Eco-Friendly Fabrication of Multifunctional and Double-Sided Heterochromatic Silk Fabric Using Tannin and Soil Humic Substances

The facile fabrication of an eco-friendly multifunctional [flame retardant, antibacterial, and ultraviolet (UV) blocking performance] and double-sided heterochromatic silk fabric was developed. In this study, silk fabric was subjected to a dyeing process using plant tannins, followed by a one-sided coating with a colloidal suspension consisting of humic acid (HA), fulic acid (FA), and green alum, and finally underwent a 15 min steaming treatment. The results revealed that the Tannin/HA/FA/Fe system had a distinctive micromorphology toward the silk fabric, characterized by a finely layered, cracked brick-like coating on the silk yarns. The prepared fabric showed a limiting oxygen index (LOI) value of 28.5%, a UV protection factor (UPF) value of 53.1, and a bacterial inhibition rate of 99.99% against Escherichia coli and Staphylococcus aureus, meeting the criteria for high-grade refractory textiles, UV-protection textiles, and antibacterial textiles. Additionally, the multifunctions and color of the fabric exhibited substantial durability to repeated home washing. The coating process did not inhibit the thermal/moisture comfortabilities and handle of the silk fabric. Promisingly, the raw materials employed in the fabrication of the prepared fabric were entirely natural or derived from nature, emphasizing the eco-friendly nature of the process.