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Retention Program And Wet End Chemistry Management With Focus On Quality And Efficiency Of Modern Calendered Grades

Programme de rtention et gestion de la chimie de la partie humide, en portant une attention particulire la qualit et l’efficacit des catgories calandres modernes

Abstract: Recent advances in calendering technology and demands on quality and production cost of supercalendered grades have created new requirements for process stability, formation, and sheet structure and system cleanliness. Supplying consistent and optimally structured sheet to the calender stack may allow the papermaker to improve results, especially with the most aggressive calendering processes.

Nalco Company has been focusing on a grade-specific approach in every major application. Some of Nalco’s applications specific to calendered grades of paper are described in this paper. This paper reviews the most important sheet properties, operational best prac- tices and structure-properties relationships relevant for results of a calendering operation. Literature review, practical mill data as well as future development suggestions are also discussed in this paper.

Specialty chemicals suppliers have to focus beyond traditional per- formance indicators of retention programs such as retention value, white water consistency, drainage, etc. The new focus should be on better understanding how to, within existing limitations of furnish and papermaking equipment, assist the papermaker in delivering uniform (MD and CD), properly structured in ZD sheet, with proper surface topography and surface strength so that maximum quality and runnability benefits from calendering process can be reached.

Some general areas where such focus may result in significant benefits to the papermaker are discussed in this paper.

Keywords: SC PAPERS, SHEET STRUCTURE, FILLER DISTRIBUTION, FORMATION, GLOSS, SMOOTHNESS, BRIGHTNESS, SYSTEM STABILITY, PH, CATIONIC DEMAND, CONDUCTIVITY, PRINTABILITY, EXTRAC- TIVES CONTROL

Paper presented at the 95th PAPTAC Annual Meeting 2009 in Montreal, Que., February 3-4, 2009.

Full manuscript available at www.paptac.ca.