Cationic oligomeric azo dyes

A method of dyeing keratin-containing fibers comprising treating the fiber with at least one dye of formula

• their salts, isomers, hydrates and other solvates, wherein
• R1 is hydrogen;
• C1-C12alkyl, which may be substituted by one or more C1-C5alkyl, C1-C5-alkoxy, hydroxy or —(CO)—H;
• —(CO)—C1-C5alkyl;
• phenyl or phenyl-C1-C4alkyl, wherein the phenyl moiety may be substituted by one or more C1-C5alkyl, C1-C5alkoxy, halogen, —NH2, mono-C1-C5alkylamino, di-C1-C5alkylamino, —NO2, carboxy or hydroxy;
• R2 is hydrogen;
• or C1-C5alkyl;
• X is C1-C10alkylene, which may be substituted by one or more C1-C5alkyl, hydroxy, C1-C5-alkoxy, amino, mono-C1-C5alkylamino, di-C1-C5alkylamino, —SH, and/or interrupted by one or more —O— or —S—S—;
• C5-C10cycloalkylene;
• C5-C12arylene;
• C5-C12arylene-(C1-C10alkylene);
• biphenylene, which may be substituted by one or more C1-C5alkyl, hydroxy, C1-C5-alkoxy, amino, mono-C1-C5alkylamino, di-C1-C5alkylamino, —SH, and/or interrupted by one or more —O —, C1-C4-alkylene, —NR3—, —S— or —S—S—;
• R3 is hydrogen;
• C1-C12alkyl;
• C2-C14alkenyl;
• C6-C12aryl;
• C6-C12alkyl;
• or —C1-C12alkyl-C6-C12aryl;
• Y is an anion;
• Z is 1,3-thiazolyl;
• 1,2-thiazolyl;
• 1,3-benzothiazolyl;
• 2,3-benzothiazolyl;
• imidazolyl;
• 1,3,4-thiadiazolyl;
• 1,3,5-thiadiazolyl;
• 1,3,4-triazolyl;
• pyrazolyl;
• benzimidazolyl;
• benzopyrazolyl;
• pyridinyl;
• quinolinyl;
• pyrimidinyl;
• or isoxazolyl;
• and
• n is a number from 2-100.