US4177334A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Microporous tubes
Assignee: Sumitomo Electric Industries Ltd
•
Filing: 1977-09-12
•
Granted: 1979-12-04
•
Expires: 1997-09-12
Abstract
Abstract Polytetrafluoroethylene resin tubes having small pore size and high porosity are produced by a process which includes stretching the tubes by drawing using a metal die and a metal plug. By using the die and plug, the stress necessary for stretching is converted to a compressive force in the thickness direction of the tube. This compressive force is an essential factor in producing the microporous structure of the tubes. In addition, when stretching is performed by drawing, a ratio of thickness to inside diameter of the tube of 0.07 or less can be easily achieved.
Inventors
- 👤 Koichi Okita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:06
CPC Classifications
B; B01; B01D; B01D71/00; B01D71/06; B01D71/30; B01D71/32; B01D71/36; B01D63/00; B01D63/06; B01D63/061; B01D69/00; B01D69/04; B01D69/043; B29; B29C; B29C48/00; B29C48/022; B29C55/00; B29C55/30; C; C08; C08J; C08J5/00; C08J5/18; B29C48/001; B29C48/0012; B29C48/03; B29C48/09; B29C48/10; B29K; B29K2027/00; B29K2027/12; B29K2027/18; B29K2105/00; B29K2105/04; B29L; B29L2023/00; B29L2031/00; B29L2031/753; B29L2031/7532; B29L2031/7534; C08J2327/00; C08J2327/02; C08J2327/12; C08J2327/18; Y; Y10; Y10S; Y10S521/00; Y10S521/919
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
137 words
A microporous tube composed of a porous polytetrafluoroethylene resin comprising nodules linked to one another by fine filaments prepared by molding a polytetrafluoroethylene resin containing a liquid lubricating agent by a paste method to form a tube, removing said liquid lubricating agent, stretching by drawing said tube in a lengthwise direction using a die and a plug, and sintering at a temperature of about 327° C. or more, said microporous tube (a) having a porosity and a bubble point in a range between the points A, B, C and D in FIG. 1 and defined in the following table: ______________________________________
porosity bubble point
______________________________________
A 96% 0.02 kg/cm.sup.2
B 54% 2.0 kg/cm.sup.2
C 20% 2.0 kg/cm.sup.2
D 30% 1.0 kg/cm.sup.2
______________________________________ and (b) having a ratio of wall thickness to inside diameter of about 0.1 or less.
Claim 2
Dependent Claim
137 words
A microporous tube composed of a porous polytetrafluoroethylene resin comprising nodules linked to one another by fine filaments prepared by molding a polytetrafluoroethylene resin containing a liquid lubricating agent by a paste method to form a tube, removing said liquid lubricating agent, stretching by drawing said tube in a lengthwise direction using a die and a plug, and sintering at a temperature of about 327° C. or more, said microporous tube (a) having a porosity and a bubble point in a range between the points A, B, C and D in FIG. 1 and defined in the following table: ______________________________________
porosity bubble point
______________________________________
A 96% 0.02 kg/cm.sup.2
B 54% 2.0 kg/cm.sup.2
C 20% 2.0 kg/cm.sup.2
D 30% 1.0 kg/cm.sup.2
______________________________________ and (b) having a ratio of wall thickness to inside diameter of about 0.1 or less.
Claim 3
Dependent Claim
35 words
A microporous tube as set forth in claim 1 having a porosity in the range of 20 to 60% and a bubble point in the range of 1.5 kg/cm 2 to 2.0 kg/cm 2 .
Claim 4
Dependent Claim
21 words
A microporous tube as set forth in claim 1, wherein a ratio of thickness to inside diameter is 0.07 or less.
Claim 5
Dependent Claim
38 words
The microporous tube as set forth in claim 1, wherein said stretching in the lengthwise direction is carried out two or more times and the final stretching is carried out by drawing using the die and the plug.
Claim 6
Dependent Claim
36 words
The microporous tube as set forth in claim 1, wherein said tube is sintered while simultaneously expanding the tube by reducing the pressure on the outside of the tube after carrying out said stretching by drawing.
References Cited (Backward Citations)
US2985918A
Cited
US3054761A
Cited
US3170858A
Cited
US3629383A
Cited
US3281511A
Cited
US3518332A
Cited
US3953566A
Cited
US3962153A
Cited
US3813461A
Cited
US4049589A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-12-03 | 1983-06-04 | 1983-12-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-12-03 | 1987-06-04 | 1987-12-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-12-03 | 1991-06-04 | 1991-12-04 | $7700.00 | Window Closed / Lapsed |