Lubeless pipe gasket and method of fabrication
A thermoplastic pipe gasket fabricated of a thermoset material is provided having a first pipe engaging surface and an exterior surface, with the exterior surface having applied thereto a water-based, flexible, slip-coating. The slip-coating comprises polyurethane, a cross-linking agent, and a dispersion of a friction reducing compound. The friction reducing compound can be selected from a fluoropolymer, silicone, or graphite, either alone or in combinations thereof. Depending on the method of fabrication, the slip-coating can be sprayed onto the thermoset material after the thermoset material has been extruded, but before the extrudate's fabrication into a gasket. Alternatively, the slip-coating can be sprayed onto the gasket following its assembly. Still further, the slip-coating can be applied to the thermoset material by dipping the thermoset material into the water-based, flexible, slip-coating.
1 . A thermoplastic pipe gasket, said gasket fabricated of a thermoset material, said gasket comprising a first pipe engaging surface and an exterior surface, said exterior surface having applied thereto a flexible, slip-coating, said slip-coating comprising a friction reducing compound.
2 . The gasket according to claim 1 wherein said slip-coating comprises polyurethane, a cross-linking agent, and a dispersion of a friction reducing compound.
3 . The gasket according to claim 1 wherein said slip-coating comprises polyurethane, a bonding promoter, and a dispersion of a friction reducing compound.
4 . The gasket according to claim 1 wherein said friction reducing compound is selected from the group comprising fluoropolymers, silicone, and graphite.
5 . The gasket according to claim 4 wherein said fluoropolymer is polytetrafluoroethylene.
6 . The gasket according to claim 1 wherein said slip-coating is water-based.
7 . The gasket according to claim 1 wherein said slip-coating is solvent-based.
8 . The gasket according to claim 1 wherein said flexible, slip-coating is applied to the thermoset material after said thermoset material has been extruded during the fabrication of said gasket.
9 . The gasket according to claim 1 wherein said flexible, slip-coating is applied to said gasket in a manner selected from the group comprising spraying, brushing, wiping or dipping.
10 . The gasket according to claim 1 wherein said flexible, slip-coating is applied in a plurality of steps, with different steps including different components of said slip-coating.
11 . The gasket according to claim 1 wherein said thermoset material is selected from the group comprising synthetic rubber and natural rubber.
12 . A thermoplastic pipe gasket formed by the process comprising the steps of:
(a) having hot thermoset material flow through a die head to form an elongate body having a predetermined cross-section, said elongate body having an exterior surface;
(b) applying a flexible, slip-coating to said exterior surface, said slip-coating comprising a friction reducing compound;
(c) curing said slip-coating;
(d) cutting said thermoset material; and
(e) splicing said elongate body to form a gasket having a first pipe engaging surface and an exterior surface.
13 . The gasket formed by the process according to claim 12 , which includes the additional step of curing the hot thermoset material after it is extruded, but before the flexible, slip-coating is applied thereto.
14 . A thermoplastic pipe gasket formed by the process comprising the steps of:
(a) having hot thermoset material flow through a die head to form an elongate body having a predetermined cross-section, said elongate body having an exterior surface;
(b) cutting said thermoset material;
(c) applying a flexible, slip-coating to said exterior surface, said slip-coating comprising a friction reducing compound;
(d) curing said slip-coating and thermoset material; and
(e) splicing the cut thermoset material to form a gasket having a first pipe engaging surface and an exterior surface.
15 . The thermoplastic pipe gasket formed by the process comprising the steps of:
(a) having hot thermoset material flow through a die head to form an elongate body having a predetermined cross-section, said elongate body having an exterior surface;
(b) curing said thermoset material;
(c) cutting said thermoset material;
(d) splicing said thermoset material to form a gasket having a first pipe engaging surface and an exterior surface;
(e) applying a flexible, slip-coating to said exterior surface, said slip-coating comprising a friction reducing compound; and
(f) curing said slip-coating.