Apparatus for coating a continuous web

Claim 1

In a web coating apparatus comprising a supporting surface on which a web to be coated is supported as it is continuously advanced; a coating hopper spaced from said supporting surface and the surface of the web supported thereon for continuously feeding a stream of liquid coating composition to the surface of the web passing over said supporting surface and causing the stream to bridge the distance from the hopper to the surface of the web being coated; means for defining a suction chamber contiguous to and ahead of said coating hopper in the direction of movement of said web and having an opening facing one side of said stream and a length of the web surface to be coated as it approaches said stream; first suction means connected to said chamber for establishing a gaseous pressure at the side of said stream of liquid composition adjacent said chamber that is less than that on the other side of said stream; the improvement which comprises: means for defining a suction knife that is located within said suction chamber, said suction knife having a relatively narrow elongated slot adapted to extend transversely across the full width of the surface of the web to be coated in slightly spaced relationship relative to the web surface; and second suction producing means substantially separate from said first suction producing means and coupled with said slot for applying suction to said slot so that the boundary layer of air flowing with said moving web may be removed through said slot.

Claim 9

An apparatus comprising: means for continuously feeding a stream of liquid composition towards a moving surface of a member so that the stream bridges at least a portion of the distance between said feeding means and said moving surface; means for defining said surface and for moving and supporting said surface in proximately spaced relationship relative to said feeding means; means for defining a suction chamber contiguous to and ahead of said feeding means in the direction of movement of said surface and including an opening facing one side of said stream and a length of said surface, said chamber including a transversely extending forward wall that has an edge thereof located closely to said surface so that said length of said surface is located substantially between said forward wall and the stream of liquid composition; first suction producing means connected to said chamber for establishing an air pressure at the side of said stream of liquid composition adjacent said chamber that is less than that on the other side of said stream; means defining a suction knife at said forward wall of said suction chamber, said suction knife comprising an elongated slot extending transversely across the full width of said surface and slightly spaced therefrom; and second suction producing means substantially separate from said first suction producing means and communicating with said slot for vacuuming a layer of air flowing with said moving surface.

Claim 10

An apparatus comprising: means for continuously feeding a stream of liquid composition towards a moving surface of a member so that the stream bridges at least a portion of the distance between said feeding means and said moving surface; means for defining said surface and for moving and supporting said surface in proximately spaced relationship relative to said feeding means; means for defining a suction chamber contiguous to and ahead of said feeding means in the direction of movement of said surface and including an opening facing one side of said stream and a length of said surface, said chamber including a transversely extending forward wall that has an edge thereof located closely to said surface so that said length of said surface is located substantially between said forward wall and the stream of liquid composition; first suction producing means connected to said chamber for establishing an air pressure at the side of said stream of liquid composition adjacent said chamber that is less than that on the other side of said stream; means defining a suction knife at said forward wall of said suction chamber, said suction knife comprising an elongated slot extending transversely across the full width of said surface and slightly spaced therefrom; and second suction producing means substantially separate from said first suction producing means and communicating with said slot for vacuuming a layer of air flowing with said moving surface.

Claim 11

An apparatus comprising: means for continuously feeding a stream of liquid composition toward a moving surface of a member; means defining a surface of the member and for moving and supporting said surface in proximately spaced relationship relative to said feeding means so that the stream of liquid composition is adapted to bridge at least a portion of the distance from said feeding means to said surface of said member; means for defining a suction chamber contiguous to and ahead of said feeding means in the direction of movement of said surface and including an opening facing one side of said stream and a length of said surface; first suction producing means connected to said chamber for establishing an air pressure at the side of said stream of liquid composition adjacent said chamber that is less than that on the other side of said stream; means defining a suction knife that is located within said suction chamber, said suction knife comprising an elongated slot extending transversely across the full width of said surface and slightly spaced therefrom; and second suction producing means substantially separate from the first suction producing means and communicating with said slot for vacuuming a layer of air flowing with said moving surface.

Claim 12

An apparatus comprising: means for continuously feeding a stream of liquid composition toward a moving surface of a member; means defining a surface of the member and for moving and supporting said surface in proximately spaced relationship relative to said feeding means so that the stream of liquid composition is adapted to bridge at least a portion of the distance from said feeding means to said surface of said member; means for defining a suction chamber contiguous to and ahead of said feeding means in the direction of movement of said surface and including an opening facing one side of said stream and a length of said surface; first suction producing means connected to said chamber for establishing an air pressure at the side of said stream of liquid composition adjacent said chamber that is less than that on the other side of said stream; means defining a suction knife that is located within said suction chamber, said suction knife comprising an elongated slot extending transversely across the full width of said surface and slightly spaced therefrom; and second suction producing means substantially separate from the first suction producing means and communicating with said slot for vacuuming a layer of air flowing with said moving surface.