The Effect of Heat‐setting Treatments on the Dyeing Behaviour of Nylon Yarns and Fabrics

The effects of dry‐heat setting and pressure‐steam setting on the dyeing behaviour of nylon yams are considered. Measurements have been made of the influence of the temperature and duration of dry‐heat setting on the rates of dyeing of nylon 6.6 yarns and fabrics with the direct dye Chlorazol Violet R (C.I. Direct Violet 3) and the 1:2 metal‐complex dyes Irgalan Red 3G (C.I. Acid Red 220) and Irgalan Grey BL (C.I. Acid Black 58). Similar measurements were carried out on steam‐set nylon 6.6 yarns to examine the influence of presteaming conditions, steam pressure, steam quality, and variation of the steam‐setting procedure. The practical implications of the results are discussed, especially with regard to uniform setting and subsequent dyeing behaviour of nylon yarns and fabrics. The effects of dry‐heat and pressure‐steam setting are interpreted in terms of the proposed molecular mechanism of setting, which considers especially the influence of moisture on the fine structure of nylon.