Metal free acid dyes, methods for the production thereof and their use

A dye of the formula (1)

• in which
• each of R1, R2, R3 and R4, independently from one another is hydrogen or (C1-C6) alkyl;
• each of R5 and R6, independently from one another is hydrogen, (C1-C6) alkyl or (C1-C6) alkyl substituted by hydroxy;
• each of R7 and R8, independently from one another is hydrogen, (C1-C6) alkyl or phenyl;
• each of R9 and R10, independently from one another is hydrogen, (C1-C6) alkyl, (C1-C6) alkoxy, trifluoromethyl, hydroxy, cyano, nitro, halogen, —NHCHO, —NHCO(C1-C6)-alkyl, —NHCOaryl, —NHSO2(C1-C6)-alkyl or —NHSO2aryl;
• and
• each of D1 and D2, independently from one another is the residue of a diazo component, which comprises at least one group —SO3M, wherein M is hydrogen, an alkali metal, ammonium or one equivalent of an alkali earth metal.