Patent ID: 6878421

Claim:
Liquid-crystalline medium based on a mixture of polar compounds of positive dielectric anisotropy, which comprises: one or more compounds of the formula I in which R is F, Cl, Br, I, CN, NCS, SF 5 or an alkyl radical having from 1 to 12 carbon atoms which is unsubstituted, monosubstituted by CN or CF 3 or monosubstituted or polysubstituted by halogen and in which one or two non-adjacent CH 2 groups are optionally replaced by —O—, —CH═CH—, —CF═CF—, —C≡C—, —CO—, —OCO— or —COO— in such a way that O atoms are not linked directly to one another, A 1 and A 2 are each, independently of one another, 1,4-phenylene, in which one or two CH groups are optionally replaced by N and which is optionally monosubstituted or polysubstituted by L, or are trans-1,4-cyclohexylene, in which one or more non-adjacent CH 2 groups are optionally replaced by —O— and/or —S—, or are 1,4-cyclohexenylene, 1,4-bicyclo[2.2.2]octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl or 1,2,3,4-tetrahydronaphthalene-2,6-diyl, L is F, Cl, Br, I, CN, NCS, SF 5 or alkyl, alkoxy, alkylcarbonyl, alkylcarbonyloxy, alkoxycarbonyl, alkenyl or oxaalkenyl having from 1 to 3 carbon atoms, in which one or more H atoms are optionally replaced by F or Cl, Z 1 and Z 2 are each, independently of one another, —CH 2 O—, —OCH 2 —, —CF 2 O—, —OCF 2 —, —COO—, —OCO—, —CF 2 CF 2 —, —CH 2 CH 2 —, —(CH 2 ) 4 —, —(CH 2 ) 3 O—, —O(CH 2 ) 3 —, —CF 2 CH 2 —, —CH═CH—, —CH═CF—, —CF═CF—, —C≡C— or a single bond, X 1 and X 2 are each, independently of one another, F, Cl, Br, I, CN, NCS, SF 5 or alkyl, alkoxy, alkylcarbonyl, alkylcarbonyloxy, alkoxycarbonyl, alkenyl or oxaalkenyl having 1 to 5 carbon atoms, in which one or more H atoms are optionally replaced by F or Cl, and one of the radicals X 1 and X 2 is alternatively H or R, and n and o are each, independently of one another, 0, 1 or 2, where n+o is ≦3 and, one or more compounds selected from the group consisting of the compounds of formulae II, III, IV, V, VI and VII: in which the individuals have the following meanings: R 0 is n-alkyl, alkoxy, fluoroalkyl, alkenyl or oxaalkenyl, each having 1 to 9 carbon atoms, Z 3 is —COO—, —CF 2 O—, —C 2 F 4 — or a single bond, Z 4 is —COO—, —CF 2 O—, —C 2 H 4 —, X 0 is F, Cl, halogenated alkyl, alkenyl or alkoxy having from 1 to 6 carbon atoms. Y 1 and Y 2 are each, independently of one another, H or F, and r is 0 or 1.