Wetting Behavior
Liquid drops placed on a solid surface exhibit a changing relationship between their surface area and the substrate as they are absorbed. Measuring contact angle dynamics provides insight into how a paper surface will interact with aqueous inks or adhesives during a high speed production run. This property dictates whether a coating will stay on the surface or be absorbed into the substrate.
Absorption Rate
Initial contact angles show the immediate resistance to wetting and the rate of decay reveals the porosity and sizing of the fibers. In corrugated board manufacturing, understanding contact angle dynamics helps in selecting the right adhesive for the linerboard. A rapid drop in the angle indicates a highly absorbent sheet that might starve the bond of glue.
Printing Quality
Inkjet systems rely on specific surface energy levels to prevent the dots from spreading too wide. If the contact angle dynamics are too slow, the ink might smudge before it dries. Conversely, if the liquid is absorbed too quickly, the resulting color density will appear washed out.
Technicians use high-speed cameras to capture the change in the drop shape at millisecond intervals. This data allows for the fine-tuning of surface sizing agents to meet the requirements of specific ink formulations.
