Abstract

In this paper, subcritical CH2Cl2 solvent was applied to the degreasing process of sheepskin. The optimal process parameters of degreasing were determined by single factor experiment and the degreasing efficiency was evaluated by the degreasing rate. The effect of degreasing temperature on the connection between hair and hair follicle, fat content of lipid cells and the fibre dispersion of the sheepskin were investigated through the use of optical microscope and the scanning electron microscope. The single experiments results showed that when the moisture content of the raw skin was about 60%, degreasing time was 50 minutes, degreasing temperature 39°C, and degreasing pressure 0.5MPa and the solid liquid ratio was 1:7. The degreasing rate of sheepskin with the subcritical CH2Cl2 extraction was 52%. The results of histological observation and scanning electron microscopy showed that the connection between the hair and the hair follicle is weakened and the lipid cells have a relatively low lipid content with increasing temperature. However; the fibres were well dispersed when the degreasing temperature was higher than 41°C, therefore, the most suitable degreasing temperature would be about 40°C. Compared with the traditional degreasing methods, subcritical CH2Cl2 extraction has the characteristics of clean and environmental protection, good fibre dispersion and good bond between hair and hair follicle.