A Multifunctional Finishing Strategy for Lyocell Fabric Integrating Durable Flame Retardancy and Enhanced Dyeing Performance via One‐Bath Process

In our previous work, a fully bio‐based flame retardant (PALA) was synthesized from phytic acid and L‐arginine and applied to Lyocell fabric, significantly enhancing its flame retardancy and washing durability. This study further develops a one‐bath synergistic process integrating PALA with reactive dyes, enabling simultaneous flame‐retardant finishing and deep dyeing. The resulting fabrics (PALA‐Lyocell R/Y/B) exhibit excellent flame retardancy, with LOI values exceeding 49.5% initially and remaining above 30.0% after 50 laundering cycles. Their thermal degradation behavior is highly consistent with PALA‐Lyocell (D) (Control sample treated only with flame retardant, without dyeing). Cone calorimetry test results show reduced peak heat release rates for the flame‐retardant‐dyed samples, while total heat release remains similar. The K/S value of PALA‐Lyocell (B) reaches 11.5, with all flame‐retardant‐dyed Lyocell fabrics showing slightly improved color depth compared with the control, indicating enhanced dye uptake. This work provides a multifunctional finishing strategy that combines durable flame retardancy and deep dyeing in Lyocell fabric.