Preparation of castor oil-based fatliquoring agent via a Pickering emulsion method for use in leather coating

A castor oil-based fatliquoring agent for use in leather coating was prepared via Pickering emulsions stabilized by metal–organic frameworks (MOFs). The partially oxidized ZIF-8 (POZIF-8) nanoparticles were used as MOF in the presence of a castor oil-based dispersant. The results of the stability test showed that the presence of POZIF-8 nanoparticles leads to a stable oil/water emulsion with higher oil content than other nanoparticles, such as TiO₂ and ZnO. The stabilized structure of the prepared fatliquoring agent was characterized by transmission electron microscopy (TEM). TEM image indicated that the castor oil either was surrounded or was encapsulated by MOF. The prepared fatliquoring agent was applied to the leather. Then, in order to prove the existence of POZIF-8 nanoparticles in collagen fibers, the cross section of the fatliquored leather was examined by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). These analyses revealed the good dispersion of POZIF-8 nanoparticles from grain to flesh side. The physical and mechanical properties of the fatliquored leather were compared with those of the control leather sample, which was fatliquored by a conventional agent. The results show that the prepared fatliquoring agent significantly improved mechanical properties, lightfastness, softness, and fullness of leather.