| 摘要 |
PROBLEM TO BE SOLVED: To provide hydroxypropylcellulose with low substitution degree, which is low in yellowing.SOLUTION: A method for producing purified hydroxypropylcellulose with low substitution degree comprises: a reaction step of reacting alkali cellulose with an etherifying agent to obtain a reaction mixture; a step of dispersing the reaction mixture in water containing a part of an acid of the amount required to neutralize the whole amount of the reaction mixture so that a part of the reaction mixture is neutralized and precipitated and then neutralizing the reaction mixture completely with the residual acid to obtain slurry containing the precipitated crude hydroxypropylcellulose with low substitution degree; a cracking step of cracking solids in the slurry containing the crude hydroxypropylcellulose with low substitution degree by using a cutter pump and discharging the cracked solid-containing slurry; a cleaning step of cleaning the discharged slurry with water to obtain cake of the purified hydroxypropylcellulose with low substitution degree; and a drying step of drying the cake, at the least. |
