Patent ID: 7481843

Claim:
A process for the extraction and preparation of bast fibers, comprises ramie, hemp or flax is subjected to two times of bleaching, two times of alkali boiling, and a step of high-temperature loosening, wherein the two times of bleaching are chlorine bleaching and oxygen bleaching respectively, and in the chlorine bleaching, sodium hypochlorite having a concentration of 3-8 g/L is used, the temperature is 35-45° C., and the duration is 40-80 minutes; in the oxygen bleaching, hydrogen peroxide of 4-6 g/L is used, the temperature is 80-100° C., and the duration is 40-80 minutes; in the alkali boilings, the first alkali boiling is performed by use of caustic soda; high-temperature loosening is performed after the bleaching and boiling, and in the high-temperature loosening, soda of 100-140 g/L is used, the temperature is 100-140° C., and the duration is 1.5-2.5 hours.