Storage-stable fluorescent whitener formulations

A storage-stable aqueous fluorescent whitener formulation consisting essentially of

• (a) 10%-60% by weight, based on the total weight of the whitener formulation, of at least
• one compound of formula (1)
• wherein
• R1 and R2 are, independently from each other, hydrogen;
• unsubstituted C1-C8alkyl or substituted C1-C8alkyl,
• X1 and X3 are —NH2,
• X2 and X4 are, independently from each other, —N(R3)R4 or —OR5, wherein
• R3 and R4 are, independently of each other, hydrogen;
• cyano;
• unsubstituted C1-C8alkyl;
• substituted C1-C8alkyl;
• unsubstituted C8-C7cycloalkyl or unsubstituted C8-C7cycloalkyl;
• or R3 and R4, together with the nitrogen atom linking them, form a heterocyclic ring, and R5 is unsubstituted C1-C8alkyl or substituted C1-C8alkyl, and
• M is hydrogen or a cation selected from the group consisting of Li, Na, K, Ca, Mg, ammonium, mono-, di, tri or tetra C1-C4 alkylammonium, and mono, di- or tri-C2-C4-hydroxyalkylammoniuim,
• (b) 0.01-1% by weight, based on the total weight of the whitener formulation, of at least one anionic polysaccharide,
• (c) 0-25% by weight, based on the total weight of the whitener formulation, of at least one electrolyte,
• (d) 0-20% by weight, based on the total weight of the whitener formulation, of at least one dispersant,
• (e) 0-30% by weight, based on the total weight of the whitener formulation, of at least one further fluorescent whitener,
• (f) 0-20% by weight, based on the total weight of the whitener formulation, of at least one further optional component, and
• (g) water to make up 100% by weight.