Colour Yield in Two Phase Wet Fixation Dyeing of Cotton Cloth with Reactive Dyes as a Function of Ti

Reactive dyestuffs are used more than other suitable dyes in dyeing and printing of cotton fabrics with relatively good washing fastness. Time, temperature and alkali concentration constitute the most important parameters affecting the fixation process, in other words, the colour yield. Reactive dyes are fixed on cotton through a covalent link formed between the reactive group of the dyestuff and hydroxyl groups of cellulose. It is the aim of this research to present a model for colour yield as a function of these three parameters. For this purpose, two phase wet fixation dyeing trials were carried out for 9 reactive dyestuffs belonging to vinyl sulphone, monocholorotriazine, dichlorotriazine and trichloropyrimidine groups. The samples were padded with dyestuff solution, dried and fixed in fixation baths with conditions according to a matrix of time, temperature and alkali concentraion values. After measuring the reflectance values of these samples, their K/S and FK values were calculated. These values with their related parameters were used to obtain models through regression analysis. From the first set of obtained models for the nine dyestuffs, only one met the necessary conditions. Modification was carried out for the other eight and at the end five other models could be accepted as a representation of the colour yield of the dyes as a function of time, temperature and alkali concentration.