Effects of ink dispersions on fabric printing by pigmented inkjet inks

Pigment dispersion technique of ink is one of the effective parameters on pigmented inkjet ink printing quality. This research aims to investigate the effects of pigment dispersion of inkjet inks for textile printing. Four sets of four pigmented inks were each prepared by polymer dispersion, surfactant dispersion, microencapsulation, and surface modification. The inks were made by different ratios of pigment to binder (P/B) at 1/0.5, 1/1 and 1/2. The ink properties were studies for viscosity, surface tension, pH and pigment particle size. The properties of the ink were found as follows: viscosity increased with increasing binder concentration, but it did not affect the ink surface tension; the ink had an acceptable pH of 7.5-9; and the pigment particle sizes were in the range of 70-140 nm. The inkjet inks were printed on the pretreated cotton fabric with a mixed solution of poly(vinyl alcohol) and alumina. The printed cotton fabric was analyzed for color gamut and its volume, air permeability, stiffness and crockfastness. The ink having a pigment-to-binder ratio of 1/2 rendered the optimum color gamut and crockfastness. This research investigated additionally the effect of three pre-treatment reagents, comprising cationic pigment, cationic polymer, and poly(ethylene oxide) of high molecular weight of 2,000,000-3,000,000 dalton, on four types of fabrics, namely, cotton, silk, polyester and cotton/polyester blend (35/65 ratio). The fabrics were printed by the ink containing 1/2 pigment/binder ratio dispersed by polymer dispersion. The pre-treatment of cationic polymer produced the better printed color and crockfastness, whereas the poly(ethylene oxide) treatment yielded the better air permeability of the printed fabrics and stiffness as well. This research explained the effect of fabric pre-treatments on fabric qualities/properties.