Liquid crystal phase

a technology of liquid crystal phase and liquid crystal structure, which is applied in the direction of liquid crystal compositions, instruments, chemistry apparatus and processes, etc., can solve the problems of unfavorable elastic properties of lc phase, unfavorable dissolution process, and inability to easily prepare optimal phase in this way, so as to achieve the effect of observing the complete dissolution process particularly easily

Inactive Publication Date: 2001-07-10
MERCK PATENT GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

It was found, surprisingly, that the combination according to the invention of compounds of the formulae I and III gives LC phases which on the one hand have wide mesophase ranges with low melting points and low smectic-nematic transition temperatures and on the other are capable of multiplexed drive at very low supply voltage by virtue of their good electro-optic steepness, viewing angle characteristic and high dielectric anisotropy.
The preparation of the phases according to the invention is effected in the conventional manner. In general, the desired amount of the components which is used in the smaller amount is dissolved in the components which constitutes the main constituent, preferably at elevated temperature. If this temperature is chosen to be above the clear point of the main constituent, the completeness of the process of dissolving can be observed particularly easily.

Problems solved by technology

However, optimal phases cannot be easily prepared in this way, since the components having the high melting and clear points frequently also confer on the mixtures a high viscosity.
As a result the switching times of the electro-optical display elements prepared therewith are changed in an undesirable manner.
This in turn gives rise to various disadvantages, such as unfavorable elastic properties of the LC phases, and high viscosity.
However, even these LC phases do not meet all the abovementioned requirements at the same time.
In particular, for many applications their threshold voltages are still too high, and, in addition, the steepnesses of the electro-optic characteristic are not sufficient for highly informative displays owing to the relatively large ratio of the elastic constants for bending (K.sub.3) and spreading (K.sub.1)K.sub.3 / K.sub.1.
The hitherto disclosed mixtures therefore have an excessively high threshold voltage and / or an unacceptably poor steepness of characteristics (characterized by an excessively high K.sub.3 / K.sub.1) and / or high temperature dependence of the threshold voltage dV / dT and / or large angular dependence of contrast.

Method used

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Examples

Experimental program
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Effect test

example 1

A liquid crystal phase consisting of

10% of 4-cyano-3-fluorophenyl p-ethylbenzoate

9% of 4-cyano-3-fluorophenyl p-propylbenzoate

7% of 2-p-cyanophenyl-5-propyl-1,3-dioxane

20% of 4-cyanobiphenyl-4'-yl trans-4-ethylcyclohexanecarboxylate

10% of 4-propyl-4'-cyanobiphenyl

3% of 4-cyanobiphenyl-4'-yl p-(p-heptylphenyl)benzoate

14.8% of p-pentylphenyl p-methylbenzoate

17.5% of p-pentylphenyl p-propylbenzoate

8.7% of p-pentylphenyl p-pentylbenzoate

has a clear point of 61.5.degree., an optical anisotropy of 0.138, a viscosity of 66.4 mPa.S at 20.degree. and a saturation voltage of 1.35 volt.

example 2

A liquid crystal phase consisting of

7% of 4-cyano-3-fluorophenyl p-ethylbenzoate

7% of 4-cyanobiphenyl-4'-yl trans-4-ethylcyclohexanecarboxylate

15% of 4-cyano-4'-(trans-4-pentylcyclohexyl)-biphenyl

4% of p-(p-propylhexoxycarbonyl)-phenyl trans-4-ethylcyclohexanecarboxylate

24.3% of p-pentylphenyl p-methylbenzoate

28.4% of p-pentylphenyl p-propylbenzoate

14.3% of p-pentylphenyl p-pentylbenzoate

has a clear point of 62.3.degree., an optical anisotropy of 0.133, a viscosity of 51.9 mPa.S at 20.degree. and a saturation voltage of 2.12 volt.

example 3

A liquid crystal phase consisting of

10% of 4-cyano-3-fluorophenyl p-ethylbenzoate

10% of 4-cyano-3-fluorophenyl p-propylbenzoate

15% of 4-ethyl-4'-cyanobiphenyl

5% of 2-p-cyanophenyl-5-propyl-1,3-dioxane

20% of 4-cyanobiphenyl-4'-yl trans-4-ethylcyclohexanecarboxylate

2% of p-(p-propylphenoxycarbonyl)-phenyl trans-4-ethylcyclohexanecarboxylate

12% of p-propylphenyl trans-4-propylcyclohexanecarboxylate

14.6% of p-pentylphenyl trans-4-propylcyclohexanecarboxylate and

11.4% of p-heptylphenyl trans-4-propylcyclohexanecarboxylate

has a clear point of 60.6.degree., an optical anisotropy of 0.142, a viscosity of 41.1 mPa.S at 20.degree. and a saturation voltage of 1.39 volt.

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Abstract

Liquid crystal phases containing components of the formulae I and IIIhave an acceptable combination of threshold steepness, viewing angle and temperature dependence at a low threshold voltage.

Description

The invention relates to liquid crystal phases (LC phases) having a particularly low threshold voltage and broad nematic phases.BACKGROUND OF THE INVENTIONLiquid crystal display elements (LC display elements) increasingly utilize the properties of nematic or nematic-cholesteric liquid crystal materials of significantly changing their optical properties such as light absorption, light scattering, birefringence, reflectance or color under the influence of electric fields. The function of such display elements is based for example on the phenomena of dynamic scattering, the deformation of aligned phases, the guest-host effect, the Schadt-Helfrich effect in the twisted cell, or the cholesteric-nematic phase transition.The industrial application of these effects in electronic components requires liquid crystal phases which must meet a large number of requirements. Of particular importance here are the chemical resistance to moisture, air and physical factors such as heat, radiation in in...

Claims

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Application Information

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IPC IPC(8): C09K19/46C09K19/20C09K19/30C09K19/34G02F1/137C09K19/42
CPCC09K19/2007C09K19/3001C09K19/3402C09K19/3444C09K19/3469C09K19/46C09K2019/3422C09K19/34C09K19/20
Inventor SAGE, IAN CHARLESCHAMBERS, MICHAEL KEVINHITTICH, REINHARDWEBER, GEORG
Owner MERCK PATENT GMBH
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