Effect of CO ₂ laser irradiation on the properties of cotton fabric

In this paper, a CO ₂ laser was used for treating cotton fabric. By controlling the laser process parameters, resolution (40, 50 and 60 dpi) and pixel time (100, 110 and 120 µs), the fabric properties changed accordingly. Fabric weight and strength decreased with increase of resolution and pixel time. However, yellowing was observed in laser treated cotton fabric but the extent of this yellowing was nearly the same under different laser process parameters. Scanning electron microscopy images showed that the surface morphology of cotton fiber was modified and it was believed that the low stress mechanical properties of the fabric were also modified. The low stress mechanical properties were evaluated by the Kawabata Evaluation System for Fabric (KES-F). The results were thoroughly evaluated and discussed. Dyeing performance of the laser treated fabric was evaluated in terms of dyeability, rate of exhaustion and color fastness. According to the reflectance curves, laser treatment reduced the amount of direct dye absorbed by the fabric and resulted in a higher reflectance. K/S values showed a decreased color strength when the resolution and pixel time were increased. The exhaustion curves indicated that laser treatment could cause color fading on cotton and a slight increase in the time of half dyeing (t _½ ) compared with untreated sample. In terms of color fastness to washing, laser treated samples performed the same as the untreated sample, irrespective of the resolution and pixel time. Laser treated samples had relatively poor crocking results when compared with the untreated sample.