Patent ID: 7537620

Claim:
A method for dyeing hair comprising the steps of: (i) applying to hair an amount of hair colorant comprising at least one thiazolium azo dye of general formula (I) sufficient for dying the hair; (ii) leaving the hair colorant on the hair at a temperature of 15C. to 50C. for a period of 1 to 60 minutes; (iii) rinsing the hair with water; and (iv) drying the hair; wherein: R1 stands for a saturated or unsaturated (C 1 -C 12 )-alkyl group, a halogen atom-substituted (C 1 -C 12 )-alkyl group, a hydroxy-(C 1 -C 12 )-alkyl group, a (C 1 -C 6 )-alkoxy-(C 1 -C 12 )-alkyl group, an amino-(C 1 -C 12 )-alkyl group, a (C 1 -C 6 )-alkylamino-(C 1 -C 12 )-alkyl group, a di(C 1 -C 6 )-alkyl-amino-(C 1 -C 12 )-alkyl group, a cyano-(C 1 -C 12 )-alkyl group, a substituted or unsubstituted phenyl group or a substituted or unsubstituted benzyl group; R2 and R3 can be equal or different and, independently of each other, stand for hydrogen, a halogen atom, a saturated or unsaturated (C 1 -C 12 )-alkyl group, (C 1 -C 12 )-alkoxy group, a nitro group, an amino group, a (C 1 -C 12 )-alkylamino group, a di(C 1 -C 12 )-alkylamino group, a (C 1 -C 12 )-hydroxyalkylamino group, a di(C 1 -C 12 )-hydroxyalkylamino group, a substituted or unsubstituted phenyl group or a substituted or unsubstituted heteroaryl group; R4 stands for hydrogen, a saturated or unsaturated (C 1 -C 12 )-alkyl group, a halogen atom-substituted (C 1 -C 12 )-alkyl group, a hydroxy-(C 1 -C 12 )-alkyl group, an amino-(C 1 -C 12 )-alkyl group or a benzyl group; R5 and R6 can be equal or different and, independently of each other, stand for hydrogen, a halogen atom, a saturated or unsaturated (C 1 -C 12 )-alkyl group, a hydroxyl group, a (C 1 -C 12 )-alkoxy group, a cyano group, a nitro group, an amino group, a (C 1 -C 12 )-alkylamino group or a di(C 1 -C 12 )-alkylamino group, and A − stands for an anion of an organic or inorganic acid.