Characterization of polymers for paper surface sizings using contact angle methods

A new test can predict the paper surface sizing performance of polymers. The method consists of spin-coating a thin film of the pure polymer from solution onto a glass microscope slide and measuring the initial contact angle with deionized water. Ranking of two commercial sizing polymers with this method correlated with rankings from the Hercules Sizing Test on paper sized with the polymers in commercial formulations. The initial contact angles of the pure polymers on glass also correlated with initial contact angles on the sized paper. The change in contact angle with time did not correlate. The new method provides a quicker route to improved for sizing applications by decreasing the time and cost of the screening process. The method could also identify the molecular origins of interactions of sizing, substrate, and ink that could lead to improved design of new sizing polymers. Application : contact angle measurements of pure polymers spincoated on glass can predict sizing performance.