US4250138A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing microporous tubes of polytetrafluoroethylene
Assignee: Sumitomo Electric Industries Ltd
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Filing: 1979-05-23
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Granted: 1981-02-10
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Expires: 1999-05-23
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 13:11
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: 4
Claim 1
Independent Claim
131 words
A process for producing microporous tubes which comprises molding a polytetrafluoroethylene resin containing a liquid lubricating agent by a paste method to form a tube, removing the liquid lubricating agent, stretching by drawing the tube in a lengthwise direction using a die and a plug, and sintering at a temperature of about 327° C. or more whereby as a result of said stretching and said drawing, a microporous tube is produced having a porosity and a bubble point in a range between the point A, B, C and D 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 having a ratio of wall thickness to inside diameter of about 0.1 or less.
Claim 2
Dependent Claim
131 words
A process for producing microporous tubes which comprises molding a polytetrafluoroethylene resin containing a liquid lubricating agent by a paste method to form a tube, removing the liquid lubricating agent, stretching by drawing the tube in a lengthwise direction using a die and a plug, and sintering at a temperature of about 327° C. or more whereby as a result of said stretching and said drawing, a microporous tube is produced having a porosity and a bubble point in a range between the point A, B, C and D 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 having a ratio of wall thickness to inside diameter of about 0.1 or less.
Claim 3
Dependent Claim
41 words
A process for producing microporous tubes as set forth in claim 1, wherein the 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 4
Dependent Claim
44 words
A process for producing microporous tubes as set forth in claim 1 which comprises sintering the tube at about 327° C. or more simultaneously with expanding the tube by reducing the pressure on the outside of the tube after carrying out stretching by drawing.
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) | 1984-02-10 | 1984-08-11 | 1985-02-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-10 | 1988-08-11 | 1989-02-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-10 | 1992-08-11 | 1993-02-10 | $7700.00 | Window Closed / Lapsed |