On-site evaluation method for the nonstick properties of paper machine drying cylinder coating materials—A description of the methodology and two case studies

Paper raw materials contain impurities, such as waxes, coating binders, hot melts and pressure-sensitive adhesives, that have a tendency to attach to the surfaces of machinery during paper production. Drying cylinders located at the beginning of the drying section are in an especially challenging position because sticky materials can easily transfer from the paper web to the hot cylinder surfaces at this point.Usually, one to four drying cylinders are coated with a nonstick coating material in order to decrease contamination. The nonstick properties of coating materials are at their best when the coatings are new, but their performance usually decreases as the materials age. To date, there is no practical method available for the on-site evaluation of the nonstick properties of coating materials or a method to monitor the condition of the coating during its life cycle.A new practical method for the on-site evaluation of nonstick cylinder coating materials has been developed. This method also provides the opportunity to compare the performance of different drying cylinder coating materials. The analysis is performed using an adhesive tape attached to a clean cylinder surface. The tape is immediately peeled off of the surface at a constant speed and peel angle. The temperature compensation is used to facilitate the comparison of surfaces at different temperatures. The force required to peel off the adhesive tape is monitored with a force meter. Our results show a linear relationship between the release force and the nonstick qualities of the coating.In this paper, a method for testing drying cylinder coatings and the results of mill tests are presented.

► Dirt repellency measurement method for paper machine drying cylinders.
► Enables comparison of different paper machine drying cylinder coatings.
► Comparison of dirt repellency between fluoroplastic and cast iron.