Patent ID: 7704566

Claim:
Liquid-crystalline medium based on a mixture of polar compounds of positive dielectric anisotropy, comprising one or more compounds of the formula I and one or more compounds of the formula IA where the proportion of the compounds of the formula I in the medium is at least 18% by weight, and in which the individual radicals have the following meanings: R 1 is an alkenyl radical having from 2 to 8 carbon atoms, R 2 is H, an alkyl radical having from 1 to 15 carbon atoms which is halogenated, substituted by CN or CF 3 or unsubstituted, where, in addition, one or more CH 2 groups in these radicals may each, independently of one another, be replaced by —C≡C—, —CO—, —CH═CH—, —O—, or in such a way that O atoms are not linked directly to one another, X 1 is an alkyl radical, alkenyl radical, alkoxy radical or alkenyloxy radical, each having up to 6 carbon atoms, in the case where a=1 also F, Cl, CN, SF 5 , SCN, NCS or OCN, X 2 is F, Cl, CN, SF 5 , SCN, NCS, OCN, a halogenated alkyl radical, halogenated alkenyl radical, OCF 3 , OCHF 2 , or halogenated alkenyloxy radical, each having up to 6 carbon atoms, Z 1 and Z 2 are each, independently of one another, —CF 2 O—, —OCF 2 — or a single bond, where Z 1 ≠Z 2 , a is 0 or 1, and are each, independently of one another, L 1-4 are each, independently of one another, H or F, with the proviso that formula IA is not in which n is 1-15.