Supercritical CO2 as a potential tool for the eco-friendly printing of meta-aramid

Large degree of orientation, crystallinity, and high glass transition temperature of aramid make the fibers exhibit ultra-high strength, high modulus, high temperature resistance, acid and alkali resistance, light weight and other excellent properties. However, the resulting poor dyeability and water pollution problems of aramid greatly limits its application in protective areas. An eco-friendly supercritical CO2 assisted printing strategy for meta-aramid was developed firstly in this study. The effects of treatment temperature, time, pressure and dye con-centration on the printing properties were investigated. The obtained results showed that the K/S values of the printed meta-aramid increased with the enhancing of CO2 temperature, treatment time and CO2 pressure. Compared to tradition printing, higher color depth can be obtained by supercritical CO2 assisted printing with 40% sodium carboxymethyl cellulose and 20% guar gum as original paste. The K/S values of the meta-aramid with Cationic Pink X-FG in supercritical CO2 was 12.18 while that of the samples with Cationic Yellow 5GL was 5.42. Washing and rubbing colorfastness rated above 4 were reached at 180 degrees C for Cationic Pink X-FG and at 160 degrees C for Cationic Yellow 5GL in supercritical CO2. In addition, up to 99% outline sharpness and acceptable stiffness, air permeability and mechanical properties was obtained, which demonstrated that the meta-aramid fabrics with supercritical assisted printing could better meet the wearability requirements.