JPS6047093A - Liquid crystal composition - Google Patents

Abstract

PURPOSE:To provide a liquid crystal compsn. consisting of specified cyclohexane, azoxy and compensation type cholesteric liquid crystals and cholesteryl nonanoate, which makes high speed input possible and has a short transient turbidity time in transition to a storage state. CONSTITUTION:The liquid crystal compsn. is prepd. by blending (A) cyclohexane liquid crystal of formula I (where R1 is 1-7C straight chain alkyl or straight chain alkoxyl), (B) azoxy liquid crystal of formula II and/or III (where R2 is 1-7C alkyl or alkoxyl; R3 is R1 or cyano), (C) compensation type cholesteric liquid crystal consisting of a mixt. of cholesteryl myristenite of formula IV and cholesteryl chloride of formula V in a blend ratio of 1-1.75:1 by weight and (D) cholesteryl nonanoate of formula VI, with (C) and (D) contained each in 6- 10wt% and used in a ratio of 2:3 or lower. EFFECT:The liquid crystal compsn. makes it possible to perform high speed input in less than 10sec and controls transient turbidity time in transition to storage state to less than 3sec.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a liquid crystal material for an accumulation type liquid crystal display, and in particular to a liquid crystal material for an accumulation type liquid crystal display, and in particular to a liquid crystal material for storage type liquid crystal display. The present invention relates to a liquid crystal composition that can shorten the period of clouding.

(2) Background of the Technology A liquid crystal having positive dielectric anisotropy changes from a transparent state to a cloudy state as an electric field voltage is applied to the liquid crystal, and then becomes transparent again when a certain voltage is reached. This transparent state can be returned to the initial transparent state by rapidly removing the applied voltage. Storage type liquid crystals with positive dielectric anisotropy have two stable states when the electric field voltage is zero:
In other words, it is characteristic of 1+5 in that the cloudy state and the transparent state can be arbitrarily selected.

An M-type liquid crystal display with positive dielectric anisotropy utilizing nematic-cholesteric phase transition is produced by utilizing the relationship between applied voltage and light transmittance as shown in FIG.

First, when no electric field is applied, it is in the state G in FIG. 1 and is transparent. When a voltage is gradually applied to this, the liquid crystal layer becomes cloudy and enters the F state.

By further applying a voltage to Vl, the liquid crystal becomes a transparent H state by applying a voltage of 1 or more. Here, the states G, , and F are both in the cholesteric phase, and the state H is in the nematic phase. That is, by applying a voltage on the VHO, the liquid crystal undergoes a phase transition from a cholesteric phase to a nematic phase.

Since the H or 1]' state after the phase transition is a state in which writing can be performed, the change in G-F-H is called initialization.

In the storage type liquid crystal display, the voltage is zeroed from this l] or 11' state and G (transparent: not selected) or Fo (/!3
2 selections), change the state and write to each. At this time, the voltage required to maintain the initialized state is the driving voltage (2), and (2) and (2) have a relationship of 2Vo and V+.

Note that when transitioning from the transparent initial state H or H' to the transparent stable state jDQ, actually H(H')-F-G
Take that route. Therefore, in principle, in storage type liquid crystal displays, cloudiness occurs for several seconds when the screen is fixed.

(3) Conventional technology and problems Conventional storage type liquid crystals have a writing time of 20 to 401 na, and although some compositions can write in several ms, the temporary clouding time when transitioning to the storage state is long, and Even if the process is performed quickly, the disadvantage is that it takes a long time to display the image as a whole. This cloudy time is called the rapid passage time π, and in conventional high-voltage storage type liquid crystals, it takes several to several tens of seconds for πkl).

(4) Purpose of the Invention The present invention enables high-speed writing of 10 m5 or less by limiting the type and mixing ratio of cholesteric liquid crystal in the storage type liquid crystal composition, and the temporary clouding time at the time of transition to the storage state is within 3 seconds. The goal is to provide a liquid crystal composition that can be controlled.

