ANIONIC DYE OR BRIGHTENER BEARING AN AMMONIUM OR PHOSPHONIUM COUNTERION, DYE COMPOSITION COMPRISING THEM AND PROCESS FOR DYEING KERATIN FIBRES USING THESE DYES
The invention relates to the dyeing of human keratin fibres, especially the hair, using anionic direct dyes bearing a particular ammonium or phosphonium counterion of formula (Ia) and/or optical brighteners of formula (Ib) Col(−)m[X+]n (Ia) Azu(−)m[X+]n (Ib) in which formulae (Ia) and (Ib): Azu/Col(−)m, R1, R2, R3, R4, m and n are as defined in the description. The invention relates to a dye composition comprising an anionic compound of formula (Ia) and/or (Ib), and to a process for dyeing keratin fibres such as the hair, using the said composition. Similarly, the invention relates to novel anionic compounds of formula (Ia) or (Ib) and to the uses thereof for dyeing keratin fibres. This composition makes it possible to obtain chromatic, powerful and particularly fast coloration on keratin fibres and particularly lightening coloration via an optical effect on dark hair.
