Novel Non-Pickling Combination Tanning for Chrome-free Leather Based on Reactive Benzenesulphonate and Tannic Acid

A non-pickling combination tanning based on reactive benzenesulphonate (rBS) and Tannic acid (TA) has been developed for the chrome-free leather manufacturing. By optimizing the tanning process, the two-bath combination tanning with 4% rBS and 10% TA at the final pH 3.0-3.5 can raise the shrinkage temperature (Ts) of goatskins to ~86°C. Morphological analysis results reveal that the chrome-free leather exhibits a clear even grain surface and isolated collagen fiber network structure. The novel combination tanning approach not only improves light fastness, but also confers high physical and mechanical properties to the chrome-free leather which can meet the Chinese standard requirements for furniture leather and shoe upper leather. The non-pickling tanning without use of salt or acid is also benefit to clean leather-making production.