Patent number: 4491532
Abstract: Liquid-crystal mixture with a pleochroic anthraquinone dye of the general formula ##STR1## with R.sup.1, R.sup.3, R.sup.4, R.sup.6 =H, OH, OCH.sub.3, NH.sub.2, NHCH.sub.3, NO.sub.2, characterized by the feature that ##STR2## (R.sup.7 =H, alkyl, cycloalkyl, alkoxy, alkylmercapto, amino, alkylamino, dialkylamino, nitro, cyano, halogen), ##STR3## COOR.sup.9, CH.sub.2 --OR.sup.9 (R.sup.8 =H, alkyl, cycloalkyl, alkoxy, alkylmercapto, amino, alkylamino, dialkylamino, nitro, cyano, halogen); R.sup.9 =H, alkyl and either R.sup.1, R.sup.4 =H, OH, NH.sub.2, NHCH.sub.3, NO.sub.2, NHCH.sub.3, NO.sub.2, OCH.sub.3, where at least one of the two radical is an NH.sub.2 or an NHCH.sub.3, R.sup.3 =R.sup.6 =H, or R.sup.3, R.sup.6 =H, OH, NH.sub.2, NHCH.sub.3, NO.sub.2, OCH.sub.3, where at least one of the two radicals is an NH.sub.2 or an NHCH.sub.3, R.sup.1 =R.sup.4 =H.
Type:
Grant
Filed:
September 10, 1981
Date of Patent:
January 1, 1985
Assignee:
Siemens Aktiengesellschaft
Inventors:
Gunther Scherowsky, Alexander Moller, Gerd Heppke, Burkhard Knippenberg