Azide Reactive Dyes. Part II – Transfer-printing Properties of Sulphonyl- and Aryl-azide Dyes on Nylon 6.6

The transfer-printing properties of dyes containing the sulphonylazide (-SO2N3) and arylazide (ArN3) groups have been examined for nylon 6.6 substrates. After sublimination at 200 ºC the arylazide groups have been examined for nylon 6.6 substrates. After sublimination at 200 ºC the azide group decomposes rapidly to nitrene species which reacts with the polymer. Dye fixaton occurs by insertion of the nitrene into the carbon-hydrogen bonds of the polymer, thus forming a nitrogen bridge. A competing reaction involves hydrogen abstraction from the substrate to give an amino derivative of the dye which is not covalently bound to the polymer. Fibre-grafting occurs to the extent of about 60-75 % for both series of dyes. Unlike the sulphonylazides, the arylazide dyes show a pronounced colour change after transfer, as the thermally-generated amino group is directly conjugated with the dye chromogen