METHOD FOR THE PREPARATION OF CELLULOSE ETHERS WITH A HIGH SOLIDS PROCESS， PRODUCT OBTAINED AND USES OF THE PRODUCT

The present invention provides a method for production of cellulose ethers in a high solids process substantially without use of organic solvents as reaction and/or washing medium. In the method of the invention the first alkalization step is carried out by using high solids content cellulose pulp and solid sodium hydroxide. This is followed by an etherification step where the solids content is preferably further increased and the use of solid etherification reactant is preferred. As no organic solvents are used as reaction media the invented method enables production of cellulose ethers directly from never dried pulp with significant savings in energy and investment costs. The method is especially suitable for the production of carboxymethyl cellulose sodium salt (CMC) with low degree of substitution (DS < 0.3). The use of the resulting none or low water soluble carboxymethylated cellulosic fibres is suitable for example for producing microfibrillated cellulose.

本发明提供了一种采用高固含量工艺制备纤维素醚的方法，该工艺基本无需使用有机溶剂作为反应介质和/或洗涤介质。本发明方法的首步碱化工序采用高固含量纤维素浆粕与固体氢氧化钠进行，随后开展醚化工序，该工序优选进一步提升固含量，且优先使用固体醚化反应物。由于无需使用有机溶剂作为反应介质，本发明方法可直接以未干燥浆粕为原料制备纤维素醚，显著节约能源与投资成本。该方法尤其适用于制备低取代度（degree of substitution，DS < 0.3）的羧甲基纤维素钠（carboxymethyl cellulose sodium salt，CMC）。所得的不溶或低水溶性羧甲基化纤维素纤维，例如可用于制备微纤化纤维素。