Enhancing the Dyeability of Basalt Fabric by Cationic Waterborne Polyurethane Modification

Basalt fiber (BF), as a high-performance inorganic fiber, exhibits excellent overall properties, including high strength, high modulus, corrosion resistance, and flame retardancy. However, its dense structure, smooth surface, and chemical inertness lead to monotonous coloration and difficulty in dyeing. In this study, cationic waterborne polyurethane (WPU) was employed as a modifier for pretreating BF fabrics and underwent protonation to create positive charges under acidic conditions, enabling dyeability with acid dyes. Three types of WPU films (MWPU, DWPU, and TWPU) were created by grafting cationic chain extenders N-methyldiethanolamine (MDEA), 3-Dimethylaminopropane-1,2-diol (DMAD), and N-t-Butyldiethanolamine (TBDEA) onto the polyurethane chains, with all light transmittances exceeding 90% and ζ potential over 50 mV to ensure robust bonding with anionic dyes. The tensile strength of fabrics modified with WPU increased by more than 71%, and their strain also improved significantly. MWPU served as the best modifier for coloring, with the 10%MDEA dosage formulation reaching a K/S value of 12, and the dye uptake rate showing 81.1%. It also exhibited excellent fastness, with sunlight fastness at grade 5, minimum rubbing fastness at grade 3∼4, and washing fastness at 4 or higher. We employed a straightforward structure to impart color to BF fabrics, achieving outstanding color fastness and offering an effective approach to advancing the application of colored inorganic textiles.