Patent ID: 7604851

Claim:
A liquid-crystalline medium comprising at least two mesogenic compounds: wherein the medium contains substantially no compounds having a cyano group; wherein at least one mesogenic compound is a compound of the formula I in which R is vinyl, CH 3 CH═CH—, CH 2 ═CHCH 2 CH 2 — or CH 3 CH═CHCH 2 CH 2 —, A 1 and A 2 are each, independently of one another, a) a 1,4-cyclohexenylene or 1,4-cyclohexylene radical, in which one or two non-adjacent CH 2 groups are optionally replaced by —O— or —S—, b) a 1,4-phenylene radical, in which one or two CH groups are optionally replaced by N, c) a radical selected from the group consisting of piperidine-1,4-diyl, 1,4-bicyclo[2.2.2]octylene, phenanthrene-2,7-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, phenanthrene-2,7-diyl and fluorene-2,7-diyl, where the radicals a), b) and c) are optionally mono- to perhalo-substituted by halogen atoms, X is F, Cl, NCS, SF 5 , or a halogenated or unsubstituted alkyl, alkoxy, alkenyloxy or alkenyl radical having 1 to 5 carbon atoms, Z 1 and Z 2 are each, independently of one another, —CO—O—, —O—CO—, —CF 2 O—, —OCF 2 —, —CH 2 O—, —OCH 2 —, —CH 2 CH 2 —, —(CH 2 ) 4 —, —C 2 F 4 —, —CH 2 CF 2 —, —CF 2 CH 2 —, —CF═CF—, —CH═CH—, —C≡C— or a single bond, a is 0, 1 or 2, b is 0, 1 or 2, provided that a and b are not both 0 and that the compound contains at least one bridge Z 1 or Z 2 which is —CF 2 O— or —OCF 2 —, and L 1 , L 2 and L 3 are each, independently of one another, H, F or Cl; and wherein at least one other mesogenic compound is a compound of one of formulae IV or V: in which: R 0 is n-alkyl, oxaalkyl, fluoroalkyl, alkenyloxy or alkenyl, each having 1 to 9 carbon atoms, X 0 is halogenated alkoxy having 1 to 7 carbon atoms, Z 0 is a single bond, Y 1 , Y 2 , Y 3 and Y 4 are each, independently of one another, H or F, and r is 0 or 1, provided that the variables are selected such that the compounds of formulae IV and V do not include compounds within the scope of formula I; and provided that the medium does not contain: a compound of the formula IV where R 0 is alkenyl, Z 0 is a single bond and r is 1, or a compound of formula RI where R 0 alkenyl, formula RII, formula RIII, formula RIV where R 0 is alkenyl, formula RV where R 0 alkenyl, formula RIX where R 0 alkenyl or formula RX where R 0 alkenyl: wherein the above formulae, alkyl* is a straight-chain or branched alkyl radical having 1-9 carbon atoms, and alkenyl and alkenyl* are each, independently of one another, a straight-chain or branched alkenyl radical having up to 9 carbon atoms.