US 6,720,025 B2Granted

Slot extrusion coating methods

Assignee3M Innovative Properties Company

InventorsRobert A. Yapel, Wayne P. Ray, David J. Scanlan, Larry A. Lien, Charles W. Simpson

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Abstract

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.

Claims17

Dependent claims

A method for slot extrusion coating comprising:

providing a liquid composition including at least one polymer and a diluent, said composition being substantially free of crosslinking and gellation and having a measurable percent solids;
operating a slot extrusion coater wherein said liquid composition is extruded from said slot extrusion coater;
determining actual values of minimum wet thickness, Tw,min at a plurality of percent solids levels;
obtaining a first graphical curve representing actual values of wet thickness, Tw,min as a function of percent solids level;
identifying the critical wet thickness, Tw,min-critical on the first graphical curve;
and
identifying a window of operability as an area defined by the boundaries:
percent solids greater than the point at which critical wet thickness, Tw,min-critical occurs;
and an actual wet thickness greater than all points above the first graphical curve and equal to or less than the critical thickness, Tw,min-critical.

6 more elements

Dependencies are inferred from the claim text.