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Expanded PTFE articles and method of making same

a technology of expanded ptfe and articles, applied in the field of unique expanded ptfe articles, can solve the problems of ineffective modification of bulk substrate properties, porosity and permeability, treatment with or following amorphous locking,

Inactive Publication Date: 2006-03-02
WL GORE & ASSOC INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention is about a special PTFE structure that has raised regions of PTFE attached to an underlying expanded PTFE structure. These raised regions, or islands, are connected at their bases to the underlying ePTFE structure. The islands are unique to the surface of the article and are not present below the surface. The unique structure of the PTFE structures of the present invention makes them useful in various applications such as dental floss, fishing line, and sutures. The technical effects of this invention include improved performance and unique characteristics in PTFE fibers and articles.

Problems solved by technology

Martakos et al. distinguish over conventional processes by noting that the prior art techniques operate on finished, fabricated and / or finally processed materials, which are “ineffective at modifying bulk substrate properties, such as porosity and permeability.” Martakos et al. teach plasma treating at six possible polymer resin process steps; however, no such treatment with or subsequent to amorphous locking is described or suggested.
However, none of the prior art references teach applicants' unique combination of processing to create a unique surface on PTFE which has heretofore not been seen.

Method used

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  • Expanded PTFE articles and method of making same
  • Expanded PTFE articles and method of making same
  • Expanded PTFE articles and method of making same

Examples

Experimental program
Comparison scheme
Effect test

example 1

Precursor material:

[0109] Expanded PTFE dental floss material made in accordance with the teachings of U.S. Pat. No. 5,518,012 was the precursor for the two continuous processing techniques performed in this example, described below as (a) and (b). This dental floss was an ePTFE flat fiber possessing the following properties: bulk density of 1.52 g / cc, thickness of 0.05 mm, width of 1.2 mm, and matrix tensile strength of 81,401 psi in the length direction, drag resistance of 0.148 and Fiber Fray Score of greater than 200 (exact numbers were not calculated because of the abundance of hairs). Representative scanning electron photomicrographs of the precursor material, all taken at 500× magnification, appear in FIGS. 4 through 6. The dashed bars present at the lower right of these and all other micrographs presented herein indicate the magnification scale. For example, the distance between the first and last dash marks in FIG. 4 corresponds to a length of 100 microns. The precursor m...

example 2

[0117] The same precursor material as described in Example 1 was used in this example. The precursor material samples were subjected to the same plasma treatment described in Example 1, part (a), then the plasma-treated samples were axially restrained and placed in a forced air oven set to 335° C. for about 10 minutes.

[0118] Surface and longitudinal cross-section scanning electron photomicrographs were obtained for this inventive material. FIG. 13 is a surface photomicrograph of the floss material sample taken at 1000× magnification. The islands that are characteristic of articles of the present invention are evident in this photomicrograph. As with the islands observed in Example 1, the island surfaces appear smooth and the individual islands are of greater surface area than any of the underlying nodes.

[0119] The inventive article had the following properties: bulk density of 1.46 g / cc, longitudinal matrix tensile strength of 64,345 psi, width of 1.1 mm, and thickness of 0.17 mm....

example 3

Precursor material:

[0120] Expanded PTFE dental floss made in accordance with the teachings of U.S. Pat. No. 6,539,951 was the precursor material for this example. This dental floss consisted essentially of ePTFE and possessed the following properties: bulk density of 0.80 g / cc, thickness of 0.08 mm, width of 1.9 mm, matrix tensile strength of 63,949 psi, and drag coefficient of 0.172. Photomicrographs of the surface and cross-section, respectively, of this precursor material appear in FIGS. 14 (500×) and 15 (1000×).

Experimental procedure:

[0121] For the present example, the precursor material was plasma-treated, then heat treated in accordance with the steps described in Example 1, part (a). FIG. 16 (surface, 200×), FIG. 17 (surface, 500×), and FIG. 18 (cross-section, 1000×) are photomicrographs of the microstructure of the inventive material. As with the prior examples, the individual islands are seen to have a much larger surface area than any of the nodes of the underlying no...

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Abstract

Unique PTFE structures comprising islands of PTFE attached to an underlying expanded polytetrafluoroethylene (ePTFE) structure and to methods of making such structures is disclosed. The ePTFE material may or may not have been exposed to amorphous locking temperatures. These unique structures exhibit islands of PTFE attached to and raised above the expanded PTFE structures.

Description

RELATED APPLICATIONS [0001] The present application is a regular application based on co-pending U.S. Provisional Patent Application 60 / 605,127 filed Aug. 26,2 004.FIELD OF THE INVENTION [0002] The present invention relates to unique expanded PTFE articles. More specifically, it is directed to novel structures of expanded PTFE and a novel process for preparing the structures. BACKGROUND OF THE INVENTION [0003] The structure of expanded PTFE (“ePTFE”) is well known to be characterized by nodes interconnected by fibrils, as taught in U.S. Pat. Nos. 3,953,566 and 4,187,390, to Gore, and which patents have been the foundation for a significant body of work directed to ePTFE materials. The node and fibril character of the ePTFE structure has been modified in many ways since it was first described in these patents. For example, highly expanded materials, as in the case of high strength fibers, can exhibit exceedingly long fibrils and relatively small nodes. Other process conditions can yi...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): A61L17/00
CPCA01K91/00A61C15/041A61L17/04Y10T428/2967Y10T428/2925Y10T428/13Y10T428/29Y10T428/24479Y10T428/2913Y10T428/2929Y10T428/2978Y10T428/249921Y10T428/3154
Inventor LUTZ, DAVID ISAACCLOUGH, NORMAN ERNEST
Owner WL GORE & ASSOC INC
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