Patent ID: 7033651

Claim:
A liquid-crystalline medium comprising a mixture of at least two compounds of formula (I) R 1 -A m -B n -Z 1 -C-Z 2 -D-R 2 (I) in which R 1 is H, an alkyl group having 1 to 15 carbon atoms or alkenyl group having 2 to 15 carbon atoms, which is unsubstituted, monosubstituted by CN or CF 3 or at least monosubstituted by halogen, in which one or more CH 2 groups are optionally, in each case independently of one another, replaced by —O—, —S—, —CO—, —CO—O—, —O—CO— or —O—CO—O— in such a way that O atoms are not linked directly to one another; A, B, C and D are each, independently of one another, C is, in addition to the above-mentioned meanings, Y 1 , Y 2 , Y 3 , Y 4 , Y 5 and Y 6 are each, independently of one another, H or F; Z 1 and Z 2 are each, independently of one another, a single bond, —CH 2 O—, —OCH 2 —, —CH 2 —CH 2 —, —CH═CH—, —C≡C—, —CF 2 —CF 2 —, —CF 2 O—, —OCF 2 — or —CO—O—; R 2 is, in addition to the above-mentioned meanings of R 1 , F, CE 3 , OCF 3 , OCHF 2 , or OCH 2 CF 2 H; and m and n are each, independently of one another, 0 or 1, with the proviso that Z 1 is a single bond when m and n are 0, wherein the mixture comprises either I) a) 40 to 80% by weight one or more compounds of formula (I) having Δε≧9; b) 0 to 25% by weight one or more compounds of formula (I) having 1<Δε<9; and c) 15 to 40% by weight one or more compounds of formula (I) having −1≦Δε≦1; or II) a) 70 to 90% by weight one or more compounds of formula (I) having Δε≧9; b) 0 to 10% by weight one or more compounds of formula (I) having 1<Δε<9; and c) 10 to 20% by weight one or more compounds of formula (I) having −1≦Δε≦1; the sum of a), b) and c) being 100% by weight, and wherein the at least two compounds of formula I are liquid crystalline and/or mesogenic.