Bentonite‐Modified <scp>TPU</scp> Composites for Thermal Sublimation Transfer Films: Improving Pattern Durability and Color Vibrancy

ABSTRACT Fabric thermal sublimation transfer technology offers vivid color and high resolution, yet transferred patterns on cotton fabrics often exhibit insufficient integrity and durability due to weak interfacial bonding. Herein, quaternary ammonium salt‐modified bentonite (MBN) was introduced into a thermoplastic polyurethane (TPU)/titanium dioxide (TiO 2 )/triglycidyl isocyanurate (TGIC) system to enhance water resistance and pattern stability. Interfacial interactions between TPU hard segments and the MBN interlayers restrict chain mobility, contributing to improved structural robustness. The optimized composite, TTTB1 (TPU/TiO 2 /TGIC/MBN = 88/10/1/1), achieves excellent transfer clarity at 150°C. Its secondary activation resistance reaches 84%, which is 42% higher than that of the TPU/TiO 2 /TGIC counterpart and 5% higher than that of pure TPU. After 48 h of water immersion, the water absorption decreases by 14%, and the peel‐strength retention after 72 h remains at 92.3. Moreover, the washing fastness consistently reaches Level 5. These findings indicate that MBN incorporation markedly enhances moisture durability and adhesion stability while maintaining mechanical performance. This work offers a practical approach for designing highly durable sublimation‐transfer adhesive films for cotton fabrics.