-(5) Structure of the Invention The storage type liquid crystal composition of the present invention is a storage type liquid crystal composition using a nematic-cholesteric mixed liquid crystal exhibiting positive dielectric constant anisotropy. consisting of an azoxy-based liquid crystal of formula 1ja and/or formula nb, a neutralized cholesteric liquid crystal of 2) and cholesteryl nonanoate of formula 1v,
The composition ratio of the compensating cholesteric liquid crystal and the cholesteryl nonanoate is 6 to 10% by weight, and the ratio of the compensating cholesteric liquid crystal to cholesteryl nonanoate is 2:3 or less (formula Medium R
7 is a straight chain alkyl group having 1 to 7 carbon atoms or υ (In both formulas, RL is an alkyl group or alkoxy group having 1 to 7 carbon atoms, and R3 is a straight chain alkyl group having 1 to 7 carbon atoms.
Formula II (compensated cholesteric liquid crystal): (2) cholesteryl myristite: cholesteryl loride 1.
00 : 1.75 weight ratio).

Formula ■ (Cholesteryl Nonanoate) If the composition ratio of the compensated cholesteric liquid crystal and cholesteryl nonanoate is greater than 10 wt%, π112P becomes too long, and if it is less than 6 wt%, a memory effect is obtained, and the composition ratio of the compensated cholesteric liquid crystal and cholesteryl nonanoate is When the ratio of cholesteryl nonanoei is 1 to 2:3, the writing speed of humans becomes slower.

The present invention aims to reduce the viscosity of the mixed liquid crystal by using the compensation type cholesteric liquid crystal in the storage type liquid crystal composition, to shorten the temporary clouding time at the time of transition to the storage state, and to reduce the helical pitch of the mixed liquid crystal by using cholesteryl nonanoate. By shortening the length and increasing the winding force of the helix, high-speed writing can be performed.

(6) Embodiments of the Invention Example 1 A storage type liquid crystal was prepared with the following composition and injected into a 9 μm cell with a gear of 7. When multiplex driving was performed, the writing time per line was 5.8 ms.

Example 2 When a concentrated liquid crystal was prepared with the composition shown below and injected into a cell with a gap of 9 μm and multiplex driving was performed, the writing time per 1 line was 6.7 ms.

According to the present invention, the writing power on one screen of A4 size (300 lines) large liquid crystal display is 8 seconds (- 6 seconds per line).
m5), and the transition to the storage state can be made within 3 seconds, which has the effect of allowing large liquid crystal displays to be driven at high speed.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the operating principle of a storage type liquid crystal that exhibits positive dielectric anisotropy using nematic-cholesteric phase transition. In the figure, H and H' are in a light transmitting state, G is a light transmitting state, F and Fo represent the light scattering pattern b+v, and drive voltage, respectively. . 1 mouthful

Claims (1)

[Claims] 1. In a storage type liquid crystal composition using a nematic-cholesteric mixed liquid crystal exhibiting positive dielectric constant anisotropy, a cyclohexane-based liquid crystal having the structure of the following formula (2), formula 11a and/or formula It consists of an azoxy liquid crystal of nb, a compensated cholesteric liquid crystal of 2), and a cholesteryl nonanoei I of the formula 2. The composition ratio of the compensating cholesteric liquid crystal to cholesteryl nonanoate I is 6 to 10% by weight, and the ratio of the compensating cholesteric liquid crystal to cholesteryl nonanoate is 2:3.
The following (in the formula, Rt is a straight alkyl group having 1 to 7 carbon atoms or a straight chain alkoxy group) υ (In both formulas, R2 is an alkyl group or an alkoxy group having 1 to 7 carbon atoms, and R3 is a straight chain alkyl group having 1 to 7 carbon atoms,
linear alkoxy group or cyano group) Formula II [(compensated cholesteric liquid crystal): (the above cholesteryl myristate: cholesteryl chloride-1,0
0: 1.75 weight ratio) Formula ■ (Cholesteryl nonanoate):