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US 4,791,965 AGranted
Co-extruded tube
AssigneeJames Hardie Irrigation, Inc.
InventorGerald E. Wynn
Life of this patent
Estimating the term…
Abstract
A tube having an elongated core composed of a flexible narrow molecular weight distribution first polymeric composition, a sheath composed of a broader molecular weight second polymeric composition co-extruded over the outer core surface, and a liner composed of a broader molecular weight distribution second polymeric composition co-extruded over the inner core surface. The core may be composed of a composition exhibiting relative poor processability, and the sheath and liner of a composition exhibiting better processability.
Claims31
A tube, comprising:
- an elongated, tubular core composed of a first polymeric composition, the core having an outer core surface and an inner core surface;
- and
- a sheath disposed over the outer core surface and a liner disposed over the inner core surface, at least one of which sheath and liner is composed of a second polymeric composition having broader molecular weight distribution than the first polymeric composition, provided that said core comprises at least about 94% of the total volume of said core, said sheath and said liner.
A tube, comprising:
- an elongated, tubular core composed of a first polymeric composition, the core having an outer core surface and in inner core surface;
- and
- a sheath disposed over the outer core surface and a liner disposed over the inner core surface, at least one of which sheath and liner is composed of a second polymeric composition which is linear and has a broader molecular weight distribution than the first polymeric composition, provided that said core comprises at least 94% of the total volume of said core, said sheath and said liner.
A tube, comprising:
- an elongated, tubular core composed of a first polymeric composition, the core having an outer core surface and an inner core surface;
- and
- a sheath disposed over the outer core surface and a liner disposed over the inner core surface, at least one of which sheath and liner consist essentially of a second polymeric composition which is linear and has a broader molecular weight distribution than the first polymeric composition.
A tube, comprising:
- an elongated, tubular core composed of a first polymeric composition, the core having an outer core surface and an inner core surface;
- and
- a sheath disposed over the outer core surface and a liner disposed over the inner core surface, at least one of which sheath and liner consists essentially of a second polymeric composition which is linear and has a broader molecular weight distribution than the first polymeric composition, provided that said core comprises at least about 99% of the total volume of said core, said sheath and said liner.
A method of decreasing tube flow resistance while improving tube appearance, comprising:
- forming a tubular core composed of a first polymeric composition having a relatively narrow molecular weight distribution;
- and
- forming a sheath and a linear over respective ones of an outer surface of the core and an inner surface of the core so that at least one of the sheath and the linear are composed of a polymeric composition having a broader molecular weight distribution than the first polymeric composition, provided that said core comprises at least about 94% of the total volume of said core, said sheath and said liner.
A method of fabricating a tube, comprising:
- forming a core having desired tubing characteristics from a first composition exhibiting relatively poor processability;
- and
- forming a sheath over an outer surface of the core from a second composition and a liner over an inner surface of the core from a third composition, at least one of which second and third compositions exhibit better processability, provided that said core comprises at least about 94% of the total volume of said core, said sheath and said liner.
A method of decreasing tube flow resistance while improving tube appearance, comprising:
- forming a tubular core composed of a first polymeric composition having a relatively narrow molecular weight distribution;
- and
- forming a sheath and a liner over respective over of an outer surface of the core and an inner surface of the core so that at least one of the sheath and the liner consists essentially or a second polymeric composition which is linear and has broader molecular weight distribution than the first polymeric composition, provided that said core comprises at least about 99% of the total volume of said core, said sheath and said liner.
A method of fabricating a tube, comprising:
- forming a core having desired tubing characteristics from a first polymeric composition exhibiting relatively poor processability;
- and
- forming a sheath over an outer surface of the core consisting essentially of a second polymeric composition and a liner over an inner surface of the core consisting essentially of a third polymeric composition, at least one of which second and third polymeric compositions is linear and exhibits better processability.
Dependencies are inferred from the claim text.