Composition of expanded polytetrafluoroethylene and similar polymers and method for producing same
AssigneeW. L. Gore & Associates, Inc.
InventorsGordon L. McGregor, Raymond B. Minor, William P. Mortimer, Jr., Daniel E. Hubis
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Abstract
The present invention provides improved compositions of expanded polytetrafluoroethylene (PTFE) and similar polymers and methods for forming and using such compositions. In its preferred embodiment, the present invention employs a mixture of PTFE and expandable thermoplastic microspheres. Through application of an energy source to the mixture, a coherent three dimensional expansion of PTFE can be achieved. The expanded mixture has many of the same beneficial properties of mechanically expanded PTFE and numerous properties previously unavailable with expanded PTFE products.
Claims24
A composition which comprises:
- a composite of ultrahigh molecular weight polyethylene and expandable microspheres;
- wherein the composite comprises a thread including unexpanded microspheres therein, the microspheres being adapted to expand the composite into a coherent mass of microspheres, polymeric nodes and interconnecting fibrils, and air spaces when exposed to an energy source once incorporated into a seam.
A composition which comprises:
- a composite of ultrahigh molecular weight polyethylene and expandable microspheres;
- wherein the composite is a coherent, resilient mass of microspheres, polymeric nodes and interconnecting fibrils, and air spaces;
- and
- wherein the composition is formed as a thread, the thread being resilient to deformation when incorporated into a seam so as to resist leakage through seam holes.
An improved method for use in forming sealed seams with minimal leakage therethrough which comprises:
- providing a thread containing a polymer resin and unexpanded microspheres, the microspheres being adapted to expand significantly when exposed to an energy source, the polymer resin selected from the group consisting of polytetrafluoroethylene or ultra-high molecular weight polyethylene;
- forming a seam with the thread;
- sealing the seam by exposing the thread to the energy source to cause the microspheres to expand and increase the width of the thread.
A thread suitable for creating a sewn seam which comprises:
- a polymer selected from the group consisting of polytetrafluoroethylene or ultra-high molecular weight polyethylene;
- a composite of the polymer and expandable microspheres, said mixture comprising a lattice of nodes and fibrils of polymer with microspheres embedded therein;
- and
- means to reinforce said thread to resist breakage of the thread upon exertion of force along the thread's longitudinal dimension.
A composition which comprises:
- a composite of polytetrafluoroethylene and expandable microspheres;
- wherein the composite comprises a thread including unexpanded microspheres therein, the microspheres being adapted to expand the composite into a coherent mass of microspheres, polymeric nodes and interconnecting fibrils, and air spaces when exposed to an energy source once incorporated into a seam.
A composition which comprises:
- a composite of polytetrafluoroethylene (PTFE) and expandable microspheres;
- wherein the composite is a coherent, resilient mass of microspheres, polymeric nodes and interconnecting fibrils, and air spaces;
- and
- wherein the composition is formed as a thread, the thread being resilient to deformation when incorporated into a seam so as to resist leakage through seam holes.
Dependencies are inferred from the claim text.