゲン原子で置換されているものも含む。Ｃ、Ｄはアルキル基、アルコキシ基、ハロゲン基などの電子吸引基または電子供与基。ｍ、ｎはそれぞれ独立した１以上の整数である。式中の軸不斉を持つ光学活性なビナフチル基の絶対配置はＲまたはＳのどちらでもよい。）
すなわち、上記一般式で示される光学活性化合物をネマチック液晶組成物に添加して得られる液晶材料。
（２） 前記一般式（化１）で表される化合物を、０．０５ｗｔ％以上５ｗｔ％以下含有することを特徴とする、（１）に記載の液晶組成物。
（３） ネマチック液晶組成物に対する、スプレイ−ベンド転移の加速およびベンド状態の安定化のための、（１）に記載の前記一般式（化１）で表される化合物の使用。 (1) A chiral nematic liquid crystal composition comprising an optically active compound represented by the following general formula (Formula 1).

(In the formula, A and B are linking groups such as ether and ester. X has a rigid structure called a core. For example, it consists of benzene, pyrimidine, cyclohexane, etc., and part of the hydrogen is a halogen atom such as fluorine. C and D are electron-withdrawing groups or electron-donating groups such as alkyl groups, alkoxy groups, halogen groups, etc. m and n are each independently an integer of 1 or more. The absolute configuration of the optically active binaphthyl group having R may be either R or S.)
That is, a liquid crystal material obtained by adding an optically active compound represented by the above general formula to a nematic liquid crystal composition.
(2) The liquid crystal composition according to (1), comprising 0.05 wt% or more and 5 wt% or less of the compound represented by the general formula (Formula 1).
(3) Use of the compound represented by the general formula (Chemical Formula 1) described in (1) for acceleration of a spray-bend transition and stabilization of a bend state for a nematic liquid crystal composition.

  Since the liquid crystal composition of the present invention is configured as described above, according to this, it is possible to accelerate the spray-bend transition in the OCB mode liquid crystal display, and the bend state, which has been difficult with the addition of a conventional chiral compound, can be achieved. A stable liquid crystal composition can be obtained.

Hereinafter, the present invention will be described in more detail.
Some specific examples of the compounds represented by the above general formula are shown below.

An example of a basic synthesis scheme for obtaining the above compound is shown below.

  That is, it is synthesized through a two-step reaction by Williamson synthesis. Both steps are reacted in the presence of potassium carbonate in cyclohexanone.

Examples of the present invention will be described below, but the present invention is not limited to such examples.
<Example 1>
A liquid crystal composition in which 0.3 wt% of the following compound (Chemical Formula 6) is added to 99.7 wt% of the host nematic liquid crystal material A is placed in an OCB cell, and the transition time from spray to bend when applied from 0 V to 6 V is 18 s, from 6 V The time to return from the bend to the spray when the voltage was 0 V was 817 s.

<Comparative Example 1>
When the host nematic liquid crystal material A was observed under the same conditions, the transition time from spray to bend was 43.5 s, and the transition time from bend to spray was 120 s.

  From the above, by adding a very small amount of the above compound (Chemical Formula 6), the transition time from spray to bend became half or less, and the time to return from bend to spray became six times or longer. This demonstrates that the compound accelerates the spray-bend transition and stabilizes the bend state.

The liquid crystal composition (liquid crystal material) of the present invention is extremely effective in producing a liquid crystal composition constituting an optoelectronic-related element such as an optical printer head or a light valve for a display such as a liquid crystal television or a personal computer monitor. It is an invention with high industrial utility value.

Claims (3)

A chiral nematic liquid crystal composition comprising an optically active compound represented by the following general formula (Formula 1):

(In the formula, A and B are linking groups such as ether and ester. X has a rigid structure called a core. For example, it consists of benzene, pyrimidine, cyclohexane, etc., and part of the hydrogen is a halogen atom such as fluorine. C and D are electron-withdrawing groups or electron-donating groups such as alkyl groups, alkoxy groups, halogen groups, etc. m and n are each independently an integer of 1 or more. The absolute configuration of the optically active binaphthyl group having R may be either R or S.) 2. The liquid crystal composition according to claim 1, wherein the compound represented by the general formula (Formula 1) is contained in an amount of 0.05 wt% to 5 wt%. Use of the compound represented by the general formula (Chemical Formula 1) according to claim 1 for acceleration of a spray-bend transition and stabilization of a bend state for a nematic liquid crystal composition.