Abstract

Tanning with basic chromium sulphate is the most commercially favoured process in the manufacture of a variety of high quality leathers. Environmental restrictions to the disposal of chromium containing solids and effluents, as well as speculations concerning the presence of toxic and carcinogenic chromium(VI) traces in leather products, have already directed the industry towards using alternatives. Wet-white tannages which consist of zirconium (IV) and aluminium (III) salts with high durability and resistance and organic alternatives which use phosphonium, aldehydes and some syntans both types with more eco friendly and biodegradable characteristics seem to be the main options for industry. However, properties like high hydrothermal stability, tensile strength, and thickness cannot be achieved by any alternative single tanning method. In this study, collagen hydrolysates derived from gelatin manufacture were used to improve wet-white leather performance properties through combination with tanning agents comprising zirconium and aluminium salts, phosphonium salts and aldehydes. The result shows that the apparent density, shrinkage temperature, denaturation temperature and strength properties of differently tanned leathers increased with the addition of collagen hydrolysates. SEM analyses show that collagen fibres are dispersed after tanning. Besides, collagen hydrolysates make the fibres loosen and the fullness of leather is increased.