Modification of natural yellow dyes for improvement of washing and light fastness

摘要

Most of the natural dyes namely Turmeric (Curcuma longa); Palas (Butea monosperma), Ganda (Tagetes Erecta) & Shiuli (Nyctanthes Arbortristis) are having poor to moderate washing fastness and very poor light fastness [1] owing to their inbuilt dye structure. They contain -OH groups along with -OMe which intensify [2] the depth of shade according to their increased numbers in one dye molecule. These -OH groups are prone to metallic mordants to produce shades of different tones. On the other hand, these groups are the common path way [3] to UV rays of sunlight and therefore, colour is faded quickly due to a photo chemical reaction. In this research work, attempts have been taken to block the -OH groups of the dye for improvement of light fastness along with intensity of color and washing fastness.