3M Innovative Properties Company

Minnesota Mining and Manufacturing Company

Wayne P Ray

Robert A Yapel

Charles W Simpson

Larry A Lien

Omar D Brown

Bernard A Scheller

Daniel V Norton

David J Scanlan

Manley C Marcellus

A method of slot extrusion coating is provided that can be used to apply thin coatings using liquid compositions having high percent solids. A window of operability advantageously identifies the limits of a process to provide these thin high solids coatings. The window of operability is determined by obtaining a first graphical curve representing actual values of wet thickness as a function of percent solids level. The critical wet thickness is then identified on the first graphical curve. The window of operability is identified as an area defined by the boundaries: percent solids greater than the point at which critical wet thickness occurs, an actual wet thickness greater than all points above the first graphical curve and equal to or less than the critical thickness.

Slot extrusion coating methods

A method and apparatus for coating and drying coated substrates without introducing significant surface imperfections while running at higher web speeds than known drying methods. The substrate is preferably coated within the drying enclosure or the coating bead may form a closure at the entrance of the drying enclosure. The substrate is moved through a first drying enclosure along a first axis. The first drying enclosure is substantially isolated from an external environment. A first low velocity, substantially laminar flow field of a drying gas is directed across the front surface of the substrate. The first flow field is generally parallel to the front surface and generally perpendicular to the first axis to minimize the formation of surface imperfections during the evaporation of the coating solvent. The substrate may then be moved to subsequent drying enclosures through transition enclosures that minimize surface imperfections due to high velocity interaction between the adjacent drying enclosures. In embodiments where the first axis is in an inclined configuration with respect to horizontal, louvers may be utilized for directing solvent evolving from the substrate to minimize surface imperfections due to solvent cascade.

Apparatus and method for drying a coating on a substrate

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Weatherford, OK, United States of America

Wayne P Ray