US5980799A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Methods of making controlled porosity expanded polytetrafluoroethylene products and fabrication
Assignee: Atrium Medical Corp
•
Filing: 1998-06-16
•
Granted: 1999-11-09
•
Expires: 2018-06-16
Abstract
Abstract A method of forming porous articles with a varying pore distribution by extrusion from a billet with a varying lubricant distribution. A single-polymer polytetrafluoroethylene is extruded and then stretched and sintered to provide a differential porous PTFE structure composed of fibers and nodes connected to one another by these fibers. The microfibrous structure has a portion within the cross-section that possesses a different pore size, accompanied by a different node and fiber geometry, than adjacent areas within that cross section. In a vascular graft, the pores taper inwardly, providing a fluid-tight lumen wall structure that prevents leakage, yet promotes cellular ingrowth and natural tissue regeneration. A node structure of radially-oriented plates provides flexibility, suture strength, and enhanced protection against collapse.
Inventors
- 👤 Paul Martakos
- 👤 Theodore Karwoski
- 👤 Steve A. Herweck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:22
CPC Classifications
B; B29; B29D; B29D23/00; B29D23/001; A; A61; A61F; A61F2/00; A61F2/02; A61F2/04; A61F2/06; A61L; A61L27/00; A61L27/14; A61L27/16; A61L27/50; A61L27/56; B01; B01D; B01D67/00; B01D67/0002; B01D67/0023; B01D67/0025; B01D67/0027; B01D69/00; B01D69/02; B01D69/12; B01D69/1212; B01D71/00; B01D71/06; B01D71/30; B01D71/32; B01D71/36; B29C; B29C48/00; B29C48/022; B29C48/03; B29C48/07; B29C48/08; B29C55/00; B29C55/005; B01D2325/00; B01D2325/02; B01D2325/0283; B29C48/001; B29C48/0012; B29C48/0018; B29C48/09; B29C48/10; B29C48/16; B29C48/18; B29C48/19; B29C48/21; B29K; B29K2027/00; B29K2027/12; B29K2027/18; B29K2105/00; B29K2105/04; B29L; B29L2023/00; B29L2023/005; B29L2023/007; Y; Y10; Y10T; Y10T428/00; Y10T428/13; Y10T428/1352; Y10T428/139; Y10T428/1397; Y10T428/24; Y10T428/24273; Y10T428/249921; Y10T428/249953; Y10T428/249986; Y10T428/249987; Y10T428/24999; Y10T428/249991; Y10T428/249992; Y10T428/31504; Y10T428/3154; Y10T428/31544
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
95 words
A method of producing a prosthesis, such method comprising the steps of forming a billet of fluoropolymer material having a lubricant property which varies corresponding to a desired porosity structure, extruding the billet to form an extruded prosthesis blank, the extruded prosthesis blank having a lubricant property distribution that varies in correspondence with said desired porosity structure, removing lubricant from and stretching the extruded prosthesis blank to form a porous prosthesis blank, and sintering the porous prosthesis blank in its stretched state to fix its dimensions thereby forming a prosthesis having the desired porosity structure.
Claim 2
Independent Claim
95 words
A method of producing a prosthesis, such method comprising the steps of forming a billet of fluoropolymer material having a lubricant property which varies corresponding to a desired porosity structure, extruding the billet to form an extruded prosthesis blank, the extruded prosthesis blank having a lubricant property distribution that varies in correspondence with said desired porosity structure, removing lubricant from and stretching the extruded prosthesis blank to form a porous prosthesis blank, and sintering the porous prosthesis blank in its stretched state to fix its dimensions thereby forming a prosthesis having the desired porosity structure.
Claim 3
Dependent Claim
23 words
The method of claim 1, wherein the lubricant property is one of the lubricant density, the lubricant viscosity, and the lubricant molecular weight.
Claim 4
Dependent Claim
26 words
The method of claim 2, wherein the prosthesis is a vascular prosthesis and the lubricant property is selected to provide a pore size for tissue growth.
Claim 5
Dependent Claim
18 words
The method of claim 3, wherein the porosity structure tapers between inside and outside of the vascular prosthesis.
