Optical brightening agents and photographic materials which contain these brightening agents
AssigneeCiba-Geigy Corporation
InventorGraham Evans
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Abstract
New optical brightening agents and photographic materials which contain in at least one layer these brightening agents are provided. The compounds have the general formula ##STR1## wherein R.sub.1 and R.sub.3 are hydrogen or methyl, R.sub.2 and R.sub.4 are alkyl R.sub.5 is hydrogen, alkyl, aryl, aralkyl, X is --NH--, --O-- or --S--, L.sub.1 and L.sub.2 are alkylene oxide chains and M.sup..sym. is a hydrogen or an alkali metal cation. These brightening agents enhance the brightness in the white areas of photographic print materials.
Claims10
A brightening agent of the general formula ##STR12## wherein R.sub.1 and R.sub.3 are each hydrogen or methyl, R.sub.2 and R.sub.4 are alkyl having at least six carbon atoms, R.sub.5 is hydrogen or alkyl, aryl or aralkyl, X is --NH--, --O-- or --S--, L.sub.1 and L.sub.2 are each alkylene oxide chains having two to 20 alkyene oxide units in the chain and M.sup..sym. is a hydrogen or an alkylene metal cation.
Dependencies are inferred from the claim text.