Eco-friendly Anti-felting Finishing and Low-Temperature Dyeing of Wool Through Plant Protease

The presence of hydrophobic scales in wool leads to felt shrinkage, stiffness and hinders the dyeing process. This study suggests that plant protease can focus on breaking down the keratin in the scale layer on the “hydrolysis mode” to achieve a controlled peeling from the surface layer of the scale gradually to the outer layer, with little damage to the inner layer and CMC layer. The opening of the channel in the scale layer enhances the adsorption and diffusion of the dye in the fiber, thus making dyeing very easy. Wool fabrics before and after enzymatic treatment were structurally characterized using Raman spectroscopy, FT-Raman spectroscopy, and X-ray diffraction. The results showed that papain and bromelain tended to cleave the amide bonds and some intermolecular disulfide bonds in the molecular chains of keratin in the wool scale layer. In comparison, papain reduced the felting shrinkage of the wool fabric to 2.11%. It also increased the anti-pilling level of wool fabric by 1 level and the antistatic property by 30%. Besides, pretreatment with bromelain had a significant effect on traditional dip dyeing, increasing the dyeing rate by 48% and the K/S value by 28%. The strategy played a positive role in promoting the sustainable development policy of energy saving and emission reduction. This study provides an alternative method for environmentally friendly anti-felting finishing and low-temperature dyeing of wool fabric that can be applied commercially.