Claim 6
Dependent Claim
48 words
In a method of manufacturing a porous PTFE article having a sintered microporous structure, the improvement comprising forming the article of PTFE mixed with lubricant, and varying a property of the lubricant through a cross-section of the article to achieve a tapered pore structure before sintering the article.
Claim 7
Dependent Claim
48 words
In a method of manufacturing a porous PTFE article having a sintered microporous structure, the improvement comprising forming the article of PTFE mixed with lubricant, and varying a property of the lubricant through a cross-section of the article to achieve a tapered pore structure before sintering the article.
Claim 8
Dependent Claim
39 words
The method of manufacture of claim 5, wherein the porous PTFE article is a sheet article having a pore size on one surface to define a region of tissue ingrowth, and having a different pore size outside said region.
Claim 9
Dependent Claim
94 words
A process for producing a shaped porous article, the process comprising the steps of providing an extrudate of a fluoropolymer material which is capable of being stretched, the extrudate having a longitudinal axis and a desired cross-section, bilaterally stretching the extrudate in two opposing directions along the longitudinal axis to yield an article which is substantially uniformly stretched over a major portion of its length and has a microstructure characterized by elongate nodes connected by fibrils, and sintering the stretched extrudate while maintaining it in its stretched state to produce the shaped porous article.
Claim 10
Dependent Claim
94 words
A process for producing a shaped porous article, the process comprising the steps of providing an extrudate of a fluoropolymer material which is capable of being stretched, the extrudate having a longitudinal axis and a desired cross-section, bilaterally stretching the extrudate in two opposing directions along the longitudinal axis to yield an article which is substantially uniformly stretched over a major portion of its length and has a microstructure characterized by elongate nodes connected by fibrils, and sintering the stretched extrudate while maintaining it in its stretched state to produce the shaped porous article.
Claim 11
Dependent Claim
18 words
The process of claim 7, wherein said bilaterally stretching step is carried out by displacing opposite ends simultaneously.
Claim 12
Dependent Claim
18 words
The process of claim 7, wherein said bilaterally stretching step is carried out by displacing opposite ends sequentially.
Claim 13
Dependent Claim
22 words
The process of claim 9, wherein each of the sequential displacements results in a stretch ratio not greater than two to one.
Claim 14
Dependent Claim
30 words
The process of claim 7, wherein said bilaterally stretching step is carried out while maintaining the extrudate at a temperature between approximately 35 degrees centigrade and approximately 327 degrees centigrade.
Claim 15
Dependent Claim
17 words
The process of claim 7, wherein said cross-section is circular and said shaped article is a tube.
Claim 16
Dependent Claim
104 words
A process for producing a shaped article of polytetrafluoroethylene comprising the steps of providing a preformed billet of a mixture of a polytetrafluoroethylene resin and a lubricant, extruding the billet to produce a tubular extrudate having a longitudinal axis and a radial thickness, removing the lubricant from the extrudate, bilaterally stretching the extrudate along the longitudinal axis in two opposing directions to yield an article having a substantially homogeneous microstructure over a major portion of its length, the microstructure being characterized by elongate nodes connected by fibrils, and sintering the stretched article while maintaining it in its stretched state to produce the shaped article.
Claim 17
Dependent Claim
104 words
A process for producing a shaped article of polytetrafluoroethylene comprising the steps of providing a preformed billet of a mixture of a polytetrafluoroethylene resin and a lubricant, extruding the billet to produce a tubular extrudate having a longitudinal axis and a radial thickness, removing the lubricant from the extrudate, bilaterally stretching the extrudate along the longitudinal axis in two opposing directions to yield an article having a substantially homogeneous microstructure over a major portion of its length, the microstructure being characterized by elongate nodes connected by fibrils, and sintering the stretched article while maintaining it in its stretched state to produce the shaped article.
Claim 18
Dependent Claim
18 words
The process of claim 13, wherein said bilaterally stretching step is carried out by displacing opposite ends simultaneously.
Claim 19
Dependent Claim
18 words
The process of claim 13, wherein said bilaterally stretching step is carried out by displacing opposite ends sequentially.
Claim 20
Dependent Claim
22 words
The process of claim 15, wherein each of the sequential displacements results in a stretch ratio not greater than two to one.
