Influence of dyeing parameters and fibre setting on the lightfastness properties of acid dyed nylon 6,6 fibres

Abstract

The influence of various dyeing and manufacturing processes have been examined with respect to the lightfastness properties of three acid dyes, namely Tectilon Red 2B, Tectilon Yellow 3R and Tectilon Blue4RS (Ciba-Geigy Ltd), and their interrelationship with the formation of photoactive luminescent carbonylic species and hydroperoxide groups in Nylon 6,6 fibres. Thus, neutral dyeing conditions, and the use of an anionic levelling agent, in conjunction with fibres which had been heat-set under dry conditions, were found to exhibit the higher lightfastness. At low and high pH conditions the dyes were found to be more prone to photofading. These conditions were found to have a marked effect on the excited state properties of the polymer fibre in terms of the formation of photoactive carbonylic species and hydroperoxides. The quenching and interaction of these species with the dyes was found to play an intricate role in the photostability of the dyed fibre system. The addition of a reducing agent to the dyebath operation, and prior extraction of the fibre with methanol to minimise the formation of these species, were found to markedly enhance the dye lightfastness.