Investigation into the Role of Water Retention Agents and Their Effect on Splice Wetting Out - A Laboratory Simulation, 1995 Coating Conference Proceedings

T. Dunn

Caledonian Paper

A new approach for investigating the role of water retention agents and their effects on the runnability of base paper on off machine coaters is presented. The method considers the rate of penetration and its effect on the runnability of the base paper instead of the amount of dewatering and its effect on the runnability of the coating colour. Mill experience has shown that, as the flying splice passes through the coating head, deformation or displacement of the coating blade can take place. This allows coatweights of up to ten times the target to be built up along the pattern of the splice. This can lead to failure of the splice in tension due to wetting out. The method is based on the application of an excess of coating onto samples of commercial base paper. The time taken from initial application of the colour to failure of the sample in tension is measured and used as the water retention value of that colour. By varying the water retention agent the effects of each on the runnability of the base paper can be assessed.