Synthesis of a Waterborne Melamine Resin and its Retanning Behaviors Investigation

Recently, the application of waterborne melamine resin (WMR) is greatly increasing in the leather industry because of its convenient operation, but it often suffers from poor storage stability. Here, two waterborne melamine resin retanning agents (WMRs) with high storage stability were prepared using melamine, glutaraldehyde and collagen hydrolysates (CHs) as raw materials at different mole ratios. FTIR, 13C-NMR and XPS were used to characterize the chemical structure of synthesized resins, and their retanning behaviors for wet blue and wet white leather were fully investigated. The particle sizes of WMR1 and WMR2 were 28.73 nm and 8.78 nm, and their zeta potentials were 4.0 and 4.5, respectively. The introduction of CHs provided not only good water solubility but also amphoteric properties to synthesized resins, thereby resulting in high absorption of retanning and fatliquoring agents. Moreover, the retanning application investigation of WMRs manifested good storage stability and excellent overall performance, which are comparable with commercial retanning agents. This work showed that glutaraldehyde and CH could be used as starting materials in the synthesis of environmentally friendly WMR.