BISAZO COMPOUND OR ITS SALT, AND THEIR APPLICATION TO FIBROUS MATERIAL

摘要

PROBLEM TO BE SOLVED: To provide a reactive dye useful for dyeing cellulose fibers dark blue. SOLUTION: The reactive dye comprises a bisazo compound of formula (1) (wherein R1 to R4 are each H or the like; U is a specified group containing a vinylsulfone based reactive group; X1 to X3 are each chloro or optionally substituted pyridinio; T is a specified group nonreactive with fibers; one of W1 and W2 is amino, and the other is hydroxyl; and one of two asterisks (*) shown in brackets is a bond to -U, and the other is a bond to -T), or its salt.