Abstract
One of the surface treatments of paper is surface sizing. In this operation, hydrophobic polymers are added to paper in a size press, usually dissolved in an aqueous starch solution. We investigated the penetration of starch solutions in paper in a puddle size press. Starch penetration in paper was followed by x‐ray microscopy. A mathematical model was developed, which explains the observed penetration depths. The model is an extension of the classical Lucas–Washburn theory, modified by a build‐up of pressure inside the sheet during liquid penetration. The model predicts liquid penetration as a function of paper speed, nip load, viscosity of sizing solution and porosity, and surface chemistry of paper.
Acknowledgments
This research was supported by the National Center of Excellence (Wood Pulps) of the Natural Sciences and Engineering Research Council of Canada.