Patent ID: 7022380

Claim:
A method for coating a traveling paper web with a film of coating, the paper web being either supported on the surface of a backing roll rotating in a downstream direction, or nipped against the surface of the backing roll, the method comprising the steps of: introducing a fresh supply of coating into a mixing chamber of a coater head and directing the fresh supply of coating into the mixing chamber in the coater head through a plurality of parallel holes aligned in a cross-machine direction; flowing a coating flow from the mixing chamber in a converging flow into, and through, a feed channel in the coater head; dividing the coating exiting the feed channel into a first portion constituting a major part of the flow from the mixing chamber and a second portion constituting a minor part of the flow from the mixing chamber; directing the first portion into a coating chamber in the coater head, and directing the second portion in an upstream direction over a baffle disposed in spaced adjacency with either the paper web supported on the backing roll, or the surface of the backing roll, to define a gap therebetween, the second portion being sufficient to seal the gap from air moving with either the traveling paper web or the surface of the backing roll; flowing the coating in the coating chamber in the downstream direction therein while maintaining a pressurized interface between the coating material and the paper web, when the paper web is supported on the surface of the backing roll to coat the paper web with the film of coating, or maintaining a pressurized interface between the coating material and the surface of the backing roll when the paper web is nipped against the surface of the backing roll downstream of the interface to coat the paper web with the film of coating; flowing coating from the coating chamber into a recirculation chamber; directing all the coating from the recirculation chamber into the mixing chamber through a plurality of flow-metering orifices formed in the coater head which are aligned parallel with one another in the cross-machine direction and which connect the recirculation chamber with the mixing chamber, the direction of flow of coating from the recirculation chamber through the plurality of flow-metering orifices being at an acute angle to the direction of flow of the fresh supply of coating being directed into the mixing chamber through the plurality of parallel holes; and mixing the coating from the recirculation chamber with the fresh coating in the mixing chamber.