# Environmental Dyeing and Functionalization of Silk Fabrics with Natural Dye Extracted from Lac

## TL;DR

This study explores using natural dye from lac to color and enhance silk fabrics, offering eco-friendly alternatives with good durability and protective properties.

## Contribution

The study introduces a green method for dyeing silk using lac extract with optimized conditions and demonstrates its functional benefits.

## Key findings

- Optimal lac dye extraction was achieved with 60:40 ethanol-water ratio at 70°C for 1 hour.
- Dyed silk showed excellent fastness and functional properties like UV protection (UPF 42.68) and antibacterial effects.
- Natural lac dyeing offers a sustainable alternative to synthetic dyes for silk fabrics.

## Abstract

Most traditional synthetic dyes and functional reagents used in silk fabrics are not biodegradable and lack green environmental protection. Natural dyes have attracted more and more attention because of their coloring, functionalization effects, and environmental benefits. In this study, natural dyes were extracted from lac and used for coloring and functionalization in silk fabrics without any other harmful dyes. The extraction conditions were studied and analyzed by the univariate method. The optimal extraction process was that the volume ratio of ethanol to water was 60:40 with a solid–liquid ratio of 1:10, and reacting under the neutrality condition for 1 h at 70 °C. Silk fabric can be dyed dark owing to the certain lifting property of lac. After being dyed by Al3+ post-medium, the levels of the washing fastness, light fastness, and friction fastness of silk fabric are all above four with excellent fastness. The results show that the dyed silk fabrics have good UV protection, antioxidation, and antibacterial properties. The UV protection coefficient UPF is 42.68, the antioxidant property is 98.57%, and the antibacterial property can reach more than 80%. Therefore, the dyeing and functionalization of silk fabrics by utilizing naturally lac dyes show broad prospects in terms of the application of green sustainable dyeing and functionalization.