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US4332035A
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Porous structure of polytetrafluoroethylene and process for production thereof
Assignee: Sumitomo Electric Industries Ltd
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Filing: 1979-11-28
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Granted: 1982-06-01
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Expires: 1999-11-28
Abstract
Abstract A porous polytetrafluoroethylene material is disclosed having a molecular microfibrous structure having, at one surface, a strong orientation in a given direction and, at another opposite surface, a strong orientation and a direction at right angles to the first, in which the orientation of the microfibrous structure progressively changes from one surface to the other. A process for preparing such an element is also disclosed.
Inventors
- 👤 Hiroshi Mano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:56
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; A; A61; A61F; A61F2/00; A61F2/02; A61F2/04; A61F2/06; A61L; A61L27/00; A61L27/14; A61L27/16; A61L29/00; A61L29/04; A61L29/041; A61L29/14; A61L29/146; B; B29; B29C; B29C48/00; B29C48/022; B29C48/03; B29C48/06; B29C48/07; B29C48/08; B29C48/09; B29C55/00; B29C55/005; B29K; B29K2027/00; B29K2027/12; B29K2027/18; B29K2105/00; B29K2105/04; C08J2327/00; C08J2327/02; C08J2327/12; C08J2327/18
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
101 words
A unitary porous structure of polytetrafluoroethylene having a microfibrous structure composed of fibers and nodes connected to one another by these fibers, said microfibrous structure having at one surface a strong orientation in one direction and at another surface a strong orientation in a direction at right angles to the aforesaid direction, the orientation of said microfibrous structure progressively changing from one surface to the other, wherein said structure has a tear strength in a first direction of at least 480 g/ply, and a tear strength in a direction at right angles to said first direction of at least 1,190 g/ply.
Claim 2
Dependent Claim
101 words
A unitary porous structure of polytetrafluoroethylene having a microfibrous structure composed of fibers and nodes connected to one another by these fibers, said microfibrous structure having at one surface a strong orientation in one direction and at another surface a strong orientation in a direction at right angles to the aforesaid direction, the orientation of said microfibrous structure progressively changing from one surface to the other, wherein said structure has a tear strength in a first direction of at least 480 g/ply, and a tear strength in a direction at right angles to said first direction of at least 1,190 g/ply.
Claim 3
Dependent Claim
44 words
The unitary porous structure of polytetrafluoroethylene of claim 1, wherein said structure has a tear strength in a first direction of at least 5,100 g/ply and a tear strength in a direction at right angles to said first direction of at least 520 g/ply.
Claim 4
Dependent Claim
37 words
The unitary porous structure of polytetrafluoroethylene of claim 1, wherein the tear strength in one said direction of strong orientation is approximately equal to the tear strength in a direction at right angles to the aforesaid direction.
Claim 5
Dependent Claim
14 words
The unitary porous structure of claim 1, wherein said structure is a porous tubing.
Claim 6
Dependent Claim
29 words
The porous tubing of claim 4, wherein said tubing is a vascular prosthesis, wherein the tear strength in the axial direction of said prosthesis is at least 3,800 g/ply.
Claim 7
Dependent Claim
101 words
A unitary porous structure of polytetrafluoroethylene having a microfibrous structure composed of fibers and nodes connected to one another by these fibers, said microfibrous structure having at one surface a strong orientation in one direction and at another surface a strong orientation in a direction at right angles to the aforesaid direction, the orientation of said microfibrous structure progressively changing from one surface to the other, wherein said structure has a tear strength in a first direction of at least 810 g/ply and a tear strength in a direction at right angles to said first direction of at least 970 g/ply.
Claim 8
Dependent Claim
101 words
A unitary porous structure of polytetrafluoroethylene having a microfibrous structure composed of fibers and nodes connected to one another by these fibers, said microfibrous structure having at one surface a strong orientation in one direction and at another surface a strong orientation in a direction at right angles to the aforesaid direction, the orientation of said microfibrous structure progressively changing from one surface to the other, wherein said structure has a tear strength in a first direction of at least 810 g/ply and a tear strength in a direction at right angles to said first direction of at least 970 g/ply.
Claim 9
Dependent Claim
88 words
A process for producing a porous structure of polytetrafluoroethylene, which comprises stretching a molded article of polytetrafluoroethylene in at least one direction, heating one surface of the article to a temperature of about 350° C. while maintaining it in a condition capable of preventing its heat shrinkage, thereby to sinter it such that the orientation of the microfibrous structure of said surface is larger in the direction at right angles to the direction of stretching than in the stretching direction, and maintaining said heating for approximately 30 minutes.
Claim 10
Dependent Claim
88 words
A process for producing a porous structure of polytetrafluoroethylene, which comprises stretching a molded article of polytetrafluoroethylene in at least one direction, heating one surface of the article to a temperature of about 350° C. while maintaining it in a condition capable of preventing its heat shrinkage, thereby to sinter it such that the orientation of the microfibrous structure of said surface is larger in the direction at right angles to the direction of stretching than in the stretching direction, and maintaining said heating for approximately 30 minutes.
Claim 11
Dependent Claim
31 words
The process of claim 7, wherein a surface opposite said heated surface is cooled simultaneously with the heating of said heated surface, thereby to provide a temperature gradient across said structure.
Claim 12
Dependent Claim
86 words
A process for producing a porous structure of polytetrafluoroethylene, which comprises stretching a molded article of polytetrafluoroethylene in at least one direction, heating one surface of the article at a temperature above about 327° C. while maintaining it in a condition capable of preventing its heat shrinkage, and maintaining said heating at sufficient temperature and time to produce a structure wherein the tear strength in said direction of stretching is approximately equal to the tear strength in a direction at right angles to the aforesaid direction.
Claim 13
Dependent Claim
86 words
A process for producing a porous structure of polytetrafluoroethylene, which comprises stretching a molded article of polytetrafluoroethylene in at least one direction, heating one surface of the article at a temperature above about 327° C. while maintaining it in a condition capable of preventing its heat shrinkage, and maintaining said heating at sufficient temperature and time to produce a structure wherein the tear strength in said direction of stretching is approximately equal to the tear strength in a direction at right angles to the aforesaid direction.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-05-31 | 1985-11-30 | 1986-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-05-31 | 1989-11-30 | 1990-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-05-31 | 1993-11-30 | 1994-06-01 | $7700.00 | Window Closed / Lapsed |