Slide bead coating method

A method of coating a moving web with a slide bead coating apparatus comprising the steps of:

• (a) forming a bottom layer on a slide surface of the slide bead coating apparatus with a pseudoplastic liquid composition having a consistency m>50 and a flow behavior index n<0.7 and a viscosity given by
• η=m(dγ/dτ)n−1
• where η is viscosity and dγ/dτ is the shear rate;
• (b) establishing a coating bead between a lip of the slide bead coating apparatus and the moving web supported on a back-up roller to thereby coat the moving web;
• and
• (c) generating an electrostatic field in an air gap between the coating bead and the moving web just prior to a dynamic wetting line by creating a potential difference across the air gap of between about 300 and about 2000 volts.

A method of improving a coating window and/or generating an additional coating window in a coating operation for coating a moving web with a bead coating apparatus comprising the steps of:

• (a) forming a bottom layer in a bead coating apparatus with a pseudoplastic liquid composition having a viscosity of at least about 8 centipoises at a shear rate of 100 sec−1 and a viscosity below 10 centipoises at a shear rate of 100,000 sec−1;
• (b) establishing a coating bead between a lip of the bead coating apparatus and the moving web supported on a back-up roller, thereby coating the moving web;
• and
• (c) generating an electrostatic field in an air gap between the coating bead and the moving web just prior to a dynamic wetting line by creating a potential difference across the air gap of between about 300 and about 2000 volts.