Compositions – Liquid crystal compositions – Containing nonsteryl liquid crystalline compound of...
Patent
1997-12-11
2000-02-08
Kelly, C. H.
Compositions
Liquid crystal compositions
Containing nonsteryl liquid crystalline compound of...
25229966, 25229967, C09K 1930, C09K 1912, C09K 1920
Patent
active
060224932
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a liquid crystal composition for a liquid crystal display device, a process for producing the liquid crystal composition, and a liquid crystal display device utilizing the liquid crystal composition.
BACKGROUND ART
In active matrix displays (AM-LCD) having an integrated non-linear device as a switching device typified by a non-linear two terminal device such as a variable resistor or diode, and a non-linear three terminals device such as a thin film transistor (TFT), liquid crystal compositions having a high voltage holding ratio are required compared with conventional displays of passive modes such as a twisted nematic mode, guest host mode, super twisted nematic mode, and SBE (Super Birefringence Effect) mode. AM-LCD utilizing a liquid crystal composition having a low voltage holding ratio can not provide a high quality display, since it causes phenomena such as spotting, flickering, and lowering in contrast. Besides, the lowering of voltage holding ratio under the environment in which an AM-LCD is used raises other problems.
Since, in many instances, liquid crystal materials, as a single compound, used for displays do not satisfy various requirements for properties such as temperature range of liquid crystal phase, viscosity, optical anisotropy, dielectric anisotropy, elastic constants (K.sub.11, K.sub.22, K.sub.33), driving voltage, chemical and physical stability and long term stability of them, consumptive electric current, specific resistance, voltage holding ratio, and temperature dependency of these parameters which meet to various displays, a mixture of a plural number of compounds (hereinafter, sometimes, referred to as liquid crystal composition) is generally used.
Heretofore, it is known that the chemical structure of liquid crystalline compounds used for displays is usually a rod-like, and that the chemical structure can roughly be divided into a terminal group portion, ring structure portion, and the portion of bonding group which links a ring with another ring. Ring bonding group portion may sometimes have lateral substitutents.
As the literature which shows such facts, for example, the following can be mentioned: Kohji OKANO and Shunsuke KOBAYASHI), pp. 178-204, published by Baifuhkan Co., Ltd. (1985) Narikazu KUSABAYASHI), pp. 67-94, published by Kohdansha Co., Ltd. (1991) Liquid Crystals, Springer-Verlag (1992) Tabellen, VEB Deutscher Verlag fuer Grundstoff Industrie, Leipzig (1976) Deutscher Verlag fuer Grundstoff Industrie, Leipzig (1984),
In more specific explanation, liquid crystalline compounds used for displays are organic compounds having the structure expressed by the following general formula (2) a group in a ring form, Z represents covalent bond or a bonding group (bridge), n is an integer of 1 or greater, and X represents an electron attractive group or a group in a chain form.
Generally, R is called "side chain", the portion of --(A.sup.1 --Z).sub.n -- A.sup.2 -- is called "core", and X is called "terminal group". When the terminal group X is an electron attractive group, it is called "polar group", and when this is a chain form group, it is called another "side chain". In some cases, the ring of the "core" has some substitutents such as halogen at its side position, and such substituents are called "lateral group". While n is an integer of 1 or greater, liquid crystalline compounds in which n is 4 or greater are rare. Also, when n is 2 or greater, in many cases, (A.sup.1 --Z) is not the repetition of the same structure.
As the side chain corresponding to R and X, an alkyl group, alkoxy group, alkenyl group, alkenyloxy group, and oxalkyl group are typical ones. Whereas these groups are usually straight chains, sometimes they are branched. As the polar group corresponding to X, cyano group, a halogen, --CF.sub.3, --OCF.sub.3, --OCHF.sub.2, --OC.sub.2 F.sub.5, --OCF.sub.2 CHF.sub.2, and --NCO are typical ones.
As the ring form group A.sup.1 and A.sup.2 in the core, while six-membered rings such as 1,4-phenylene, trans-1,4-cyc
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Kitano Kisei
Koyama Susumu
Suzuki Toshiharu
Chisso Corporation
Kelly C. H.
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