| abstract |
A liquid crystal mixture for electro-optical displays without polarizing cover disks essentially consists of a nematic liquid crystal mass with positive or negative DK anisotropy as the host phase, an optically active additive for cholesteric orientation of the host phase and at least one as a guest phase in the host phase embedded pleochroic anthraquinone dye; the anthraquinone dye is one of the formula (1) <IMAGE> in which R¹, R², R³ and R <4> are hydrogen atoms, hydroxylamines or nitro groups, m is 1 or 2, n is zero, 1 or 2 , R <5> and R <6> are identical or different and denote hydrogen atoms or radicals of the formulas (1a) or (1b) <IMAGE>, in which a is an integer from 1 to 10, b is zero or an integer from 1 to 6 and X represent the oxygen or sulfur atom, a single bond or the oxycarbonyl group and R 7 is the hydrogen atom, an alkyl or alkoxy group having 1 to 12 C atoms or a phenyl or phenoxy group. |