The 'Umpol' (charge reversal)-Concept for improved AKD retention

摘要

AKD is usually employed in the form of cationically stabilized dispersions/emulsions in order that self-retention of the micron sized AKD particles is achieved. However, our studies have shown that when dosed inappropriately these "cationic AKDs" can desorb from fibers leading to reduced AKD retention. In order to reduce this desorption and increase the cost performance of AKD, BASF has developed a new concept. It comprises the combination of anionically charged AKD particles with a tailor made fixative. Hence by application of the two products in the correct sequence and at the correct dosing points of a paper machine the retention of AKD can be increased. This concept which we coined "Umpol" - meaning charge reversal - was successfully applied in two mill trials. BASFs product line of four different types of AKD dispersion is discussed. As a major supplier of innovative products to the paper industry BASF has developed a new process for AKD manufacture. The wax produced is of high quality and solvent free. The new process is discussed, as is the quality of the wax. Finally BASFs vision for further progress in AKD sizing is presented.