Massgeschneiderte kationische Polymere für die Fixierung primärer und sekundärer Störstoffe

The increasing use of mixed waste paper as a source of raw materials in the production of paper has entailed that large quantities of sticky, water-soluble substances find their way into the white water. These substances are a significant source of stickies and white pitch. If the white water is left untreated, these substances frequently tend to form deposits on moving parts and in the hot areas of the paper machine, which in turn leads to web breaks. This has a highly detrimental effect on the runnability and the productivity of paper machines. Tailor-made cationic polymers are very effective for fixing interfering substances, because they reduce the tendency of adhesive, hydrophobic substances to agglomerate and slow down the rate at which secondary stickies are formed. Nonionic, adhesive and lipophilic substances can be maintained in a finely divided form, and be made to adsorb on fibres, fines and fillers in order for them to be removed from the system along with the paper. The use of polymers leads to a large reduction in the levels of interfering substance contained in white water circuits. A new class of fixing agents is introduced with the aid of a selected example, and the high performance of these products is illustrated by means of a laser-optic method for counting pitch particles.