System for coating using a grooved backing roller and electrostatic assist

Abstract

A coating method and apparatus are taught for coating a liquid composition onto a surface of a moving web. A coating hopper for delivering the liquid composition to the surface of the moving web is provided with a rotatable backing roller. The moving web is wrapped around a portion of the rotatable backing roller with the rotatable backing roller supporting the moving web through a dynamic wetting line. The rotatable backing roller includes a plurality of circumferential grooves therein at a groove pitch of at least two per millimeter. An electrostatic field generated across the gap between the moving web and the liquid composition immediately prior to the dynamic wetting line. The method and apparatus permit either coating at a higher speed or higher viscosity than may be achieved in the prior art, or greatly reduced groove line nonuniformity at a given coating speed and viscosity.

Dependencies are inferred from the claim text.