Influence of Freesheet and Groundwood Basepaper Formation on Coated and Printed Paper Properties, 1999 Coating Conference Proceedings

Dr. Gill Drage, Mr. Craig Vaughan, Mr. Ken Henderson, Mr. John Parsons & Dr. Tony Hiorns

ECC International

A poor quality basepaper gives a poor quality coated sheet and a sub-standard, probably mottled, printed image and will also tend to run badly (i.e. more web breaks) during papermaking and paper coating. In this study, pilot papermaking and coating equipment was used to study the effect of formation on paper properties for both freesheet and LWC grades.

The results from papermaking trials showed that improving the basepaper formation gave better sheet strength, optical properties (brightness) and smoothness. The basepapers were coated using either a blade coater or a Metered Size Press. The coating formulation was either a generic North American formulations or a 100% GCC formulation, the latter giving more show-through of the base. The results of the LWC blade coating trial was almost unequivocally positive as paper gloss, print gloss, print density, brightness, smoothness and the mottle on commercially printed samples all improved with improving formation. The same LWC basepapers coated with the MSP gave less clear results; this is probably because a MSP is less severe than a blade coater and the defects of the basepaper are covered up to a greater extent. For freesheet grades, improving the basepaper formation either improved or had no detrimental effect on coated paper gloss and print gloss and smoothness.