Compositions – Liquid crystal compositions – Containing nonsteryl liquid crystalline compound of...
Patent
1998-04-08
1999-11-23
Kelly, C. H.
Compositions
Liquid crystal compositions
Containing nonsteryl liquid crystalline compound of...
25229966, 25229961, 570128, 570129, C09K 1930, C09K 1912, C09K 1934, C07C 1908
Patent
active
059894520
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to liquid crystalline compounds and liquid crystal compositions. More specifically, it relates to novel liquid crystalline compounds having a fluorine substituted alkenyl group at an end and having a fluorine substituted or unsubstituted alkenyl group at the other end of the molecule; relates to liquid crystal compositions comprising the compound; and relates to liquid crystal display devices comprising the composition.
BACKGROUND ART
Display devices comprising liquid crystalline compounds have widely been employed for the displays of watches, tabletop calculators, word processors, TV sets, or the likes. These display devices employ the optical anisotropy and dielectric anisotropy of liquid crystalline compounds.
Liquid crystal phase exists between a solid phase and a liquid phase, and the liquid crystal phase includes a nematic phase, smectic phase, and cholesteric phase as its specific form. Among which, the nematic phase is most in use at present for display devices. As the specific type of display mode, TN (twisted nematic) mode, DS (dynamic scattering) mode, GH (guest-host) mode, DAP (deformation of aligned phases) mode all of which exhibit electro-optic effects have been developed. Meanwhile, display of liquid crystals in color is further progressing lately, and particularly devices of TFT (thin-film-transistor) mode and STN (super twisted nematic) mode both of which form a class of TN mode have now become a main current.
Whereas many liquid crystalline compounds including ones which are currently at a stage of research are known up to now, compounds which can be filled in display devices as a single compound to actually use as liquid crystal composition have not been developed. This is because whereas liquid crystalline compounds expected to be used as a material for display devices must exhibit a liquid crystal phase at room temperature, at which display devices are most often used, as well as in a temperature range as wide as possible with the room temperature being its center; must be sufficiently stable against environmental factors under conditions in which the devices are used; and must have physical properties sufficient to drive display devices, no compounds which can satisfy these requirements by a single compound have been found. Accordingly, it is an actual circumstance at present that several kind or several tens kind of liquid crystalline compounds, and non liquid-crystalline compounds when necessary, are mixed to prepare liquid crystal compositions having the required characteristics. It is considered to be necessary that these liquid crystal compositions are stable against moisture, light, heat, and air which are usually present under the conditions in which display devices are used; are stable also against electric field and electromagnetic radiation; and are chemically stable against liquid crystalline compounds to be mixed. Also, it is considered to be necessary that liquid crystal compositions have an appropriate value of physical properties such as optical anisotropy (.DELTA.n), dielectric anisotropy (.DELTA..epsilon.), viscosity (.eta.), electroconductivity, and ratio of elastic constants (K.sub.33 /K.sub.11 ; K.sub.33 : bend elastic constant, K.sub.11 : splay elastic constant) depending on the display modes and the shape of display devices. Further, it is important that each component in liquid crystal compositions have a good mutual solubility to one another.
It is considered to be necessary that the liquid crystal compounds used in displays of STN mode particularly have a low viscosity, large K.sub.33 /K.sub.11, and wide temperature range of a liquid crystal phase in addition to the properties described above. Further, a low threshold voltage (Vth) is quite recently considered to be necessary accompanied with driving of display devices at a low voltage.
That is, low viscosity is an essential property for achieving a high speed response. Also, large K.sub.33 /K.sub.11 makes the change of transmittance around V.sub.th steep and
REFERENCES:
patent: 5183587 (1993-02-01), Kitano et al.
patent: 5653911 (1997-08-01), Kondo et al.
Hachiya Norihisa
Kato Takashi
Matsui Shuichi
Miyazawa Kazutoshi
Nakagawa Etsuo
Chisso Corporation
Kelly C. H.
LandOfFree
Fluoroalkenyl derivative and liquid crystal composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fluoroalkenyl derivative and liquid crystal composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fluoroalkenyl derivative and liquid crystal composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1217392