Alkaline Hydrolysis and Dyeing Characteristics of Sea-Island-Type Ultramicrofibers of PET Tricot Fabrics with Black Disperse Dye

In this study, we investigated conditions for the alkaline hydrolysis and black-disperse dyeing of sea-island-type polyethylene terephthalate (PET) ultramicrofiber tricot fabric. We examined the weight loss ratios and tensile strengths according to the NaOH content (10%-30% on mass of fabric (omf)) during treatment; the optimal conditions used 25% omf NaOH for 30 min at 100 °C for an average weight loss ratio of 23.47%. By scanning electron microscope (SEM) analysis, the 'sea' components are extracted with increasing NaOH concentration until 25% omf NaOH, and damage of the 'island' components above 25% omf NaOH leads to a reduction in tensile strength. The dyeing conditions, including temperature (95-135 °C), time (20-60 min), pH buffer solution concentration (1-9 g/L), and contents of dispersant (1-9 g/L) and UV-absorbent (5%-25% omf) were also explored. The optimal dyeing conditions were established as a dye concentration of 8% omf with 1 g/L dispersant, 1 g/L pH buffer solution concentration, and 10% omf UV-absorbent at 135 °C for 40 min at a 1:10 goods-to-liquor ratio. The rubbing colorfastness values for the fabrics dyed with the black disperse dye spanned four grades under dry and wet conditions. The light colorfastness values of the dyed fabrics were good to excellent in the range of 4-5 grades.