Enhancement of Flame Resistance in Polyester Blended Furnishing Fabrics Using Dip–Nip Processing Methods

Flame retardancy is essential for ensuring fire safety compliance in home-furnishing textiles such as curtainsand upholstery. Polyester and polyester–cotton (PC) blended fabrics are widely used for these applications;however, their inherent flammability necessitates effective flame-retardant (FR) treatments. In this study, 100%polyester, 80:20 PC, and 67:33 PC fabrics were treated with a halogen-free flame-retardant formulation usinga pad–dry–cure process with controlled dip–nip sequences (1D–1N, 2D–2N, and 4D–4N), both with andwithout sodium hydroxide pre-treatment. The effect of dip–nip repetition on FR uptake, vertical flammabilitybehaviour, and washing durability was evaluated using ASTM D6413 and ISO 6330 standard test methods. Theresults showed a significant reduction in char length from approximately 15 cm (untreated samples) to 4.5–5.5cm (post FR treatment). Although FR uptake increased with the number of dip–nip cycles, no substantialimprovement was observed beyond the 2D–2N sequence. The treated samples retained palpable flameretardant performance of up to four laundering cycles, indicating moderate durability of the applied finish.Among the investigated samples, the 80:20 Polyester–Cotton blend exhibited the best flame-retardantperformance, attributed to enhanced interaction between the flame-retardant formulation and the hydroxylgroups present in the cellulosic component. The study demonstrates that an optimized 2D–2N sequenceprovides an effective balance between chemical uptake, flame-retardant performance, and durability forpolyester-based home-furnishing textiles.