Abstract

The objective of this study is to develop a novel melamine based resin suitable for producing formaldehyde-free leather with improved retanning properties. A series of resins was prepared by condensation of melamine, glyoxal and metanilic acid at varied mole ratios of reactants. Prepared resins were evaluated for retanning performance in leather in comparison with a commercial melamine resin to select the optimal resin. The mechanical and organoleptic properties of the optimal resin were found to be better than those of the commercial melamine resin. Tensile strength, tear strength and elongation of leather were increased by 17.43%, 10.41% and 8.62% in direction parallel to backbone while the increase in these parameters was 15.17%, 9.79% and 6.0% respectively in direction perpendicular to the backbone at same dosages. 100% reduction of free formaldehyde content was apparent in retanned leather and in the effluent produced by novel melamine resin. Pollution load study of the effluent showed a reduction in chemical oxygen demand, total suspended solids and total dissolved solids by 9.21%, 5.60% and 6.97% for the novel melamine resin reflecting its improved exhaustion. The fibre structure of the leather produced using the optimal melamine resin was arranged in a more orderly pattern as confirmed by scanning electron microscopy, thus showing its improved retanning capability. These results prove that the optimal melamine resin is an effective retanning agent suitable for producing formaldehyde-free leather with a reduction in effluent pollution load. This work also presents an alternative for formaldehyde for amino resins to address its carcinogenic effects.