Electrostatically assisted coating method with focused web-borne charges

A method of applying a fluid coating onto a substrate, wherein the substrate has a first surface and a second surface, and wherein the method comprises:

• providing relative longitudinal movement between the substrate and a fluid coating station;
• forming a fluid wetting line by introducing, at an angle of from 0 degrees through 180 degrees, a stream of fluid onto the first side of the substrate along a laterally disposed fluid-substrate contact area at the coating station;
• forming electrical charges as first charges at a location distant from the substrate;
• transferring the first charges from the distant location toward the second surface of the substrate to be adjacent the second surface of the substrate at the fluid substrate contact area;
• and
• applying the first charges onto the second surface of the substrate at a location on the substrate that is substantially at and downstream of the fluid wetting line to create an electrical force on the fluid.

A method of applying a fluid coating onto a substrate, wherein the substrate has a first surface and a second surface, and wherein the method comprises:

• providing relative longitudinal movement between the substrate and a fluid coating station;
• forming a fluid wetting line by introducing, at an angle of from 0 degrees through 180 degrees, a stream of fluid onto the first surface of the substrate along a laterally disposed fluid-substrate contact area at the fluid coating station;
• and
• exposing effective electrical charges on the substrate to the fluid only at a location on the substrate that is substantially at and downstream of the fluid wetting line.

A method of applying a fluid coating onto a substrate, wherein the substrate has a first side and a second side, and wherein the method comprises:

• providing relative longitudinal movement between the substrate and a fluid coating station;
• forming a fluid wetting line by introducing a stream of fluid onto the first side of the substrate along a laterally disposed fluid-substrate contact area at the coating station;
• and
• attracting the fluid to the first side of the substrate by electrical forces from an effective electrical field originating at a location on the second side of the substrate that is substantially at and downstream of the fluid wetting line.

A method of applying a fluid coating onto a substrate, wherein the substrate has a first side and a second side, and wherein the method comprises:

• providing relative longitudinal movement between the substrate and a fluid coating station;
• forming a fluid wetting line by introducing a stream of fluid onto the first side of the substrate along a laterally disposed fluid-substrate contact area at the coating station;
• and
• attracting the fluid to the first side of the substrate by electrical forces from an effective electrical field originating at a location on the second side of the substrate that is substantially at and downstream of the fluid wetting line, wherein the step of attracting the fluid includes at least one of the following steps:
• transferring the electrical charges through a fluid medium and depositing the electrical charges onto the second surface of the substrate;
• transferring the electrical charges from a charge source and depositing the electrical charges onto the second surface of the substrate using physical contact between a portion of the charge source and the substrate;
• and
• transferring the electrical charges through a fluid medium and depositing the electrical charges onto the second surface of the substrate from a laterally extending corona discharge source closely spaced from the second surface of the substrate at the fluid coating station.

A method of applying a fluid coating onto a substrate, wherein the substrate has a first surface and a second surface, and wherein the method comprises:

• providing relative longitudinal movement between the substrate and a fluid coating station;
• forming a fluid wetting line by introducing, at an angle of from 0 degrees through 180 degrees, a stream of fluid onto the first side of the substrate along a laterally disposed fluid-substrate contact area at the coating station;
• forming electrical charges as first charges at a location distant from the substrate;
• transferring the first charges from the distant location toward a portion of the second surface of the substrate to be adjacent the second surface of the substrate at the fluid-substrate contact area;
• and
• then applying the first charges onto the second surface of the substrate to create an electrical force that is substantially at and downstream of the fluid wetting line.