Coating Optimization Using a Pilot Coater - Experiences at the IMERYS Technicentre, 2002 Coating Conference Proceedings

A. G. Hiorns and M. V. Reynolds--A pilot coater can be used to investigate many problems associated with paper coating. The most common use on our pilot coater involves pigment and formulation development to either improve runnability or paper quality. The biggest challenge at present is the development of pigments with narrow particle size distributions. The use of this type of pigment in a formulation usually gives higher viscosities and more dewatering. These combine to give runnability problems at the coater. Although narrow particle size distribution pigment.s will give good paper properties when coated at lower solids, the costs associated with drying will always force the paper maker to look for the highest coating solids level possible that gives good runnability.

The pilot coater is also used to evaluate new coating machinery. The introduction of high speed coating technology, such as the metered size press and the jet applicator, in the last few years means that paper makers need to compare the new and existing technologies, especially before any major investment decisions are made. The demands that this technology makes on the coating formulation can be significantly different compared to existing systems and both the pigments and formulation need to be optimised to get the best performance.

Several examples are given where the pilot coater has been used to compare formulations, running conditions and equipment changes to achieve good runnability and paper quality.