Effect of Finishing Auxiliaries on Permeability of Leathers

Abstract

The unique fibrous arrangement and architectural marvel of collagen in skin matrix are the basis for various physical properties of leather. Air permeability is one of the unique features of skin, which makes the leather matrix superior to synthetic materials. In leather manufacturing finishing process determines the air permeability of the final leather. Therefore, knowledge of the impact of different finishing auxiliaries on the permeability of leather may helpful in selecting an appropriate finishing system for a particular type of leather. In this work, an attempt has been made to analyze the effect of various auxiliaries used in protein, acrylic and polyurethane (PU) based finish coatings on the air permeability of leather. Capillary flow porometer was used to monitor the air permeability (Flow rate cc/sec) at different pressures (psi). The results show that the effect of wax/filler/slip and dye solution on air permeability reduction is low when compared to pigment and binder. In protein and PU finishes, the binder alone and season (combination of all finishing auxiliaries like pigment, binder, and other auxiliaries) has a strong influence on permeability reduction whereas in case of an acrylic based finish, the pigment and binder plays an important role in permeability reduction. Leather coated solely with protein binder shows minimal permeability reduction than compared to leather coated with acrylic or polyurethane binders, whereas in season, acrylic based finishing has a lower permeability profile than that of protein and PU. In that case the permeability profile of protein and PU season coated leathers is almost similar.