Phenyl biphenyl carboxylates or biphenyl benzoates - as additives to liq crystals for dielectrics for electronic components

摘要

Biphenyl estes of formula (I): where X is -CO-O- or -O-CO- and R' and R2 are (un)branched 1-8C alkyl or alkoxy groups are used for prepn. of liq. crystals, esp. dielectrics for electronic components. They cannot be used alone in electronic indicators for use at room temp. because of high m.pt. (>90 degrees C) and clear points (>170 degrees C), but as additives to other liq. crystals they cause lowering of the m.pt. and increase in the clear point, without great increase in viscosity. Pref. esters have a nematic phase and a smectic phase and are esp. those in which X is -CO-O-. Many liq. crystals which have an unsuitable temp. range of the nematic mesophase can be used as dielectrics in admixt. with I. Dielectrics with positive or negative dielectric anisotropy can be obtd. by suitable choice of the initial liq. crystal.