Eastman-Kodak Company

Felipe M Joos

Douglas S Finnicum

Robert R Quiel

Alain E Gros

Alfred K Anders

A method of bead coating a liquid composition onto the surface of a moving web is taught which provides uniform coatings over a wider range of operating parameters including new coating windows. In addition, the bead coating method typically demonstrates a reduction in coating sensitivity to vacuum pressure noise below the coating bead. The method comprises the steps of forming a bottom layer on a slide surface of a slide bead coating apparatus with a pseudoplastic liquid composition having a viscosity between 8 and 200 centipoises at a shear rate of 100 sec and a viscosity below 10 centipoises at a shear rate of 100,000 sec ; forming at least one other liquid coating layer above the bottom layer on the slide surface of the slide bead coating apparatus; establishing a coating bead between a lip of the slide bead coating apparatus and the moving web supported on a back-up roller, generating an electrostatic field in an air gap between the coating bead and the moving web just prior to a dynamic wetting line by creating a potential difference across the air gap of between about 300 and about 2000 volts.

Slide bead coating method

An apparatus and method to measure different properties of a liquid film or coating traveling or resting on a horizontal support, including dynamic viscosity, dynamic surface tension and surface dilational elasticity, the apparatus comprising: a series of wires placed above a moving wet film or coating to which high voltage is applied inducing an electrostatic field that lifts the free surface of said film preferentially near the wires; a means for detecting the free surface displacement of the free surface in the section where the voltage is applied to the coating, possibly the means being a CCD camera coupled to a digital acquisition system; and means for processing the signal to determine the properties of the coating.

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Pittsford, NY, United States of America

Felipe M Joos