Formation of Cross-links in Silk by Dyeing with a Difluorochloropyrimidyl Dye

The dyeing of silk using a monoazo difluorochloropyrimidyl reactive dye has been studied with respect to exhaustion, fixation ratio, solubility of the dyed fibres in lithium thiocyanate solution, work recovery and tensile strain recovery. The results indicate the formation of cross-links between the reactive group by reaction of the two fluorine atoms in the dye with functional groups in the silk fibroin, probably mainly tyrosine OH groups