Stilbene dyestuffs and light-polarizing films or sheets containing stilbene

A dyestuff, which, in the form of the free acid, conforms to the formula I:

• ##STR50## in which X and Y independently represent N.dbd.N--R, CF.sub.3, CONH.sub.2, CONHR.sup.1, CONR.sup.1 R.sup.2, COOH, COOR.sup.1, CN, NO.sub.2, NH.sub.2, NR.sup.1 R.sup.2, NHR.sup.1, OH, OR.sup.1, NHCOR.sup.1, O--CO--R.sup.1, or halogen, and
• R.sup.1 and R.sup.2 independently represent alkyl, cycloalkyl, aryl or aralkyl, which are uninterrupted or interrupted by O, S or both O and S;
• provided that at least one of the radicals X or Y represents N.dbd.N--R, in which
• R represents an aryl radical of the formula:
• ##STR51## in which R.sup.3 represents H, OH, OR.sup.1, NH.sub.2, NHR.sup.1, NR.sup.1 R.sup.2, NHCOR.sup.1, O--CO--R.sup.1, or N.dbd.N--R.sup.11,
• R.sup.4, R.sup.5, R.sup.7, R.sup.8, R.sup.9 and R.sup.10 independently represent H, halogen, OH, OR.sup.1, NH.sub.2, NHR.sup.1, NR.sup.1 R.sup.2, R.sup.1, SO.sub.3 H, SO.sub.2 NH.sub.2, SO.sub.2 NHR.sup.1, SO.sub.2 NR.sup.1 R.sup.2, O--CO--R.sup.1, and NH--CO--R.sup.1 ;
• R.sup.6 represents H or N.dbd.N--R.sup.11 ;
• and
• R.sup.11 represents an aryl radical of the formula:
• ##STR52## in which R.sup.12 represents OH or NH.sub.2 ;
• R.sup.13 represents H, if R.sup.14 .dbd.N.dbd.N--R.sup.11, and represents N.dbd.N--R.sup.11, if R.sup.14 .dbd.OH or NH.sub.2 ;
• R.sup.14 represents OH, NH.sub.2 or N.dbd.N--R.sup.11 ;
• R.sup.15 represents H, OH, OR.sup.1, O--CO--R.sup.1, NH.sub.2, NHR.sup.1, NR.sup.1 R.sup.2, NHCOR.sup.1 or SO.sub.3 H;
• R.sup.17 represents H or SO.sub.3 H;
• R.sup.18 represents H, OH, NH.sub.2, NHCOR.sup.1, NHR.sup.1, N.dbd.N--R.sup.11, or SO.sub.3 H;
• R.sup.19 represents H or N.dbd.N--R.sup.11 ;
• and
• R.sup.20 and R.sup.21 independently represent OH, NH.sub.2, O--CO--R.sup.1, or NHCOR.sup.1 ;
• and in which the radicals R.sup.1 and R.sup.2 are unsubstituted or substituted by a substituent selected from the group consisting of halogen, OH, CN and C.sub.1-4 -alkyl where R.sup.1 or R.sup.2 is alkyl or cyclalkyl or from the group consisting of halogen, OH, C.sub.1-4 -alkoxy, C.sub.1-4 -alkoxy, CF.sub.3, NO.sub.2 and CN where R.sup.1 or R.sup.2 is aryl or aralkyl, the dyestuff containing a maximum of eight azo bridges, and with the exception of the dyestuff, which, in the form of its free acid, conforms to the formula I wherein:
• ##STR53##