Claim 21
Dependent Claim
30 words
The process of claim 13, wherein said bilaterally stretching step is carried out while maintaining the extrudate at a temperature between approximately 35 degrees centigrade and approximately 327 degrees centigrade.
Claim 22
Dependent Claim
17 words
The process of claim 13, wherein said cross-section is circular and said shaped article is a tube.
Claim 23
Dependent Claim
25 words
The process of claim 13, wherein the lubricant is mixed in the billet at a level which is greater than approximately fifteen percent by weight.
Claim 24
Dependent Claim
25 words
The process of claim 13, wherein the lubricant is mixed in the billet at a level which is greater than approximately twenty percent by weight.
Claim 25
Dependent Claim
14 words
The process of claim 13, wherein the lubricant level is varied through the cross-section.
Claim 26
Dependent Claim
109 words
A process for producing a porous tube of polytetrafluoroethylene comprising the steps of providing a preformed billet of a mixture of a polytetrafluoroethylene resin and a lubricant, extruding the billet to produce a tubular extrudate having a longitudinal axis and a radial thickness, removing the lubricant from the extrudate, stretching the extrudate along the longitudinal axis at a rate of less than ten percent per second to yield an article having a substantially homogeneous microstructure over a major portion of its length, the microstructure being characterized by elongate nodes connected by fibrils, and sintering the stretched article while maintaining it in its stretched state to produce the porous tube.
Claim 27
Dependent Claim
109 words
A process for producing a porous tube of polytetrafluoroethylene comprising the steps of providing a preformed billet of a mixture of a polytetrafluoroethylene resin and a lubricant, extruding the billet to produce a tubular extrudate having a longitudinal axis and a radial thickness, removing the lubricant from the extrudate, stretching the extrudate along the longitudinal axis at a rate of less than ten percent per second to yield an article having a substantially homogeneous microstructure over a major portion of its length, the microstructure being characterized by elongate nodes connected by fibrils, and sintering the stretched article while maintaining it in its stretched state to produce the porous tube.
Claim 28
Dependent Claim
22 words
The process of claim 22, wherein said stretching step is carried out a rate not greater than approximately five percent per second.
Claim 29
Dependent Claim
22 words
The process of claim 22, wherein said stretching step is carried out a rate not greater than approximately two percent per second.
Claim 30
Dependent Claim
22 words
The process of claim 22, wherein said stretching step is carried out a rate not greater than approximately one percent per second.
Claim 31
Dependent Claim
25 words
The process of claim 22, wherein said stretching step is carried out by bilaterally stretching the extrudate along the longitudinal axis in two opposing directions.
Claim 32
Dependent Claim
107 words
A process for producing a shaped porous article having a desired length along an axis and a microstructure adapted for supporting a biological material thereon, such process comprising the steps of forming an extruded article of fluoropolymer material having an end-to-end dimension related to the desired length, stretching the extruded article at an elevated temperature to form a stretched article of the desired length by actively moving each end of the extruded article in opposite directions away from a central portion of the extruded article, and sintering the stretched article while maintaining it in a stretched state to produce the shaped porous article having the desired length.
Claim 33
Dependent Claim
107 words
A process for producing a shaped porous article having a desired length along an axis and a microstructure adapted for supporting a biological material thereon, such process comprising the steps of forming an extruded article of fluoropolymer material having an end-to-end dimension related to the desired length, stretching the extruded article at an elevated temperature to form a stretched article of the desired length by actively moving each end of the extruded article in opposite directions away from a central portion of the extruded article, and sintering the stretched article while maintaining it in a stretched state to produce the shaped porous article having the desired length.
Claim 34
Dependent Claim
47 words
The process of claim 26, wherein the step of forming includes forming a billet having a thickness dimension and a lubricant distribution across the thickness dimension, and extruding the billet to form an extruded tubular article, whereby the step of stretching introduces corresponding radial variations of microstructure.
Claim 35
Dependent Claim
29 words
The process of claim 27, wherein the billet is formed with a lubricant distribution for introducing a radially tapering pore structure extending from a surface of the stretched article.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2002-11-08 | 2003-05-10 | 2003-11-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-11-08 | 2007-05-10 | 2007-11-09 | $3760.00 | Window Closed / Lapsed |
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