Coating layer formation and liquid-phase penetration in metered size press coating

U. Forsström, E. Saharinen, R. J. Dickson, K. Fagerholm

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5 Citations (Scopus)

Abstract

The aim of the study was to investigate how base paper characteristics influence coating layer formation and coverage in coating paper with a metered size press. Laboratory woodfree base sheets were produced on a dynamic sheet former. The sheet properties were changed by varying softwood pulp refining and alkyl ketene dimer sizing. The base sheets were taped on a supporting mil paper and coated on a pilot metered size press at 1000 m/min. Coating layer formation was controlled by base paper permeability, which dictated coating colour penetration into the surface voids. The coating coverage was measured with a scanning electron microscope in the backscattering mode. Coating coverage was higher on the denser paper, even though the coat weight was lower. The internal/hydrophobic sizing of the fibres had no effect on the coat weight and coating coverage. The main transport mechanism was pressure-induced penetration of the coating colour into the surface voids.

Original languageEnglish
Pages (from-to)159-166
Number of pages8
JournalJournal of Pulp and Paper Science
Volume29
Issue number5
Publication statusPublished - 1 May 2003
MoE publication typeNot Eligible

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Keywords

  • Coating color
  • Covering power
  • Density
  • Layers
  • Metering equipment
  • Paper properties
  • Paper stock
  • Permeability
  • Size presses
  • Surface sizing

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