Chemical developments leading to cleaner production Part 2: Wet post-tanning operations and finishing

摘要

Products applied in wet post-tanning operations are mainly expected to be taken up by the leather forming a permanent bond with the substrate. These products can be placed into groups and are presented in Figure 7. Very many different combinations are possible, and the order in which they are added can vary considerably. Most of them are solubilised or emulsified with anionic groups in order to allow them to be taken up by the cationic wet blue. Problems can be caused if they are not fully exhausted as the COD can be very high. This is especially so if large amounts are added in order to obtain special effects. The COD values of some typical post-tanning treatment processes are shown in Figure 8.