Closer Look at Fiber Characteristics and Laboratory Evaluation of Pulp, 1999 Pulping Conference Proceedings

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Patricia Hurter, Ph.D.
Hurter Associates

With the evolution of pulping and bleaching processes towards more environmentally friendly ECF and TCF sequences, it has become increasingly important to be able to identify key pulp quality parameters that can be used to predict ultimate papermaking performance on the papermachine. Traditionally, pulp viscosity and handsheet tear/tensile curves (on Valley beaten or PFI mill refined pulps) have been used to evaluate pulp quality. It will be shown that these techniques do not adequately predict mill performance. In order to evaluate new pulps realistically, it is important to identify the key papermaking properties that are required for the end-use application, and then measure these properties using laboratory techniques that more closely mimic the mill environment.

In this presentation, fundamental fiber characteristics that relate to the papermaking potential of pulps are discussed. An improved method of evaluating pulps in the laboratory is presented. The main components of this improved method are:

1. Ensuring that the pulps produced for evaluation are similar to pulps that will be produced on a manufacturing scale, by examining fundamental fiber properties after each pulping and bleaching stage.
2. Using a more realistic laboratory refiner, such as the Voith-Sulzer laboratory refiner, which is capable of refining pulps at defined specific energy levels and varying intensity
3. Measuring the physical properties of the handsheets with both full and partial drying restraint, to mimic drying conditions on the machine more closely.

Using these techniques allows a more representative evaluation of the papermaking potential of pulps of varying quality. Along with these experimental methods, it is important to design the studies using appropriate statistical techniques, so that differences which are important to the quality of the final product will be seen, and not obscured by data scatter.