Forward roll coating of Newtonian fluids with deformable rolls: An experimental investigation

Experimental investigations on forward roll coating of Newtonian fluids with deformable rolls were conducted, with the primary aim of predicting the coating thickness. First, it was shown that the elastic modulus of the rubber that covers the deformable rolls is often time dependent, and therefore must be determined according to the time-scale of the process. Having done this, a satisfactory agreement in terms of coating thickness was obtained with previous theoretical results. This agreement is limited to relatively thick rubber covers. It was shown, indeed, that decreasing the thickness of the cover below a critical value tends to decrease the coating thickness significantly. The time dependence of the mechanical properties of the rubbers involved in roll coating operations and the influence of the thickness of the cover may both explain why previous experimental correlations disagree significantly with available theoretical predictions. (C) 1997 Elsevier Science Ltd.