Abstract

A novel fluorine-containing aqueous copolymer emulsion, which was used for waterproof leather fatliquoring, was prepared via free radical copolymerization from maleic anhydride and natural oil (rapeseed oil and fish oil) followed by an esterification reaction with dodecafluoro heptanol and octadecyl alcohol. The reaction was monitored on-line by FTIR analysis and the combining fastness [strength of the combination] between the fatliquoring agent and leather fibre was examined by extraction with dichloromethane and water. Simultaneously, the effects of the fluorine content on contact angle (water-surface of leather), dynamic waterproofness time and static water absorption ratio of leather were also investigated. The X-ray photoelectron spectroscopy (XPS) showed that most of the hydrophobic fluorine-containing groups were orientated onto the surface of the leather and formed a hydrophobic film layer, whilst the hydrophilic carboxyl groups were enveloped in the inner layer. The fact the combination fastness is greater for the fluorine-containing copolymer than for other types of fatliquoring agents, shows that the carboxyl groups in the inner layer have coordinated with chrome(III) in the form of chemical bonding rather than by physical absorption. Chrome tanned leather treated with this type of fluorine-containing copolymer fatliquoring agent shows good durable waterproofness. When the fluorine content in fatliquoring agent is varied from 0wt% to 5wt% (based on solid content), the contact angle increases from 125° to 155°, the static water absorption ratio of leather is less than 9wt% and the dynamic waterproofness time reaches 55 minutes.