Compositions – Liquid crystal compositions – Containing nonsteryl liquid crystalline compound of...
Patent
1994-04-20
1995-05-30
Wu, Shean
Compositions
Liquid crystal compositions
Containing nonsteryl liquid crystalline compound of...
25229901, 25229961, 25229964, 25229965, 25229966, 544335, 549380, 560 8, 570127, 359103, C09K 1930, C09K 1952, C07C 2513, G02F 113
Patent
active
054198518
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to difluoro-derivative compounds, compounds having a liquid crystal property selected from such derivatives, liquid crystal compositions containing the difluoro-derivative compounds, and liquid crystal electro-optical devices using the liquid crystal compositions.
BACKGROUND ART
Liquid crystal display devices have been used for watches and electronic calculators and in recent years for various applications including measuring devices, automobile meters, copying machines, cameras, display devices for office appliances and display devices for consumer products. Accordingly, various functions including a wide temperature range for operation, a low voltage for driving, a high response speed, a high contrast ratio, a wide visual angle and chemical stability, are required for such liquid display devices.
However, at present, there is no single material which by itself satisfies all of such requirements, and it is common to satisfy such requirements by a liquid crystal composition prepared by mixing a plurality of liquid crystal materials and non-liquid crystal materials. Accordingly, it is desired to develop a liquid crystal material or a non-liquid crystal material which is excellent in one or more functions, if not in all the required functions.
In the field of the display device using liquid crystal, it is desired to improve its performance. For this purpose, low voltage driving, highly fine display, a high contrast ratio, a wide visual angle characteristic, a low temperature response characteristic and a wide range of driving temperature are, for example, desired. These functions have a tendency such that when some of them are improved, others have to be sacrificed.
Recently, improvement of a response speed is particularly desired. For example, in driving the device by an electrical cell, low voltage drive and high speed response are desired; in e.g. the office appliances, highly fine display and high speed response are required; and in the display for automobiles, low temperature response or high speed response within a wide temperature range for operation is desired.
In this respect, several methods for improvement are conceivable. One of them is to adopt a liquid crystal composition having a low viscosity. Namely, if the viscosity of the liquid crystal composition is reduced, the response speed can be improved so that a display will be possible at a practical speed even at a low temperature. Further, if the response speed may be at a level equal to the conventional speed, it will be possible to drive the device at a lower voltage, or a higher duty drive or highly fine drive, will be possible.
For such a purpose, a p,p'-disubstituted difluorostilbene compound has been proposed, as disclosed at the 16th Liquid Crystal Discussion Meeting. This compound has a chemical structure as shown by the following formula (3): ##STR1## provided that in the formula (3), each of R.sup.A and R.sup.B is a n-alkyl group, a n-alkoxy group or a n-alkoxycarbonyl group.
The compound of this formula (3) has a low viscosity and has the stability against light improved over a stilbene compound which is not substituted by fluorine. However, as compared with commonly employed liquid crystal compounds, its stability against light is still poor, whereby in many cases, the useful environment has been rather limited, or it has been required to use an ultraviolet ray-preventive film.
Accordingly, a liquid crystal material having a low viscosity and having a high stability against light, has been desired.
It is an object of the present invention to provide a novel material thereby to solve the above problem.
The present invention provides a difluoro-derivative compound of the following formula (1): --(Y.sup.2 --A.sup.4).sub.n --R.sup.2 ( 1) Y.sup.1, Y.sup.2, m, n, R.sup.1 and R.sup.2 are as follows:
each of A.sup.1, A.sup.2, A.sup.3 and A.sup.4, which are independent from one another, is a cyclic group selected from a trans-1,4-cyclohexylene group, a 1,4-cyclohexenylene group and a 1,4-phen
REFERENCES:
CA96: 1991852, Abstract, 1982.
Irisawa Jun
Koh Hidemasa
Yokokoji Osamu
Asahi Glass Company Ltd.
Wu Shean
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