Application of Mechanical Deaeration to a Short Dwell Blade Coater, 2000 Coating Conference Proceedings

S. Koepke, T. Jarvensivu--For several years mechanical deaeration units have been used to remove extremely small air bubbles from coating applied by jet coaters [1]. Chemical defoamers have traditionally been added to the coating to prevent foam buildup in the coating applied by high-speed short dwell blade coaters. Without addition of chemical defoamers, foam generated in the circulation loop of the high-speed short dwell blade coater during operation can cause coating skips on the paper surface. This paper describes the application of mechanical deaeration as a replacement for chemical defoamers to prevent foam buildup during high-speed short dwell blade coating at Champion International-Sartell mill. Theoretical principles behind mechanical deaeration will be reviewed; and initial trials using a pilot deaeration unit to determine air removal efficiencies and results obtained from two production units that were subsequently installed will be discussed. Empirical data generated by the pilot unit and operating data obtained with the production units were found to correlate well.