Development of Formaldehyde-free Leathers in Perspective of Retanning: Part 1. Benchmarking for the Evolution of a Single Syntan System

摘要

The awareness of health risks due to the use of leather products is escalating day by day. The demand for eco-labeled leather and leather products is increasing in the developed countries. Eco-labeling concepts force the tanners to look into various options for developing eco-benign products. Formaldehyde is classified as a probable human carcinogen. In this study, an attempt has been made to produce leather without formaldehyde by employing formaldehyde-free syntans. A relative measure of performance of formaldehyde-free and formaldehyde based syntans has been done to test their ability to produce leathers with desired properties by employing these syntans individually. Three formaldehyde-free syntans (resin, acrylic and protein) and two formaldehyde based syntans have been chosen for optimization trials. Trials have been carried out to find out the optimal amount of individual syntans required for providing sufficient properties to the leather. Based on organoleptic and strength properties as well as other property evaluation, it has been found that 12 and 8% formaldehyde based syntans A and B and 8, 10 and 12% formaldehyde-free resin, acrylic and protein syntans are capable of providing sufficient properties to the leather. There seems to be a considerable relation between the nature of the syntans and properties imparted to the leather. Aromatic syntans tend to decrease the strength and softness properties of leathers with increasing offer. Relation between the fullness of leathers and offer of syntans has been substantiated through scanning electron microscopy. The leathers treated with formaldehyde-free syntans do not contain free formaldehyde when analyzed using standard procedure and hence do not possess any health risks.