A Novel Approach for Lightfast Wet-white Leather Manufacture Based on Sulfone Syntan-aluminum Tanning Agent Combination Tannage

Abstract

Wet-white tanning as an eco-friendly leather-making processhas been attracting considerable attention. Herein, we haveinvestigated a novel combination tannage for lightfast wet-whiteleather based on sulfone syntan and aluminium tanning agent.By optimizing the technology, 10% sulfone syntan and 3%aluminum tanning agent at final pH 4.0 - 4.5 can raise theshrinkage temperature (Ts) of the wet-white leather to ~81oC.The synergistic tanning mechanism of the two has beenillustrated. As verified by Zeta potential measurements, theintroduction of Al3+ into the sulfone syntan system led to theincrease in the isoelectric point (IEP) of wet-white leather, whichis favorable for the subsequent post-tanning process. Scanningelectron microscope-Energy dispersive X-ray spectroscopy(SEM-EDX) results reveal that sulfone syntan and aluminumtanning agent can be evenly bound within the leather matrixand promote the formation of tightly woven networks of collagenfibers. The novel combination tanning approach not onlyimproves light fastness and lighter shade, but also confers highphysical and mechanical properties to the wet-white leather.