On-Line Soft-Nip Calendering and Supercalendering Studies II: Effects of Operating Variables on Optical Quality, Printability, Runnability, Stiffness, and Caliper, 1998 Coating Conference Proceedings

Previous on-line pilot studies demonstrated that supercalender-like gloss and smoothness are attainable in lwc webs at temperature/nip load combinations from 50-150°C / 300-120 kN/m at line speeds of 1000m/min. The on-line mode is more efficient in finishing the sheet, indeed is critical to achieving the desired level of finishing at modest conditions, while providing economic incentives in production costs. Formulation is also of prime importance in maximizing performance.

Additional pilot trials have certainly confirmed the initial conclusions regarding mild conditions, examined print performance, and included other property issues in answer to comments and questions which arose from the original study. These trials encompassed several other basestocks, ranging from 32 to 46 gsm and focused on lower coat weights. Coating colors, applied by a high speed short dwell coater, included an all mineral control and a system containing synthetic pigment. Print trials were directed toward sheet gloss in the 50-55 range plus trial points representing the maximum gloss development for the pilot equipment’s practical operating limits of 150°C and 300 kN/m. The moisture variable, an important factor in finishing efficiency and runnability, was characterized in greater detail. Its significance must never be underestimated.