UV-Protection Finishing Of Silk Fabric

Silk fabric has the defects of photoyellowing and poor UV-protection behavior due to its light and thin texture during the course of usage. In this paper, a water-soluble benzotriazole UV-absorber was used to increase the UV-protection capability of silk fabric. The properties of the adsorption of the UV-absorber on silk were invertigated in comparison with wool and nylon, and the adsorption mechanism was discussed through isotherm experiments and the ultraviolet protection factors of the finished silk fabrics were measured. In order to improve the fastness of the UV-absorber to washing, the treatment using the cationic fixing agent was performed. In addition, the influence of acid dyeing on the ultraviolet protection factor of silk fabric was discussed, and the relationship between the UV spectra of dye solutions and the ultraviolet protection factors of the corresponding dyed fabrics were studied with the aim to make silk fabrics achieve the better UV-protection properties through simultaneous dyeing and finishing.The extent of the adsoption of the water-soluble benzotriazole UV-absorber on silk was found to decrease with increasing pH and temperature, and the adsorption rate was fast and the exhaustion extent was high. The adsorption isotherm of the UV-absorber on silk fitted a dual sorption mechanism consisting of partition and Langmuir type models. The Langmuir adsorption was a result of the ion-ion interaction between the protonated amino groups in silk and the sulfonated groups in the UV-absorber, whereas the Nernst adsorption was a result of the hydrogen bonding and the hydrophobic interaction between the UV-absorber and silk. The adsorption of the UV-absorber on silk had the characteristics of low affinity constant and high saturation value.The ultraviolet protection factor of finished silk fabric increased with an increase in the dosage of the UV-absorber, and exceeded 30 when the suitable dosage of the UV-absorber was used. The washing fastness of the UV-absorber on silk was poor due to its small molecular dimension and electrovalent bond with silk, but could be improved through the treatment using an appropriate cationic fixing agent.Acid dyes on silk fabric had some UV-protection function because they possessed the adsorption properties in UV region. The higher the adsorption intensity of acid dyes, the higher the ultraviolet protection factor of the corresponding dyed fabric. For pale dyeings, the simultaneous dyeing and finishing would obviously improve the UV-protection function of silk fabric.