Solvent‐assisted Dyeing of Nylon 6.6 and Polyester Fibres

The results of laboratory semi‐bulk and bulk trial work on the dyeing of nylon 6.6, with anionic dyes in the presence of n‐butanol, in an aqueous dyebath are described. The method gives improvements in coverage of barre which cannot be achieved in other ways, without detectable adverse effects on the physical properties of the nylon 6.6 or the colour and fastness properties of the dyes. Results of work by a similar, solvent‐assisted dyeing method for polyester fibre are given. Improvements in migration and speed of fixation of dye in the presence of n‐butanol are noted, but these are similar in magnitude to the improvements obtainable with conventional carriers for polyester dyeing at much lower concentrations. The method is likely to be commercially viable only if a substantial proportion of the butanol added to the dyebath can be recovered for re‐use. This should theoretically be possible, but experimental confirmation of the process has not yet been obtained.