Lip preparation apparatus and method for improving the uniformity of a liquid curtain in a curtain coating system

The method of claim 7, wherein the lip is positioned vertically above the third surface portion as the liquid composition is supplied to the slide die.

An apparatus for improving the uniformity of a liquid curtain in a coating system comprising a lip of a slide die wherein the lip includes a front surface on which a liquid composition flows by gravity, comprising:

• a ledge having a first, second, and third surface portion wherein the first surface portion is disposed intermediate the second and third surface portions, the first surface portion being substantially horizontal, the second surface portion being contiguous with the first surface portion and upwardly inclined away from the first surface portion, the third surface portion being contiguous with the first surface portion and downwardly inclined away from the first and second surface portions;
• and
• positioning means for positioning the ledge and lip relative to each other (1) in a first orientation wherein the lip is disposed proximate the first surface portion whereby the liquid composition flows from the front surface of the lip onto the first surface portion, through a gap between the lip and the first surface portion such that the liquid composition partially wets the back surface of the lip, and onto the third surface portion, and (2) in a second orientation wherein the lip and the ledge are spaced from each other whereby the liquid composition forms a vertical liquid curtain in free fall.

An apparatus for improving the uniformity of a liquid curtain in a coating system comprising a lip of a slide die wherein the lip includes a front surface on which a liquid composition flows by gravity, comprising:

• a ledge having a first, second, and third surface portion wherein the first surface portion is disposed intermediate the second and third surface portions, the first surface portion being substantially horizontal, the second surface portion being contiguous with the first surface portion and upwardly inclined, the third surface portion being contiguous with the first surface portion and downwardly inclined away from the first and second surface portions, the ledge comprising at least one side plate disposed on the third surface portion and extending toward the slide die by a projecting length that gradually increases as elevation decreases;
• and
• positioning means for positioning the ledge and lip relative to each other (1) in a first orientation wherein the lip is disposed proximate the first surface portion whereby the liquid composition flows from the slide die onto the first surface portion such that the liquid composition partially wets the back surface of the lip, and (2) in a second orientation wherein the lip and the ledge are spaced from each other whereby the liquid composition forms a vertical liquid curtain in free fall.