| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for purifying carboxymethyl cellulose(CMC), capable of remarkably decreasing a content of residual organic solvent in the CMC, especially decreasing the content of methanol to 500 ppm or below, when the CMC is prepared in a solvent method. SOLUTION: This method for purifying the crude CMC comprises bringing the crude CMC containing the residual organic solvent into contact with an aqueous solution of an organic solvent, removing the aqueous solution, then drying, when the CMC is prepared by the solvent method in which mercerized cellulose is etherified with sodium monochloroacetate, etc. The above organic solvent preferably comprises one or more solvents selected from a group comprising isopropyl alcohol, ethanol, methanol and acetone. The aqueous solution of the organic solvent preferably contains water in an amount of 5-50 wt.% based on the total amount of the solution. The crude CMC obtained from the above solution-removing process or the downstream process thereof is preferably subjected to this purifying method.
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