Influence of oxyethylenated alkylamines in the dyeing of polyamide 66 fibres

Abstract

This paper analyzes the influence of the chemical structure of a series of oxyethylenated laurylamines (LA-EO) on the formation of complexes with the dye C.I. Direct Red 1, as well as on the dyeing kinetics of the polyamide 66 fibres. The spectrophotometric analysis of the dyebath in the absence and in the presence of different LA-EO has been carried out. The variables studied were the molar ratio (MR) between the dye and the LA-EO (1:0-1:16), the chemical structure of the LA-EO (15, 20, 25, 40 and 60 mol of ethylene oxide) and the temperature (25 degrees C and 60 degrees C. The results reveal the stoichiometry of the complex formation (DnSm) between the dye and the LA-EO. There are two different types of complexes formed. The first-one is insoluble, formed at lower molar ratios (MR). The second-one is soluble, formed at higher MR, being able to control the dyebath exhaustion. The stoichiometry of the dye-auxiliary complex depends on the temperature and the chemical structure of the LA-EO. The dyeing behaviour of PA66 fibres is in correlation with the type of complex formed. It was shown that the presence of LA-EO slows down the dyeing rate and improves levelling.