Synergistic Pretreatment of <scp>l</scp> -Cysteine and Hydroxypropyl Methylcellulose for High-Quality Inkjet Printing on Wool Fabric without Structural Damage

Textile inkjet printing has gained significant traction due to its cleanliness, flexibility, and efficiency. However, its application on wool fabrics is hindered by the inherent ultrahydrophobicity and steric hindrance of the surface scale layer, which leads to poor printing quality. Conventional methods often destructively remove the scale layer to improve the inkjet printing quality, which damages the original structure and strength properties of the fabric. Herein, a novel method based on hydroxylamine chloride (HC)/l-cysteine (L-C) and hydroxypropyl methylcellulose (HPMC) was developed to improve the inkjet printing quality while preserving the raw structure and physical properties of wool fibers. Results showed that HC/L-C cleaved disulfide bonds within the keratin, opening the capillary channel for ink to enter the fiber interior. Meanwhile, amphiphilic HPMC significantly enhanced surface wettability. After combined treatment, the apparent color strength (K/S value) of the printed wool fabric greatly increased from 6.9 to 26.3, which was one of the best performances among existing methods. Moreover, the original structure and physical properties of the wool were preserved. The excellent color fastness was maintained due to the unchanged covalent dye-fixation mechanism. Successful application in the textile industry demonstrated the method's practical viability. This work presents an efficient and nondestructive approach, offering significant promise for advancing sustainable textile digital printing.