Azo dyestuffs and liquid-crystal material containing azo dyestuffs

Liquid-crystal material containing 0.01 to 30% by weight of a azo dyestuff of the formula ##STR20## in which Z denotes an O or S atom and

• R'.sub.1, R'.sub.2, R'.sub.4 and R'.sub.5 denote chlorine, C.sub.1 -C.sub.10 -alkyl and C.sub.1 -C.sub.10 -alkoxy,
• R.sub.7, R.sub.8 denote hydrogen, alkyl, alkyl interrupted by 1-3 non-adjacent O atoms, cycloalkyl, aryl, aralkyl, aralkyl in which the alkyl portion is interrupted by 1-3 non-adjacent O atoms and
• R'.sub.7, R'.sub.8 and R.sub.11 denote hydrogen, halogen, cyano, nitro, alkyl or alkoxy.

Liquid-crystal material containing 0.01 to 30% by weight of an azo dyestuff of the formula ##STR21## in which R.sub.1 ", R.sub.2 ", R.sub.4 " and R.sub.5 " denote halogen, hydrogen, C.sub.1 -C.sub.4 -alkyl or C.sub.1 -C.sub.4 -alkoxy

• R'.sub.9 and R'.sub.10 represent C.sub.1 -C.sub.4 -alkyl or benzyl which can be substituted in the phenyl nucleus by halogen, C.sub.1 -C.sub.4 -alkyl, or C.sub.1 -C.sub.4 -alkoxy or represent aminocarbonyl,
• R.sub.7 " and R.sub.8 " denote hydrogen, halogen, C.sub.1 -C.sub.4 -alkyl and C.sub.1 -C.sub.4 -alkoxy and
• R.sub.11 denote hydrogen, halogen, cyano, nitro, alkyl or alkoxy.