Cationic-dyeability Of PET Fabrics By Deep UV Laser Irradiation

The irradiation of UV laser which is friendly to the environment is one of the physical methods for surface modification of polymers. This method of surface modification can reduce the usage of chemical reagents or use no chemicals. In recent years, our team has made some achievements in treating textile by UV laser. On one hand, the UV laser irradiated PET fabric got deeper shade in K/S value, dye uptake improved, dyeing temperature could decreased from 130°C to 100°C, color fastness to washing and rubbing weren't affected. On the other hand, the UV laser irradiated silk fabric also got deeper shade and washing fastness while using less salt(10g/L), reactive dyestuff and the dyeing temperature dropped from 60°C to 45°C.Therefore, this research was aimed to study on the physical & chemical properties of PET fabric irradiated by 266nm UV laser, and the cationic dyeability (including fastness) of the UV laser irradiated PET fabric, the dyeing property of the chemical modification cationic-dyeable PET using the same cationic dyestuffs was also studied. It is one of the factors to evaluate the feasibility of dyeing the UV laser irradiated PET fabric through analyzing the dyeing results of laser irradiated PET and chemical modificated cationic-dyeable PET. In addition, the differential dyeing patterns were designed using laser software and the fabric gained differential dyeingeffect.Scanning electron microscope (SEM) observation revealed the morphological modification of the PET fabric irradiated by 266nm UV laser with the appearance of ripples perpendicular to the axis of the fiber, which was similar to the 193nm, 248nm, 308nm laser. This may be related to PET for different wavelengths of laser absorption rate. Pulse energy density, under certain preconditions, 193nm wavelength was relatively shallow depth of etching to form a fine structure of the surface fluctuations; and 308nm wavelength would lead to polyester ablation, undulating structure was more evident. X-ray diffraction analysis showed that the crystalline region of the UV laser irradiated PET fabric was reduced. The crystallinity reduced from 35.64% to 32.87% when the time delay was increased from 10μs to 60μs. Hydrophilic character of the PET fabric irradiated by UV solid laser was greatly improved owing to the increase of the O/C ratio of the surface. The antistatic property was also improved. The static voltage and half life were reduced.Experiments revealed that whiteness, tensile strength and elongation of the PET fabric irradiated by UV laser decreased and were affected by time delay between valid vector steps of laser. The tensile strength decreased from 23.8N to 22.0N when the time delay increased to 30μs. We could know that laser irradiation didn't damage the PET fabric. The enhanced color depth could be achieved when dyeing laser irradiated PET fabric with cationic dyes, owing to the anions on the surface of fabric. Furthermore, the K/S value was also affected by laser time delay between valid vector steps. The UV laser irradiated PET fabric got deeper shade than the cationic-dyeable PET fabric when they were dyed with the cationic dyes(98°C water bath at atmospheric pressure). Cationic red, for example, the K/S value of irradiated PET fabric was 6.2, while the cationic-dyeable PET was about 3.0. However, Compared with color fastness of the cationic-dyeable PET fabric, color fastness to rubbing, washing with soap and light of the UV laser irradiated PET fabric dyed with cationic dyes were a little lower, 4-5 grade of dry rubbing, about 4 grade of wet rubbing, more than 4 grade of washing with soap and 3-4 grade of light fastness. The differential dyeing patterns were designed by the laser software, and the good differential dyeing effects were finally achieved.Through the UV laser irradiation, anion groups were generated on the surface of PET fabric, thus increasing the dye seats for cationic dyestuffs. This was the main reason for the UV laser irradiated PET fabric got cationic dyeability. In the experiment, the optimized of dyeing process was also another reason for the feasibility of dyeing the UV laser irradiated PET fabric with cationic dyestuffs.