Evaluation and control of microstickies deposition using QCM technique, 2010 TAPPI PEERS Conference

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The deposition of hydrophobic substances including microstickies in both the deinking and papermaking processes was investigated using a combination of quartz crystal microbalance (QCM) and image analyses. The amount and morphology of deposits on the QCM sensor surface, which was modified with hydrophobic polystyrene, were evaluated as indices of the deposition tendency of microstickies.

The results showed that the amount of microstickies decreased as deinking progressed from the early stage of the process to the final deinked pulp (DIP). In the cases of Mills A to E, the amount of microstickies in the furnish in the headbox of the paper machine was less than that in the DIP. In the papermaking process, the amount decreased during the process, and the behavior differed from that observed by solvent extraction and other wet-end measurements. However, microscopic observation of the QCM sensor surface revealed that the size and proportion of large agglomerates in deposits increased during the course of the papermaking process. The results from the measurements of the white water and fiber recovery system in the paper machine, suggest that agglomerated microstickies in the white water were recovered and accumulated in the long circulation of the paper machine water system. Moreover, the microstickies in papermaking processes formed large agglomerates when the paper machine had an outbreak of deposits. Thus, the QCM technique can be a useful tool for evaluating microstickies deposition.