APPLICATION OF POLYMERIC FLOCCULANT IN NEWSPRINT STOCK SYSTEMS FOR FINES RETENTION IMPROVEMENT

Basing on bibliographic data, the author shows that cationic flocculants did not perform satisfactorily on the newsprint stock systems for fines retention control based on a dynamic jar test, mainly because of strong interference by water-soluble substances originating from wood constituents. Among them, lignosulfonate from the sulfite pulping plant was found to be most harmful because of its strong dispersing action. A nonionic polyethylene oxide with a molecular weight exceeding 4 million was exceptionally effective on all newsprint stock examined. At a 0. 5 lb/ton addition rate, the dynamic jar one-pass fines retention showed a very significant improvement of about 20-30% over the control.