Eco-friendly natural dyeing of submicron cotton fabrics

To explore the color diversity and performance of functional submicron cotton fabric dyed with ecological natural dyes, three types of natural dyes sappanwood, madder, and gardenia and orchid, were used to dye the fabric. The optimal dyeing conditions for sappanwood were found to be an insulation temperature of 95°C, a dyeing bath pH of 5.5, and a dyeing time of 60 min, resulting in the highest apparent color value ( K/S). For madder, the optimal conditions were an insulation temperature of 90°C, a dyeing bath pH value of 6, and a dyeing time of 60 min. Similarly, for gardenia and orchid, the optimal conditions were an insulation temperature of 90°C, a dyeing bath pH value of 5, and a dyeing time of 60 min. Based on these preferred dyeing processes, the K/S value, color characteristic value, color fastness, and biodegradability of the three natural dyes were compared and analyzed with synthetic dyes. The results showed that natural dyeing resulted in higher brightness ( L* values), lower color depth ( C* values), lower red-green ( a*) and yellow-blue ( b*) values, similar hues, and lower K/S values compared to synthetic dyeing. The color fastness of the natural dyes was slightly lower than that of chemical dyes by 0.5 grade. Additionally, the average breaking strength, elongation at break, tearing strength, and bursting strength of the fabric increased by 9.34%, 5.69%, 9.75%, and 7.31%, respectively. Furthermore, the biodegradability of the natural dyes was over 93%, significantly higher than that of synthetic dyes. These findings provide a theoretical basis for the production of eco-friendly dyeing of functional submicron cotton fabrics and their textile color applicability.