Process for the acid-catalyzed, hydrolytic depolymerization of cellulose ethers

A process for the acid-catalyzed, hydrolytic depolymerization of cellulose ethers with subsequent separation and, if necessary, purification and drying of the depolymerized cellulose ethers without changing the space used, which comprises, in a sealed, pressure-tight, heatable space consisting of acid-resistant materials;

• provided with an inlet and an outlet which are separated from one another by a filter element, and fitted with a stirrer, depolymerizing the cellulose ether to be depolymerized, which is introduced through the inlet and retained by the filter element, in the form of an acidic slurry with stirring at a temperature above the flocculation temperature of the depolymerized cellulose ether, if necessary under pressure, and, when the depolymerization is complete, neutralizing the cellulose ether by introducing caustic lye and, if desired, additives, and subsequently, by opening the outlet, under the effect of gravity and/or if desired by applying an external pressure to the space, separating off the cellulose ether from the filtrate, which is not retained by the filter element, and, if necessary, subsequently purifying the cellulose ether by introducing water or a mixture of water and one or more organic suspension media one or more times at a temperature above the flocculation temperature of the depolymerized cellulose ether and subsequently releasing the water or water/suspension medium mixture, and subsequently, if necessary, drying the cellulose ether by applying a vacuum to the space or passing a gas through the space.