Abstract

The retanning process plays an important role in optimizing the leather’s colour, levelness, softness, fullness, and hydrophobicity. Polymer retanning agents are important materials for this process. The present study used maleic anhydride modified castor oil (MCO), PEG1000 (polyethylene glycol) and IPDI (isophorone diisocyanate) as main materials to synthesize polyurethane microemulsions (MC-PURs) and employed them to retan chrometanned leathers. The hydroxyl functionality of MCO was investigated by chemical and 1HNMR analysis, and confirmed to be about 2.0. The chemical structures of MCO, prepolymer and MC-PUR were characterized by IR. The optimized synthesis formulation and polyurethane microemulsion MC-PUR3 for MC-PURs as retanning agent was selected by comparing the properties of retanned leathers, such as softness, fullness, grain tightness, tensile strength, extension at break, depth of shade, waterproof properties et al. Then, MC-PUR3 was characterized by means of DSC, TG/DTG and TEM techniques. SEM microgram of MC-PUR3 retanned leather shows that the fibres are well dispersed.