Deposition of direct dyes in washing of cotton fabric with ecological surfactants

Abstract

In this work the performance of several DTI copolymers (PVP, PV betaine, PVNO and PVNO with PVP) was tested for use as dye transfer inhibitors in washing undyed cotton fabric, in the presence of a direct dye in the washing bath. Three direct dyes were tested: red, blue and yellow. The detergent used was composed of an LAS anionic surfactant and a non-ionic fatty alcohol ethoxylate surfactant with 7 m.OE, both separately and in the different molar proportions anionic with non ionic, at a total concentration of 5 x 10-3 M, and in the presence of zeolite as a builder. Washing temperature was 40ºC and washing time was 30 minutes. Staining of the undyed cotton fabric was assessed as the CIELAB colour differences between the original fabric and the stained fabric after washing, with and without the different DTIs tested and the dye in the washing bath.