| abstract |
The invention relates to a liquid-crystalline medium based on a mixture of polar compounds having a positive dielectric anisotropy, characterized in that it contains one or more compounds of the formula I. and one or more compounds of the formula IA, in which R 1 , R 2 , ring A, ring B, L 1-4 , Z 1 , Z 2 , X 1 , X 2 and a have the meanings given in claim 1, contains, wherein the proportion of the compounds of formula I in the medium is at least 18 wt .-%. |