Abstract

Sulfonated amino resins like urea and melamine formaldehyde resins are widely used in retanning of leather. Both urea and melamine formaldehyde resins show free formaldehyde contents in the retanned leather greater than permissible limits (≤10ppm). In this research sulfonated isophthalic dihydrazide formaldehyde condensates have been prepared through controlled reaction of isophthalic dihydrazide with formaldehyde and sodium metabisulfite under different reactant conditions to optimize the free formaldehyde content in retanned leather within permissible limits. The retanning behaviours of these resin have been investigated. Tear strength, tensile strength, elongation at break and morphology of grain and cross section of fibre through scanning electron microscopy of the retanned leather has been studied. TGA was performed to evaluate the thermal stability of the resin. Structural elucidation of the optimized resin was characterized by FTIR.