NATURAL DYE AND PREPARATION METHOD THEREOF

摘要

PURPOSE: A natural dye and its preparation method are provided to obtain a natural colored and nontoxic dye massively by the environmentally-friendly process using carbon dioxide as a critical fluid. CONSTITUTION: The natural dye comprises the dye extracted from a natural material, and at least one selected from lime powder and quartz porphyry power in the ratio of 1:1 to 1:9 by weight. Also the natural dye comprises the dye extracted from a natural material, and the starch powder extracted a potato in the ratio of 1:1 to 1:9 by weight. The dye is adsorbed to the powder. The method comprises the steps of extracting a dye from a natural material at a critical temperature and at a critical pressure by using carbon dioxide as a critical fluid; dissolving the extracted dye into water; adding the powder selected from lime powder, quartz porphyry power and potato starch powder to the solution to allow the dye to be adsorbed to the powder; and concentrating the solution under reduced pressure and drying the obtained one. Preferably the critical temperature is 31.06-90 deg.C and the critical pressure is 73.8-300 bar.