POLYURETHANE-POLYETHYLENE DELAMINATION RESISTANT TUBING WITH GAS BARRIER PROPERTIES

1 .- 25 . (canceled)

26 . Method of forming a medical tube comprising an outer layer, an innermost layer and an intermediate layer disposed between the outer layer and the innermost layer, the method comprising:

selecting a first polymeric material having a selected structural stability;

selecting a second polymeric material that is inert to aqueous fluids;

selecting a third polymeric material that acts as a barrier to gas;

selecting a fourth polymeric material that readily bonds and adheres to the first and second polymeric materials on co-extrusion and cooling of the materials;

co-extruding the selected first, second, third and fourth polymeric materials to form the medical tubing in a configuration that has an outer layer comprising at least about 90% by weight of the first polymeric material, an inner layer comprising at least about 90% weight of the second polymeric material, a layer disposed between the inner and outer layers that comprises at least about 90% by weight of the third polymeric material, a layer of the fourth material disposed between the outer layer and the layer of the third polymeric material and a layer of the fourth material disposed between the inner layer and the layer of the third polymeric material.

27 . The method of claim 26 wherein the first polymeric material is selected to be a polyurethane, the second polymeric material is selected to be a polyethylene, the third polymeric material is selected from the group consisting of an ethylene vinyl alcohol copolymer and a polyamide and the fourth polymeric material is one or more ethylene acrylic copolymers.

28 . The method of claim 26 wherein the first polymeric material is selected to be a polyurethane, the second polymeric material is selected to be a polyethylene, the third polymeric material is selected from the group consisting of an ethylene vinyl alcohol copolymer and a polyamide and the fourth polymeric material is selected such that the medical tubing does not visually delaminate after being submersed in water at 60° C. for 36 hours.

29 . The method of claim 28 wherein the fourth polymeric material comprises one or more anhydride grafted ethylene acrylate copolymers.

30 .- 34 . (canceled)

35 . The method of claim 29 wherein the fourth polymeric material comprises one or more anhydride grafted ethylene methyl acrylate copolymers.

36 . The method of claim 26 wherein the first polymeric material comprises an aromatic or aliphatic polyether based polyurethane and the second polymeric material comprises polyethylene.

37 . The method of claim 36 , wherein the polyethylene comprises one or more of a low density polyethylene, a linear low density polyethylene and a high density polyethylene and wherein the aromatic polyether based polyurethane comprises a polytetramethyleneglycol-based polyurethane.

38 . The method of claim 36 , wherein the polyethylene comprises a low density polyethylene (LDPE), and the first polymeric material comprises a polytetramethyleneglycol-based polyurethane.

39 . The method of claim 27 , where the thickness of the polyurethane outer layer is between 0.001 inches and 0.025 inches, the thickness of the inner polyethylene layer is between 0.001 inches and 0.025 inches and the thickness of the barrier layer is between 0.001 inches and 0.025 inches.

40 . The method of claim 26 , wherein the inner and outer layers do not visually delaminate when subjected to a stress and strain up to the tube's elastic yield point as measured in a mechanical tester at a pull rate of about 12 inches per minute at ambient conditions of 72 degrees F. and 50% relative humidity.

41 . The method of claim 26 , wherein the tube has a central axial fluid flow passage, the inner layer having a radially inner wall surface that defines the passage, the outer and inner layers resisting delamination when subjected to a stress and strain up to the tube's elastic yield point as measured in a mechanical tester at a pull rate of about 12 inches per minute at ambient conditions of 72 degrees F. and 50% relative humidity.

42 . The method of claim 26 , wherein the thickness of the layer of the fourth material disposed between the barrier layer and the outer layer is between 0.0001 inches and 0.025 inches and wherein the thickness of the layer of the fourth material disposed between the barrier layer and the inner layer is between 0.001 inches and 0.025 inches.

43 . The method of claim 26 , wherein the tube does not visually delaminate when submersed in water at 60° C. for 36 hours.