Liquid crystal medium contg. ethyl, butyl or hexyl cyclohexyl benzene cpd. - to reduce threshold voltage and use in electro=optical display

摘要

The medium based on a mixt. of polar cpds. with positive dielectric anisotropy, contains 4-(4-ethyl, 4-n-butyl- or 4-n-hexyl-cyclohexyl)-fluoro-, chloro-, trifluoromethyl-, trifluoromethoxy or difluoro-methoxy-benzene cpd(s). (I) of formula H-(CH2CH2)n-Cyc-Phe-X where, Cyc is trans-1,4-cyclohexylene; Phe is 1,4-phenylene; X is F, Cl,CF3, OCF3 or OCHF2; n is 1, 2 or 3. (I) are known cpds. or can be prepd. by methods analogous to those for known cpds. No details are given in the text. Pref. the medium also contains 4-(trans-cyclohexyl)- or 4-(trans-4-(trans-cyclohexyl)-cyclohexyl)-benzene cpds. (II); 1-cyclohexyl- or 1-(4-(cyclohexyl)-cyclohexyl)-2-phenyl-ethane cpd(s). (III); 1-cyclohexyl-2-(4-(phenyl)-cyclohexyl)ethane cpd(s). (IV). USE/ADVANTAGE - The medium is claimed for use for electrooptical purposes, esp. in electrooptical LCDs. It has very high specific resistance and very low threshold voltage. Even small amts. of (I) improve the response time and threshold voltage and wide nematic phases with low smectic-nematic transition temps. are obtd. (I) are colourless, stable and miscible with other LC material