Characterization of Paper Microstructure: A New Tool for Assessing the Effects of Base Sheet Structure on Paper Properties, 1999 Coating Fundamentals Symposium Proceedings

Rafik Allem and Tetsu Uesaka

Most end-use properties of paper, including opacity, absorbency, linting, and printability depend on the uniformity of the paper structure at the sub-millimetre scale. Suitable means are required, therefore, to measure small-scale distributions of porosity, mass, and surface smoothness of a paper base sheet, in order to determine their relationship to paper properties. To achieve this goal, we have developed a new method based on scanning electron microscopy of paper cross-sections combined with image analysis to measure the distribution of structural parameters of coated and uncoated paper at the level of the basic fibre dimension. We used a spectral analysis method based on point-to-point measurements to establish the relationship between the various parameters.

In lightweight coated papers, recent work at Paprican and elsewhere has shown that small-scale variations of coating layer thickness have direct effects on printing properties. The method described in this report has allowed us to establish relationships between structural parameters of the underlying paper and the coating layer at the microscopic level. Information derived from these results could be used to design a base sheet with suitable properties to achieve more uniform coating and improved printability.