New approaches for the reactive dyeing of the retanned carbohydrate crust leather

A number of reactive dyestuffs of three different categories, i.e., monochlorotriazine, dichlorotriazine and vinyl sulfone have been examined with some carbohydrates, i.e., glucose, galactose and fructose in the crust leather dyeing to determine the correlation between the reactive groups of the different dyestuffs and retanned leather. These carbohydrates were used as retanning agents to develop the dye–leather affinity. There are indications that some correlation could exist and for the dyestuffs examined, pH plays an important role to give a reasonable measure for the dye–leather affinity and the behaviour of the dyestuff. The effect of carbohydrates on the mechanical properties, thermal stability and the main amino acids' content of the crust leather were investigated. The average affinity numbers of the used dyestuffs were also evaluated.