Cyan disazo dyestuffs in photographic materials - esp. for silver colour bleach process are diffusion fast, stable in aq. soln. and bleachable to white

摘要

At least one coat of the material contains a disazo dyestuff of formula I: (in which A is a benzene or naphthalene gp.; B is an arom. gp. with an OH gp. in the o- or p-position to the azo gp. or a gp. with an active methylene gp.; R1 and R2 are H or lower (hydroxy) alkyl and R1 can also be a cycloalkyl or benzene gp.; V and W are sulpho or sulphonamide gps. and W can also be H; the dyestuff mol. contains at least 2 sulpho gps.). These dyestuffs can be used in the cyan-coloured (red-sensitive) coat of a multi-coloured emulsion or in an auxiliary coat or a coat adjacent to a light-sensitive coat and also re retouching. The absorption max. is esp. useful in Ag colour bleach photography. The aq. solns. are insensitive to Ca++ ions.