Runnability problems, sheet picking, and dusting caused by poor dryer cylinder release are challenges troubling many paper mills. Dirty dryer cylinder surfaces that reduce drying capacity and lead to sheet moisture profile deviations are also often encountered. The solution to problems like these is Metso's DryOnyx H release coating for doctored drying and cooling cylinders. It continues the good work of DryOnyx Z and DryOnyx ZL – with improved features.
DryOnyx H is designed for efficient onsite application. The benefits of onsite coating application include reduced shutdown time and low cylinder temperatures, made possible by a special release polymer that cures under powerful UV light. Time-consuming cylinder heating is no longer needed, and such adverse effects of heating as cylinder deformation, balancing changes and head sealing damage can be completely avoided.
DryOnyx H has very low surface energy, which results in improved release and cleanliness. This innovative polymer also maintains its hardness at high dryer cylinder operating temperatures, which means less wear and longer coating lifetimes.
Another major benefit is the coating's good doctorability. Thanks to special additives used in the new release polymer matrix, its friction coefficient is 80% lower than that of previous coating versions. The resulting benefits include more stable doctoring, less heat build-up at the tip of the doctor blade, a better cleaning result, longer coating and doctor blade lifetimes, as well as lower drive power consumption.
In addition to DryOnyx H, Metso also offers a GuideOnyx H coating for doctored dryer section lead rolls and paper guide rolls. It works especially well in positions after sizing and coating stations and improves their cleanliness.