Merck Patent Gesellschaft MIT Beschrankter Haftung

Fernando Del Pino

Ludwig Pohl

Joachim Krause

Georg Weber

Rudolf Eidenschink

Rolf Steinstrasser

Rainer Klink

Ralf Streinstrasser

A liquid-crystalline dielectric having a positive dielectric anisotropy comprises a biphenyl derivative of the formula ##STR1## wherein R.sub.1 is alkyl of 1-4 C atoms or alkoxy of 1-3 C atoms, and a phenylcyclohexane derivative of the formula ##STR2## wherein R.sub.2 is alkyl of 1-4 C atoms, in a weight ratio of 3:1 to 1:3.

Liquid-crystalline dielectric

Biphenyl esters of the formula ##STR1## wherein X is --CO--O-- or --O--CO-- and R.sub.1 and R.sub.2 each are alkyl or alkoxy of 1 - 8 carbon atoms, enlarge significantly the temperature range of the nematic phase of liquid-crystalline compositions without adversely affecting other properties.

Biphenyl esters and liquid crystalline mixtures comprising them

Biphenyl derivatives of the formula ##STR1## wherein R.sub.1 and R.sub.2 are the same or different and are straight-chain alkyl of 2 - 12 carbon atoms and collectively have at least 5 carbon atoms, are added to known liquid crystalline materials to significantly lower the viscosity thereof.

Liquid crystalline materials of reduced viscosity

A liquid crystalline dielectric composition contains 0.001-5% by weight of a monocyclic or bicyclic amino compound of the formula ##STR1## wherein R.sub.1 and R.sub.2 each are hydrogen or collectively are CH.sub.2 --(CH.sub.2 --Z--CH.sub.2).sub.p --CH.sub.2 ; X is --CH.sub.2 or --CO--; Y is --Z--CH.sub.2 --CH.sub.2 -- or ##STR2## Z is O, S, or NH; m and n are 0, 1 or 2; p is 1, 2 OR 3; OR AN ACID ADDITION SALT OR METAL SALT CHELATE COMPLEX THEREOF.

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Darmstadt, Germany

Fernando Del Pino