Patent US3944477A successfully refreshed from Google Patents.
US3944477A
Expired / Lapsed
US
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Diaphragm for electrolytic cell for chlorine production
Assignee: BASF Corp
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Filing: 1974-10-15
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Granted: 1976-03-16
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Expires: 1994-10-15
Abstract
Abstract In an electrolytic cell for the production of halogen and caustic from an aqueous alkali metal halide solution containing anode and cathode compartments separated by a diaphragm an improved diaphragm is provided. The diaphragm is a porous sheet material made of a tetrafluoroethylene polymer having a low amorphous content and a micro-structure characterized by nodes interconnected by fibrils having a porosity of about 50 to 90 percent and a very tortuous path of interconnection. The improved diaphragm has an extremely long service life.
Inventors
- 👤 Shyam D. Argade
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:15
CPC Classifications
C; C25; C25B; C25B13/00
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
114 words
In an electrolytic cell for the production of halogen and caustic from an aqueous alkali metal halide solution containing anode and cathode compartments separated by a diaphragm, the improvement comprising: a diaphragm of porous tetrafluoroethylene polymer sheet material which has an amorphous content not exceeding about 5 percent and a micro-structure characterized by nodes interconnected by fibrils, said fibrils having a diameter of about 5 to about 1,000 angstroms, said nodes having lengths of about 0.5 to about 400 microns, said sheet having a porosity of about 50 to about 90 percent, a bulk density of less than about 1.0 and a bulk tensile strength of greater than about 3,000 pounds per square inch.
Claim 2
Dependent Claim
114 words
In an electrolytic cell for the production of halogen and caustic from an aqueous alkali metal halide solution containing anode and cathode compartments separated by a diaphragm, the improvement comprising: a diaphragm of porous tetrafluoroethylene polymer sheet material which has an amorphous content not exceeding about 5 percent and a micro-structure characterized by nodes interconnected by fibrils, said fibrils having a diameter of about 5 to about 1,000 angstroms, said nodes having lengths of about 0.5 to about 400 microns, said sheet having a porosity of about 50 to about 90 percent, a bulk density of less than about 1.0 and a bulk tensile strength of greater than about 3,000 pounds per square inch.
Claim 3
Dependent Claim
21 words
The improvements of claim 1 wherein the diaphragm has a thickness of about 5 to about 100 thousandths of an inch.
Claim 4
Dependent Claim
24 words
The improvement of claim 2 wherein the porosity is about 50 to 90 percent with a pore size of 0.2 to about 1.0 microns.
Claim 5
Dependent Claim
28 words
The improvement of claim 2 wherein the thickness is 30 thousandths of an inch, the porosity is 50 to 90 percent and the Gurley Number is 25-100 seconds.
Claim 6
Dependent Claim
23 words
The improvement of claim 1 wherein the diaphragm thickness is 10 to 80 thousandths of an inch with a porosity of 85 percent.
Claim 7
Dependent Claim
21 words
The improvement of claim 1 where a number of such films are suitably bonded by an adhesive in a sandwich fashion.
Claim 8
Dependent Claim
23 words
The improvement of claim 1 where a number of such films are thermally bonded together, maintaining the polytetrafluoroethylene content to the same level.
References Cited (Backward Citations)
JPS4213560B1
Cited
GB1081046A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-03-16 | 1979-09-15 | 1980-03-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-16 | 1983-09-15 | 1984-03-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-16 | 1987-09-15 | 1988-03-16 | $7700.00 | Window Closed / Lapsed |