Modification of natural dyes for superior dyeing capability, high fastness and wide colour gamut

• Main Author: McAllister, Liam John
• Published: University of Leeds 2012
• Subjects: 667.26
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.590472

The issue of sustainability has pervaded many areas of technology in recent years, in response to concerns over the possible impact of such technologies on the environment. One such technology is the textile industry, which is at present heavily dependent upon the supply of petrochemicals. The petrochemical industry will at some point in the immediate future, have to tackle not only the price of oil but also the gradual decrease in its availability. The development of technologies that offer genuine solutions to these problems are of crucial importance. Azo dyes account for a major percentage of the dyes currently in use, with anthracene-9,IO-dione based dyes responsible for a sizeable proportion of the remaining market. Azo dyes have many excellent characteristics from a dyeing perspective, but their suspected toxicity following degradation may at some point in the future curtail their use. The synthesis of anthracene-9,10-dione based dyes requires multi-stage synthesis coupled with isomeric separation, and from a commercial viewpoint only blues and reds prove cost effective. By means of simple one-step synthetic modifications this study has shown, that modified naturally occurring anthracene-9,lO-dione based dyes show excellent technical performance in some cases on poly(lactic acid) (PLA) and poly(ethylene terephthalate) (PET). The improvements made over their natural precursors include; higher dye exhaustion, improved colour strength, better saturation chroma (C*), and improvements in light fastness. The most effective derivatives are produced following alkyl substitution across adjacent hydroxyl groups, which yielded cyclic acetals and ethers with improved dyeing characteristics.