Patent ID: 6929667

Claim:
A method for the fluorescent whitening of cotton in a discontinuous process comprising contacting the cotton, in an aqueous bath having a pH value of 6 or less, with one or more compounds of the formula wherein R 2 is —NH 2 , —NH(C 1 -C 4 alkyl), —N(C 1 -C 4 alkyl) 2 , —NH(C 2 -C 4 hydroxyalkyl), —N(C 2 -C 4 hydroxyalkyl) 2 , —NH(C 1 -C 4 alkoxy)(C 1 -C 4 alkyl), —N[(C 1 -C 4 alkoxy)(C 1 -C 4 alkyl)] 2 , NHC 2 -C 4 alkylsulphonic acid, morpholino, piperidino pyrrolidino, an amino acid or amino acid amide residue from which a hydrogen atom on the amino group has been removed, —OC 1 -C 4 alkyl or —OC 1 -C 4 hydroxyalkyl, R 3 and R 4 each, independently, represent hydrogen, C 1 -C 4 alkyl, C 2 -C 4 hydroxyalkyl or C 1 -C 4 alkoxyC 1 -C 4 alkyl and M is H, Na, Li, K, Ca, Mg, ammonium, or ammonium that is mono-, di-, tri- or tetrasubstituted by C 1 -C 4 alkyl, C 2 -C 4 hydroxyalkyl or a mixture thereof.