Azide Reactive Dyes. Part I – The Mechanism of Fixation of Sulphonazide Disperse Dyes on Nylon 6

Reactive dyes containing a sulphonylazide group can undergo fixation on nylon substrates by two different mechanisms. Under Aqueous dyeing conditions, at or below 120 ºC, the free amino end-groups of the polymer attack the sulphonamide linkage. In contrast, if the dyed substrate is subjected to a dry heat fixation at 170 ºC, the azide group decomposes to a sulphonamide bridge, but in this case the amount of dye that can be fixed is independent of the amino end-group content of the polymer