Method for dehydrating hydrous low-substituted hydroxypropyl cellulose and method for producing low-substituted hydroxypropyl cellulose by using same

A method for dehydrating hydrous low-substituted hydroxypropyl cellulose with a compression type dehydrator by feeding the hydrous low-substituted hydroxypropyl cellulose to a screw conveyer connected to an inlet of the compression type dehydrator, comprising the steps of:

• starting operation of the screw conveyor to fill the screw conveyer and the compression type dehydrator with the hydrous low-substituted hydroxypropyl cellulose to obtain a filled compression type dehydrator,
• starting operation of the filled compression type dehydrator, and
• feeding the hydrous low-substituted hydroxypropyl cellulose to the screw conveyer, while discharging dehydrated low-substituted hydroxypropyl cellulose from an outlet of the compression type dehydrator,
• wherein a feed rate of feeding the hydrous low-substituted hydroxypropyl cellulose to the screw conveyer is equal to a discharge rate of discharging the dehydrated low-substituted hydroxypropyl cellulose in terms of net weight of cellulose ether,
• wherein filling the compression type dehydrator with the hydrous low-substituted hydroxypropyl cellulose results in a pressure at an inlet of the compression type dehydrator of from 0.10 to 0.25 MPa, and
• wherein the low-substituted hydroxypropyl cellulose is water insoluble but swells in water.