Veb Werk Fur Fernsehelektronik Im Veb Kombinat Mikroelektronik

Veb Werk Fur Fernsehelektronik Berlin Im Veb Kombinat Mikroelektronik

Rudolf Wolff

Dietrich Demus

Horst Zaschke

Horst Kresse

Wolfgang Weissflog

Gerhard Pelzl

The invention relates to liquid-crystalline nematic mixtures which are used in electro-optical components, as well as to methods for their preparation. The object of the invention is liquid-crystalline mixtures for electro-optical arrangements possessing high positive electrical anisotropy at a high clarification point, as well as methods for their preparation. According to the invention, liquid-crystalline nematic mixtures are used, wherein at least one component is a 1,4-disubstituted benzene derivative and the other compound is an ester of 4-[2,2-dicyano-ethenyl]-phenol of the general formula ##STR1## wherein R.sup.1 denotes added groups of various characters such as alkyl or alkoxy for example, X is aromatic, cycloaliphatic or a heterocyclic ring system such as phenyl or cyclohexyl for example; and Y is a connector such as carbonyloxy, azomethine, azoxy. These are prepared by reaction with reactive acid derivatives, particularly acid chlorides, or by a Knoevenagel-condensation by reacting respective 4-subst.-benzoic acid-[4-formyl-phenyl esters] or 4-alkyl-cyclohexanecarboxylic acid-[4-formyl-phenyl esters] with malonic acid dinitrile.

Esters of 4-[2,2-dicyano-ethenyl]-phenols

A nematic liquid crystal mixture for modulation of the transmitted or incident light and for rendition of colored numerals, symbols and images in electro-optical devices, the said mixture comprising

Nematic liquid crystal mixtures

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Halle, Germany

Rudolf Wolff