| The crude lacquer wax should be refined to improve its quality because of its high acid value and dark color. The crude lacquer wax was deacidified, bleached and deodorized,and the acid value, peroxide value, color, glycerides and fatty acid composition of lacquer wax before and after refining were analyzed. The crystalline shape of lacquer wax was determined by X-ray diffraction technique, and the thermal properties of lacquer wax were analyzed by solid fat content determination and differential scanning calorimetry. The results showed that after deacidification, the acid value of lacquer wax decreased from (35.06±0.05)mgKOH/g to (0.12±0.01)mgKOH/g; after refining, the color changed from brown to milky white, and the peroxide value was (0.28±0.04) mmol/kg. The glycerides and fatty acid compositions of lacquer wax did not change in the refining process, but in deacidification process, the contents of triglycerides increased significantly, the contents of monoglyceride and diglyceride decreased significantly, and the palmitic acid content increased obviously, while the oleic acid and linoleic acid contents decreased obviously. There was no significant effect of bleaching and deodorization processes on the glycerides and fatty acid contents of lacquer wax. The solid fat content analysis showed that the melting range of crude lacquer wax was 20-55 ℃, and the melting range of deacidified, bleached and deodorized lacquer wax was 30-60 ℃. The X-ray diffraction data showed that the crude lacquer wax was dominated by β-type crystals, and a small amount of α-type crystals existed, while the α-type crystals disappeared after refining. The differential scanning calorimetric analysis showed that the melting points of deacidified, bleached and deodorized lacquer waxes increased. These changes might be due to the removal of most of the free fatty acids, some diglycerides and some volatile substances from the crude lacquer wax during refining. |
