Preparation of Formaldehyde-free Melamine Resin using Furfural as Condensation Agent and its Retanning Performances Investigation

Amino resins are one of the most important retanning agents used in the leather industry. However, the generally presence of formaldehyde greatly restricts the widespread application of amino resins. In this study, furfural, an organic compound derived from biomass material, was used to substitute for formaldehyde in the synthesis of melamine resin based on an alkaline-acid procedure. The as-synthesized formaldehyde-free melamine resin (MRf) showed excellent performances in leather processing. FTIR and C-13-NMR were used to characterize the chemical structure of MRf. The particle size as well as zeta potential were also determined. The retanning performances of MRf indicated that the overall performances of MRf are comparable to conventional formaldehyde contained melamine resin (MR) and commercial melamine resin (CMR). In particular, the thickness of the leather retanned by MRf was enhanced around 10.33%, which is significantly higher than that of controls MR (6.16%) and CMR (5.94%). Color measurements showed that MRf imparted leather with higher dark intensity. This present work demonstrated that furfural could be a potential candidate to replace formaldehyde in the production of formaldehyde-free melamine resin.