US 5,874,032 A · Method for manufacturing expanded polytetrafluoroethylene products

Abstract

An improved method is provided for extruding ePTFE tube (12) for use in medical applications. A tube (12) of PTFE is extruded, preferably in an extrusion process, using counter-rotated die components (22, 26). The die component (16) is maintained at a constant temperature during processing. The resulting green tube (12) has enhanced fibrous state formation in a direction perpendicular to the direction of extrusion. The PTFE green tube (12) is then subjected to secondary operations such as stretching and expansion to yield medical product. The ePTFE tube (12) structure is defined by nodes interconnected by elongate fibrils. Both the nodes and fibrils are substantially randomly tilted with respect to the longitudinal axis of the tube (12). This particular structure yields a tube (12) which exhibits a high degree of radial tear strength useful in medical applications.

Claims8

Dependent claims

A method of forming a PTFE tube comprising the steps of:

providing an extrusion apparatus having an elongate die defining a die cavity and an elongate mandrel substantially concentrically located within said die cavity,
rotating at least one of said die or said mandrel;
passing a PTFE paste through an elongate annular passage defined between said die and said mandrel;
controlling the temperature of said extrusion apparatus to maintain said PTFE paste passing through said annular cavity at a substantially uniform constant temperature;
and
extruding said PTFE paste through an extrusion die located at one end of said elongate annular passage whereby fibrous state formation of said formed tube is enhanced in a direction which is non-aligned with said elongate annular passage.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application

08/545,799Filed 15 Apr 1996 · continuation in part

Priority

10 Mar 1994

Granted

23 Feb 1999

Term ends

Not estimatedThe source records don’t support an estimate.

Classification16 codes

A61L 29/041
Macromolecular materials: obtained by reactions only involving carbon-to-carbon unsaturated bonds
B29C 48/022
Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor:…
B29C 48/09
Characterised by the shape of the extruded material at extrusion: articles with cross-sections having partially or fully enclosed cavities, e.g.…
B29C 48/10
Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels: flexible, e.g. blown foils

Method for manufacturing expanded polytetrafluoroethylene products

Life of this patent

Method for manufacturing expanded polytetrafluoroethylene products

Life of this patent

Abstract

Claims8