Degrading Natural Armor of Wool: Triple-Synergistic Scale Degradation via Limited Swelling, Disulfide Bond Reduction, and Controlled Proteolysis

Wool fabrics are susceptible to issues related to felting as a result of their surface scales, which significantly impact their usability. Traditional chlorinated shrink-proof finishing is effective but it produces organic halogen pollutants, which cause significant environmental risks. This study aimed to develop an effective and eco-friendly wool shrink-proof finishing process with an innovative combination of lithium bromide (LiBr), glycerol monomercaptoacetate (GMT), and protease (Savinase Ultra 16 XL). These ingredients work synergistically to precisely remove wool scales through a two-stage ″steam-batch″ process. The study systematically investigated the synergistic mechanisms of LiBr-induced microexpansion of fiber cortex, GMT cleavage of disulfide bonds, and hydrolysis of scale keratins by proteases. The combined use of 10 g/L LiBr, 10g/L GMT, and 6 U/mL protease endowed the wool fabric with a promising shrink-resistance property, achieving a felting shrinkage from 11.58 to 2.88% and a fabric strength retention rate of 95%. Compared to the traditional maceration method, this treatment system significantly reduces water and energy consumption while meeting the standards of machine washing. This innovative steam-batch system reduces water use by around 80% compared to traditional maceration. By molecular-level synergy of swelling-reduction-hydrolysis, it overcomes the contradiction between efficiency, environmental protection, and cost inherent in the traditional protease shrinkage prevention process.