HIGH-STABILITY ORGANIC TANNING USING PLANT POLYPHENOLS - PART 1 - THEINTERACTIONS BETWEEN VEGETABLE TANNINS AND ALDEHYDIC CROSS-LINKERS

This new tannage is based on natural products, the plant polyphenols o r vegetable tannins. The chemistry applies only to the condensed or ca techol tannins, because it involves crosslinking the flavonoid ring sy stem. The preferred vegetable tannin is mimosa, in which the presence of pyrogallol groups appears to aid the reaction. The preferred crossl inker is oxazolidine. High shrinkage temperature is achieved by heatin g to 60 degrees C to drive the reaction; note, the pH requirements for fixing the two components of the tannage are mutually exclusive. Shri nkage temperatures > 110 degrees C are easily achieved.