Patent ID: 7270771

Claim:
A fluorescent whitening agent which is a composition comprising a mixture of two symmetrical compounds (1a) and 1(c) and one asymmetrical compound 1(b) of the formulae in which R 1 and R 2 are different and R 1 represents —NH 2 , —NHC 1 -C 4 alkyl, —N(C 1 -C 4 alkyl) 2 , —NHC 2 -C 4 hydroxyalkyl, —N(C 2 -C 4 hydroxyalkyl) 2 , —N(C 1 -C 4 alkyl)(C 2 -C 4 hydroxyalkyl), a morpholino, piperidino or pyrrolidino residue, R 2 represents —NHC 2 -C 4 hydroxyalkyl, —N(C 2 -C 4 hydroxyalkyl) 2 , —N(C 1 -C 4 alkyl)(C 2 -C 4 hydroxyalkyl), or an amino acid or an amino acid amide residue from which a hydrogen has been removed from the amino group, each R 3 , independently, represents hydrogen, C 1 -C 4 alkyl or C 1 -C 4 alkoxy and M represents hydrogen, an alkali metal atom, ammonium or a cation formed from an amine.