Dyeing of cationised cotton using nanoscale pigment dispersions

Cotton modified with a cationic reagent has been dyed by an exhaustion process using nanoscale pigment dispersions. Pigment uptake, colour yield and fastness properties on cotton were measured. Uptake of pigment was found to be closely related to the concentration of cationic reagent, pH of the pretreatment bath, pretreatment temperature and time of cationisation. These factors also influenced the fastness properties of the fabric. Nanoscale pigment dispersions gave a much higher colour yield than conventional pigment dispersions on cotton. Fastness properties were acceptable for wash-down effects. It is clear that exhaust dyeing using nanoscale pigment dispersions offers a number of advantages in terms of pigment requirement, improved handle and appearance, and also in environmental protection.