Developments in the production and application of cellulose ethers

Cellulose ethers are produced industrially for about 60 years, whereby water soluble derivatives became most accepted. The aim of the cellulose etherification is to disturb the tight connection of hydrogen bridges by the implementation of small substituents and so to develop the hydrophilic character of cellulose. Four technically available reagents impart different properties to the products and predestinate them to special fields of application. The use of monochloroacetic acid or of the sodium salt gives the anionic carboxymethylcellulose. By ethylenoxide the non-ionic hydroxyethylcellulose is formed. Methylchloride imparts a more hydrophobic character to the resulting methylcellulose what can be compensated by a mixed etherification with ethylenoxide or propylenoxide to adjust complete solubility in water. In all three cases sodium hydroxide is used as a reaction partner. The technical processes have basic principals in common. They have been adapted to the properties of the different ethers and have been optimized in a variety of directions. The selection of technical units has to consider not only pros and cons of these but also the interconnection of the single production steps. Simultaneously to the optimization of the processes the quality of the products has been developed further, partly by special derivatisation. Besides this the adjustment of the molecular weight, of the grain size distribution, and of the compounding ingredients is of important influence on the quality performance.