Abstract

Leather tanning reactions between collagen and dihydroxynaphthalenes (DHNs) or diphenols and oxazolidine have been investigated using hide powder and sheepskin pickled pelt. This investigation showed that some DHNs have a tanning effect on collagen. The measurement of combined and cross-linked DHNs on collagen showed that 30-40% 1,6- and 2,6-DHNs were fixed through covalent bonding. Shrinkage temperature of the leather changed little after the non combined DHNs had been removed from the leather, indicating that the high stability of the combination tanned leather comes from the covalent bonding formed between DHNs and collagen through oxazolidine.