The Use of Polycationic Agent to Modify the Dyeing Behaviour of Direct Dyes on Cotton Fabric

Abstract

In the current practice, cotton fabric is predominantly dyed with direct dyes in the presence of a considerable amount of electrolyte (Salt) to reduce negative charge on fiber surface. Thus, the high concentration (40-100 g/l) of electrolyte required in cotton fabric dyeing may pose additional effluent problem and waste water treatment costs. The use of polycationic agent to modify the dyeing behaviour of direct dyes on cotton fabric is investigated. Normally, polycationic agent had been treated on dyed fabric to improve fastness properties. The comparison of untreated and pretreated cotton fabric was found that the polycationic agent offers the potential for different dyeing patterning possibilities. The dyes was fixed on the fiber by ionic force. So, color strength and exhaustion of pretreated fabric was better than untreated fabric and increased in fastness properties, even when dyeing had been carried out in the absence of electrolyte. The purpose of the present work was to determine whether the pretreatment of cotton fabric with polycationic agent could enhance the dyeability of the fiber with direct dyes under appropriate condition such as assuming a positive charge on fiber which permitted “electrolyte-free” dyeing after modification without drain and helped reduce dyeing cost.