Sorption, Desorption And Application Characteristics Of UV Absorbers On Textiles

In the present work, two reactive water-soluble UV absorbers, two non-reactive water-soluble UV absorbers and a water-insoluble UV absorber were applied in the UV protection finishing of nylon, silk, and cotton fabrics as well as silk/polyactic acid (PLA) mixture, and polyester/cotton blend using the immersion method. The sorption, desorption and UV protection properties of various UV absorbers on these fabrics were investigated. The primary conclusions were drawn as follows:(a) The adsorption of water-soluble UV absorbers on nylon and silk was mainly dependent on the pH value of finishing solution. The uptake of water-soluble UV absorbers by nylon and silk was found to increase with decreasing pH under acidic condition. Under alkaline condition, UV absorbers on silk exhibited better adsorption and fixation performance, and their adsorption was less influenced by alkali dosage. The UV absorber with one dichlorotriazine group exhibited a very low extent of desorption due to its higher reactivity in comparison with the UV absorber with heterobifunctional monochlorotriazine and sulphatoethylsulphone groups. The desorption of the two reactive UV absorbers from silk was various from their application conditions, and two UV absorbers showed lower desorption when previously applied to silk under alkaline condition. The difference between the desorption of reactive UV absorbers from the silk samples previously finished under various applied conditions provided indirect evidence for the mechanism of the uptake of reactive UV absorbers by silk.(b) The building-up properties of the water-soluble UV absorbers were different from their molecular structures, reactive groups, the treated fibers and the pH value of the treated solution. For different water-soluble UV absorbers, the extent of adsorption of UV absorbers in UV-A region had great influence on the UV protection performance of the finished fabrics. On the basis of the desorption test, it was predicted that the wash resistance of the UV protection performance should be improved by means of employing reactive UV absorbers and raising the immersion temperature properly. (c) When silk/PLA mixture and polyester/cotton blend were finished with UV absorbers, the water-insoluble UV absorber was mainly adsorbed on the PLA and polyester components, but also had stain on the silk and cotton components. When finished by the water-insoluble UV absorber with low dosage, the silk/PLA mixture could exhibit very good UV protection capability, although the water-soluble UV absorbers were not used for the finishing of silk component. The washing resistance of the UV protection effect of the mixture finished with the water-soluble reactive UV absorber was relatively good. When the water-insoluble and water-soluble UV absorbers were simultaneously employed in one bath, the silk/PLA and polyester/cotton fabrics showed better UV protection property than with those finished with water-insoluble or water-soluble UV absorbers alone.(d) When the dyeing and the UV protection finishing were simultaneously performed in one bath, the light fastness of pale colored fabrics was improved by about half level.