Blade Force Measurements on a Laboratory Puddle Coater, 1995 Coating Conference Proceedings

Erdin Guler and Douglas W. Bousfield

University of Maine

A new technique is described to characterize the blade forces during coating with a laboratory coater. A position detector is mounted on the bottom side of a laboratory puddle coater. The blade position is recorded every millisecond. From the blade deflection and a calibration step. the actual forces on the blade are known in time. Glycerin-water mixtures and coating suspensions are coated onto wood containing base stocks and plastic films. Speeds and coat weights near commercial application are used. Blade forces are compared to fluid mechanics models of the laboratory coater. In all cases, model predictions are low compared to the experimental results unless the proper blade geometry and the effect of paper roughness or absorbency is included in the model. The technique has value in screening coating suspensions for commercial use. in validating theoretical analyses. and understanding the rheological behavior of coating at shear rates that are the same as commercial coaters.