Cyprus Mines Corporation

Robert E Roeder

Kenneth E Weber

Richard Seyb Lamar

William E Pratt

A method of and substances for reducing pitch in pulping and papermaking operations, particularly in furnishes made by mechanical pulping processes containing wood pulp in amounts greater than about 10% by weight, are disclosed. The method comprises adding to a pitch-containing furnish a stable, water dispersible particulate composite substance prepared by irreversibly adsorbing a water soluble cationic polymer, e.g., a poly(diallyldimethylammonium chloride), onto an essentially water insoluble particulate substrate, e.g., kaolin, thereby rendering the cationic polymer insoluble and immobile, the cationic polymer being sufficiently electropositive so that the particulate composite pitch control substance exhibits a zeta potential of at least about +30 mV, and preferably from about +60 mV to about +80 mV, the amount of the composite substance added to the furnish being effective to finely disperse pitch for removal as finely-dispersed pitch-containing aggregates in a paper sheet produced from said furnish. Further improvements in pitch control can be achieved using these particulate composite pitch control substances together with alum and/or relatively high molecular weight alkylene oxide polymers, and other desirable effects, including improved fines retention, better drainage and lower waste treatment costs are also obtained when practicing this method.

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Parker, CO, United States of America

Robert E Roeder