Flame-retardant treatment of wool and wool-rich blends: A study of bath composition

Wool and wool-polyamide blended yarns (88.6% wool–11.4% polyamide 6,6 and 78.5% wool–21.5% polyamide 6,6) were knitted and the produced fabrics were treated by exhaustion method with zirconium complexes. Six different baths containing potassium hexafluorozirconate and zirconium acetate were studied. The flammability hazard was evaluated considering parameters such as the spread of flame, the heat release and the smoke release rate. Regardless of the blend composition, the untreated fabrics could not pass the vertical flammability test. 100% wool fabric could pass the vertical flammability test when treated with only 1% potassium hexafluorozirconate and 10% zirconium acetate solution. Higher compositions of metal complexes were required for the blended fabrics to pass the vertical flammability test. In the cone calorimeter test, 100% wool treated with 5% potassium hexafluorozirconate and 10% zirconium acetate solution gave the lowest peak heat release and smoke release rate values as 146.4 kW/m ² and 1.2 s ⁻¹ , respectively.