Hyperbranched polyester/Borax/TEOS for potentially improving the flame retardancy and printability of natural ramie fabrics

Protecting flammable natural renewable fibers is essential. Flame-retardant sol-gel coatings are widely used to enhance surface properties of cellulosic textiles. This study targets ramie fiber, a traditional, renewable textile with excellent qualities without major limitations such as high flammability, low thermal stability, and poor direct dye affinity. A novel sol-gel composite of hyperbranched bis-MPA polyester-16 hydroxyl (HBPE, generation 2), borax, and tetraethyl orthosilicate (TEOS) was developed for ramie fabric finishing via pad-dry and IR methods. It imparts good flame retardancy, printability, and durability. The composite's structure, crystallinity, and morphology were characterized by FT-IR, XRD, TEM, particle size distribution analysis using dynamic light scattering (DLS), and EDX. The composite's efficacy as a finishing agent for conventional flat screen-printing of ramie fabrics with direct orange 39 dye was studied. The prints were examined using SEM, colour strength, colour parameters, fastness to rubbing, washing, and light, and UV-protection factor. The resulting composite had a particle size of about 368 ± 72 d.nm with an amorphous structure. When HBPE/borax/TEOS was coated onto the surface of ramie fabric, the flame-retardant and colour properties improved significantly compared with the usual printing approach. It can be concluded that the tri-component composite coating, synthesized via sol-gel, applied by IR, and printed by heat transfer, successfully turns ramie fabric into a high-performance textile.