Compositions – Liquid crystal compositions – Containing nonsteryl liquid crystalline compound of...
Patent
1988-12-23
1993-03-23
Stoll, Robert L.
Compositions
Liquid crystal compositions
Containing nonsteryl liquid crystalline compound of...
25229961, 25229962, 25229963, 25229964, 25229966, 25229967, 25229901, 570129, 359103, 359106, C09K 1906, C09K 1934, C09K 1952, G02F 113
Patent
active
051961407
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an electro-optical liquid crystal display element containing a dielectric with at least two liquid-crystalline components, characterized in that, for shortening the switching times, the dielectric contains at least one fluorine-containing compound of the formula I unsubstituted or substituted alkyl group having 1-15 C atoms, in which one or two CH.sub.2 groups can also be replaced by a grouping selected from the group comprising --O--, --CO--, --O--CO--, --CO--O--, --CH--halogen--, --CHCN--, --CCH.sub.3 CN--, --C.tbd.C-- and --CH.dbd.CH--, no 2 heteroatoms being directly linked to one another, C atoms, in which one or more CF.sub.2 groups can also be replaced by a grouping selected from the group comprising --O--, --CO--, --O--CO--, --CO--O--, --CH.sub.2 --, --CH--halogen--, --CHCN--, --C.tbd.C--, --CH.dbd.CH--, --CH.dbd.C--halogen-- and --C--halogen.dbd.C--halogen--, no two heteroatoms being directly linked to one another and the perfluoroalkyl group containing at least two CF.sub.2 groups, which is unsubstituted or substituted by one or two F and/or Cl atoms and/or CH.sub.3 groups and/or CN groups and in which one or two CH groups can also be replaced by N atoms, 1,4-cyclohexylene in which one or two non-adjacent CH.sub.2 groups can also be replaced by 0 atoms and/or S atoms, piperidine-1,4-diyl, 1,4-bicyclo[2.2.2]octylene, unsubstituted or CN-substituted decahydronaphthalene-2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl, and A.sup.2 is also a single bond, --CH.sub.2 --, substituted ethylene or a single bond, different in the case of m=2 or 3, with the proviso that, in the case of m=0, the sum of the number of C atoms in the two groups R.sup.1 and R.sup.2 is at least 8, and to fluorine-containing additives for liquid-crystalline dielectrics which are suitable for shortening the switching times in electro-optical liquid crystal display elements. The invention also relates to novel compounds of the formula I, which correspond to the formulae I, III and IV.
Liquid-crystalline dielectrics can be used in various electro-optical display elements, in particular in displays which . . . (sic) on the principle of the twisted cell (TN displays), the Guest-Host effect, the effect of the deformation of aligned phase, the effect of dynamic scattering, the SBE effect (supertwisted birefringent effect), in STN displays (supertwisted nematic displays) and in ferroelectric displays, for example based on SSFLC technology. The expression "dielectric" used in this application thus relates to mixtures which contain a nematic, cholesteric or smectic (especially Sc*) mesophase.
In order to be suitable for the display elements listed above, the dielectrics must meet a large number of very diverse demands matched to the particular display principle, which, however, include in virtually every case very short switching times which, inter alia, can also be achieved by viscosity-reducing additives. Such additives have already been described in the literature (German Offenlegungsschrift 2,548,360, German Offenlegungsschrift 2,823,909). Disadvantages of these known additives are, however, the lowering of the clear point which must be accepted and/or the high vapor pressure of these additives.
It was the object of the invention to provide novel stable dielectrics with fluorine-containing additives, which do not show the above disadvantages, or only to a small extent.
It has now been found that the compounds of the formula I are outstandingly suitable as additives for diverse dielectrics.
Moreover, by the provision of the compounds of the formula I, the range of additives for liquid-crystalline dielectrics, which are suitable for the preparation of liquid-crystalline mixtures under various application aspects, is quite generally widened considerably.
For the sake of simplicity, in the text which follows, Phe designates a 1,4-phenylene group, Cy designates a 1,4-cyclohexylene group, Dio designates a 1,3-dioxane-2,5-diyl group, Bi designates a bicyclo(2,2,2)octylene group, Pyd designates a pyridine-2,5-diyl gr
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Eidenschink Rudolf
Kurmeier Hans A.
Poetsch Eike
Wachtler Andreas
Weber Georg
Harris C.
Merck Patent Gesellschaft mit beschrankter Haftung
Stoll Robert L.
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