Liquid-crystalline material containing azo dyestuffs

Claim 1

A liquid-crystal composition useful for displays comprising a liquid-crystal material having a positive dielectric antisotropy and 0.01 to 10% by weight of an azo dyestuff of the formula ##STR99## in which R 1 ', R 2 ', R 4 ' and R 5 ' designate hydrogen, halogen, C 1 -C 6 -alkyl C 1 -C 6 -alkoxy, with the proviso that at least one of these radicals is different from hydrogen, R 7 and R 8 designate hydrogen, halogen, C 1 -C 6 -alkyl, or C 1 -C 6 -alkoxy and X represents --OR 9 , --SR 9 or ##STR100## Y represents --OR 12 , --SR 12 or ##STR101## wherein R 9 and R 12 designate hydrogen, C 1 -C 6 -alkyl, cyclopentyl, cyclohexyl, phenyl, naphthyl, benzyl, phenethyl, acyl, aminocarbonyl, or benzyl which is substituted by halogen, nitro, C 1 -C 4 -alkyl, or C 1 -C 4 -alkoxy and wherein R 10 , R 11 , R 13 and R 14 represent hydrogen, C 1 -C 4 -alkyl, C 1 -C 4 -alkyl which is substituted by hydroxyl, cyano, phenoxy, C 1 -C 4 -alkoxy or by (C 1 -C 4 -alkoxy)-carbonyloxy, or R 10 , R 11 , R 13 and R 14 represent cyclohexyl, phenyl, naphthyl, benzyl, phenethyl, (C 1 -C 4 -alkyl)-carbonyl, benzoyl, (C 1 -C 4 -alkyl)-aminocarbonyl or phenylaminocarbonyl, and wherein X and Y are in the para position relation to --N═N--.