On-Line Cationic Demand Measurement for Wet End Papermaking, 1997 Papermakers Conference Proceedings

There are many methods in existence for measuring the physical properties of the papermaking furnish which influence machine efficiency. Among these are drainage, retention, formation, wet strength, and others. However, very few methods exist for monitoring the performance and effectiveness of additives used to control these properties. A practical and economical method has been developed for online cationic demand determination. The Electrokinetic Charge Titrator, ECT is a online charge analyzer and automatic titrator which determines the cationic demand of the wet end and stock approach system. The instrument is used to quantify the effect of various additives on system charge, providing a useful tool for assessing and improving process efficiency.

The control of cationic materials in the wet end of papermaking has long been a concern. For several years, the work of investigators has been reported in the potential use of streaming current devices. (1) The charge titrator utilizes a control strategy, along with the “streaming current” technique of charge analysis, for a reliable method of measuring process charge and determining cationic demand. Even though streaming current theory is complex and not completely understood, the results can be interpreted in a quantitative sense. The charge titrator can measure the capacity of a pulp sample to adsorb cationic materials such as those used to give wet strength or optimize retention. The strength of the treated paper increases with greater adsorption of the cationic material on the pulp. The increased strength is directly proportional to the cationic material concentration until the neutral charge point is reached. (1) Other reasons for optimizing control of cationic materials include improving runnability, achieving proper drainage and formation.