Effect of nanometer-sized binder of ink jet inks on silk printing

This research investigated the effect of nanometer-sized binder of ink jet inks on silk printing. Ink jet inks were prepared from two different sizes of copolymer of acrylic acid ester/styrene based binder having average particle sizes of 70 and 180 nm. The main compositions of the inks were fixed and the pigment-to-binder ratio was varied at 1:1 and 1:2 (by weight). The inks were characterized in terms of pH, viscosity, surface tension, zeta potential, and particle size. The inks so prepared were then printed on the untreated and chitosan treated silk fabrics. The printed fabrics were then analyzed for color gamut, crock fastness, wash fastness, ink penetration, bleeding, air permeability, and stiffness. The four color inks (CMYK) had a pH in the range of 7.5–8.5 and exhibited the Newtonian flow. The average particle sizes of the resulting inks were found in a range of 50–90 nm for the 70-nm binder and 110–200 nm for the 180-nm binder. The surface tension of the inks was in a range of 42–45 mN m-1. The zeta potential of both inks was in a range of (–32) to (–45) mV. The inks were stable for at least 6 months. Color gamut of the treated fabrics printed with the inks having 70-nm was slightly wider than those of the ink having 180-nm binder. The dry and wet crock fastnesses of the untreated and treated fabrics obtained from the 70-nm binder were better than those of the 180-nm binder, whereas wash fastness of the all printed fabrics was excellent. Bleeding of the inks on the fabrics was slightly different as that the inks containing 70-nm binder spread slightly wider. Air permeability was not much affected by the binder size but the 180-nm binder rendered slight stiffness to the fabrics. Air permeability and stiffness of the treated and printed fabrics were significantly higher than that of the untreated fabric in which increases the chitosan concentrations imposed a stronger and favorable effect. Chitosan coating increased the fabrics color gamut and optical density. Chitosan pretreatment helped improve the ink deposition on the fabrics surfaces and thus increased color strength. The fabrics printed with the inks containing the 70-nm binder displayed overall the better quality of printed fabric.