Textile Dyeing & Printing With Ultrafine-pigment

Pigment dyeing & printing has several noticeable advantages compared to dyestuffs. These advantages are a simple technical process, good lightfastness, comprehensive color range, applicability to all fibre types, lower costs, reduced water consumption and reduced impact on effluent etc. Therefore, it has been more and more popular and have great developmental potentialities. However, there are also some disadvantages such as stiffer hand than dyes, reduced brightness, poorer fastness properties to rubbing and so on, which limit its applicability.In this paper, knitted cotton fabrics were dyed with ultrafine-pigments. The key factors including the concentration of cationic reactant, pH values, as well as temperature and time, which affect the cationised degree of cotton were discussed. The optimum application conditions of PAE were acquired: 7%(owf.) of PAE, at pH 9-10, at 80℃ for 20min. The effects of dyeing pH, electrolyte and the concentration of binder on the performance of dyeing were studied. It was found that the uptake of pigment and the color strength (K/S) reached to the maximum in the neutral bath. In different conditions, the effect of salt when dyeing quaternised cellulose was different. At pigment concentrations well below the saturation limit of the treated cotton, the uptake of pigment decreased with increasing salt concentration. When pigment concentrations nearly get to the saturation value of the fibre, electrolyte addition favoured pigment adsorption. The concentration of binder can also exert an impact on the performance of dyeing. The more the binder was added, the better the colorfastness was obtained, but the worse K/S and handle became. Moreover, three ultrafine-pigment pastes were used for dyeing and their suitability for use on the treated cotton was assessed. Compared with conventional pigment, It was observed that the fabrics dyed withultrafine-pigment had much higher color strength, more brilliant shades and softer handle.Two pigment pastes with different average pigment particle sizes were used for printing woven cotton fabrics and the performance of prints was investigated. The results showed that there were certain binding forces between ultafine-pigment and fabric, displaying certain color fastness properties of the printed fabrics in the absence of binder. And the amount of binder had a less effect on the color fastness properties of the fabrics printed by ultrafine-pigment than those printed by conventional pigment. It also can be seen that the fabrics printed by ultrafine-pigment exhibited significantly higher color strength, more bright and purer color as well as better rubbing fastness, compared to those of the corresponding fabrics printed by conventional pigment.The dyeing principles of pigment were also investigated. Introducing a cationic charge to the goods will give the cotton substantivity for the pigment. The photos of cross-sections and surfaces of the dyeing fibres examined by microscope and scanning electron microscope indicated that pigment particles just adsorbed on the surface of fibres and didn't diffuse into the fibres. Therefore, pigment dyeing is a coloring process other than a classic dyeing process.Besides, rubbing fastness improver was applied to the dyed or printed fabrics in order to achieve the required wet rubbing fastness. After the treatment, color fastness to wet rubbing can be improved one lever.