| 摘要 |
A liquid-crystal mixture for guest/public host electro-optical displays essentially comprises a nematic liquid-crystal material having positive or negative dielectric anisotropy as the host phase, with which without an optically active additive for cholesteric alignment of the host phase, and at least one pleochroic anthraquinone dye included as guest phase in the host phase; the anthraquinone dye has the Formula (1) <IMAGE> in which R<1>, R<2>, R<3> and R<4> are hydrogen atoms, hydroxyl, methoxy, amino, methylamino, dimethylamino or nitro groups, m is 1 or 2, n is zero, 1 or 2, X is a single bond, -CH=N-, -COO-, -COS-, -CH2O-, -CH2CH2-, -O-, -S-, or -SO3-, R<5> or R<6> are identical or different and are hydrogen atoms, R, OR, OROH, OROR, RORSROH, NHR, the 2-hydroxyethyl radical or radicals of the formula (1a) or (1b) <IMAGE> in which Z is halogen, R, OR, OROH, OROR, COOR, OOCR, OCOOR, NO2, NHR, CN, NH2 or NCH3R, R is an alkyl group having 1 to 15 carbon atoms, and R' is C1-C15-alkylene. The above formula (1) excludes antiquinone dyes described in Swiss patents 641 828, 643 250 and 643 289 and in the publication Xerox Discl. J. 1,61-62 (1976 (formula (1f)).
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