Patent ID: 6342279
Filing Date: 2002-01-29
Classification: C09K

Abstract:
A liquid-crystalline medium having positive dielectric anisotropy, comprising a mesogenic compound of formula I in which L1 is H or F, and, at least one compound of formula II in which R1 is H, an alkyl or alkenyl radical having 1 to 15 carbon atoms which is unsubstituted, monosubstituted by CN or CF3 or at least monosubstituted by halogen, where, in addition, one or more CH2 groups in these radicals may each, independently of one another, be replaced by â€”Oâ€”, â€”Sâ€”, â€ƒâ€”COâ€”, â€”COâ€”Oâ€”, â€”Oâ€”COâ€” or â€”Oâ€”COâ€”Oâ€” in such a way that O atoms are not linked directly to one another, Q is a radical of the formula â€”(O)q (CEH2)râ€”(CF2)sâ€”in which q is 0 or 1 r is 0 or an integer of 1 to 6, and s is an integer of 0 to 6, X is F or Cl, and in the case where sâ‰ 0, is alternatively H, and A1 and A2 are each, independently of one another, (a) 1,4-cyclohexenylene or trans-1,4-cyclohexylene in which, in addition, one or more non-adjacent CH2 groups may be replaced by â€”Oâ€” and/or â€”Sâ€”, (b) 1,4-phenylene in which, in addition, one or two CH groups may be replaced by N, (c) 1,4-bicyclo[2.2.2]octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl and 1,2,3,4 tetrahydronaphthalene-2,6-diyl, where (a) and (b) may be substituted by one or two fluorine atoms, L2 and L3 are each, independently of one another, H or F, Z1 and Z2 are each, independently of one another, â€”COâ€”Oâ€”, â€”Oâ€”COâ€”, â€”CH2Oâ€”, â€”OCH2â€”, â€”CH2CH2â€”, â€”CH&boxH;CHâ€”, â€”C&boxH;Câ€” or a single bond, or one of the radicals Z1 and Z2 is alternatively â€”(CH2)4â€”O or â€”CH&boxH;CHâ€”CH2CH2â€”, and m is 0, 1 or 2, and at least one compound selected from the group of compounds of formulae IIIa, IIIb, and IIIc wherein R3 and R4 are each, independently of one another, as defined for R1, and