Dyeing Of Polysulfonamide Fabric With Mixed Carrier

Polysulfonamide (PSA) fiber is a kind of aramid fiber and its thermal stability is very good. There are aryl groups, amido groups and sulfone groups in the main chain of its macromolecule. PSA is difficult to obtain a satisfactory dyeing depth because of its compact molecular structure and strong intermolecular cohesion between polymer and its congeries. Now the methods to dye PSA include high-temperature-high-pressure dyeing with disperse dyestuffs, carrier dyeing with disperse or cationic dyestuffs, and dyeing after pretreating PSA with swelling agent.A low-toxicity and lowly-irritant mixed carrier MC was applied in dyeing PSA. MC could improve the dyeability of PSA fabric obviously. The optimized dyeing condition with MC was that dyeing temperature was 130℃and the MC concentration was 8g/L. The PSA fabric was dyed with Maxilon Red SL 200% (2%, owf) using the above optimized condition and the fabric shrinkage percentage was 7.8% and its K/S value was 24.7. When PSA fabric was dyed with the carrier of acetophenone at the concentration of 20 g/L, the fabric shrinkage percentage was 24.4% and its K/S value was 25.9.Compared with the other dyeing methods, dyeing with MC exhibited obvious advantages. The K/S value of the fabric dyed with MC was slightly lower than that of the fabric dyed with acetophenone, but MC has lower toxicity and irritant odor than acetophenone, and there was just a little irritant odor remaining on the dyed fabric. Compared with the dyeing with Sa, the dosage of MC was far lower and the K/S value was higher than that of Sa. The shrinkage percentage of the fabric dyed via MC was lower than that of pretreating dyeing method. The dyeing process of MC was simple and convenient.The optical microscope photos of the PSA cross section indicated that the dyestuffs penetrated levelly into the fiber. The colorfastness to washing, rubbing and perspiration was above 4, and the colorfastness to light was about 3. The SEM photos of the longitudinal morphology indicated that the surface of the fiber treated with MC was a little etched. The X-ray diffraction curves indicated that the fiber crystallinity increased after treatment with MC. The tensile strength of the fabric or yarn treated with MC decreased obviously. The TGA test indicated that MC not only swelled the PSA, but also slightly damaged the main chain of PSA macromolecule. The DSC test combined with the dyeing data indicated that a suitable dyeing carrier was the one that was a polar compound of lower-water solubility and could swell the PSA fiber. MC had the ability of dissolving the dyes, and the solubility of pure disperse dyestuff (Foron Scarlet RD-2R) was 3.96 g/L. Compared with the untreated PSA fabric, the MC-treated fabric exhibited the same vertical combustibility and the decreased LOI value. Also, the mixed carrier MC was suitable for the dyeing of polyester fabric and aramid fabric with disperse dyestuffs.