Curtain coating method with reduced neck-in

Abstract

A film applying method in which a coating solution is applied by a solution injector having an edge guide onto a support member as a freely falling coating film, includes forming a solution contact surface of the edge guide to have one of a radius greater than 1.0 mm or a width d greater than 0.7 mm when the coating solution has at least one of a viscosity greater than 45 cp and a dynamic surface tension difference greater than 8 dyne/cm. The edge guide solution contacting surface is narrowed to have a radius less than 1.0 mm or a width d less than 0.7 mm when the coating solution has at least one of a viscosity less than 45 cp and a dynamic surface tension difference less than 8. In a second embodiment, the coating solution is prepared to have at least one of a viscosity greater than 45 cp and a dynamic surface tension difference greater than 8 dyne/cm when the solution contacting part of the edge guide has either a radius r greater than 1.0 mm or a width d greater than 0.7 mm. Alternatively, the coating solution is prepared to have at least one of a viscosity less than 45 cp and a dynamic surface tension difference less than 8 dyne/cm when the solution contacting part of the edge guide has either a radius r less than 1.0 mm or a width d less than 0.7 mm.

Dependencies are inferred from the claim text.