Effects of additives on the dyeing of nylon-6 with dyes containing hydrophobic and hydrophilic moieties

A series of azo disperse dyes with variable hydrophobic chain length and hydrophilic (hydroxy or glucosyl group) head were synthesised. H-1 and C-13 NMR spectra indicated that the glucosyl moiety was linked to the azo structure with a beta anomeric bond. The dyeing properties on polyamide fibres were assessed with dyeing isotherms and Linitest experiments. The positive effects of additives, as ternary systems (SDS, Brij 35 and octanol) or cyclodextrins, on the dyeing uniformity were shown by tristimulus colorimetry.