Retanning Performance of Carboxymethyl Starch and Its Effects on Dyeing

The tanning characteristics of starch samples modified by different methods were investigated in our previous studies. In this study, utilization of modified starch in leather making as a retanning agent and its effect on dyeing process have been investigated. For this purpose, the molecular size of native corn starch was reduced by H2O2 oxidation and then carboxymethylated. A series of analyses (water solubility, degree of substitution, Fourier Transform Infrared Spectroscopy, Proton and Carbon Nuclear Magnetic Resonance Spectroscopy) were carried out for characterization. Then, carboxymethyl starches were used in retanning processes to be 3, 5 and 10% based on leather weight and the shrinkage temperatures and filling coefficients of the leathers were determined. Acid and metal complex dyestuffs were used in dyeing processes and the effect of carboxymethyl starch on dyeing was also investigated by examining dye consumption, dry and wet rubbing fastness and color of the leathers. From the results it was concluded that carboxymethyl starch showed a noticeable solo performance in terms of filling property and shrinking temperature without any considerable adverse effect on dyeing.