A reactive black dye composition is disclosed, which comprises: (A) a reactive blue dye represented by the following formula (I) or a salt thereof; and (B) a reactive red dye or a salt thereof, a reactive yellow dye or a salt thereof, or a combination thereof.

##STR00001##

Herein, R.sub.11, X.sub.1, X.sub.2, X.sub.31, X.sub.41 and n are defined in the specification. In addition, a method for dying fibers using the aforesaid reactive black dye composition is also disclosed.

A reactive black dye composition is disclosed, which comprises: (A) a reactive blue dye represented by the following formula (I) or a salt thereof; and (B) a reactive red dye or a salt thereof, a reactive yellow dye or a salt thereof, or a combination thereof.

##STR00001##

Herein, R.sub.11, X.sub.1, X.sub.2, X.sub.31, X.sub.41 and n are defined in the specification. In addition, a method for dying fibers using the aforesaid reactive black dye composition is also disclosed.

A pigment dispersion has low viscosity and good dispersion property without depending on pigment species. The pigment dispersion contains a dispersion medium, an organic pigment, and a triazo compound having a specific structure.

A pigment dispersion has low viscosity and good dispersion property without depending on pigment species. The pigment dispersion contains a dispersion medium, an organic pigment, and a triazo compound having a specific structure.

A compound of formula (I) or (II) or (III): ##STR00001##
wherein R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.8 and R.sub.8 are as defined herein. This compound can be used in a composition for the dyeing of fibers.

A compound of formula (I) or (II) or (III): ##STR00001##
wherein R.sub.5, R.sub.6, R.sub.7, R.sub.8, R.sub.8 and R.sub.8 are as defined herein. This compound can be used in a composition for the dyeing of fibers.